201
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García-Betancur JC, Goñi-Moreno A, Horger T, Schott M, Sharan M, Eikmeier J, Wohlmuth B, Zernecke A, Ohlsen K, Kuttler C, Lopez D. Cell differentiation defines acute and chronic infection cell types in Staphylococcus aureus. eLife 2017; 6. [PMID: 28893374 PMCID: PMC5595439 DOI: 10.7554/elife.28023] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 08/09/2017] [Indexed: 12/13/2022] Open
Abstract
A central question to biology is how pathogenic bacteria initiate acute or chronic infections. Here we describe a genetic program for cell-fate decision in the opportunistic human pathogen Staphylococcus aureus, which generates the phenotypic bifurcation of the cells into two genetically identical but different cell types during the course of an infection. Whereas one cell type promotes the formation of biofilms that contribute to chronic infections, the second type is planktonic and produces the toxins that contribute to acute bacteremia. We identified a bimodal switch in the agr quorum sensing system that antagonistically regulates the differentiation of these two physiologically distinct cell types. We found that extracellular signals affect the behavior of the agr bimodal switch and modify the size of the specialized subpopulations in specific colonization niches. For instance, magnesium-enriched colonization niches causes magnesium binding to S. aureusteichoic acids and increases bacterial cell wall rigidity. This signal triggers a genetic program that ultimately downregulates the agr bimodal switch. Colonization niches with different magnesium concentrations influence the bimodal system activity, which defines a distinct ratio between these subpopulations; this in turn leads to distinct infection outcomes in vitro and in an in vivo murine infection model. Cell differentiation generates physiological heterogeneity in clonal bacterial infections and helps to determine the distinct infection types. While in hospital, patients can be unwittingly exposed to bacteria that can cause disease. These hospital-associated bacteria can lead to potentially life-threatening infections that may also complicate the treatment of the patients’ existing medical conditions. Staphylococcus aureus is one such bacterium, and it can cause several types of infection including pneumonia, blood infections and long-term infections of prosthetic devices. It is thought that S. aureus is able to cause so many different types of infection because it is capable of colonizing distinct tissues and organs in various parts of the body. Understanding the biological processes that drive the different infections is crucial to improving how these infections are treated. S. aureus lives either as an independent, free-swimming cell or as part of a community known as a biofilm. These different lifestyles dictate the type of infection the bacterium can cause, with free-swimming cells producing toxins that contribute to intense, usually short-lived, infections and biofilms promoting longer-term infections that are difficult to eradicate. However, it is not clear how a population of S. aureus cells chooses to adopt a particular lifestyle and whether there are any environmental signals that influence this decision. Here, Garcia-Betancur et al. found that S. aureus populations contain small groups of cells that have already specialized into a particular lifestyle. These groups of cells collectively influence the choice made by other cells in the population. While both lifestyles will be represented in the population, environmental factors influence the numbers of cells that initially adopt each type of lifestyle, which ultimately affects the choice made by the rest of the population. For example, if the bacteria colonize a tissue or organ that contains high levels of magnesium ions, the population is more likely to form biofilms. In the future, the findings of Garcia-Betancur et al. may help us to predict how an infection may develop in a particular patient, which may help to diagnose the infection more quickly and allow it to be treated more effectively.
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Affiliation(s)
- Juan-Carlos García-Betancur
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany.,Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
| | - Angel Goñi-Moreno
- School of Computing Science, Newcastle University, Newcastle, United Kingdom
| | - Thomas Horger
- Department of Mathematics, Technical University of Munich, Garching, Germany
| | - Melanie Schott
- Institute of Clinical Biochemistry and Pathobiochemistry, University Hospital Würzburg, Würzburg, Germany
| | - Malvika Sharan
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
| | - Julian Eikmeier
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany.,Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany
| | - Barbara Wohlmuth
- Department of Mathematics, Technical University of Munich, Garching, Germany
| | - Alma Zernecke
- Institute of Clinical Biochemistry and Pathobiochemistry, University Hospital Würzburg, Würzburg, Germany
| | - Knut Ohlsen
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
| | - Christina Kuttler
- Department of Mathematics, Technical University of Munich, Garching, Germany
| | - Daniel Lopez
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany.,Research Center for Infectious Diseases, University of Würzburg, Würzburg, Germany.,National Center for Biotechnology, Madrid, Spain
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202
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Vestergaard M, Nøhr-Meldgaard K, Ingmer H. Multiple pathways towards reduced membrane potential and concomitant reduction in aminoglycoside susceptibility in Staphylococcus aureus. Int J Antimicrob Agents 2017; 51:132-135. [PMID: 28843820 DOI: 10.1016/j.ijantimicag.2017.08.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/09/2017] [Accepted: 08/15/2017] [Indexed: 10/19/2022]
Abstract
Staphylococcus aureus is responsible for life-threatening and difficult-to-treat infections worldwide and antimicrobial resistance is an increasing concern. Whilst acquired resistance has been widely studied, little is known of the contributions from chromosomal determinants that upon inactivation may reduce the susceptibility of S. aureus to antibiotics. The aim of this study was to identify genetic determinants that upon inactivation reduce aminoglycoside susceptibility in S. aureus. The Nebraska Transposon Mutant Library of 1920 single-gene inactivations in S. aureus strain JE2 was screened for reduced susceptibility to gentamicin. Nine mutants were confirmed by Etest to display between 2- and 16-fold reduced susceptibility to this antibiotic. All of the identified genes were associated with the electron transport chain and energy metabolism. Four mutant strains (menD, hemB, aroC and SAUSA300_0355) conferred the largest decrease in gentamicin susceptibility and three exhibited a small colony variant phenotype, whereas the remaining mutants (qoxA, qoxB, qoxC, ndh and hemX) displayed colony morphology similar to the wild-type. All of the mutants, except hemX, displayed reduced membrane potential suggesting that reduced uptake of gentamicin is the predominant mechanism leading to reduced susceptibility. The results of this study demonstrate that S. aureus possesses multiple genes that upon inactivation by mutagenesis reduce the membrane potential and thereby reduce the lethal activity of gentamicin.
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Affiliation(s)
- Martin Vestergaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, Frederiksberg C DK-1870, Denmark
| | - Katrine Nøhr-Meldgaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, Frederiksberg C DK-1870, Denmark
| | - Hanne Ingmer
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, Frederiksberg C DK-1870, Denmark.
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203
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Banno H, Kimura K, Tanaka Y, Sekizuka T, Kuroda M, Jin W, Wachino JI, Yamada K, Shibayama K, Arakawa Y. Analysis of multidrug resistant group B streptococci with reduced penicillin susceptibility forming small, less hemolytic colonies. PLoS One 2017; 12:e0183453. [PMID: 28817704 PMCID: PMC5560676 DOI: 10.1371/journal.pone.0183453] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/06/2017] [Indexed: 11/29/2022] Open
Abstract
Group B streptococci (GBS; Streptococcus agalactiae) are the leading cause of neonatal invasive diseases and are also important pathogens for elderly adults. Until now, nearly all GBS with reduced penicillin susceptibility (PRGBS) have shown β-hemolytic activity and grow on sheep blood agar. However, we have previously reported three PRGBS clinical isolates harboring a CylK deletion that form small less hemolytic colonies. In this study, we examined the causes of small, less hemolytic colony formation in these clinical isolates. Isogenic strains were sequenced to identify the mutation related to a small colony size. We identified a 276_277insG nucleic acid insertion in the thiamin pyrophosphokinase (tpk) gene, resulting in premature termination at amino acid 103 in TPK, as a candidate mutation responsible for small colony formation. The recombinant strain Δtpk, which harbored the 276_277insG insertion in the tpk gene, showed small colony formation. The recombinant strain ΔcylK, which harbored the G379T substitution in cylK, showed a reduction in hemolytic activity. The phenotypes of both recombinant strains were complemented by the expression of intact TPK or CylK, respectively. Moreover, the use of Rapid ID 32 API and VITEK MS to identify strains as GBS was evaluated clinical isolates and recombinant strains. VITEK MS, but not Rapid ID 32 API, was able to accurately identify the strains as GBS. In conclusion, we determined that mutations in tpk and cylK caused small colonies and reduced hemolytic activity, respectively, and characterized the clinical isolates in detail.
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Affiliation(s)
- Hirotsugu Banno
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
| | - Kouji Kimura
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
| | - Yosuke Tanaka
- Department of Microbiology Laboratory, Yokohama City Seibu Hospital, St. Marianna University School of Medicine, Asahi-ku, Yokohama, Kanagawa, Japan
| | - Tsuyoshi Sekizuka
- Pathogen Genomic Center, National Institute of Infectious Diseases, Shinjyuku-ku, Tokyo, Japan
| | - Makoto Kuroda
- Pathogen Genomic Center, National Institute of Infectious Diseases, Shinjyuku-ku, Tokyo, Japan
| | - Wanchun Jin
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
| | - Jun-ichi Wachino
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
| | - Keiko Yamada
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
| | - Keigo Shibayama
- Department of Bacteriology II, National Institute of Infectious Diseases, Musashi-Murayama, Tokyo, Japan
| | - Yoshichika Arakawa
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Aichi, Japan
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204
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Jaśkiewicz M, Neubauer D, Kamysz W. Comparative Study on Antistaphylococcal Activity of Lipopeptides in Various Culture Media. Antibiotics (Basel) 2017; 6:antibiotics6030015. [PMID: 28767074 PMCID: PMC5617979 DOI: 10.3390/antibiotics6030015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/17/2017] [Accepted: 07/31/2017] [Indexed: 01/01/2023] Open
Abstract
Staphylococcus aureus bacteria are one of the leading microorganisms responsible for nosocomial infections as well as being the primary causative pathogen of skin and wound infections. Currently, the therapy of staphylococcal diseases faces many difficulties, due to a variety of mechanisms of resistance and virulence factors. Moreover, a number of infections caused by S. aureus are connected with biofilm formation that impairs effectiveness of the therapy. Short cationic lipopeptides that are designed on the basis of the structure of antimicrobial peptides are likely to provide a promising alternative to conventional antibiotics. Many research groups have proved a high antistaphylococcal potential of lipopeptides, however, the use of different protocols for determination of antimicrobial activity may be the reason for inconsistency of the results. The aim of this study was to learn how the use of various bacteriological media as well as solvents may affect activity of lipopeptides and their cyclic analogs. Obtained results showed a great impact of these variables. For example, cyclic analogs were more effective when dissolved in an aqueous solution of acetic acid and bovine serum albumin (BSA). The greater activity against planktonic cultures was found in brain-heart infusion broth (BHI) and tryptic-soy broth (TSB), while the antibiofilm activity was higher in the Mueller-Hinton medium.
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Affiliation(s)
- Maciej Jaśkiewicz
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, 80-416 Gdańsk, Poland.
| | - Damian Neubauer
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, 80-416 Gdańsk, Poland.
| | - Wojciech Kamysz
- Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdańsk, 80-416 Gdańsk, Poland.
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205
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Sabaté Brescó M, Harris LG, Thompson K, Stanic B, Morgenstern M, O'Mahony L, Richards RG, Moriarty TF. Pathogenic Mechanisms and Host Interactions in Staphylococcus epidermidis Device-Related Infection. Front Microbiol 2017; 8:1401. [PMID: 28824556 PMCID: PMC5539136 DOI: 10.3389/fmicb.2017.01401] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/11/2017] [Indexed: 12/25/2022] Open
Abstract
Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin and mucous membranes. By adhering to tissue surface moieties of the host via specific adhesins, S. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. In its role as a commensal organism, S. epidermidis is thought to provide benefits to human host, including out-competing more virulent pathogens. However, largely due to its capacity to form biofilm on implanted foreign bodies, S. epidermidis has emerged as an important opportunistic pathogen in patients receiving medical devices. S. epidermidis causes approximately 20% of all orthopedic device-related infections (ODRIs), increasing up to 50% in late-developing infections. Despite this prevalence, it remains underrepresented in the scientific literature, in particular lagging behind the study of the S. aureus. This review aims to provide an overview of the interactions of S. epidermidis with the human host, both as a commensal and as a pathogen. The mechanisms retained by S. epidermidis that enable colonization of human skin as well as invasive infection, will be described, with a particular focus upon biofilm formation. The host immune responses to these infections are also described, including how S. epidermidis seems to trigger low levels of pro-inflammatory cytokines and high levels of interleukin-10, which may contribute to the sub-acute and persistent nature often associated with these infections. The adaptive immune response to S. epidermidis remains poorly described, and represents an area which may provide significant new discoveries in the coming years.
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Affiliation(s)
- Marina Sabaté Brescó
- Musculoskeletal Infection, AO Research Institute DavosDavos, Switzerland.,Molecular Immunology, Swiss Institute of Allergy and Asthma Research, University of ZurichDavos, Switzerland
| | - Llinos G Harris
- Microbiology and Infectious Diseases, Institute of Life Science, Swansea University Medical SchoolSwansea, United Kingdom
| | - Keith Thompson
- Musculoskeletal Infection, AO Research Institute DavosDavos, Switzerland
| | - Barbara Stanic
- Musculoskeletal Infection, AO Research Institute DavosDavos, Switzerland
| | - Mario Morgenstern
- Department of Orthopedic and Trauma Surgery, University Hospital BaselBasel, Switzerland
| | - Liam O'Mahony
- Molecular Immunology, Swiss Institute of Allergy and Asthma Research, University of ZurichDavos, Switzerland
| | - R Geoff Richards
- Musculoskeletal Infection, AO Research Institute DavosDavos, Switzerland
| | - T Fintan Moriarty
- Musculoskeletal Infection, AO Research Institute DavosDavos, Switzerland
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206
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Influence of IS 256 on Genome Variability and Formation of Small-Colony Variants in Staphylococcus aureus. Antimicrob Agents Chemother 2017; 61:AAC.00144-17. [PMID: 28584147 DOI: 10.1128/aac.00144-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/30/2017] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus has acquired resistance to nearly all antibiotics used in clinical practice. Whereas some resistance mechanisms are conferred by uptake of resistance genes, others evolve by mutation. In this study, IS256 has been shown to play a role, e.g., in S. aureus strains displaying intermediate resistance to vancomycin (VISA). To characterize the IS256 insertion sites in the genomes of two closely related sequence type 247 (ST247) VISA strains, all insertions were mapped in both VISA and a susceptible control strain. The results showed that the three ST247 strains contained the highest number so far of IS256 insertions for all sequenced S. aureus strains. Furthermore, in contrast to the case with the other IS elements in these genomes, the IS256 insertion sites were not identical in the closely related strains, indicating a high transposition frequency of IS256 When IS256 was introduced into a laboratory strain which was then cultured in the presence of antibiotics, it was possible to isolate small-colony variants (SCVs) that possessed IS256 insertions in guaA and hemY that displayed increased resistance to vancomycin and aminoglycosides, respectively. For these clones, a very rapid reversion to the wild type that resembled the fast reversion of clinical SCVs was observed. The reversion was caused by excision of IS256 in a small number of fast-growing clones that quickly outcompeted the SCVs in broth cultures. In conclusion, the presence of IS256 confers a strong genomic plasticity that is useful for adaptation to antibiotic stress.
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207
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Rollin G, Tan X, Tros F, Dupuis M, Nassif X, Charbit A, Coureuil M. Intracellular Survival of Staphylococcus aureus in Endothelial Cells: A Matter of Growth or Persistence. Front Microbiol 2017; 8:1354. [PMID: 28769913 PMCID: PMC5515828 DOI: 10.3389/fmicb.2017.01354] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/04/2017] [Indexed: 11/23/2022] Open
Abstract
The Gram-positive human pathogen Staphylococcus aureus is a leading cause of severe bacterial infections. Recent studies have shown that various cell types could readily internalize S. aureus and infected cells have been proposed to serve as vehicle for the systemic dissemination of the pathogen. Here we focused on the intracellular behavior of the Community-Associated Methicillin-Resistant S. aureus strain USA300. Supporting earlier observations, we found that wild-type S. aureus strain USA300 persisted for longer period within endothelial cells than within macrophages and that a mutant displaying the small colony variant phenotype (ΔhemDBL) had increased intracellular persistence. Time-lapse microscopy revealed that initial persistence of wild-type bacteria in endothelial cells corresponded to distinct single cell events, ranging from active intracellular bacterial proliferation, leading to cell lysis, to non-replicating bacterial persistence even 1 week after infection. In sharp contrast, ΔhemDBL mutant bacteria were essentially non-replicating up to 10 days after infection. These findings suggest that internalization of S. aureus in endothelial cells triggers its persistence and support the notion that endothelial cells might constitute an intracellular persistence niche responsible for reported relapse of infection after antibiotic therapy.
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Affiliation(s)
- Guillaume Rollin
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
| | - Xin Tan
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
| | - Fabiola Tros
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
| | - Marion Dupuis
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
| | - Xavier Nassif
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France.,Assistance Publique - Hôpitaux de Paris, Hôpital Necker Enfants MaladesParis, France
| | - Alain Charbit
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
| | - Mathieu Coureuil
- Université Paris Descartes, Sorbonne Paris Cité, Bâtiment LericheParis, France.,Institut National de la Santé et de la Recherche Médicale U1151 - Centre National de la Recherche Scientifique UMR 8253, Institut Necker-Enfants Malades, Equipe 11: Pathogénie des Infections SystémiquesParis, France
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208
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Rodríguez-Arce I, Martí S, Euba B, Fernández-Calvet A, Moleres J, López-López N, Barberán M, Ramos-Vivas J, Tubau F, Losa C, Ardanuy C, Leiva J, Yuste JE, Garmendia J. Inactivation of the Thymidylate Synthase thyA in Non-typeable Haemophilus influenzae Modulates Antibiotic Resistance and Has a Strong Impact on Its Interplay with the Host Airways. Front Cell Infect Microbiol 2017; 7:266. [PMID: 28676846 PMCID: PMC5476696 DOI: 10.3389/fcimb.2017.00266] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/02/2017] [Indexed: 12/29/2022] Open
Abstract
Antibacterial treatment with cotrimoxazol (TxS), a combination of trimethoprim and sulfamethoxazole, generates resistance by, among others, acquisition of thymidine auxotrophy associated with mutations in the thymidylate synthase gene thyA, which can modify the biology of infection. The opportunistic pathogen non-typeable Haemophilus influenzae (NTHi) is frequently encountered in the lower airways of chronic obstructive pulmonary disease (COPD) patients, and associated with acute exacerbation of COPD symptoms. Increasing resistance of NTHi to TxS limits its suitability as initial antibacterial against COPD exacerbation, although its relationship with thymidine auxotrophy is unknown. In this study, the analysis of 2,542 NTHi isolates recovered at Bellvitge University Hospital (Spain) in the period 2010–2014 revealed 119 strains forming slow-growing colonies on the thymidine low concentration medium Mueller Hinton Fastidious, including one strain isolated from a COPD patient undergoing TxS therapy that was a reversible thymidine auxotroph. To assess the impact of thymidine auxotrophy in the NTHi-host interplay during respiratory infection, thyA mutants were generated in both the clinical isolate NTHi375 and the reference strain RdKW20. Inactivation of the thyA gene increased TxS resistance, but also promoted morphological changes consistent with elongation and impaired bacterial division, which altered H. influenzae self-aggregation, phosphorylcholine level, C3b deposition, and airway epithelial infection patterns. Availability of external thymidine contributed to overcome such auxotrophy and TxS effect, potentially facilitated by the nucleoside transporter nupC. Although, thyA inactivation resulted in bacterial attenuation in a lung infection mouse model, it also rendered a lower clearance upon a TxS challenge in vivo. Thus, our results show that thymidine auxotrophy modulates both the NTHi host airway interplay and antibiotic resistance, which should be considered at the clinical setting for the consequences of TxS administration.
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Affiliation(s)
- Irene Rodríguez-Arce
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain
| | - Sara Martí
- Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain.,Departamento Microbiología, Hospital Universitari Bellvitge, University of Barcelona, Institut d'Investigació Biomédica de BellvitgeBarcelona, Spain
| | - Begoña Euba
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain.,Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain
| | - Ariadna Fernández-Calvet
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain
| | - Javier Moleres
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain
| | - Nahikari López-López
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain
| | | | - José Ramos-Vivas
- Servicio Microbiología, Hospital Universitario Marqués de Valdecilla and Instituto de Investigación Marqués de ValdecillaSantander, Spain.,Red Española de Investigación en Patología Infecciosa, Instituto de Salud Carlos IIIMadrid, Spain
| | - Fe Tubau
- Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain.,Departamento Microbiología, Hospital Universitari Bellvitge, University of Barcelona, Institut d'Investigació Biomédica de BellvitgeBarcelona, Spain
| | - Carmen Losa
- Servicio de Microbiología, Clínica Universidad de NavarraNavarra, Spain
| | - Carmen Ardanuy
- Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain.,Departamento Microbiología, Hospital Universitari Bellvitge, University of Barcelona, Institut d'Investigació Biomédica de BellvitgeBarcelona, Spain
| | - José Leiva
- Servicio de Microbiología, Clínica Universidad de NavarraNavarra, Spain
| | - José E Yuste
- Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain.,Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - Junkal Garmendia
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública Navarra-GobiernoNavarra, Spain.,Centro de Investigación Biomédica en Red de Enfermedades RespiratoriasMadrid, Spain
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209
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Wang Y, Liu X, Dou C, Cao Z, Liu C, Dong S, Fei J. Staphylococcal protein A promotes osteoclastogenesis through MAPK signaling during bone infection. J Cell Physiol 2017; 232:2396-2406. [PMID: 28185243 PMCID: PMC5485048 DOI: 10.1002/jcp.25774] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/04/2017] [Indexed: 01/31/2023]
Abstract
Bone infection is a common and serious complication in the orthopedics field, which often leads to excessive bone destruction and non‐union. Osteoclast is the only type of cells which have the function of bone resorption. Its over activation is closely related to excessive bone loss. Staphylococcus aureus (S. aureus) is a major pathogen causing bone infection, which can produce a large number of strong pathogenic substances staphylococcal protein A (SPA). However, few studies were reported about the effects of SPA on osteoclastogenesis. In our study, we observed that S. aureus activated osteoclasts and promoted bone loss in bone infection specimens. Then, we investigated the effects of SPA on RANKL‐induced osteoclastogenesis in vitro, the results revealed that SPA promoted osteoclastic differentiation and fusion, and enhanced osteoclastic bone resorption. In addition, we also showed that SPA upregulated the expression of NFATc1 and c‐FOS through the activation of MAPK signaling to promote osteoclastogenesis. Our findings might help us better understand the pathogenic role of S. aureus in bone infection and develop new therapeutic strategies for infectious bone diseases.
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Affiliation(s)
- Yuan Wang
- Center of Trauma of Daping Hospital, Third Military Medical University, Chongqing, China
| | - Xin Liu
- Center of Trauma of Daping Hospital, Third Military Medical University, Chongqing, China
| | - Ce Dou
- Department of Biomedical Materials Science, School of Biomedical Engineering, Third Military Medical University, Chongqing, China
| | - Zhen Cao
- Department of Biomedical Materials Science, School of Biomedical Engineering, Third Military Medical University, Chongqing, China
| | - Chuan Liu
- Department of Biomedical Materials Science, School of Biomedical Engineering, Third Military Medical University, Chongqing, China
| | - Shiwu Dong
- Department of Biomedical Materials Science, School of Biomedical Engineering, Third Military Medical University, Chongqing, China
| | - Jun Fei
- Center of Trauma of Daping Hospital, Third Military Medical University, Chongqing, China.,State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China
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210
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Antibiotic tolerance and the alternative lifestyles of Staphylococcus aureus. Essays Biochem 2017; 61:71-79. [PMID: 28258231 DOI: 10.1042/ebc20160061] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/22/2016] [Accepted: 11/25/2016] [Indexed: 12/11/2022]
Abstract
Staphylococcus aureus has an incredible ability to survive, either by adapting to environmental conditions or defending against exogenous stress. Although there are certainly important genetic traits, in part this ability is provided by the breadth of modes of growth S. aureus can adopt. It has been proposed that while within their host, S. aureus survives host-generated and therapeutic antimicrobial stress via alternative lifestyles: a persister sub-population, through biofilm growth on host tissue or by growing as small colony variants (SCVs). Key to an understanding of chronic and relapsing S. aureus infections is determining the molecular basis for its switch to these quasi-dormant lifestyles. In a multicellular biofilm, the metabolically quiescent bacterial community additionally produces a highly protective extracellular polymeric substance (EPS). Furthermore, there are bacteria within a biofilm community that have an altered physiology potentially equivalent to persister cells. Recent studies have directly linked the cellular ATP production by persister cells as their key feature and the basis for their tolerance of a range of antibiotics. In clinical settings, SCVs of S. aureus have been observed for many years; when cultured, these cells form non-pigmented colonies and are approximately ten times smaller than their counterparts. Various genotypic factors have been identified in attempts to characterize S. aureus SCVs and different environmental stresses have been implicated as important inducers.
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211
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Mariathasan S, Tan MW. Antibody-Antibiotic Conjugates: A Novel Therapeutic Platform against Bacterial Infections. Trends Mol Med 2017; 23:135-149. [PMID: 28126271 DOI: 10.1016/j.molmed.2016.12.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 11/26/2022]
Abstract
Antibodies are potent components of the immune repertoire and have been successfully exploited to treat bacterial infections. Recently an antibody-antibiotic conjugate (AAC) that combines key attributes of an antibody and antibiotic has been shown to be efficacious against Staphylococcus aureus infection. An AAC has three components: an antibiotic payload to kill bacteria, an antibody to target delivery of the payload to bacteria, and a linker attaching the payload to the antibody. With increasing understanding of the biology and pathophysiology of S. aureus, this article highlights how this knowledge has led to the design principles of an efficacious AAC, and discusses how the AAC platform could be translationally applied to treat other perilous infectious diseases.
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Affiliation(s)
- Sanjeev Mariathasan
- Department of Late-Stage Oncology Biomarkers Development, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
| | - Man-Wah Tan
- Department of Infectious Diseases, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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212
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Vestergaard M, Paulander W, Leng B, Nielsen JB, Westh HT, Ingmer H. Novel Pathways for Ameliorating the Fitness Cost of Gentamicin Resistant Small Colony Variants. Front Microbiol 2016; 7:1866. [PMID: 27920765 PMCID: PMC5119051 DOI: 10.3389/fmicb.2016.01866] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/04/2016] [Indexed: 01/08/2023] Open
Abstract
Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin. The SCVs carried mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500 generations with or without sub-lethal concentrations of gentamicin. Amelioration of the fitness cost followed three evolutionary trajectories and was dependent on the initial mutation type (point mutation vs. deletion) and the passage condition (absence or presence of gentamicin). For SCVs evolved in the absence of gentamicin, 12 out of 15 lineages derived from SCVs with point mutations acquired intra-codonic suppressor mutations restoring membrane potential, growth rate, gentamicin susceptibility and colony size to WT levels. For the SCVs carrying deletions, all lineages enhanced fitness independent of membrane potential restoration without alterations in gentamicin resistance levels. By whole genome sequencing, we identified compensatory mutations in genes related to the σB stress response (7 out of 10 lineages). Inactivation of rpoF that encode for the alternative sigma factor SigB (σB) partially restored fitness of SCVs. For all lineages passaged in the presence of gentamicin, fitness compensation via membrane potential restoration was suppressed, however, selected for secondary mutations in fusA and SAUSA300_0749. This study is the first to describe fitness compensatory events in SCVs with deletion mutations and adaptation of SCVs to continued exposure to gentamicin.
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Affiliation(s)
- Martin Vestergaard
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Wilhelm Paulander
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Bingfeng Leng
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Jesper B Nielsen
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital Hvidovre, Denmark
| | - Henrik T Westh
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital Hvidovre, Denmark
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
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213
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Curtis TD, Gram L, Knudsen GM. The Small Colony Variant of Listeria monocytogenes Is More Tolerant to Antibiotics and Has Altered Survival in RAW 264.7 Murine Macrophages. Front Microbiol 2016; 7:1056. [PMID: 27458449 PMCID: PMC4932272 DOI: 10.3389/fmicb.2016.01056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022] Open
Abstract
Small Colony Variant (SCV) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. They form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic enzyme production, aminoglycoside resistance, and increased intracellular persistence. They are clinically relevant in Staphylococcus aureus and Pseudomonas aeruginosa, serving as a reservoir for recurrent or prolonged infections. Here, we found that a SCV mutant in the foodborne pathogen Listeria monocytogenes (strain SCV E18), similar to the high persister mutant phenotype, survived significantly better than the wild type when exposed over a 48-h period to concentrations above Minimal Inhibitory Concentration for most tested antibiotics. SCV E18 survived more poorly than the wildtype in unactivated RAW264.7 macrophage cells, presumably because of its reduced listeriolysin O expression, however, it survived better in reactive oxygen species producing, phorbol 12-myristate 13-acetate-activated macrophages. Although SCV E18 was sensitive to oxygen as it entered the stationary phase, it was significantly more tolerant to H2O2 than the wild type, which may result from a shift in metabolism, however, further investigation is needed to resolve this. SCV E18 is a spontaneous mutant with a point mutation in the hemA gene. A wild type copy of hemA was complemented on plasmid pSOG30222, which restored the wild type phenotype. The results reported here suggest that the SCV of L. monocytogenes could be of clinical importance and highlight a need for adequate clinical screening for this phenotype, as it could affect antibiotic treatment outcomes.
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Affiliation(s)
- Thomas D Curtis
- Gram Lab, Department of Systems Biology, Technical University of Denmark Kongens Lyngby, Denmark
| | - Lone Gram
- Gram Lab, Department of Systems Biology, Technical University of Denmark Kongens Lyngby, Denmark
| | - Gitte M Knudsen
- Gram Lab, Department of Systems Biology, Technical University of Denmark Kongens Lyngby, Denmark
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214
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Significance of Staphylococcus epidermidis in Health Care-Associated Infections, from Contaminant to Clinically Relevant Pathogen: This Is a Wake-Up Call! J Clin Microbiol 2016; 54:1679-1681. [PMID: 27170016 DOI: 10.1128/jcm.00743-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, have been recognized as an important cause of health care-associated infections. Concurrently, S. epidermidis is a common contaminant in clinical cultures, which poses a diagnostic challenge. An article in this issue of Journal of Clinical Microbiology (I. Tolo, J. C. Thomas, R. S. B. Fischer, E. L. Brown, B. M. Gray, and D. A. Robinson, J Clin Microbiol 54:1711-1719, 2015, http://dx.doi.org/10.1128/JCM.03345-15) describes a rapid single nucleotide polymorphism-based assay for distinguishing between S. epidermidis isolates from hospital and nonhospital sources, which represents an important contribution to the characterization and understanding of S. epidermidis health care-associated infections.
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