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Schwartbeck B, Rumpf CH, Hait RJ, Janssen T, Deiwick S, Schwierzeck V, Mellmann A, Kahl BC. Various mutations in icaR, the repressor of the icaADBC locus, occur in mucoid Staphylococcus aureus isolates recovered from the airways of people with cystic fibrosis. Microbes Infect 2024; 26:105306. [PMID: 38316375 DOI: 10.1016/j.micinf.2024.105306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/16/2024] [Accepted: 01/29/2024] [Indexed: 02/07/2024]
Abstract
Staphylococcus aureus is one of the major pathogens isolated from the airways of people with cystic fibrosis (pwCF). Recently, we described a mucoid S. aureus phenotype from respiratory specimens of pwCF, which constitutively overproduced biofilm that consisted of polysaccharide intercellular adhesin (PIA) due to a 5bp-deletion (5bp-del) in the intergenic region of the intercellular adhesin (ica) locus. Since we were not able to identify the 5bp-del in mucoid isolates of two pwCF with long-term S. aureus persistence and in a number of mucoid isolates of pwCF from a prospective multicenter study, these strains were (i) characterized phenotypically, (ii) investigated for biofilm formation, and (iii) molecular typed by spa-sequence typing. To screen for mutations responsible for mucoidy, the ica operon of all mucoid isolates was analyzed by Sanger sequencing. Whole genome sequencing was performed for selected isolates. For all mucoid isolates without the 5 bp-del, various mutations in icaR, which is the transcriptional repressor of the icaADBC operon. Mucoid and non-mucoid strains belonged to the same spa-type. Transformation of PIA-overproducing S. aureus with a vector expressing the intact icaR gene restored the non-mucoid phenotype. Altogether, we demonstrated a new mechanism for the emergence of mucoid S. aureus isolates of pwCF.
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Affiliation(s)
- Bianca Schwartbeck
- Institute of Medical Microbiology, University Hospital Muenster, Germany
| | - Christine H Rumpf
- Institute of Medical Microbiology, University Hospital Muenster, Germany
| | | | - Timo Janssen
- Institute of Medical Microbiology, University Hospital Muenster, Germany
| | - Susanne Deiwick
- Institute of Medical Microbiology, University Hospital Muenster, Germany
| | | | | | - Barbara C Kahl
- Institute of Medical Microbiology, University Hospital Muenster, Germany.
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2
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Goormaghtigh F, Van Bambeke F. Understanding Staphylococcus aureus internalisation and induction of antimicrobial tolerance. Expert Rev Anti Infect Ther 2024; 22:87-101. [PMID: 38180805 DOI: 10.1080/14787210.2024.2303018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 01/04/2024] [Indexed: 01/07/2024]
Abstract
INTRODUCTION Staphylococcus aureus, a human commensal, is also one of the most common and serious pathogens for humans. In recent years, its capacity to survive and replicate in phagocytic and non-phagocytic cells has been largely demonstrated. In these intracellular niches, bacteria are shielded from the immune response and antibiotics, turning host cells into long-term infectious reservoirs. Moreover, neutrophils carry intracellular bacteria in the bloodstream, leading to systemic spreading of the disease. Despite the serious threat posed by intracellular S. aureus to human health, the molecular mechanisms behind its intracellular survival and subsequent antibiotic treatment failure remain elusive. AREA COVERED We give an overview of the killing mechanisms of phagocytes and of the impressive arsenal of virulence factors, toxins and stress responses deployed by S. aureus as a response. We then discuss the different barriers to antibiotic activity in this intracellular niche and finally describe innovative strategies to target intracellular persisting reservoirs. EXPERT OPINION Intracellular niches represent a challenge in terms of diagnostic and treatment. Further research using ad-hoc in-vivo models and single cell approaches are needed to better understand the molecular mechanisms underlying intracellular survival and tolerance to antibiotics in order to identify strategies to eliminate these persistent bacteria.
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Affiliation(s)
- Frédéric Goormaghtigh
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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3
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Becker K. Detection, Identification and Diagnostic Characterization of the Staphylococcal Small Colony-Variant (SCV) Phenotype. Antibiotics (Basel) 2023; 12:1446. [PMID: 37760742 PMCID: PMC10525764 DOI: 10.3390/antibiotics12091446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
While modern molecular methods have decisively accelerated and improved microbiological diagnostics, phenotypic variants still pose a challenge for their detection, identification and characterization. This particularly applies if they are unstable and hard to detect, which is the case for the small-colony-variant (SCV) phenotype formed by staphylococci. On solid agar media, staphylococcal SCVs are characterized by tiny colonies with deviant colony morphology. Their reduced growth rate and fundamental metabolic changes are the result of their adaptation to an intracellular lifestyle, regularly leading to specific auxotrophies, such as for menadione, hemin or thymidine. These alterations make SCVs difficult to recognize and render physiological, biochemical and other growth-based methods such as antimicrobial susceptibility testing unreliable or unusable. Therefore, diagnostic procedures require prolonged incubation times and, if possible, confirmation by molecular methods. A special approach is needed for auxotrophy testing. However, standardized protocols for SCV diagnostics are missing. If available, SCVs and their putative parental isolates should be genotyped to determine clonality. Since their detection has significant implications for the treatment of the infection, which is usually chronic and relapsing, SCV findings should be specifically reported, commented on, and managed in close collaboration with the microbiological laboratory and the involved clinicians.
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Affiliation(s)
- Karsten Becker
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße 1, 17489 Greifswald, Germany
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4
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Ryan H, Ballard E, Stockwell RE, Duplancic C, Thomson RM, Smith K, Bell SC. A systematic review of the clinical impact of small colony variants in patients with cystic fibrosis. BMC Pulm Med 2023; 23:323. [PMID: 37658311 PMCID: PMC10474644 DOI: 10.1186/s12890-023-02611-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 08/24/2023] [Indexed: 09/03/2023] Open
Abstract
BACKGROUND Cystic fibrosis (CF) is a life-limiting disorder that is characterised by respiratory tract inflammation that is mediated by a range of microbial pathogens. Small colony variants (SCVs) of common respiratory pathogens are being increasingly recognised in CF. The aim of this systematic review is to investigate the prevalence of SCVs, clinical characteristics and health outcomes for patients with CF, and laboratory diagnostic features of SCVs compared to non-small colony variants (NCVs) for a range of Gram-positive and Gram-negative respiratory pathogens. METHODS A literature search was conducted (PubMed, Web of Science, Embase and Scopus) in April 2020 to identify articles of interest. Data pertaining to demographic characteristics of participants, diagnostic criteria of SCVs, SCV prevalence and impact on lung function were extracted from included studies for analysis. RESULTS Twenty-five of 673 studies were included in the systematic review. Individuals infected with SCVs of Staphylococcus aureus (S. aureus) were more likely to have had prior use of the broad-spectrum antibiotic trimethoprim sulfamethoxazole (p < 0.001), and the prevalence of SCVs in patients infected with S. aureus was estimated to be 19.3% (95% CI: 13.5% to 25.9%). Additionally, patients infected with SCVs of Gram-negative and Gram-positive pathogens were identified to have a lower forced expiratory volume in one second percentage predicted (-16.8, 95% CI: -23.2 to -10.4) than those infected by NCVs. Gram-positive SCVs were commonly described as small and non-haemolytic, grown on Mannitol salt or blood agar for 24 h at 35°C and confirmed using tube coagulase testing. CONCLUSION The findings of this systematic review demonstrate that SCVs of S. aureus have a high prevalence in the CF community, and that the occurrence of SCVs in Gram-positive and Gram-negative pathogens is linked to poorer respiratory function. Further investigation is necessary to determine the effect of infection by SCVs on the CF population.
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Affiliation(s)
- Harrigan Ryan
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Emma Ballard
- Statistics Unit, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Rebecca E Stockwell
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, QLD, Australia
| | - Christine Duplancic
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Rachel M Thomson
- Respiratory Research Group, Gallipoli Medical Research Foundation, Greenslopes, QLD, Australia
| | - Kimberley Smith
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Scott C Bell
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia.
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, QLD, Australia.
- Translational Research Institute, Woolloongabba, QLD, Australia.
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5
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Oliveira M, Cunha E, Tavares L, Serrano I. P. aeruginosa interactions with other microbes in biofilms during co-infection. AIMS Microbiol 2023; 9:612-646. [PMID: 38173971 PMCID: PMC10758579 DOI: 10.3934/microbiol.2023032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/10/2023] [Accepted: 07/26/2023] [Indexed: 01/05/2024] Open
Abstract
This review addresses the topic of biofilms, including their development and the interaction between different counterparts. There is evidence that various diseases, such as cystic fibrosis, otitis media, diabetic foot wound infections, and certain cancers, are promoted and aggravated by the presence of polymicrobial biofilms. Biofilms are composed by heterogeneous communities of microorganisms protected by a matrix of polysaccharides. The different types of interactions between microorganisms gives rise to an increased resistance to antimicrobials and to the host's defense mechanisms, with the consequent worsening of disease symptoms. Therefore, infections caused by polymicrobial biofilms affecting different human organs and systems will be discussed, as well as the role of the interactions between the gram-negative bacteria Pseudomonas aeruginosa, which is at the base of major polymicrobial infections, and other bacteria, fungi, and viruses in the establishment of human infections and diseases. Considering that polymicrobial biofilms are key to bacterial pathogenicity, it is fundamental to evaluate which microbes are involved in a certain disease to convey an appropriate and efficacious antimicrobial therapy.
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Affiliation(s)
- Manuela Oliveira
- CIISA—Center for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisboa, Portugal
| | - Eva Cunha
- CIISA—Center for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisboa, Portugal
| | - Luís Tavares
- CIISA—Center for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisboa, Portugal
| | - Isa Serrano
- CIISA—Center for Interdisciplinary Research in Animal Health, Faculty of Veterinary Medicine, University of Lisbon, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- Associate Laboratory for Animal and Veterinary Sciences (AL4AnimalS), 1300-477 Lisboa, Portugal
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6
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Thornton CS, Parkins MD. Microbial Epidemiology of the Cystic Fibrosis Airways: Past, Present, and Future. Semin Respir Crit Care Med 2023; 44:269-286. [PMID: 36623820 DOI: 10.1055/s-0042-1758732] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Progressive obstructive lung disease secondary to chronic airway infection, coupled with impaired host immunity, is the leading cause of morbidity and mortality in cystic fibrosis (CF). Classical pathogens found in the airways of persons with CF (pwCF) include Pseudomonas aeruginosa, Staphylococcus aureus, the Burkholderia cepacia complex, Achromobacter species, and Haemophilus influenzae. While traditional respiratory-tract surveillance culturing has focused on this limited range of pathogens, the use of both comprehensive culture and culture-independent molecular approaches have demonstrated complex highly personalized microbial communities. Loss of bacterial community diversity and richness, counteracted with relative increases in dominant taxa by traditional CF pathogens such as Burkholderia or Pseudomonas, have long been considered the hallmark of disease progression. Acquisition of these classic pathogens is viewed as a harbinger of advanced disease and postulated to be driven in part by recurrent and frequent antibiotic exposure driven by frequent acute pulmonary exacerbations. Recently, CF transmembrane conductance regulator (CFTR) modulators, small molecules designed to potentiate or restore diminished protein levels/function, have been successfully developed and have profoundly influenced disease course. Despite the multitude of clinical benefits, structural lung damage and consequent chronic airway infection persist in pwCF. In this article, we review the microbial epidemiology of pwCF, focus on our evolving understanding of these infections in the era of modulators, and identify future challenges in infection surveillance and clinical management.
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Affiliation(s)
- Christina S Thornton
- Department of Medicine, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Michael D Parkins
- Department of Medicine, Cumming School of Medicine, University of Calgary, Alberta, Canada.,Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Alberta, Canada
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7
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Jin Q, Xie X, Zhai Y, Zhang H. Mechanisms of folate metabolism-related substances affecting Staphylococcus aureus infection. Int J Med Microbiol 2023; 313:151577. [PMID: 36841056 DOI: 10.1016/j.ijmm.2023.151577] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 01/28/2023] [Accepted: 02/15/2023] [Indexed: 02/18/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is one of the critical clinical pathogens which can cause multiple diseases ranging from skin infections to fatal sepsis. S. aureus is generally considered to be an extracellular pathogen. However, more and more evidence has shown that S. aureus can survive inside various cells. Folate plays an essential role in multiple life activities, including the conversion of serine and glycine, the remethylation of homocysteine to methionine, and the de novo synthesis of purine /dTMP, et al. More and more studies reported that S. aureus intracellular infection requires the involvement of folate metabolism. This review focused on the mechanisms of folate metabolism and related substances affecting S. aureus infection. Loss of tetrahydrofolic acid (THF)-dependent dTMP directly inhibits the nucleotide synthesis pathway of the S. aureus due to pabA deficiency. Besides, trimethoprim-sulfamethoxazole (TMP/SMX), a potent antibiotic that treats S. aureus infections, interferes in the process of the folate mechanism and leads to the production of thymidine-dependent small-colony variants (TD-SCVs). In addition, S. aureus is resistant to lysostaphin in the presence of serine hydroxymethyltransferase (SHMT). We provide new insights for understanding the molecular pathogenesis of S. aureus infection.
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Affiliation(s)
- Qiyuan Jin
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Xiaolu Xie
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Yaxuan Zhai
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Haifang Zhang
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China.
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8
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Keim KC, George IK, Reynolds L, Smith AC. The Clinical Significance of Staphylococcus aureus Small Colony Variants. Lab Med 2022; 54:227-234. [PMID: 36226897 DOI: 10.1093/labmed/lmac101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Abstract
A burdensome, atypical phenotype of Staphylococcus aureus (SA) called S aureus small colony variant (SA-SCV) has been identified, which is induced as a result of a combination of environmental stressors, including polymicrobial interactions. The SA-SCVs exhibit altered phenotypes as a result of metabolic dormancy caused by electron transport deficiency, leading to increased biofilm production and alterations to antimicrobial susceptibility. The SA-SCVs typically exhibit altered colony morphology and biochemical reactions compared with wild-type SA, making them difficult to detect via routine diagnostics. The SA-SCVs have been found to contribute to chronic or recurrent infections, including skin and soft-tissue infections, foreign-body associated infection, cystic fibrosis, and sepsis. There is evidence that SA-SCVs contribute to patient morbidity and mortality as a result of diagnostic difficulties and limited treatment options. New detection methods may need to be developed that can be incorporated into routine diagnostics, which would allow for better assessment of specimens and introduce new considerations for treatment.
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Affiliation(s)
- Klara C Keim
- Department of Immunology and Microbiology, School of Medicine, Anschutz Medical Campus, University of Colorado , Aurora, CO , USA
| | - Isaiah K George
- Department of Honors Studies, Texas Tech University , Lubbock, TX , USA
| | - Landrye Reynolds
- Department of Honors Studies, Texas Tech University , Lubbock, TX , USA
| | - Allie C Smith
- Department of Honors Studies, Texas Tech University , Lubbock, TX , USA
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9
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Acute Infection with a Tobramycin-Induced Small Colony Variant of Staphylococcus aureus Causes Increased Inflammation in the Cystic Fibrosis Rat Lung. Infect Immun 2022; 90:e0023722. [PMID: 36165627 PMCID: PMC9671023 DOI: 10.1128/iai.00237-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cystic fibrosis (CF) disease is characterized by lifelong infections with pathogens such as Staphylococcus aureus, leading to eventual respiratory failure. Small colony variants (SCVs) of S. aureus have been linked to worse clinical outcomes for people with CF. Current studies of SCV pathology in vivo are limited, and it remains unclear whether SCVs directly impact patient outcomes or are a result of late-stage CF disease. To investigate this, we generated a stable menadione-auxotrophic SCV strain by serially passaging a CF isolate of S. aureus with tobramycin, an aminoglycoside antibiotic commonly administered for coinfecting Pseudomonas aeruginosa. This SCV was tobramycin resistant and showed increased tolerance to the anti-staphylococcal combination therapy sulfamethoxazole-trimethoprim. To better understand the dynamics of SCV infections in vivo, we infected CF rats with this strain compared with its normal colony variant (NCV). Analysis of bacterial burden at 3 days postinfection indicated that NCVs and SCVs persisted equally well in the lungs, but SCV infections ultimately led to increased weight loss and neutrophilic inflammation. Additionally, cellular and histopathological analyses showed that in CF rats, SCV infections yielded a lower macrophage response. Overall, these findings indicate that SCV infections may directly contribute to lung disease progression in people with CF.
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10
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LiPuma JJ. The Sense and Nonsense of Antimicrobial Susceptibility Testing in Cystic Fibrosis. J Pediatric Infect Dis Soc 2022; 11:S46-S52. [PMID: 36069902 DOI: 10.1093/jpids/piac040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022]
Abstract
Antimicrobial susceptibility testing (AST) has been used to guide therapy of airway infection in persons with cystic fibrosis (CF) for decades. However, evidence that AST adds benefit to treatment outcomes in CF is lacking. In fact, the routine use of AST has potential to exacerbate inappropriate antibiotic use. Several features of airway infection in CF contribute to the limitations of AST in predicting treatment outcomes, providing rationale for abandoning this practice altogether. Other features of CF infection suggest, however, that select use of AST can provide worthwhile guidance to antibiotic selection.
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Affiliation(s)
- John J LiPuma
- Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, USA
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11
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Cho J, Rigby WFC, Cheung AL. The thematic role of extracellular loop of VraG in activation of the membrane sensor GraS in a cystic fibrosis MRSA strain differs in nuance from the CA-MRSA strain JE2. PLoS One 2022; 17:e0270393. [PMID: 35737676 PMCID: PMC9223312 DOI: 10.1371/journal.pone.0270393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/09/2022] [Indexed: 11/19/2022] Open
Abstract
Patients with cystic fibrosis (CF) often suffer recurrent bronchial bacterial infections that lead to deterioration of lung function over time. The infections in CF patients are often due to S. aureus and P. aeruginosa that colonize the airways. Significantly, methicillin-resistant S. aureus (MRSA) makes it challenging for treatment in CF patients due to its feature of multiple antibiotic resistance. In bronchial airways, cationic antimicrobial peptides are often present in mucosa cells, neutrophils, and macrophages that interfere with bacterial proliferation. The major mechanism for resistance to the bactericidal activity of cationic peptides in S. aureus is mediated by the GraRS two-component system that activates expression of MprF and DltABCD to increase surface positive charge to repel interactions with cationic peptides. We recently found that VraG, a membrane permease component of the VraFG efflux pumps, harbors a long 200-residue extracellular loop (EL) that utilizes K380 to interact with the negatively charged 9-residue extracellular loop of the membrane sensor GraS to control mprF expression in a community-acquired MRSA strain JE2. In this study, we extended this observation to a CF MRSA strain CF32A1 where we affirmed that the EL loop of VraG controls GraS-mediated signal transduction; however, in contrast to community acquired MRSA strain JE2, the CF MRSA strain CF32A1 requires both K380 and K388 in the EL of VraG to properly modulate signal transduction mediated by GraS. This effect was not attributable to the several single nucleotide polymorphisms that exist between VraG and GraS in the two MRSA strains.
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Affiliation(s)
- Junho Cho
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
- * E-mail:
| | - William F. C. Rigby
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
- Department of Medicine, Geisel School of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, United States of America
| | - Ambrose L. Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire, United States of America
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12
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Tang Q, Precit MR, Thomason MK, Blanc SF, Ahmed-Qadri F, McFarland AP, Wolter DJ, Hoffman LR, Woodward JJ. Thymidine starvation promotes c-di-AMP-dependent inflammation during pathogenic bacterial infection. Cell Host Microbe 2022; 30:961-974.e6. [PMID: 35439435 DOI: 10.1016/j.chom.2022.03.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/01/2022] [Accepted: 03/23/2022] [Indexed: 11/03/2022]
Abstract
Antimicrobials can impact bacterial physiology and host immunity with negative treatment outcomes. Extensive exposure to antifolate antibiotics promotes thymidine-dependent Staphylococcus aureus small colony variants (TD-SCVs), commonly associated with worse clinical outcomes. We show that antibiotic-mediated disruption of thymidine synthesis promotes elevated levels of the bacterial second messenger cyclic di-AMP (c-di-AMP), consequently inducing host STING activation and inflammation. An initial antibiotic screen in Firmicutes revealed that c-di-AMP production was largely driven by antifolate antibiotics targeting dihydrofolate reductase (DHFR), which promotes folate regeneration required for thymidine biosynthesis. Additionally, TD-SCVs exhibited excessive c-di-AMP production and STING activation in a thymidine-dependent manner. Murine lung infection with TD-SCVs revealed STING-dependent elevation of proinflammatory cytokines, causing higher airway neutrophil infiltration and activation compared with normal-colony S. aureus and hemin-dependent SCVs. Collectively, our results suggest that thymidine metabolism disruption in Firmicutes leads to elevated c-di-AMP-mediated STING-dependent inflammation, with potential impacts on antibiotic usage and infection outcomes.
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Affiliation(s)
- Qing Tang
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Mimi R Precit
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Maureen K Thomason
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Sophie F Blanc
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Fariha Ahmed-Qadri
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Adelle P McFarland
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA
| | - Daniel J Wolter
- Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Pulmonary and Sleep Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Lucas R Hoffman
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA; Pulmonary and Sleep Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Joshua J Woodward
- Department of Microbiology, University of Washington, Seattle, WA 98105, USA.
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13
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Biswas L, Götz F. Molecular Mechanisms of Staphylococcus and Pseudomonas Interactions in Cystic Fibrosis. Front Cell Infect Microbiol 2022; 11:824042. [PMID: 35071057 PMCID: PMC8770549 DOI: 10.3389/fcimb.2021.824042] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 12/16/2021] [Indexed: 11/15/2022] Open
Abstract
Cystic fibrosis (CF) is an autosomal recessive genetic disorder that is characterized by recurrent and chronic infections of the lung predominantly by the opportunistic pathogens, Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. While S. aureus is the main colonizing bacteria of the CF lungs during infancy and early childhood, its incidence declines thereafter and infections by P. aeruginosa become more prominent with increasing age. The competitive and cooperative interactions exhibited by these two pathogens influence their survival, antibiotic susceptibility, persistence and, consequently the disease progression. For instance, P. aeruginosa secretes small respiratory inhibitors like hydrogen cyanide, pyocyanin and quinoline N-oxides that block the electron transport pathway and suppress the growth of S. aureus. However, S. aureus survives this respiratory attack by adapting to respiration-defective small colony variant (SCV) phenotype. SCVs cause persistent and recurrent infections and are also resistant to antibiotics, especially aminoglycosides, antifolate antibiotics, and to host antimicrobial peptides such as LL-37, human β-defensin (HBD) 2 and HBD3; and lactoferricin B. The interaction between P. aeruginosa and S. aureus is multifaceted. In mucoid P. aeruginosa strains, siderophores and rhamnolipids are downregulated thus enhancing the survival of S. aureus. Conversely, protein A from S. aureus inhibits P. aeruginosa biofilm formation while protecting both P. aeruginosa and S. aureus from phagocytosis by neutrophils. This review attempts to summarize the current understanding of the molecular mechanisms that drive the competitive and cooperative interactions between S. aureus and P. aeruginosa in the CF lungs that could influence the disease outcome.
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Affiliation(s)
- Lalitha Biswas
- Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, India
| | - Friedrich Götz
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Tübingen, Germany
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14
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Guo H, Tong Y, Cheng J, Abbas Z, Li Z, Wang J, Zhou Y, Si D, Zhang R. Biofilm and Small Colony Variants-An Update on Staphylococcus aureus Strategies toward Drug Resistance. Int J Mol Sci 2022; 23:ijms23031241. [PMID: 35163165 PMCID: PMC8835882 DOI: 10.3390/ijms23031241] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.
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Rumpf C, Lange J, Schwartbeck B, Kahl BC. Staphylococcus aureus and Cystic Fibrosis-A Close Relationship. What Can We Learn from Sequencing Studies? Pathogens 2021; 10:pathogens10091177. [PMID: 34578208 PMCID: PMC8466686 DOI: 10.3390/pathogens10091177] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 01/13/2023] Open
Abstract
Staphylococcus aureus is next to Pseudomonas aeruginosa the most isolated pathogen from the airways of cystic fibrosis (CF) patients, who are often infected by a dominant S. aureus clone for extended periods. To be able to persist, the pathogen has to adapt to the hostile niche of the airways to counteract host defence, antibiotic therapy and the competition with coinfecting pathogens. S. aureus is equipped with many virulence factors including adhesins, toxins that are localized on the chromosome, on plasmids or are phage-related. S. aureus is especially versatile and adaptation and evolution of the pathogen occurs by the acquisition of new genes by horizontal gene transfer (HGT), changes in nucleotides (single nucleotide variations, SNVs) that can cause a selective advantage for the bacteria and become fixed in subpopulations. Methicillin-resistant S. aureus are a special threat to CF patients due to the more severe lung disease occurring in infected patients. Today, with decreasing costs for sequencing, more and more studies using S. aureus isolates cultured from CF patients are being published, which use whole genome sequencing (WGS), multilocus sequence typing (MLST) or spa-sequence typing (spa-typing) to follow the population dynamics of S. aureus, elucidate the underlying mechanisms of phenotypic variants, newly acquired resistance or adaptation to the host response in this particular niche. In the first part of this review, an introduction to the genetic make-up and the pathogenesis of S. aureus with respect to CF is provided. The second part presents an overview of recent studies and their findings using genotypic methods such as single or multilocus sequencing and whole genome sequencing, which identify factors contributing to the adaptation of S. aureus and its evolution in the airways of individuals with CF.
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Sweeney E, Harrington NE, Harley Henriques AG, Hassan MM, Crealock-Ashurst B, Smyth AR, Hurley MN, Tormo-Mas MÁ, Harrison F. An ex vivo cystic fibrosis model recapitulates key clinical aspects of chronic Staphylococcus aureus infection. MICROBIOLOGY-SGM 2021; 167. [PMID: 33186093 DOI: 10.1099/mic.0.000987] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Staphylococcus aureus is the most prevalent organism isolated from the airways of people with cystic fibrosis (CF), predominantly early in life. Yet its role in the pathology of lung disease is poorly understood. In mice, and many experiments using cell lines, the bacterium invades cells or interstitium, and forms abscesses. This is at odds with the limited available clinical data: interstitial bacteria are rare in CF biopsies and abscesses are highly unusual. Bacteria instead appear to localize in mucus plugs in the lumens of bronchioles. We show that, in an established ex vivo model of CF infection comprising porcine bronchiolar tissue and synthetic mucus, S. aureus demonstrates clinically significant characteristics including colonization of the airway lumen, with preferential localization as multicellular aggregates in mucus, initiation of a small colony variant phenotype and increased antibiotic tolerance of tissue-associated aggregates. Tissue invasion and abscesses were not observed. Our results may inform ongoing debates relating to clinical responses to S. aureus in people with CF.
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Affiliation(s)
- Esther Sweeney
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | | | | | - Marwa M Hassan
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.,Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | | | - Alan R Smyth
- Division of Child Health, Obstetrics and Gynecology, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Matthew N Hurley
- Paediatric Respiratory Medicine, Nottingham Children's Hospital, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - María Ángeles Tormo-Mas
- Instituto de Investigación Sanitaria La Fe, Avenida Fernando Abril Martorell, 106 Torre A Lab. 6.13, 46026 Valencia, Spain
| | - Freya Harrison
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
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Emergence of Thymidine-Dependent Staphylococcus aureus Small-Colony Variants in Cystic Fibrosis Patients in Southern Brazil. Microbiol Spectr 2021; 9:e0061421. [PMID: 34319160 PMCID: PMC8552798 DOI: 10.1128/spectrum.00614-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We characterized Staphylococcus aureus small-colony variant (SCV) strains isolated from cystic fibrosis (CF) patients in southern Brazil. Smaller colonies of S. aureus were isolated from respiratory samples collected consecutively from 225 CF patients from July 2013 to November 2016. Two phenotypic methods—the auxotrophic classification and a modified method of antimicrobial susceptibility testing—were employed. PCR was conducted to detect the mecA, ermA, ermB, ermC, msrA, and msrB resistance genes. Furthermore, DNA sequencing was performed to determine the mutations in the thyA gene, and multilocus sequence typing was used to identify the genetic relatedness. S. aureus strains were isolated from 186 patients (82%); suggestive colonies of SCVs were obtained in 16 patients (8.6%). The clones CC1 (ST1, ST188, and ST2383), CC5 (ST5 and ST221), and ST398 were identified. Among SCVs, antimicrobial susceptibility testing showed that 77.7% of the isolates were resistant to multiple drugs, and all of them were susceptible to vancomycin. mecA (2), ermA (1), ermB (1), ermC (3), and msrB (18) were distributed among the isolates. Phenotypically thymidine-dependent isolates had different mutations in the thyA gene, and frameshift mutations were frequently observed. Of note, revertants showed nonconservative or conservative missense mutations. SCVs are rarely identified in routine laboratory tests. IMPORTANCE Similar findings have not yet been reported in Brazil, emphasizing the importance of monitoring small-colony variants (SCVs). Altogether, our results highlight the need to improve detection methods and review antimicrobial therapy protocols in cystic fibrosis (CF) patients.
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Liu J, Shen Z, Tang J, Huang Q, Jian Y, Liu Y, Wang Y, Ma X, Liu Q, He L, Li M. Extracellular DNA released by glycine-auxotrophic Staphylococcus epidermidis small colony variant facilitates catheter-related infections. Commun Biol 2021; 4:904. [PMID: 34294851 PMCID: PMC8298460 DOI: 10.1038/s42003-021-02423-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
Though a definitive link between small colony variants (SCVs) and implant-related staphylococcal infections has been well-established, the specific underlying mechanism remains an ill-explored field. The present study analyzes the role SCVs play in catheter infection by performing genomic and metabolic analyses, as well as analyzing biofilm formation and impacts of glycine on growth and peptidoglycan-linking rate, on a clinically typical Staphylococcus epidermidis case harboring stable SCV, normal counterpart (NC) and nonstable SCV. Our findings reveal that S. epidermidis stable SCV carries mutations involved in various metabolic processes. Metabolome analyses demonstrate that two biosynthetic pathways are apparently disturbed in SCV. One is glycine biosynthesis, which contributes to remarkable glycine shortage, and supplementation of glycine restores growth and peptidoglycan-linking rate of SCV. The other is overflow of pyruvic acid and acetyl-CoA, leading to excessive acetate. SCV demonstrates higher biofilm-forming ability due to rapid autolysis and subsequent eDNA release. Despite a remarkable decline in cell viability, SCV can facilitate in vitro biofilm formation and in vivo survival of NC when co-infected with its normal counterparts. This work illustrates an intriguing strategy utilized by a glycine-auxotrophic clinical S. epidermidis SCV isolate to facilitate biofilm-related infections, and casts a new light on the role of SCV in persistent infections.
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Affiliation(s)
- Junlan Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Zhen Shen
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Jin Tang
- Department of Laboratory Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Qian Huang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Ying Jian
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Yao Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Yanan Wang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Xiaowei Ma
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Qian Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Lei He
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.
| | - Min Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China. .,Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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Scoffone VC, Trespidi G, Barbieri G, Irudal S, Perrin E, Buroni S. Role of RND Efflux Pumps in Drug Resistance of Cystic Fibrosis Pathogens. Antibiotics (Basel) 2021; 10:863. [PMID: 34356783 PMCID: PMC8300704 DOI: 10.3390/antibiotics10070863] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 01/21/2023] Open
Abstract
Drug resistance represents a great concern among people with cystic fibrosis (CF), due to the recurrent and prolonged antibiotic therapy they should often undergo. Among Multi Drug Resistance (MDR) determinants, Resistance-Nodulation-cell Division (RND) efflux pumps have been reported as the main contributors, due to their ability to extrude a wide variety of molecules out of the bacterial cell. In this review, we summarize the principal RND efflux pump families described in CF pathogens, focusing on the main Gram-negative bacterial species (Pseudomonas aeruginosa, Burkholderia cenocepacia, Achromobacter xylosoxidans, Stenotrophomonas maltophilia) for which a predominant role of RND pumps has been associated to MDR phenotypes.
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Affiliation(s)
- Viola Camilla Scoffone
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.C.S.); (G.T.); (G.B.); (S.I.)
| | - Gabriele Trespidi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.C.S.); (G.T.); (G.B.); (S.I.)
| | - Giulia Barbieri
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.C.S.); (G.T.); (G.B.); (S.I.)
| | - Samuele Irudal
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.C.S.); (G.T.); (G.B.); (S.I.)
| | - Elena Perrin
- Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Silvia Buroni
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, 27100 Pavia, Italy; (V.C.S.); (G.T.); (G.B.); (S.I.)
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Bashir G, Bhat JI, Mohammad S, Fomda BA, Bali NK, Altaf I. Airway Microbiology in Children with Cystic Fibrosis: A Prospective Cohort Study from Northern India. J Trop Pediatr 2021; 67:6294507. [PMID: 34100087 DOI: 10.1093/tropej/fmab030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE The objective of this study is to find the organism profile and antimicrobial susceptibility patterns in children with cystic fibrosis (CF). DESIGN Prospective cohort study. SETTING Hospital-based study. INTERVENTION Sputum cultures/throat swabs were collected from the study population. Relevant details like anthropometry, systemic examination findings and investigations were entered in a pre-designed format. Sputum culture was subjected to microbiological analysis at the hospital microbiology laboratory. MAIN OUTCOME MEASURE Prevalence of positive sputum/cough swab culture in CF patients, their organism profile and antibiotic sensitivity. RESULTS A total of 63 patients were enrolled in the study. A total of 136 organisms were grown in our study population. Thirteen different organisms were isolated, which included five gram-positive bacteria, six gram-negative bacteria, eight Candida spp. and one filamentous. Antibiotic sensitivity profile of the Pseudomonas aeruginosa showed excellent sensitivity to all the aminoglycosides, piperacillin-tazobacteum and polymixin, similarly methicillin-sensitive Staphylococcus aureus, methicillin-resistant S. aureus and Enterococcus spp. were uniformly sensitive to vancomycin, linezolid and teicoplanin. Fungal isolates showed 100% sensitivity to all the antifungals tested including azoles and amphotericin B. CONCLUSION We observed 61% of culture positivity for different organisms in our study. Staphylococcus aureus and P. aeruginosa were the most frequently isolated organisms. Pseudomonas aeruginosa isolates were largely sensitive to aminoglycosides, carbapenems and polymixin. We found an unusually higher incidence of enterococcal infection in our study cohort with few vancomycin-resistant isolates.
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Affiliation(s)
- Gulnaz Bashir
- Department of Microbiology, SKIMS, Soura, Jammu and Kashmir 190011, India
| | - Javeed Iqbal Bhat
- Department of Pediatrics, SKIMS, Soura, Jammu and Kashmir 190011, India
| | - Sozia Mohammad
- Department of Microbiology, SKIMS, Soura, Jammu and Kashmir 190011, India
| | - Bashir Ahmad Fomda
- Department of Microbiology, SKIMS, Soura, Jammu and Kashmir 190011, India
| | - Nargis K Bali
- Department of Microbiology, SKIMS, Soura, Jammu and Kashmir 190011, India
| | - Insha Altaf
- Department of Microbiology, SKIMS, Soura, Jammu and Kashmir 190011, India
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Roch M, Varela MC, Taglialegna A, Rosato AE. Tedizolid is a promising antimicrobial option for the treatment of Staphylococcus aureus infections in cystic fibrosis patients. J Antimicrob Chemother 2021; 75:126-134. [PMID: 31617901 DOI: 10.1093/jac/dkz418] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 09/07/2019] [Accepted: 09/09/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Tedizolid is a protein synthesis inhibitor in clinical use for the treatment of Gram-positive infections. Pulmonary MRSA infections are a growing problem in patients with cystic fibrosis (CF) and the efficacy of tedizolid-based therapy in CF pulmonary infections is unknown. OBJECTIVES To evaluate the in vitro and in vivo activity of tedizolid and predict the likelihood of tedizolid resistance selection in CF-background Staphylococcus aureus strains. METHODS A collection of 330 S. aureus strains (from adult and paediatric patients), either of normal or small colony variant (SCV) phenotypes, gathered at three CF centres in the USA was used. Tedizolid activity was assessed by broth microdilution, Etest and time-kill analysis. In vivo tedizolid efficacy was tested in a murine pneumonia model. Tedizolid in vitro mutants were obtained by 40 days of exposure and progressive passages. Whole genome sequencing of clinical S. aureus strains with reduced susceptibility to tedizolid was performed. RESULTS MRSA strain MIC90s were tedizolid 0.12-0.25 mg/L and linezolid 1-2 mg/L; for MSSA strains, MIC90s were tedizolid 0.12 mg/L and linezolid 1-2 mg/L. Two strains, WIS 441 and Seattle 106, with tedizolid MICs of 2 mg/L and 1 mg/L, respectively, had MICs above the FDA tedizolid breakpoint (0.5 mg/L). Tedizolid at free serum concentrations exhibited a bacteriostatic effect. Mean bacterial burdens in lungs (log10 cfu/g) for WIS 423-infected mice were: control, 11.2±0.5; tedizolid-treated (10 mg/kg), 3.40±1.87; linezolid-treated (40 mg/kg), 4.51±2.1; and vancomycin-treated (30 mg/kg), 5.21±1.93. For WIS 441-infected mice the (log10 cfu/g) values were: control, 9.66±0.8; tedizolid-treated, 3.18±1.35; linezolid-treated 5.94±2.19; and vancomycin-treated, 4.35±1.7. CONCLUSIONS These results suggest that tedizolid represents a promising therapeutic option for the treatment of CF-associated MRSA/MSSA infections, having potent in vivo activity and low resistance potential.
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Affiliation(s)
- Melanie Roch
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Maria Celeste Varela
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Agustina Taglialegna
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Adriana E Rosato
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
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Herrin BE, Islam S, Rentschler KN, Pert LH, Kopanski SP, Wakeman CA. Haem toxicity provides a competitive advantage to the clinically relevant Staphylococcus aureus small colony variant phenotype. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001044. [PMID: 33749578 PMCID: PMC8289220 DOI: 10.1099/mic.0.001044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Microorganisms encounter toxicities inside the host. Many pathogens exist as subpopulations to maximize survivability. Subpopulations of Staphylococcus aureus include antibiotic-tolerant small colony variants (SCVs). These mutants often emerge following antibiotic treatment but can be present in infections prior to antibiotic exposure. We hypothesize that haem toxicity in the host selects for respiration-deficient S. aureus SCVs in the absence of antibiotics. We demonstrate that some but not all respiration-deficient SCV phenotypes are more protective than the haem detoxification system against transient haem exposure, indicating that haem toxicity in the host may contribute to the dominance of menaquinone-deficient and haem-deficient SCVs prior to antibiotic treatment.
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Affiliation(s)
- Brittany E. Herrin
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
- Present address: Department of Biology, Indiana University, Bloomington, IN, USA
| | - Shariful Islam
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | | | - Lauren H. Pert
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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Sato T, Uno T, Kawamura M, Fujimura S. In vitro Tolerability of Biofilm-Forming Trimethoprim-/Sulfamethoxazole-Resistant Small Colony Variants of Staphylococcus aureus Against Various Antimicrobial Agents. Microb Drug Resist 2021; 27:1282-1289. [PMID: 33689487 DOI: 10.1089/mdr.2020.0379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Trimethoprim-/sulfamethoxazole-resistant small colony variants (SCVs) of Staphylococcus aureus, which are selected by use of trimethoprim/sulfamethoxazole, are involved in intractable biofilm-forming infection. This study aimed to determine the biofilm formation ability in trimethoprim-/sulfamethoxazole-resistant SCVs of S. aureus and investigate the bactericidal activity of differential antimicrobial agents to its biofilm-forming S. aureus. Between 32 S. aureus wild type (WT) and 32 SCVs selected from its WT, the amount of formed biofilm was compared. Vancomycin, daptomycin, rifampicin, and minocycline were exposed to biofilm-forming S. aureus to determine viable bacterial counts and its susceptibility. The biofilm-producing quantify of SCVs was approximately twice that formed by its WT. Vancomycin and daptomycin reduce 4 logs the bacterial counts of biofilm-forming WT at 24 hours, but did not affect SCVs. Rifampicin and minocycline considerably decreased both WT and SCVs; however, both bacterial counts recovered to an initial number 48 hours later. These survival strains showed resistance to each drug, and rpoB mutation or tet38 mRNA overexpression was confirmed.
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Affiliation(s)
- Takumi Sato
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Takashi Uno
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Masato Kawamura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Shigeru Fujimura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, Sendai, Japan
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Virulence alterations in staphylococcus aureus upon treatment with the sub-inhibitory concentrations of antibiotics. J Adv Res 2021; 31:165-175. [PMID: 34194840 PMCID: PMC8240104 DOI: 10.1016/j.jare.2021.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/09/2021] [Accepted: 01/12/2021] [Indexed: 12/24/2022] Open
Abstract
Background The treatment of patients with Staphylococcus aureus infections mainly relies on antistaphylococcal regimens that are established with effective antibiotics. In antibiotic therapy or while living in nature, pathogens often face the sub-inhibitory concentrations (sub-MICs) of antibiotics due to drug pharmacokinetics, diffusion barriers, waste emission, resistant organism formation, and farming application. Different categories of antibiotics at sub-MICs have diverse effects on the physiological and chemical properties of microorganisms. These effects can result in virulence alterations. However, the mechanisms underlying the actions of antibiotics at sub-MICs on S. aureus virulence are obscure. Aim of review In this review, we focus on the effects of sub-MICs of antibiotics on S. aureus virulence from the aspects of cell morphological change, virulence factor expression, bacterial adherence and invasion, staphylococcal biofilm formation, and small-colony variant (SCV) production. The possible mechanisms of antibiotic-induced S. aureus virulence alterations are also addressed. Key scientific concepts of review Five main aspects of bacterial virulence can be changed in S. aureus exposure to the sub-MIC levels of antibiotics, resulting in deformed bacterial cells to stimulate abnormal host immune responses, abnormally expressed virulence factors to alter disease development, changed bacterial adhesion and invasion abilities to affect colonization and diffusion, altered biofilm formation to potentate material-related infections, and increased SCV formation to achieve persistent infection and recurrence. These advanced findings expand our knowledge to rethink the molecular signaling roles of antibiotics beyond their actions as antimicrobial agents.
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25
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Huemer M, Mairpady Shambat S, Brugger SD, Zinkernagel AS. Antibiotic resistance and persistence-Implications for human health and treatment perspectives. EMBO Rep 2020; 21:e51034. [PMID: 33400359 PMCID: PMC7726816 DOI: 10.15252/embr.202051034] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/13/2020] [Accepted: 11/02/2020] [Indexed: 12/24/2022] Open
Abstract
Antimicrobial resistance (AMR) and persistence are associated with an elevated risk of treatment failure and relapsing infections. They are thus important drivers of increased morbidity and mortality rates resulting in growing healthcare costs. Antibiotic resistance is readily identifiable with standard microbiological assays, and the threat imposed by antibiotic resistance has been well recognized. Measures aiming to reduce resistance development and spreading of resistant bacteria are being enforced. However, the phenomenon of bacteria surviving antibiotic exposure despite being fully susceptible, so-called antibiotic persistence, is still largely underestimated. In contrast to antibiotic resistance, antibiotic persistence is difficult to measure and therefore often missed, potentially leading to treatment failures. In this review, we focus on bacterial mechanisms allowing evasion of antibiotic killing and discuss their implications on human health. We describe the relationship between antibiotic persistence and bacterial heterogeneity and discuss recent studies that link bacterial persistence and tolerance with the evolution of antibiotic resistance. Finally, we review persister detection methods, novel strategies aiming at eradicating bacterial persisters and the latest advances in the development of new antibiotics.
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Affiliation(s)
- Markus Huemer
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Silvio D Brugger
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
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Varela MC, Roch M, Taglialegna A, Long SW, Saavedra MO, Rose WE, Davis JJ, Hoffman LR, Hernandez RE, Rosato RR, Rosato AE. Carbapenems drive the collateral resistance to ceftaroline in cystic fibrosis patients with MRSA. Commun Biol 2020; 3:599. [PMID: 33093601 PMCID: PMC7582194 DOI: 10.1038/s42003-020-01313-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 07/30/2020] [Indexed: 01/14/2023] Open
Abstract
Chronic airways infection with methicillin-resistant Staphylococcus aureus (MRSA) is associated with worse respiratory disease cystic fibrosis (CF) patients. Ceftaroline is a cephalosporin that inhibits the penicillin-binding protein (PBP2a) uniquely produced by MRSA. We analyzed 335 S. aureus isolates from CF sputum samples collected at three US centers between 2015-2018. Molecular relationships demonstrated that high-level resistance of preceding isolates to carbapenems were associated with subsequent isolation of ceftaroline resistant CF MRSA. In vitro evolution experiments showed that pre-exposure of CF MRSA to meropenem with further selection with ceftaroline implied mutations in mecA and additional mutations in pbp1 and pbp2, targets of carbapenems; no effects were achieved by other β-lactams. An in vivo pneumonia mouse model showed the potential therapeutic efficacy of ceftaroline/meropenem combination against ceftaroline-resistant CF MRSA infections. Thus, the present findings highlight risk factors and potential therapeutic strategies offering an opportunity to both prevent and address antibiotic resistance in this patient population.
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Affiliation(s)
- Maria Celeste Varela
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Melanie Roch
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Agustina Taglialegna
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Scott W Long
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Matthew Ojeda Saavedra
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA
| | - Warren E Rose
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - James J Davis
- Argonne National Laboratory (DOE), Lemont, IL, USA
- Computation Institute, University of Chicago, Chicago, IL, USA
| | - Lucas R Hoffman
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA
- Center for Clinical and Translational Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Rafael E Hernandez
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA
- Center for Clinical and Translational Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Roberto R Rosato
- Houston Methodist Cancer Center, Houston Methodist Hospital, Houston, USA
| | - Adriana E Rosato
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, USA.
- Riverside University Health System-Medical Center, 26520 Cactus Avenue, Moreno Valley, CA, 92555, USA.
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27
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Miller LS, Fowler VG, Shukla SK, Rose WE, Proctor RA. Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms. FEMS Microbiol Rev 2020; 44:123-153. [PMID: 31841134 PMCID: PMC7053580 DOI: 10.1093/femsre/fuz030] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/13/2019] [Indexed: 12/12/2022] Open
Abstract
Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.
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Affiliation(s)
- Lloyd S Miller
- Immunology, Janssen Research and Development, 1400 McKean Road, Spring House, PA, 19477, USA.,Department of Dermatology, Johns Hopkins University School of Medicine, 1550 Orleans Street, Cancer Research Building 2, Suite 209, Baltimore, MD, 21231, USA.,Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine, 1830 East Monument Street, Baltimore, MD, 21287, USA.,Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, 601 North Caroline Street, Baltimore, MD, 21287, USA.,Department of Materials Science and Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA
| | - Vance G Fowler
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, 315 Trent Drive, Hanes House, Durham, NC, 27710, USA.,Duke Clinical Research Institute, Duke University Medical Center, 40 Duke Medicine Circle, Durham, NC, 27710, USA
| | - Sanjay K Shukla
- Center for Precision Medicine Research, Marshfield Clinic Research Institute, 1000 North Oak Avenue, Marshfield, WI, 54449, USA.,Computation and Informatics in Biology and Medicine, University of Wisconsin, 425 Henry Mall, Room 3445, Madison, WI, 53706, USA
| | - Warren E Rose
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI, 53705, USA.,Pharmacy Practice Division, University of Wisconsin-Madison, 777 Highland Avenue, 4123 Rennebohm Hall, Madison, WI, 53705 USA
| | - Richard A Proctor
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI, 53705, USA.,Department of Medical Microbiology and Immunology, University of Wisconsin-Madison School of Medicine and Public Health, 1550 Linden Drive, Microbial Sciences Building, Room 1334, Madison, WI, 53705, USA
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28
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Kang J, Dietz MJ, Hughes K, Xing M, Li B. Silver nanoparticles present high intracellular and extracellular killing against Staphylococcus aureus. J Antimicrob Chemother 2020; 74:1578-1585. [PMID: 30778552 DOI: 10.1093/jac/dkz053] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/20/2018] [Accepted: 01/15/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES Bone and joint infections caused by Staphylococcus aureus are becoming increasingly difficult to treat due to rising antibiotic resistance, resilient biofilms and intracellular survival of S. aureus. It has been challenging to identify and develop antimicrobial agents that can be used to kill extracellular and intracellular bacteria while having limited toxicity towards host cells. In addressing this challenge, this study investigates the antimicrobial efficacy and toxicity of silver nanoparticles (AgNPs). METHODS Intracellular bacteria were generated using a co-culture model of human osteoblast cells and S. aureus. Extracellular and intracellular S. aureus were treated with AgNPs, antibiotics and their combinations, and numbers of colonies were quantified. Toxicity of AgNPs against human osteoblast cells was determined by quantifying the number of viable cells after treatment. RESULTS AgNPs demonstrated excellent antimicrobial activity against extracellular S. aureus with a 100% killing efficacy at concentrations as low as 56 μM, along with a high intracellular killing efficacy of 76% at 371 μM. AgNPs were non-toxic or slightly toxic towards human osteoblasts at the concentrations studied (up to 927 μM). Moreover, smaller-sized (40 nm) AgNPs were more efficacious in killing bacteria compared with their larger-sized (100 nm) counterparts and synergistic antimicrobial effects against extracellular bacteria were observed when AgNPs were combined with gentamicin. CONCLUSIONS AgNPs and their combination with antibiotics have demonstrated high extracellular and intracellular bacterial killing and presented unique aspects for potential clinical applications, especially for chronic and recurrent infections where intracellular bacteria may be the cause.
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Affiliation(s)
- Jason Kang
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV, USA
| | - Matthew J Dietz
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV, USA
| | - Krystal Hughes
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV, USA
| | - Malcolm Xing
- Department of Mechanical Engineering, University of Manitoba, Winnipeg, Canada
- The Children's Hospital Research Institute of Manitoba, Winnipeg, Canada
| | - Bingyun Li
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV, USA
- Mary Babb Randolph Cancer Center, Morgantown, WV, USA
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29
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Molecular characterization of a carbon dioxide-dependent Escherichia coli small-colony variant isolated from blood cultures. Int J Med Microbiol 2020; 310:151431. [PMID: 32654769 DOI: 10.1016/j.ijmm.2020.151431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 04/22/2020] [Accepted: 05/23/2020] [Indexed: 11/23/2022] Open
Abstract
A carbon dioxide-dependent small-colony variant of Escherichia coli SH4888 was isolated from blood cultures of a patient with cholangitis. To date, little is known regarding the molecular mechanisms leading to formation of carbon dioxide-dependent phenotypes in clinical isolates, but abnormalities in the carbonic anhydrase are thought to cause carbon dioxide autotrophy. In this study DNA sequence analysis of the carbonic anhydrase-encoding can locus in the carbon dioxide-dependent E. coli SH4888 revealed that the isolate had a 325-bp deletion spanning from the 3'-terminal region of can to the 3'-terminal region of hpt, which encodes a hypoxanthine phosphoribosyltransferase. To confirm that the carbon dioxide-dependent SCV phenotype of E. coli SH4888 was due to the can mutation, we performed a complementation test with a plasmid carrying an intact can that restored the normal phenotype. However, E. coli SH4888 had increased virulence compared to the can-complemented E. coli SH4888 in a murine infection model. In conclusion, these data confirm that impaired carbonic anhydrase function can cause a carbon dioxide-dependent SCV phenotype in E. coli SH4888 and provides a fitness advantage in terms of infection.
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30
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Chang J, Lee RE, Lee W. A pursuit of Staphylococcus aureus continues: a role of persister cells. Arch Pharm Res 2020; 43:630-638. [PMID: 32627141 DOI: 10.1007/s12272-020-01246-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 06/29/2020] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus is a pathogen that causes critical diseases, such as pneumonia, endocarditis, and bacteremia, upon gaining access to the bloodstream of the host. Because host innate immunity alone cannot fight against this rapidly expanding pathogen, the use of antibiotic agents is necessary to clear out S. aureus. However, sub-populations of S. aureus fail to respond to the antibiotics resulting in ineffective clearance of the bacteria. One mechanism by which S. aureus does not respond to the antibiotics is by developing resistance through alterations in its genetic makeup, and genetic studies have revealed a major portion of mechanisms that are responsible for the rise of these antibiotic-resistant strains. Another sub-population that fails to respond to the antibiotics is called persister cells. There is a mounting clinical evidence that these persister cells significantly contribute to the antibiotic failure and persistent infection, but a clear mechanistic picture of the formation of the S. aureus persister cells is unavailable. This review focuses on drawing out a mechanistic map of factors that contribute to the formation of S. aureus persister cells. Understanding the mechanism will provide future direction for the development of novel antibiotic strategies to more efficiently tackle infections caused by S. aureus.
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Affiliation(s)
- JuOae Chang
- School of Pharmacy, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, 16419, Gyeonggi-do, South Korea
| | - Rho-Eun Lee
- School of Pharmacy, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, 16419, Gyeonggi-do, South Korea
| | - Wonsik Lee
- School of Pharmacy, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, 16419, Gyeonggi-do, South Korea.
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31
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Stoneham SM, Cantillon DM, Waddell SJ, Llewelyn MJ. Spontaneously Occurring Small-Colony Variants of Staphylococcus aureus Show Enhanced Clearance by THP-1 Macrophages. Front Microbiol 2020; 11:1300. [PMID: 32595630 PMCID: PMC7303551 DOI: 10.3389/fmicb.2020.01300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/20/2020] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a common cause of chronic and relapsing infection, especially when the ability of the immune system to sterilize a focus of infection is compromised (e.g., because of a foreign body or in the cystic fibrosis lung). Chronic infections are associated with slow-growing colony phenotypes of S. aureus on solid media termed small-colony variants (SCVs). Stable SCVs show characteristic mutations in the electron transport chain that convey resistance to antibiotics, particularly aminoglycosides. This can be used to identify SCVs from within mixed-colony phenotype populations of S. aureus. More recently, populations of SCVs that rapidly revert to a “wild-type” (WT) colony phenotype, in the absence of selection pressure, have also been described. In laboratory studies, SCVs accumulate through prolonged infection of non-professional phagocytes and may represent an adaptation to the intracellular environment. However, data from phagocytic cells are lacking. In this study, we mapped SCV and WT colony populations in axenic growth of multiple well-characterized methicillin-sensitive and methicillin-resistant S. aureus strains. We identified SCVs populations on solid media both in the presence and absence of gentamicin. We generated stable SCVs from Newman strain S. aureus, and infected human macrophages with WT S. aureus (Newman, 8325-4) and their SCV counterparts (SCV3, I10) to examine intracellular formation and survival of SCVs. We show that SCVs arise spontaneously during axenic growth, and that the ratio of SCV:WT morphology differs between strains. Exposure to the intracellular environment of human macrophages did not increase formation of SCVs over 5 days and macrophages were able to clear stable SCV bacteria more effectively than their WT counterparts.
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Affiliation(s)
- Simon M Stoneham
- Department of Microbiology and Infection, Royal Sussex County Hospital, Brighton, United Kingdom.,Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Daire M Cantillon
- Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Simon J Waddell
- Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Martin J Llewelyn
- Department of Microbiology and Infection, Royal Sussex County Hospital, Brighton, United Kingdom.,Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
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32
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Cogen JD, Kahl BC, Maples H, McColley SA, Roberts JA, Winthrop KL, Morris AM, Holmes A, Flume PA, VanDevanter DR, Waters V, Muhlebach MS, Elborn JS, Saiman L, Bell SC. Finding the relevance of antimicrobial stewardship for cystic fibrosis. J Cyst Fibros 2020; 19:511-520. [PMID: 32122785 DOI: 10.1016/j.jcf.2020.02.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 01/29/2020] [Accepted: 02/12/2020] [Indexed: 12/15/2022]
Abstract
Antimicrobials have undoubtedly improved the lives of people with CF, but important antimicrobial-related toxicities and the emergence of antimicrobial-resistant bacteria associated with their use must be considered. Antimicrobial stewardship (AMS) is advocated across the spectrum of healthcare to promote the appropriate use of antimicrobials to preserve their current effectiveness and to optimise treatment, and it is clear that AMS strategies are applicable to and can benefit both non-CF and CF populations. This perspective explores the definition and components of an AMS program, the current evidence for AMS, and the reasons why AMS is a challenging concept in the provision of CF care. We also discuss the elements of CF care which align with AMS programs and principles and propose research priorities for AMS in CF.
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Affiliation(s)
- Jonathan D Cogen
- Division of Pulmonary & Sleep Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA.
| | - Barbara C Kahl
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Holly Maples
- Department of Pharmacy Practice, University of Arkansas for Medical Sciences and Arkansas Children's Hospital, Little Rock, AR, USA
| | - Susanna A McColley
- Division of Pulmonary and Sleep Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, and Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Jason A Roberts
- University of Queensland Centre for Clinical Research and School of Pharmacy, The University of Queensland, Departments of Pharmacy and Intensive Care Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia; Division of Anaesthesiology, Critical Care, Emergency and Pain Medicine, Nîmes University Hospital, University of Montpelier, Nîmes France
| | - Kevin L Winthrop
- Oregon Health and Science University School of Medicine and Public Health, Portland, Oregon, USA
| | - Andrew M Morris
- Division of Infectious Diseases, Department of Medicine, Sinai Health, University Health Network, and University of Toronto, Toronto, Canada
| | - Alison Holmes
- National Institute for Health Research (NIHR) Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, Imperial College London, Hammersmith Campus, London, UK
| | | | - Donald R VanDevanter
- Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland OH, USA
| | - Valerie Waters
- Division of Infectious Diseases, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Marianne S Muhlebach
- Department of Pediatrics, Division Pulmonology, University of North Carolina at Chapel Hill, NC, USA
| | - J Stuart Elborn
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | - Lisa Saiman
- Columbia University Irving Medical Center and New York-Presbyterian Hospital, New York, NY, USA
| | - Scott C Bell
- Department of Thoracic Medicine, The Prince Charles Hospital, and QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
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33
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Chalmers SJ, Wylam ME. Methicillin-Resistant Staphylococcus aureus Infection and Treatment Options. Methods Mol Biol 2020; 2069:229-251. [PMID: 31523777 DOI: 10.1007/978-1-4939-9849-4_16] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infection worldwide, including a wide array of both hospital- and community-acquired infections-most commonly bacteremia, upper and lower respiratory tract infection, skin and soft-tissue infection, osteomyelitis, and septic arthritis. This chapter describes the epidemiology of MRSA infection, its ability to confer antibiotic resistance and produce a wide array of virulence factors, and its pivotal role in human infection, especially cystic fibrosis. It also provides an introduction to the strategies for treatment of both chronic and acute MRSA infections.
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Affiliation(s)
- Sarah J Chalmers
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Mark E Wylam
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA.
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34
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Abstract
Although survival of individuals with cystic fibrosis (CF) has been continuously improving for the past 40 years, respiratory failure secondary to recurrent pulmonary infections remains the leading cause of mortality in this patient population. Certain pathogens such as Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and species of the Burkholderia cepacia complex continue to be associated with poorer clinical outcomes including accelerated lung function decline and increased mortality. In addition, other organisms such as anaerobes, viruses, and fungi are increasingly recognized as potential contributors to disease progression. Culture-independent molecular methods are also being used for diagnostic purposes and to examine the interaction of microorganisms in the CF airway. Given the importance of CF airway infections, ongoing initiatives to promote understanding of the epidemiology, clinical course, and treatment options for these infections are needed.
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Affiliation(s)
- Ana C Blanchard
- Division of Infectious Diseases, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Valerie J Waters
- Division of Infectious Diseases, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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35
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Wolter DJ, Onchiri FM, Emerson J, Precit MR, Lee M, McNamara S, Nay L, Blackledge M, Uluer A, Orenstein DM, Mann M, Hoover W, Gibson RL, Burns JL, Hoffman LR. Prevalence and clinical associations of Staphylococcus aureus small-colony variant respiratory infection in children with cystic fibrosis (SCVSA): a multicentre, observational study. THE LANCET RESPIRATORY MEDICINE 2019; 7:1027-1038. [PMID: 31727592 DOI: 10.1016/s2213-2600(19)30365-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/08/2019] [Accepted: 09/05/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND Staphylococcus aureus is the bacterium cultured most often from respiratory secretions of people with cystic fibrosis. Both meticillin-susceptible S aureus and meticillin-resistant S aureus (MRSA) can adapt to form slow-growing, antibiotic-resistant isolates known as small-colony variants that are not routinely identified by clinical laboratories. We aimed to determine the prevalence and clinical significance of S aureus small-colony variants and their subtypes among children with cystic fibrosis. METHODS The Small Colony Variant Staphylococcus aureus (SCVSA) study was a 2-year longitudinal study of children aged 6-16 years at five US cystic fibrosis centres, using culture methods sensitive for small-colony variants. Children were eligible if they had a documented diagnosis of cystic fibrosis and a minimum of two cystic fibrosis clinic visits and two respiratory cultures in the previous 12 months at enrolment. Participants attended clinic visits quarterly, at which respiratory tract samples were taken and measures of lung function (percentage of predicted forced expiratory volume in 1 s [FEV1] and frequency of respiratory exacerbations) were recorded. We determined the prevalence of small-colony variants and their subtypes, and assessed their independent associations with lung function and respiratory exacerbations using linear mixed-effects and generalised estimating equation logistic regression models. Analyses included both univariate models (unadjusted) and multivariate models that adjusted for potential confounders, including age, sex, race, baseline microbiology, treatment with CFTR modulator, and CTFR genotype. FINDINGS Between July 1, 2014, and May 26, 2015, we enrolled 230 children. Participants were followed-up for 2 years, with a mean of 6·4 visits (SD 1·14) per participant (range 2-9 visits) and a mean interval between visits of 3·94 months (SD 1·77). Across the 2-year period, S aureus small-colony variants were detected in 64 (28%) participants. Most (103 [56%] of 185) of the small-colony variants detected in these participants were thymidine dependent. Children with small-colony variants had significantly lower mean percentage of predicted FEV1 at baseline than did children without small-colony variants (85·5 [SD 19] vs 92·4 [SD 18·6]; p=0·0145). Small-colony variants were associated with significantly lower percentage of predicted FEV1 throughout the study in regression models, both in univariate analyses (regression coefficient -7·07, 95% CI -12·20 to -1·95; p=0·0068) and in multivariate analyses adjusting for potential confounders (-5·50, -10·51 to -0·48; p=0·0316). Small colony variants of the thymidine-dependent subtype had the strongest association with lung function in multivariate regression models (regression coefficient -10·49, -17·25 to -3·73; p=0·0024). Compared with children without small-colony variants, those with small-colony variants had significantly increased odds of respiratory exacerbations in univariate analyses (odds ratio 1·73, 95% CI 1·19 to 2·52; p=0·0045). Children with thymidine-dependent small-colony variants had significantly increased odds of respiratory exacerbations (2·81, 1·69-4·67; p=0·0001), even after adjusting for age, sex, race, genotype, CFTR modulator, P aeruginosa culture status, and baseline percentage of predicted FEV1 (2·17, 1·33-3·57; p=0·0021), whereas those with non-thymidine-dependent small-colony variants did not. In multivariate models including small-colony variants and MRSA status, P aeruginosa was not independently associated with lung function (regression coefficient -4·77, 95% CI -10·36 to 0·83; p=0·10) and was associated with reduced odds of exacerbations (0·54, 0·36 to 0·81; p=0·0028). Only the small-colony variant form of MRSA was associated with reduced lung function (-8·44, -16·15 to -0·72; p=0·0318) and increased odds of exacerbations (2·15, 1·24 to 3·71; p=0·0061). INTERPRETATION Infection with small-colony variants, and particularly thymidine-dependent small-colony variants, was common in a multicentre paediatric population with cystic fibrosis and associated with reduced lung function and increased risk of respiratory exacerbations. The adoption of small-colony variant identification and subtyping methods by clinical laboratories, and the inclusion of small-colony variant prevalence data in cystic fibrosis registries, should be considered for ongoing surveillance and study. FUNDING The Cystic Fibrosis Foundation and the National Institutes of Health.
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Affiliation(s)
- Daniel J Wolter
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | | | - Julia Emerson
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | - Mimi R Precit
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Michael Lee
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Sharon McNamara
- Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | - Laura Nay
- Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | | | - Ahmet Uluer
- Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Brigham and Women's Hospital, Boston, MA, USA
| | - David M Orenstein
- Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michelle Mann
- Department of Pediatrics, Texas Children's Hospital, Houston, TX, USA
| | - Wynton Hoover
- Department of Pediatrics, University of Alabama, Tuscaloosa, AL, USA
| | - Ronald L Gibson
- Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | - Jane L Burns
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA
| | - Lucas R Hoffman
- Department of Pediatrics and Department of Microbiology, University of Washington, Seattle, WA, USA; Department of Pediatrics, Seattle Children's Hospital, Seattle, WA, USA.
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Esposito S, Pennoni G, Mencarini V, Palladino N, Peccini L, Principi N. Antimicrobial Treatment of Staphylococcus aureus in Patients With Cystic Fibrosis. Front Pharmacol 2019; 10:849. [PMID: 31447669 PMCID: PMC6692479 DOI: 10.3389/fphar.2019.00849] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/03/2019] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is a ubiquitous human commensal pathogen. It is commonly isolated in cystic fibrosis (CF) patients and is considered one of the main causes of the recurrent acute pulmonary infections and progressive decline in lung function that characterize this inherited life-threatening multisystem disorder. However, the true role of S. aureus in CF patients is not completely understood. The main aim of this narrative review is to discuss the present knowledge of the role of S. aureus in CF patients. Literature review showed that despite the fact that the availability and use of drugs effective against S. aureus have coincided with a significant improvement in the prognosis of lung disease in CF patients, clearly evidencing the importance of S. aureus therapy, how to use old and new drugs to obtain the maximal effectiveness has not been precisely defined. The most important problem remains that the high frequency with which S. aureus is carried in healthy subjects prevents the differentiation of simple colonization from infection. Moreover, although experts recommend antibiotic administration in CF patients with symptoms and in those with persistent detection of S. aureus, the best antibiotic approach has not been defined. All these problems are complicated by the evidence that the most effective antibiotic against methicillin-resistant S. aureus (MRSA) cannot be used in patients with CF with the same schedules used in patients without CF. Further studies are needed to solve these problems and to assure CF patients the highest level of care.
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Affiliation(s)
- Susanna Esposito
- Pediatric Clinic, Cystic Fibrosis Center of Umbria Region, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Perugia, Italy
| | - Guido Pennoni
- Pediatric Unit, Cystic Fibrosis Center of Umbria Region, Branca Hospital, Branca, Italy
| | - Valeria Mencarini
- Pediatric Unit, Cystic Fibrosis Center of Umbria Region, Branca Hospital, Branca, Italy
| | - Nicola Palladino
- Pediatric Unit, Cystic Fibrosis Center of Umbria Region, Branca Hospital, Branca, Italy
| | - Laura Peccini
- Pediatric Clinic, Cystic Fibrosis Center of Umbria Region, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Perugia, Italy
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Irvine S, Bunk B, Bayes HK, Spröer C, Connolly JPR, Six A, Evans TJ, Roe AJ, Overmann J, Walker D. Genomic and transcriptomic characterization of Pseudomonas aeruginosa small colony variants derived from a chronic infection model. Microb Genom 2019; 5:e000262. [PMID: 30920365 PMCID: PMC6521587 DOI: 10.1099/mgen.0.000262] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 03/10/2019] [Indexed: 01/26/2023] Open
Abstract
Phenotypic change is a hallmark of bacterial adaptation during chronic infection. In the case of chronic Pseudomonas aeruginosa lung infection in patients with cystic fibrosis, well-characterized phenotypic variants include mucoid and small colony variants (SCVs). It has previously been shown that SCVs can be reproducibly isolated from the murine lung following the establishment of chronic infection with mucoid P. aeruginosa strain NH57388A. Using a combination of single-molecule real-time (PacBio) and Illumina sequencing we identify a large genomic inversion in the SCV through recombination between homologous regions of two rRNA operons and an associated truncation of one of the 16S rRNA genes and suggest this may be the genetic switch for conversion to the SCV phenotype. This phenotypic conversion is associated with large-scale transcriptional changes distributed throughout the genome. This global rewiring of the cellular transcriptomic output results in changes to normally differentially regulated genes that modulate resistance to oxidative stress, central metabolism and virulence. These changes are of clinical relevance because the appearance of SCVs during chronic infection is associated with declining lung function.
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Affiliation(s)
- Sharon Irvine
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Boyke Bunk
- Leibniz-Institut DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen, Inhiffenstraße 7B, 38124 Braunschweig, Germany
- German Centre of Infection Research (DZIF), Partner site Hannover-Braunschweig, Braunschweig, Germany
| | - Hannah K. Bayes
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Cathrin Spröer
- Leibniz-Institut DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen, Inhiffenstraße 7B, 38124 Braunschweig, Germany
| | - James P. R. Connolly
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Anne Six
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Thomas J. Evans
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Andrew J. Roe
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Jörg Overmann
- Leibniz-Institut DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen, Inhiffenstraße 7B, 38124 Braunschweig, Germany
- German Centre of Infection Research (DZIF), Partner site Hannover-Braunschweig, Braunschweig, Germany
| | - Daniel Walker
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Limoli DH, Hoffman LR. Help, hinder, hide and harm: what can we learn from the interactions between Pseudomonas aeruginosa and Staphylococcus aureus during respiratory infections? Thorax 2019; 74:684-692. [PMID: 30777898 PMCID: PMC6585302 DOI: 10.1136/thoraxjnl-2018-212616] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/10/2019] [Accepted: 01/14/2019] [Indexed: 12/15/2022]
Abstract
Recent studies of human respiratory secretions using culture-independent techniques have found a surprisingly diverse array of microbes. Interactions among these community members can profoundly impact microbial survival, persistence and antibiotic susceptibility and, consequently, disease progression. Studies of polymicrobial interactions in the human microbiota have shown that the taxonomic and structural compositions, and resulting behaviours, of microbial communities differ substantially from those of the individual constituent species and in ways of clinical importance. These studies primarily involved oral and gastrointestinal microbiomes. While the field of polymicrobial respiratory disease is relatively young, early findings suggest that respiratory tract microbiota members also compete and cooperate in ways that may influence disease outcomes. Ongoing efforts therefore focus on how these findings can inform more 'enlightened', rational approaches to combat respiratory infections. Among the most common respiratory diseases involving polymicrobial infections are cystic fibrosis (CF), non-CF bronchiectasis, COPD and ventilator-associated pneumonia. While respiratory microbiota can be diverse, two of the most common and best-studied members are Staphylococcus aureus and Pseudomonas aeruginosa, which exhibit a range of competitive and cooperative interactions. Here, we review the state of research on pulmonary coinfection with these pathogens, including their prevalence, combined and independent associations with patient outcomes, and mechanisms of those interactions that could influence lung health. Because P. aeruginosa-S. aureus coinfection is common and well studied in CF, this disease serves as the paradigm for our discussions on these two organisms and inform our recommendations for future studies of polymicrobial interactions in pulmonary disease.
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Affiliation(s)
- Dominique Hope Limoli
- Microbiology and Immunology, University of Iowa Roy J and Lucille A Carver College of Medicine, Iowa City, Iowa, USA
| | - Lucas R Hoffman
- Departments of Pediatrics and Microbiology, University of Washington, Seattle, Washington, USA
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Akil N, Muhlebach MS. Biology and management of methicillin resistant Staphylococcus aureus in cystic fibrosis. Pediatr Pulmonol 2018; 53:S64-S74. [PMID: 30073802 DOI: 10.1002/ppul.24139] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/20/2018] [Indexed: 02/06/2023]
Abstract
Staphylococcus aureus is one of the earliest bacteria isolated from the respiratory tract in people with cystic fibrosis (CF). Its methicillin resistant form, MRSA, has gained attention due to the rapid increase in the last decades and worse outcomes with chronic infection. In the United States, prevalence of MRSA in CF is around 27%, but is much lower (3-18%) in most other countries. Methicillin is typically genetically encoded by the mecA gene, which encodes for an alternative penicillin binding protein (PRBa). This PRBa has low affinity to β-lactams, thereby enabling growth of S. aureus in the presence of penicillinase resistant penicillins and most other β-lactams. Non-mecA positive strains of MRSA, so-called borderline resistant (BORSA) have also been described. In addition to production of toxins, the virulence of S. aureus is conferred by its adaptability allowing persistence in face of antibiotic therapies and host defense. These adaptive growth mechanisms include small colony variants, biofilms, and growth under anaerobic conditions. Several reports have described successful eradication of MRSA, yet only two randomized trials of eradication during early infection have been conducted. A list of MRSA specific antibiotics with dosing relevant to CF patients is presented here. Many of these require special dosing in people with CF. Novel antibiotics are in trials for skin and soft tissue infections and it is unclear if and when those might be available for lung infections. Thus the best strategies for MRSA would be primary prevention.
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Affiliation(s)
- Nour Akil
- Division of Pulmonology, Department of Pediatrics, University of NC at Chapel Hill, Chapel Hill, North Carolina
| | - Marianne S Muhlebach
- Division of Pulmonology, Department of Pediatrics, University of NC at Chapel Hill, Chapel Hill, North Carolina.,Marisco Lung Institute, University of NC at Chapel Hill, Chapel Hill, North Carolina
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Roch M, Varela MC, Taglialegna A, Rose WE, Rosato AE. Activity of Telavancin against Staphylococcus aureus Isolates, Including Those with Decreased Susceptibility to Ceftaroline, from Cystic Fibrosis Patients. Antimicrob Agents Chemother 2018; 62:e00956-18. [PMID: 29914961 PMCID: PMC6125506 DOI: 10.1128/aac.00956-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 06/13/2018] [Indexed: 11/21/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) acquisition in cystic fibrosis (CF) patients confers a clinical outcome worse than that in non-CF patients with an increased rate of declined lung function. Telavancin, an approved lipoglycopeptide used to treat infections due to S. aureus, has a dual mode of action causing inhibition of peptidoglycan synthesis and membrane depolarization. MRSA infections in CF patients remain an important problem with no foreseeable decline in prevalence rates. Although telavancin is currently in clinical use for the treatment of complicated skin infections and hospital-acquired pneumonia, the activity against S. aureus infections in CF patients has not been investigated. In this work, we studied the activity of telavancin against CF patient-derived S. aureus strains collected from geographically diverse CF centers in the United States. We found that the telavancin MIC90 was 0.06 μg/ml, 8-fold lower than the ceftaroline or daptomycin MIC90 and 25-fold lower than the linezolid and vancomycin MIC90 We demonstrate that telavancin at serum free concentrations has rapid bactericidal activity, with a decrease of more than 3 log10 CFU/ml being achieved during the first 4 to 6 h of treatment, performing better in this assay than vancomycin and ceftaroline, including against S. aureus strains resistant to ceftaroline. Telavancin resistance was infrequent (0.3%), although we found that it can occur in vitro in both CF- and non-CF patient-derived S. aureus strains by progressive passages with subinhibitory concentrations. Genetic analysis of telavancin-resistant in vitro mutants showed gene polymorphisms in cell wall and virulence genes and increased survival in a Galleria mellonella infection model. Thus, we conclude that telavancin represents a promising therapeutic option for infections in CF patients with potent in vitro activity and a low resistance development potential.
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Affiliation(s)
- Melanie Roch
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, Texas, USA
| | - Maria Celeste Varela
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, Texas, USA
| | - Agustina Taglialegna
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, Texas, USA
| | - Warren E Rose
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Adriana E Rosato
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, Texas, USA
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Sato T, Kawamura M, Furukawa E, Fujimura S. Screening method for trimethoprim/sulfamethoxazole-resistant small colony variants of Staphylococcus aureus. J Glob Antimicrob Resist 2018; 15:1-5. [PMID: 29857058 DOI: 10.1016/j.jgar.2018.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/08/2018] [Accepted: 05/13/2018] [Indexed: 10/16/2022] Open
Abstract
OBJECTIVES Trimethoprim/sulfamethoxazole (SXT) is used to treat Staphylococcus aureus infections. However, the effect of treatment with SXT is sometimes not sufficient and there are patients whose treatment has to be prolonged. There are few reports of isolated strains of SXT-resistant S. aureus, but it is possible that some resistant strains cannot be detected by current testing methods We have therefore developed a tool to identify these resistant strains. METHODS The mutant selection window (MSW) of SXT for 40 clinical isolates of S. aureus, including 20 methicillin-resistant S. aureus (MRSA), was determined. The optimum concentration of SXT and thymidine in agar for detecting SXT-resistant small colony variants (SCVs) of S. aureus was investigated. RESULTS The MSW50 and MSW90 of SXT, presented as a multiple of the minimum inhibitory concentration (MIC), were 16× MIC and >256× MIC, respectively. SCVs were detected within the MSW in 32 (80%) of the 40 clinical isolates studied. To maintain the morphology of SCVs, the most suitable concentrations of SXT and thymidine for screening were 4mg/L and 0.01μg/mL, respectively. All 32 SCVs were resistant to SXT (MIC >32mg/L). The sensitivity and specificity of this screening method was 100% and 88.9%, respectively. CONCLUSIONS SXT-resistant SCVs are not usually detected by routine laboratory tests performed in hospitals. However, the screening test described here can easily distinguish SXT-resistant SCVs among S. aureus isolated from specimens. This newly developed screening test could become an important tool to prevent inappropriate use of SXT.
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Affiliation(s)
- Takumi Sato
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Masato Kawamura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Emiko Furukawa
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Shigeru Fujimura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan.
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Emergence of livestock-associated MRSA isolated from cystic fibrosis patients: Result of a Belgian national survey. J Cyst Fibros 2018; 18:86-93. [PMID: 29805051 DOI: 10.1016/j.jcf.2018.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/20/2018] [Accepted: 04/26/2018] [Indexed: 11/23/2022]
Abstract
BACKGROUND This study aims to determine the prevalence and characteristics of Staphylococcus aureus in Belgian cystic fibrosis (CF) patients. METHODS Non-duplicate respiratory samples from 510 CF-patients (2012-2013) were examined. One isolate per patient was analysed unless different phenotypes were recovered. Isolates were investigated for mecA/mecC, toxins presence, spa-typing, MLST and SCCmec-typing. Potential livestock-associated (LA) isolates were examined for their immune-evasion-cluster (IEC) genes. RESULTS S. aureus (n = 380), including 41 small-colony variants (SCVs), were isolated from 66.7% patients. The prevalence of methicillin-resistant S. aureus (MRSA) colonization was 4.9%. Two MRSA isolates carried toxic shock syndrome toxin 1 (TSST-1). Most MRSA (65%) belonged to two nosocomial epidemic clones (CC5, CC8) widespread in Belgium. Methicillin susceptible S. aureus (MSSA) showed great genetic diversity. Five of 33 isolates belonging to potential LA-lineages were IEC negative, including three methicillin-resistant isolates, suggesting an animal origin. CONCLUSIONS The MRSA-prevalence in Belgian CF-patients remained constant (2001-2013), but SCV-prevalence increased. Most MRSA belonged to health-care-associated clones. Three patients carrying LA-MRSA were found, requiring further investigation to determine the risk factors for LA-MRSA acquisition.
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Schwerdt M, Neumann C, Schwartbeck B, Kampmeier S, Herzog S, Görlich D, Dübbers A, Große-Onnebrink J, Kessler C, Küster P, Schültingkemper H, Treffon J, Peters G, Kahl BC. Staphylococcus aureus in the airways of cystic fibrosis patients - A retrospective long-term study. Int J Med Microbiol 2018; 308:631-639. [PMID: 29501453 DOI: 10.1016/j.ijmm.2018.02.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 02/13/2018] [Accepted: 02/20/2018] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Cystic fibrosis (CF) is an autosomal recessive disease associated with chronic airway infections by Staphylococcus aureus as one of the earliest and most prevalent pathogens. We conducted a retrospective study to determine the S. aureus infection status of CF patients treated since 1994 at two certified CF-centres in Münster, Germany, to get insights into the dynamics of S. aureus airway infection and the clinical impact on lung function on a long-term perspective. MATERIALS AND METHODS We used data from our microbiological database collected between 1994 and 2016 for patients treated at two centres in Münster, Germany, respectively, to determine the infection status for S. aureus. Furthermore, the resistance to selected antibiotics was determined for all patients' isolates and for 15 patients on a longitudinal basis. In addition, the prevalence of adaptive phenotypes such as small colony variants (SCVs) and mucoid S. aureus was assessed. RESULTS For this study, 2867 patient years with respiratory specimens (mean of 9.3 years for every patient, range 1-22 years) were evaluated for 283 CF patients (median age of 7 years at the beginning of the observation period, range 0-57 years, 51% male). 18% of patients were rarely infected by S. aureus (≤24% of observation years), 20% of patients intermittently (25-49%) and 61% persistently (≥50% of observation period). Susceptibility testing for 12969 S. aureus isolates resulted in resistance to methicillin in 9%, trimethoprim/sulfamethoxazole in 10%, levofloxacin in 14%, gentamicin in 20%, erythromycin and/or clindamycin in 30% and penicillin in 80% of all isolates. S. aureus isolates of 15 patients revealed dynamics of resistance with increase, decrease and loss of resistant isolates to the analysed antibiotics during the study period. SCVs were isolated at least once from 42% (n = 118) of patients and mucoid isolates from 2% (n = 7) of patients. In the last study year, 89 patients were infected by S. aureus only, 44 patients by S. aureus and Pseudomonas aeruginosa and 18 by P. aeruginosa only. Patients infected by S. aureus only were younger and had better lung function compared to the other two groups. CONCLUSIONS We determined a high percentage of patients with persistent S. aureus infection. During persistence, mostly fluctuation of resistance against various antibiotics was observed in the isolates indicating acquisition and loss of resistance genes by S. aureus. The prevalence of adaptive phenotypes during long-term persistence was high for SCVs (42% of patients), but low for mucoid isolates (2% of patients), which might be underestimated for mucoid phenotypes due to the retrospective study design and the difficulty to detect mucoid isolates in primary cultures. While patients with S. aureus only had better lung function and were younger, no difference was found between the group of P. aeruginosa and S. aureus co-infection and P. aeruginosa only with previous S. aureus infection.
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Affiliation(s)
- Mathias Schwerdt
- Institute of Medical Microbiology, University Hospital Münster, Germany
| | - Claudia Neumann
- Institute of Medical Microbiology, University Hospital Münster, Germany
| | | | | | - Susann Herzog
- Institute of Medical Microbiology, University Hospital Münster, Germany
| | - Dennis Görlich
- Institute of Biostatistics and Clinical Research, University Hospital Münster, Germany
| | | | | | | | - Peter Küster
- Department of Pediatrics, Clemenshospital, Münster, Germany
| | | | - Janina Treffon
- Institute of Medical Microbiology, University Hospital Münster, Germany
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital Münster, Germany
| | - Barbara C Kahl
- Institute of Medical Microbiology, University Hospital Münster, Germany.
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Guay I, Boulanger S, Isabelle C, Brouillette E, Chagnon F, Bouarab K, Marsault E, Malouin F. Tomatidine and analog FC04-100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp. BMC Pharmacol Toxicol 2018; 19:7. [PMID: 29439722 PMCID: PMC5812199 DOI: 10.1186/s40360-018-0197-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 01/30/2018] [Indexed: 02/07/2023] Open
Abstract
Background Tomatidine (TO) is a plant steroidal alkaloid that possesses an antibacterial activity against the small colony variants (SCVs) of Staphylococcus aureus. We report here the spectrum of activity of TO against other species of the Bacillales and the improved antibacterial activity of a chemically-modified TO derivative (FC04–100) against Listeria monocytogenes and antibiotic multi-resistant S. aureus (MRSA), two notoriously difficult-to-kill microorganisms. Methods Bacillus and Listeria SCVs were isolated using a gentamicin selection pressure. Minimal inhibitory concentrations (MICs) of TO and FC04–100 were determined by a broth microdilution technique. The bactericidal activity of TO and FC04–100 used alone or in combination with an aminoglycoside against planktonic bacteria was determined in broth or against bacteria embedded in pre-formed biofilms by using the Calgary Biofilm Device. Killing of intracellular SCVs was determined in a model with polarized pulmonary cells. Results TO showed a bactericidal activity against SCVs of Staphylococcus aureus, Bacillus cereus, B. subtilis and Listeria monocytogenes with MICs of 0.03–0.12 μg/mL. The combination of an aminoglycoside and TO generated an antibacterial synergy against their normal phenotype. In contrast to TO, which has no relevant activity by itself against Bacillales of the normal phenotype (MIC > 64 μg/mL), the TO analog FC04–100 showed a MIC of 8–32 μg/mL. Furthermore, FC04–100 showed a strong bactericidal activity against L. monocytogenes SCVs in kill kinetics experiments, while TO did not. The addition of FC04–100 (4 μg/mL) to a cefalexin:kanamycin (3:2) combination improved the activity of the combination by 32 fold against cefalexin and kanamycin-resistant MRSA strains. In combination with gentamicin, FC04–100 also exhibited a strong bactericidal activity against biofilm-embedded S. aureus. Also, FC04–100 and TO showed comparable intracellular killing of S. aureus SCVs. Conclusions Chemical modifications of TO allowed improvement of its antibacterial activity against prototypical S. aureus and of its bactericidal activity against L. monocytogenes. Antibacterial activities against such prominent pathogens could be useful to prevent Listeria contamination in the food chain or as treatment for MRSA infections.
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Affiliation(s)
- Isabelle Guay
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Simon Boulanger
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Charles Isabelle
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Eric Brouillette
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Félix Chagnon
- Département de pharmacologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, 3001, 12 th avenue Nord, Sherbrooke, QC, J1H 5N4, Canada
| | - Kamal Bouarab
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Eric Marsault
- Département de pharmacologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, 3001, 12 th avenue Nord, Sherbrooke, QC, J1H 5N4, Canada.
| | - François Malouin
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada.
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Suwantarat N, Rubin M, Bryan L, Tekle T, Boyle MP, Carroll KC, Jennings MT. Frequency of small-colony variants and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus in cystic fibrosis patients. Diagn Microbiol Infect Dis 2017; 90:296-299. [PMID: 29343421 DOI: 10.1016/j.diagmicrobio.2017.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 11/09/2017] [Accepted: 11/19/2017] [Indexed: 01/15/2023]
Abstract
BACKGROUND Small-colony variants (SCVs) are a distinct phenotype of Staphylococcus aureus, known for their role in chronic, difficult to treat infections, including cystic fibrosis (CF) lung disease. The goal of this study was to characterize SCV MRSA infection in an adult and pediatric CF population and to identify antibiotic susceptibility patterns unique to SCV MRSA. METHODS We recovered methicillin-resistant S. aureus (MRSA) from respiratory culture samples from CF patients at the Johns Hopkins Hospital during a 6month study period. RESULTS Of 1161 samples, 200 isolates (17%) were identified as MRSA, and 37 isolates from 28 patients were identified as SCV MRSA. A higher proportion of MRSA was found among SCV isolates (37/66, 56%) compared to normal colony variant (NCV) isolates (163/417, 39%), p=0.02. All SCV MRSA isolates from individual patients were susceptible to vancomycin and ceftaroline, but they demonstrated higher rates of antibiotic resistance to trimethoprim/sulfamethoxazole, moxifloxacin, and erythromycin, compared to NCV MRSA isolates. Additionally, individuals with SCV MRSA had lower lung function, higher rates of persistent MRSA infection, and higher rates of previous antibiotic use, compared to individuals with NCV MRSA. CONCLUSIONS A significant proportion of MRSA isolates recovered from patients with CF have the SCV morphology. Compared to individuals with NCV MRSA, those with SCV MRSA have higher rates of persistent MRSA infection and lower lung function. SCV MRSA isolates were more resistant than NCV, but they are highly susceptible to vancomycin, linezolid and ceftaroline.
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Affiliation(s)
- Nuntra Suwantarat
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Chulabhorn International College of Medicine, Thammasat University, PathumThani, Thailand
| | - Mayer Rubin
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Latetia Bryan
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tsigereda Tekle
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael P Boyle
- The Cystic Fibrosis Foundation, Bethesda, MD, USA; Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Karen C Carroll
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mark T Jennings
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Hosseinkhan N, Mousavian Z, Masoudi-Nejad A. Comparison of gene co-expression networks in Pseudomonas aeruginosa and Staphylococcus aureus reveals conservation in some aspects of virulence. Gene 2017; 639:1-10. [PMID: 28987343 DOI: 10.1016/j.gene.2017.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 09/23/2017] [Accepted: 10/03/2017] [Indexed: 12/13/2022]
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus are two evolutionary distant bacterial species that are frequently isolated from persistent infections such as chronic infectious wounds and severe lung infections in cystic fibrosis patients. To the best of our knowledge no comprehensive genome scale co-expression study has been already conducted on these two species and in most cases only the expression of very few genes has been the subject of investigation. In this study, in order to investigate the level of expressional conservation between these two species, using heterogeneous gene expression datasets the weighted gene co-expression network analysis (WGCNA) approach was applied to study both single and cross species genome scale co-expression patterns of these two species. Single species co-expression network analysis revealed that in P. aeruginosa, genes involved in quorum sensing (QS), iron uptake, nitrate respiration and type III secretion systems and in S. aureus, genes associated with the regulation of carbon metabolism, fatty acid-phospholipids metabolism and proteolysis represent considerable co-expression across a variety of experimental conditions. Moreover, the comparison of gene co-expression networks between P. aeruginosa and S. aureus was led to the identification of four co-expressed gene modules in both species totally consisting of 318 genes. Several genes related to two component signal transduction systems, small colony variants (SCVs) morphotype and protein complexes were found in the detected modules. We believe that targeting the key players among the identified co-expressed orthologous genes will be a potential intervention strategy to control refractory co-infections caused by these two bacterial species.
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Affiliation(s)
- Nazanin Hosseinkhan
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
| | - Zaynab Mousavian
- Department of Computer Science, School of Mathematics, Statistics, and Computer Science, University of Tehran, Tehran, Iran; Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
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Anand R, Moss RB, Sass G, Banaei N, Clemons KV, Martinez M, Stevens DA. Small Colony Variants of Pseudomonas aeruginosa Display Heterogeneity in Inhibiting Aspergillus fumigatus Biofilm. Mycopathologia 2017; 183:263-272. [DOI: 10.1007/s11046-017-0186-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/28/2017] [Indexed: 11/25/2022]
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Geisinger E, Isberg RR. Interplay Between Antibiotic Resistance and Virulence During Disease Promoted by Multidrug-Resistant Bacteria. J Infect Dis 2017; 215:S9-S17. [PMID: 28375515 DOI: 10.1093/infdis/jiw402] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Diseases caused by antibiotic-resistant bacteria in hospitals are the outcome of complex relationships between several dynamic factors, including bacterial pathogenicity, the fitness costs of resistance in the human host, and selective forces resulting from interventions such as antibiotic therapy. The emergence and fate of mutations that drive antibiotic resistance are governed by these interactions. In this review, we will examine how different forms of antibiotic resistance modulate bacterial fitness and virulence potential, thus influencing the ability of pathogens to evolve in the context of nosocomial infections. We will focus on 3 important multidrug-resistant pathogens that are notoriously problematic in hospitals: Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus. An understanding of how antibiotic resistance mutations shape the pathobiology of multidrug-resistant infections has the potential to drive novel strategies that can control the development and spread of drug resistance.
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Affiliation(s)
- Edward Geisinger
- Howard Hughes Medical Institute, and.,Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Ralph R Isberg
- Howard Hughes Medical Institute, and.,Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
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50
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Carzino R, Hart E, Sutton P, King L, Ranganathan S. Lack of small colony variants of Staphylococcus aureus from lower respiratory tract specimens. Pediatr Pulmonol 2017; 52:632-635. [PMID: 28328157 DOI: 10.1002/ppul.23699] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 03/04/2017] [Indexed: 11/09/2022]
Abstract
BACKGROUND Small-colony variants (SCVs) of Staphylococcus aureus are associated with worse lung disease in children with Cystic Fibrosis (CF), exhibit a higher resistance to antibiotics and co-colonize more commonly with Pseudomonas aeruginosa compared to the normal phenotype. The prevalence of SCVs in lower airway specimens from children with CF is largely unknown. METHODS Each visible morphotype of S. aureus was subcultured onto horse blood agar (HBA) to enable identification of SCVs. RESULTS Sixty-one samples from 41 children (mean age 11.7 (SD 5.3) years) were identified with a positive S. aureus culture from lower respiratory tract specimens collected in 2014-2015. None of the differing morphotypes isolated were identified as S. aureus SCVs. CONCLUSION In a center where anti staphylococcal prophylaxis is adopted, S. aureus SCVs were not isolated from the lower airways specimens in young children with CF indicating that acquisition of small colony variant S. aureus may not be a significant clinical problem in young children with CF.
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Affiliation(s)
- Rosemary Carzino
- Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Australia
| | - Emily Hart
- Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Australia
| | - Philip Sutton
- Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Australia.,The University of Melbourne, Parkville, Australia
| | - Louise King
- Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Australia
| | - Sarath Ranganathan
- Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, Australia.,The University of Melbourne, Parkville, Australia
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