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Gil-Campillo C, González-Díaz A, Rapún-Araiz B, Iriarte-Elizaintzin O, Elizalde-Gutiérrez I, Fernández-Calvet A, Lázaro-Díez M, Martí S, Garmendia J. Imipenem heteroresistance but not tolerance in Haemophilus influenzae during chronic lung infection associated with chronic obstructive pulmonary disease. Front Microbiol 2023; 14:1253623. [PMID: 38179447 PMCID: PMC10765533 DOI: 10.3389/fmicb.2023.1253623] [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: 07/05/2023] [Accepted: 11/24/2023] [Indexed: 01/06/2024] Open
Abstract
Antibiotic resistance is a major Public Health challenge worldwide. Mechanisms other than resistance are described as contributors to therapeutic failure. These include heteroresistance and tolerance, which escape the standardized procedures used for antibiotic treatment decision-making as they do not involve changes in minimal inhibitory concentration (MIC). Haemophilus influenzae causes chronic respiratory infection and is associated with exacerbations suffered by chronic obstructive pulmonary disease (COPD) patients. Although resistance to imipenem is rare in this bacterial species, heteroresistance has been reported, and antibiotic tolerance cannot be excluded. Moreover, development of antibiotic heteroresistance or tolerance during within-host H. influenzae pathoadaptive evolution is currently unknown. In this study, we assessed imipenem resistance, heteroresistance and tolerance in a previously sequenced longitudinal collection of H. influenzae COPD respiratory isolates. The use of Etest, disc diffusion, population analysis profiling, tolerance disc (TD)-test methods, and susceptibility breakpoint criteria when available, showed a significant proportion of imipenem heteroresistance with differences in terms of degree among strains, absence of imipenem tolerance, and no specific trends among serial and clonally related strains could be established. Analysis of allelic variation in the ftsI, acrA, acrB, and acrR genes rendered a panel of polymorphisms only found in heteroresistant strains, but gene expression and genome-wide analyses did not show clear genetic traits linked to heteroresistance. In summary, a significant proportion of imipenem heteroresistance was observed among H. influenzae strains isolated from COPD respiratory samples over time. These data should be useful for making more accurate clinical recommendations to COPD patients.
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Affiliation(s)
- Celia Gil-Campillo
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Conexion Nanomedicina CSIC (NanomedCSIC), Madrid, Spain
| | - Aida González-Díaz
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, Hospital Universitari Bellvitge, IDIBELL-UB, L’Hospitalet de Llobregat, Barcelona, Spain
| | - Beatriz Rapún-Araiz
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
- Conexion Nanomedicina CSIC (NanomedCSIC), Madrid, Spain
| | - Oihane Iriarte-Elizaintzin
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
| | - Iris Elizalde-Gutiérrez
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
| | - Ariadna Fernández-Calvet
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
| | - María Lázaro-Díez
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
| | - Sara Martí
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, Hospital Universitari Bellvitge, IDIBELL-UB, L’Hospitalet de Llobregat, Barcelona, Spain
| | - Junkal Garmendia
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas (IdAB-CSIC)-Gobierno de Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Conexion Nanomedicina CSIC (NanomedCSIC), Madrid, Spain
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2
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Nageeb WM, AlHarbi N, Alrehaili AA, Zakai SA, Elfadadny A, Hetta HF. Global genomic epidemiology of chromosomally mediated non-enzymatic carbapenem resistance in Acinetobacter baumannii: on the way to predict and modify resistance. Front Microbiol 2023; 14:1271733. [PMID: 37869654 PMCID: PMC10587612 DOI: 10.3389/fmicb.2023.1271733] [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: 08/02/2023] [Accepted: 09/05/2023] [Indexed: 10/24/2023] Open
Abstract
Introduction Although carbapenemases are frequently reported in resistant A. baumannii clinical isolates, other chromosomally mediated elements of resistance that are considered essential are frequently underestimated. Having a wide substrate range, multidrug efflux pumps frequently underlie antibiotic treatment failure. Recognizing and exploiting variations in multidrug efflux pumps and penicillin-binding proteins (PBPs) is an essential approach in new antibiotic drug discovery and engineering to meet the growing challenge of multidrug-resistant Gram-negative bacteria. Methods A total of 980 whole genome sequences of A. baumannii were analyzed. Nucleotide sequences for the genes studied were queried against a custom database of FASTA sequences using the Bacterial and Viral Bioinformatics Resource Center (BV-BRC) system. The correlation between different variants and carbapenem Minimum Inhibitory Concentrations (MICs) was studied. PROVEAN and I-Mutant predictor suites were used to predict the effect of the studied amino acid substitutions on protein function and protein stability. Both PsiPred and FUpred were used for domain and secondary structure prediction. Phylogenetic reconstruction was performed using SANS serif and then visualized using iTOL and Phandango. Results Exhibiting the highest detection rate, AdeB codes for an important efflux-pump structural protein. T48V, T584I, and P660Q were important variants identified in the AdeB-predicted multidrug efflux transporter pore domains. These can act as probable targets for designing new efflux-pump inhibitors. Each of AdeC Q239L and AdeS D167N can also act as probable targets for restoring carbapenem susceptibility. Membrane proteins appear to have lower predictive potential than efflux pump-related changes. OprB and OprD changes show a greater effect than OmpA, OmpW, Omp33, and CarO changes on carbapenem susceptibility. Functional and statistical evidence make the variants T636A and S382N at PBP1a good markers for imipenem susceptibility and potential important drug targets that can modify imipenem resistance. In addition, PBP3_370, PBP1a_T636A, and PBP1a_S382N may act as potential drug targets that can be exploited to counteract imipenem resistance. Conclusion The study presents a comprehensive epidemiologic and statistical analysis of potential membrane proteins and efflux-pump variants related to carbapenem susceptibility in A. baumannii, shedding light on their clinical utility as diagnostic markers and treatment modification targets for more focused studies of candidate elements.
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Affiliation(s)
- Wedad M. Nageeb
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Nada AlHarbi
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Amani A. Alrehaili
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif, Saudi Arabia
| | - Shadi A. Zakai
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed Elfadadny
- Department of Animal Internal Medicine, Faculty of Veterinary Medicine, Damanhour University, Damanhour, El-Beheira, Egypt
| | - Helal F. Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt
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Roch M, Sierra R, Andrey DO. Antibiotic heteroresistance in ESKAPE pathogens, from bench to bedside. Clin Microbiol Infect 2023; 29:320-325. [PMID: 36270588 DOI: 10.1016/j.cmi.2022.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/23/2022] [Accepted: 10/13/2022] [Indexed: 11/27/2022]
Abstract
BACKGROUND Heteroresistance refers to subpopulation-mediated differential antimicrobial susceptibility within a clonal bacterial population. Usually, it designates a resistant subpopulation identified within an isolate considered susceptible by classical antimicrobial susceptibility testing. Heteroresistance lacks a uniform microbiological definition for diagnostic laboratories, and its clinical impact remains unclear for most bacterial species. OBJECTIVES This narrative review aims to provide a practical overview on the latest developments in the field of heteroresistance for both clinical microbiologists and physicians, with a particular focus on ESKAPE pathogens. SOURCES A literature search was performed on Pubmed and Google with the key words heteroresistance (heterogeneity OR heterogeneous) AND antibiotic resistance. Among the 836 publications selected based on their abstracts, the most relevant for the detection, epidemiology and clinical impact of heteroresistance in ESKAPE pathogens are discussed here. CONTENT Heteroresistance is only clearly defined for heterogeneous vancomycin intermediate Staphylococcus aureus. We compiled a larger microbiological definition to be applicable to other bacterial species and antibiotics in the clinical context. We highlighted the key technical points of population analysis profile, which is the reference standard for detecting heteroresistance. Heteroresistance to polymyxins, β-lactams (carbapenems, cefiderocol), fosfomycin, tigecycline and aminoglycosides is frequently reported in multidrug-resistant gram-negative pathogens. Treatment failure due to heteroresistance has been described in case reports or retrospective studies, so far confirmed by meta-analyses in the case of heterogeneous vancomycin intermediate S. aureus only. Finally, to treat pandrug-resistant bacterial infections, the option of targeting susceptible subpopulations of resistant isolates using tailored antibiotic combinations is also discussed. IMPLICATIONS Systematic heteroresistance screening by clinical laboratories is not currently recommended. Nevertheless, we should be aware of this phenomenon, and in specific cases, such as treatment failure, heteroresistance should be tested by reference laboratories. Additional studies using standardized methods are needed to improve our understanding of heteroresistance and further assess its clinical impact.
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Affiliation(s)
- Mélanie Roch
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Roberto Sierra
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Division of Infectious Diseases, Department of Medicine, Geneva University Hospitals and Medical School, Geneva, Switzerland
| | - Diego O Andrey
- Division of Infectious Diseases, Department of Medicine, Geneva University Hospitals and Medical School, Geneva, Switzerland; Division of Laboratory Medicine, Department of Diagnostics, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
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RecA inactivation as a strategy to reverse the heteroresistance phenomenon in clinical isolates of Escherichia coli. Int J Antimicrob Agents 2023; 61:106721. [PMID: 36642235 DOI: 10.1016/j.ijantimicag.2023.106721] [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: 07/15/2022] [Revised: 11/25/2022] [Accepted: 12/31/2022] [Indexed: 01/13/2023]
Abstract
RecA inhibition could be an important strategy to combat antimicrobial resistance because of its key role in the SOS response, DNA repair and homologous recombination contributing to bacterial survival. This study evaluated the impact of RecA inactivation on heteroresistance in clinical isolates of Escherichia coli and their corresponding recA-deficient isogenic strains to multiple classes of antimicrobial agents. A high frequency (>30%) of heteroresistance was observed in this collection of clinical isolates. Deletion of the recA gene led to a marked reduction in heteroresistant subpopulations, especially against quinolones or β-lactams. The molecular basis of heteroresistance was associated with an increase in copy number of plasmid-borne resistance genes (blaTEM-1B) or tandem gene amplifications (qnrA1). Of note, in the absence of the recA gene, the increase in copy number of resistance genes was suppressed. This makes the recA gene a promising target for combating heteroresistance.
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Manrique PD, López CA, Gnanakaran S, Rybenkov VV, Zgurskaya HI. New understanding of multidrug efflux and permeation in antibiotic resistance, persistence, and heteroresistance. Ann N Y Acad Sci 2023; 1519:46-62. [PMID: 36344198 PMCID: PMC9839546 DOI: 10.1111/nyas.14921] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Antibiotics effective against Gram-negative ESKAPE pathogens are a critical area of unmet need. Infections caused by these pathogens are not only difficult to treat but finding new therapies to overcome Gram-negative resistance is also a challenge. There are not enough antibiotics in development that target the most dangerous pathogens and there are not enough novel drugs in the pipeline. The major obstacle in the antibiotic discovery pipeline is the lack of understanding of how to breach antibiotic permeability barriers of Gram-negative pathogens. These barriers are created by active efflux pumps acting across both the inner and the outer membranes. Overproduction of efflux pumps alone or together with either modification of the outer membrane or antibiotic-inactivating enzymes and target mutations contribute to clinical levels of antibiotics resistance. Recent efforts have generated significant advances in the rationalization of compound efflux and permeation across the cell envelopes of Gram-negative pathogens. Combined with earlier studies and novel mathematical models, these efforts have led to a multilevel understanding of how antibiotics permeate these barriers and how multidrug efflux and permeation contribute to the development of antibiotic resistance and heteroresistance. Here, we discuss the new developments in this area.
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Affiliation(s)
- Pedro D. Manrique
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
- Present address: Physics Department, George Washington University, Washington D.C. 20052, United States
| | - Cesar A. López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
| | - S. Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
| | - Valentin V. Rybenkov
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, United States
| | - Helen I. Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, United States
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Zhao B, Han H, He K, Hou WF, Liang YL, Cui JL, He DD, Hu GZ, Liu JH, Yuan L. Decreased cyclic-AMP caused by ATP contributes to fosfomycin heteroresistance in avian Escherichia coli. J Antimicrob Chemother 2022; 78:216-224. [PMID: 36374526 DOI: 10.1093/jac/dkac377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 10/18/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Fosfomycin is an important broad-spectrum bactericidal antibiotic to treat multidrug-resistant bacteria infections. It is generally accepted that heteroresistant bacteria are an intermediate stage in the formation of drug resistance, but there are few studies on the formation mechanism underlying fosfomycin heteroresistance (FHR). OBJECTIVES To reveal the characteristics and formation mechanisms of FHR in Escherichia coli isolates obtained from chickens. METHODS We identified the FHR according to the population analysis profile (PAP) test and in vitro time-kill assay. Growth curves for FHR E. coli and their subpopulations were measured. Also, the subpopulations were repeatedly cultured in fosfomycin-free medium for 5-20 overnight incubation periods. The formation mechanisms of FHR in E. coli isolates were identified through accumulation assay, carbohydrate utilization testing, real-time relative quantitative PCR analysis, DNA sequencing, transcriptomic analysis, intracellular ATP and cAMP-level assessment. RESULTS Four of six E. coli strains were confirmed to show FHR, with a total of six subpopulations. The subpopulations restored phenotypic susceptibilities to fosfomycin within 5-20 overnight incubation sessions, but four of six subpopulations still maintained FHR characteristics. Differing from their parental isolates, the uptake of fosfomycin in the subpopulations through GlpT was reduced remarkably. Further studies identified that the low expression of glpT was due to the decrease of intracellular cAMP levels in the subpopulations, which was caused by the decreased ATP levels in cells. CONCLUSIONS Our findings revealed the formation mechanism of E. coli isolates showing FHR obtained from chicken in China and characterized the dynamic change traits in vitro of the subpopulations.
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Affiliation(s)
- Bing Zhao
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Han Han
- Norman Bethune Health Science Center, Jilin University, Changchun, China
| | - Kun He
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Wen-Fei Hou
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Yu-Lei Liang
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Jun-Ling Cui
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Dan-Dan He
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Gong-Zheng Hu
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Jian-Hua Liu
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Li Yuan
- International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
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Xu Y, Zheng X, Zeng W, Chen T, Liao W, Qian J, Lin J, Zhou C, Tian X, Cao J, Zhou T. Mechanisms of Heteroresistance and Resistance to Imipenem in Pseudomonas aeruginosa. Infect Drug Resist 2020; 13:1419-1428. [PMID: 32523360 PMCID: PMC7234976 DOI: 10.2147/idr.s249475] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/21/2020] [Indexed: 11/23/2022] Open
Abstract
Background Heteroresistance is a phenomenon that occurs in all bacteria and can cause treatment failure. Yet, the exact mechanisms responsible for heteroresistance still remain unknown. The following study investigated the mechanisms of imipenem-heteroresistance and -resistance in Pseudomonas aeruginosa clinical isolates from Wenzhou, China. Methods Imipenem resistance was detected by the agar dilution method; heteroresistance was determined by population analysis profiles. Biofilm formation assay and modified carbapenem inactivation methods were also performed. Polymerase chain reaction (PCR) was conducted to detect oprD, and quantitative real-time PCR was used to determine expression levels of oprD, ampC and four efflux pump coding genes (mexB, mexD, mexE and mexY). Results Six imipenem-heteroresistant and -resistant P. aeruginosa isolates were selected respectively. Deficient oprD was detected in all resistant isolates and two heteroresistant isolates. No strains produced carbapenemases. Expression levels of oprD were down-regulated in heteroresistant isolates. Transcription levels of the mexE and mexY were significantly increased in all heterogeneous subpopulations compared with their respective native ones. Compared with the susceptible group, increased mean relative expression levels of mexE and mexY or the decreased mean relative expression levels of oprD were observed in the resistant group (P < 0.05), whereas transcription levels of the mexB and mexD remained unchanged. Conclusion Down-regulation of oprD contributed to the resistance and heteroresistance of imipenem in our P. aeruginosa clinical isolates. In addition, the marginal up-regulation of efflux systems may indirectly affect imipenem resistance. Contrarily, defective oprD was less common in our experimental heteroresistant strains than resistant strains.
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Affiliation(s)
- Ye Xu
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Xiangkuo Zheng
- Department of Medical Laboratory Science, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Weiliang Zeng
- Department of Medical Laboratory Science, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Tao Chen
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Wenli Liao
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Jiao Qian
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Jie Lin
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Cui Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Xuebin Tian
- Department of Medical Laboratory Science, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Jianming Cao
- Department of Medical Laboratory Science, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Tieli Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
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8
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Mechanisms and clinical relevance of bacterial heteroresistance. Nat Rev Microbiol 2019; 17:479-496. [DOI: 10.1038/s41579-019-0218-1] [Citation(s) in RCA: 161] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2019] [Indexed: 02/08/2023]
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9
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Affiliation(s)
- Victor I. Band
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, United States of America
- Emory Vaccine Center, Emory University, Atlanta, Georgia, United States of America
| | - David S. Weiss
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, United States of America
- Emory Vaccine Center, Emory University, Atlanta, Georgia, United States of America
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
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Fernández-Cuenca F, Tomás M, Caballero-Moyano FJ, Bou G, Pascual Á. Reporting antimicrobial susceptibilities and resistance phenotypes in Acinetobacter spp: a nationwide proficiency study. J Antimicrob Chemother 2019; 73:692-697. [PMID: 29244131 DOI: 10.1093/jac/dkx464] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/07/2017] [Indexed: 01/30/2023] Open
Abstract
Objectives To evaluate the proficiency of Spanish microbiology laboratories with respect to the antimicrobial susceptibility testing (AST) of Acinetobacter spp. Methods Eight Acinetobacter spp. with different resistance mechanisms were sent to 48 Spanish centres which were asked to report: (i) the AST system used; (ii) MICs; (iii) breakpoints used (CLSI versus EUCAST); (iv) clinical category; and (v) resistance mechanisms inferred. Minor, major and very major errors (mE, ME and VME, respectively) were determined. Results The greatest percentages of discrepancies were: (i) by AST method: 18.5% Etest, 14.3% Vitek 2 and Sensititre; (ii) by breakpoints: 20.5% (CLSI) and 10.8% (EUCAST); and (iii) by antimicrobial agent: ampicillin/sulbactam (56.2% CLSI), minocycline (40.7% CLSI), tobramycin (38.7% CLSI, 16.8% EUCAST), imipenem (27.8% CLSI, 30.0% EUCAST) and meropenem (25.4% CLSI, 20.8% EUCAST). Categorical error rates: (i) by AST method ranged from 30.0% (Phoenix) to 100% (Sensititre and disc diffusion) for mE, 0.0% (Etest, Sensititre, disc diffusion) to 40% (Phoenix) for ME, and 0.0% (Sensititre and disc diffusion) to 30% (Phoenix) for VME; (ii) by breakpoints: mE (80.1% CLSI, 58.4% EUCAST), ME (3.5% CLSI, 12.4% EUCAST) and VME (16.4% CLSI, 29.2% EUCAST); and (iii) by antimicrobial agent: mE (100% levofloxacin/CLSI, 100% levofloxacin and meropenem/EUCAST), ME (35.3% colistin/CLSI, 25.0% colistin/EUCAST) and VME (64.7% colistin/CLSI, 86.7% gentamicin/EUCAST). Conclusions Clinical microbiology laboratories must improve their ability to determine antimicrobial susceptibilities of Acinetobacter spp. isolates. Higher discrepancies using CLSI when compared with EUCAST are mainly due to mE and to a much lesser extent to ME or VME.
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Affiliation(s)
- Felipe Fernández-Cuenca
- Unidad Clínica de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Sevilla, Spain.,Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.,Spanish Network for the Research in Infectious Diseases (REIPIRD12/0015), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla (IBIs), Sevilla, Spain
| | - María Tomás
- Spanish Network for the Research in Infectious Diseases (REIPIRD12/0015), Instituto de Salud Carlos III, Madrid, Spain.,Servicio de Microbiología, Complexo Hospitalario Universitario de A Coruña (CHUAC), A Coruña, Spain.,Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Francisco-Javier Caballero-Moyano
- Unidad Clínica de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Sevilla, Spain.,Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain
| | - Germán Bou
- Spanish Network for the Research in Infectious Diseases (REIPIRD12/0015), Instituto de Salud Carlos III, Madrid, Spain.,Servicio de Microbiología, Complexo Hospitalario Universitario de A Coruña (CHUAC), A Coruña, Spain.,Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Álvaro Pascual
- Unidad Clínica de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Sevilla, Spain.,Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain.,Spanish Network for the Research in Infectious Diseases (REIPIRD12/0015), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Biomedicina de Sevilla (IBIs), Sevilla, Spain
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de Azevedo FKSF, Dutra V, Nakazato L, Mello CM, Pepato MA, de Sousa ATHI, Takahara DT, Hahn RC, Souto FJD. Molecular epidemiology of multidrug-resistant Acinetobacter baumannii infection in two hospitals in Central Brazil: the role of ST730 and ST162 in clinical outcomes. J Med Microbiol 2018; 68:31-40. [PMID: 30516469 DOI: 10.1099/jmm.0.000853] [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] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Acinetobacter baumannii is a major cause of multidrug-resistant nosocomial infections. The characteristics of A. baumannii at two hospitals in a city in Central Brazil are described by analysing the phenotypes and molecular profiles of isolates recovered from 87 patients. METHODOLOGY The isolates were identified and their antimicrobial susceptibility was evaluated using the the Bact/Alert 3D and Vitek2 methods. Patients' clinical data were obtained from medical files. Genes associated with resistance to carbapenems were analysed by multilocus sequence typing, clinical and bacteriological variables were analysed by descriptive statistics, and logistic models were generated to adjust the associations. RESULTS Sixty-four (73.5 %) out of 87 A. baumannii isolates analysed were from patients in intensive care. The mortality rate was 43.7 %. Eighty (91.9 %) isolates were resistant to imipenem and 86 were susceptible to colistin (98.8 %). The blaOXA-23 gene (78.2 %) and its upstream insertion ISAba1 (55.2 %) were predominant, followed by blaOXA-24 (55.2 %) and blaOXA-143 (28.7 %). The blaOXA-23 gene and ISAba1 were independently associated with resistance to imipenem (P<0.05). There were 13 different sequence types (STs) among the 35 isolates. ST1 (nine; 25.7 %), ST162 (eight; 22.8 %) and ST730 (six; 17.1 %) were the most common, and four new STs were identified. The isolates were grouped into five clonal complexes (CC1, CC15, CC79, CC108 and CC162) plus a singleton using eburst. CONCLUSION Respiratory infection, age >60 years and use of noradrenaline were factors associated with fatality. ST730 (CC79) was associated with higher mortality (P<0.05) and ST162 (CC162) was associated with increased survival probability (P<0.05).
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Affiliation(s)
| | - Valéria Dutra
- 2Laboratory of Veterinary Microbiology and Molecular Biology, College of Veterinary Medicine, Federal University of Mato Grosso, Mato Grosso, Brazil
| | - Luciano Nakazato
- 2Laboratory of Veterinary Microbiology and Molecular Biology, College of Veterinary Medicine, Federal University of Mato Grosso, Mato Grosso, Brazil
| | - Camila Martines Mello
- 1College of Medicine, Júlio Muller Hospital University, Federal University of Mato Grosso, Mato Grosso State, Brazil
| | - Marco Andrey Pepato
- 1College of Medicine, Júlio Muller Hospital University, Federal University of Mato Grosso, Mato Grosso State, Brazil
| | | | - Doracilde Terume Takahara
- 1College of Medicine, Júlio Muller Hospital University, Federal University of Mato Grosso, Mato Grosso State, Brazil
| | - Rosane Christine Hahn
- 1College of Medicine, Júlio Muller Hospital University, Federal University of Mato Grosso, Mato Grosso State, Brazil
| | - Francisco José Dutra Souto
- 1College of Medicine, Júlio Muller Hospital University, Federal University of Mato Grosso, Mato Grosso State, Brazil
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He J, Jia X, Yang S, Xu X, Sun K, Li C, Yang T, Zhang L. Heteroresistance to carbapenems in invasive Pseudomonas aeruginosa infections. Int J Antimicrob Agents 2017; 51:413-421. [PMID: 29127047 DOI: 10.1016/j.ijantimicag.2017.10.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/14/2017] [Accepted: 10/28/2017] [Indexed: 11/24/2022]
Abstract
Heteroresistance is common in a variety of microbes, however carbapenem heteroresistance among invasive Pseudomonas aeruginosa infections has not been thoroughly characterised to date. The objective of this study was to investigate the mechanisms, molecular epidemiology and risk factors for invasive carbapenem-heteroresistant P. aeruginosa (CHPA) infections between 2011 and 2015 in Chongqing, China. A significant increase in the rates of heteroresistance to imipenem and meropenem was observed during the study period. Mechanistic analysis revealed that efflux system overexpression and decreased OprD could have contributed to carbapenem heteroresistance in P. aeruginosa. It was also observed that all of the subpopulations produced enhanced levels of biofilm compared with their native strains. Moreover, previous carbapenem exposure was identified as a common independent risk factor for imipenem-heteroresistant (IPM-HR) and meropenem-heteroresistant (MEM-HR) isolates, but patients infected with MEM-HR isolates were at higher risk of poor outcomes than those with IPM-HR isolates. Most importantly, there was a remarkable increase in the prescription of carbapenems during the study period, which was demonstrated to correlate significantly with the quarterly increasing prevalence of IPM-HR and MEM-HR isolates, respectively. These findings show the necessity of routine detection of carbapenem-heteroresistant strains and that strict control of carbapenem use is critical to reduce CHPA infections in hospitalised patients.
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Affiliation(s)
- Jianchun He
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Xiaojiong Jia
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Shuangshuang Yang
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Xiuyu Xu
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Kunling Sun
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Congya Li
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Tianxiang Yang
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China
| | - Liping Zhang
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing 400016, PR China.
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Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations. Transplant Rev (Orlando) 2017; 32:36-57. [PMID: 28811074 DOI: 10.1016/j.trre.2017.07.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/02/2017] [Indexed: 12/17/2022]
Abstract
Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate's phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.
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García-Salguero C, Rodríguez-Avial I, Picazo JJ, Culebras E. Can Plazomicin Alone or in Combination Be a Therapeutic Option against Carbapenem-Resistant Acinetobacter baumannii? Antimicrob Agents Chemother 2015; 59:5959-66. [PMID: 26169398 PMCID: PMC4576036 DOI: 10.1128/aac.00873-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 07/06/2015] [Indexed: 12/26/2022] Open
Abstract
Nosocomial pathogens can be associated with a variety of infections, particularly in intensive care units (ICUs) and in immunocompromised patients. Usually these pathogens are resistant to multiple drugs and pose therapeutic challenges. Among these organisms, Acinetobacter baumannii is one of the most frequent being encountered in the clinical setting. Carbapenems are very useful to treat infections caused by these drug-resistant Gram-negative bacilli, but carbapenem resistance is increasing globally. Combination therapy is frequently given empirically for hospital-acquired infections in critically ill patients and is usually composed of an adequate beta-lactam and an aminoglycoside. The purpose of this study was to evaluate the in vitro activity of plazomicin against carbapenem-resistant Acinetobacter baumannii. Amikacin was used as a comparator. The activity of plazomicin in combination with several different antibiotics was tested by disk diffusion, the checkerboard method, and time-kill studies. Synergy was consistently observed with carbapenems (meropenem and/or imipenem) along with plazomicin or amikacin. When the aminoglycosides were combined with other classes of antibiotics, synergy was observed in some cases, depending on the strain and the antibiotic combination; importantly, there was no antagonism observed in any case. These findings indicate the potential utility of plazomicin in combination with other antibiotics (mainly carbapenems) for the treatment of A. baumannii infections, including those caused by carbapenem-resistant isolates.
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Affiliation(s)
| | | | - Juan J Picazo
- Microbiology Department, Hospital Clínico San Carlos, Madrid, Spain
| | - Esther Culebras
- Microbiology Department, Hospital Clínico San Carlos, Madrid, Spain
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Fernández-Cuenca F, Tomás M, Caballero-Moyano FJ, Bou G, Martínez-Martínez L, Vila J, Pachón J, Cisneros JM, Rodríguez-Baño J, Pascual Á. Reduced susceptibility to biocides in Acinetobacter baumannii: association with resistance to antimicrobials, epidemiological behaviour, biological cost and effect on the expression of genes encoding porins and efflux pumps. J Antimicrob Chemother 2015; 70:3222-9. [PMID: 26517560 DOI: 10.1093/jac/dkv262] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/29/2015] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES The objective of this study was to analyse whether there is an association between reduced susceptibility to biocides in Acinetobacter baumannii and (i) antimicrobial resistance (co-resistance), (ii) prevalent (epidemic) clones, (iii) changes in the fitness or (iv) expression of genes related to efflux pumps and porins. METHODS Susceptibility to biocides and antimicrobials was determined in 49 clonally unrelated isolates of A. baumannii. Biological cost, in terms of mean generation time, was determined by spectrophotometry. Quantitative real-time RT-PCR was used to determine the relative expression of genes encoding several efflux pumps and porins. RESULTS Reduced susceptibility to chlorhexidine digluconate, benzalkonium chloride and Irgasan(®) was associated with resistance to aminoglycosides, tetracycline and ciprofloxacin (P < 0.05). The MICs of carbapenems, aminoglycosides, doxycycline and ciprofloxacin for isolate Ab70 (epidemic clone) exposed to these biocides increased by ≥2 dilutions. Reduced susceptibility to Orsan(®) was more frequent among prevalent clones than non-prevalent clones (P < 0.05). Mean generation times for Ab70 before and after exposure to benzalkonium chloride were 57.8 and 78.1 min, respectively (P = 0.02). Relative expression of abeS and adeB was increased in Ab46 and Ab70 after exposure to chlorhexidine digluconate, but was decreased for ompA and carO after exposure to Irgasan(®). CONCLUSIONS Reduced susceptibility to biocides is associated with co-resistance to carbapenems, aminoglycosides, tetracycline and ciprofloxacin. Reduced susceptibility to Orsan(®) may be a marker of prevalent clones. Acquisition of reduced susceptibility to benzalkonium chloride has a biological cost. Exposure to biocides affects the relative expression of genes related to some efflux pump genes (increased expression) or porins (reduced expression).
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Affiliation(s)
- Felipe Fernández-Cuenca
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain
| | - María Tomás
- Servicio de Microbiología, Complexo Hospitalario Universitario de A Coruña (CHUAC), A Coruña, Spain Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Francisco-Javier Caballero-Moyano
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain
| | - Germán Bou
- Servicio de Microbiología, Complexo Hospitalario Universitario de A Coruña (CHUAC), A Coruña, Spain Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Luis Martínez-Martínez
- Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla, Santander, Spain Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Spain Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Jordi Vila
- Department of Clinical Microbiology, Biomedical Diagnostic Centre (CDB), Hospital Clínic, School of Medicine, University of Barcelona, Barcelona, Spain ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic, University of Barcelona, Barcelona, Spain
| | - Jerónimo Pachón
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Medicina, Universidad de Sevilla, Sevilla, Spain Instituto de Biomedicina de Sevilla (IBIS), Sevilla, Spain
| | - José-Miguel Cisneros
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Medicina, Universidad de Sevilla, Sevilla, Spain Instituto de Biomedicina de Sevilla (IBIS), Sevilla, Spain
| | - Jesús Rodríguez-Baño
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Medicina, Universidad de Sevilla, Sevilla, Spain
| | - Álvaro Pascual
- Unidad Clínica de Enfermedades Infecciosas, Microbiología Clínica y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Sevilla, Spain Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain
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Nodari CS, Ribeiro VB, Barth AL. Imipenem heteroresistance: high prevalence among Enterobacteriaceae
Klebsiella pneumoniae carbapenemase producers. J Med Microbiol 2015; 64:124-126. [DOI: 10.1099/jmm.0.081869-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Carolina Silva Nodari
- Laboratório de Pesquisa em Resistência Bacteriana - LABRESIS, Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
| | | | - Afonso Luis Barth
- Laboratório de Pesquisa em Resistência Bacteriana - LABRESIS, Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Brazil
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
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Impact of carbapenem heteroresistance among clinical isolates of invasive Escherichia coli in Chongqing, southwestern China. Clin Microbiol Infect 2014; 21:469.e1-10. [PMID: 25649300 DOI: 10.1016/j.cmi.2014.12.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 12/09/2014] [Accepted: 12/13/2014] [Indexed: 11/21/2022]
Abstract
Although heteroresistance is common in a wide range of microorganisms, carbapenem heteroresistance among invasive Escherichia coli infections has not been reported. The objective of this study was to evaluate the clinical significance of carbapenem heteroresistance and to identify risk factors for its acquisition. A case-control study was conducted at a 3200-bed teaching hospital in Chongqing, southwestern China. Successive and non-duplicate nosocomial E. coli isolates (n = 332) were obtained from July 2011 to June 2013. Bloodstream isolates made up 50.6% of the strains collected. The rates of heteroresistance were 25.0% to imipenem, 17.2% to ertapenem, and 3.9% to meropenem. The population analysis profile revealed the presence of subpopulations with higher carbapenem resistance, showing MICs ranging from 2.0-128.0mg/L. Male gender, invasive intervention, antibiotic use and bacterial extended-spectrum β-lactamase (ESBL) production contributed to invasive infections by carbapenem-heteroresistant E. coli (CHEC). The production of ESBL was identified as the common independent risk factor for heteroresistance to both ertapenem and imipenem. Pulsed-field gel electrophoresis revealed clonal diversity among the CHEC isolates. Most importantly, characterization of two successive E. coli strains isolated from the same patient indicated that carbapenem resistance evolved from heteroresistance. In conclusion, the high prevalence of heteroresistance to carbapenem among invasive E. coli merits great attention. Routine detection of ESBLs and the prudent use of imipenem and ertapenem are advocated. The early targeted intervention should be formulated to reduce CHEC infection and carbapenem resistance of E. coli.
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Multidrug resistant Acinetobacter baumannii reaches a new frontier: prosthetic hip joint infection. Infection 2014; 43:95-7. [PMID: 25037735 DOI: 10.1007/s15010-014-0661-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
Abstract
Acinetobacter baumannii is an emerging nosocomial pathogen primarily in countries with a high prevalence of multidrug resistance. Here we report the detection of a bla OXA23 carbapenemase-producing A. baumannii strain in a German patient with prosthetic hip joint infection following several hip joint surgeries but no history of foreign travel.
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Heteroresistance at the single-cell level: adapting to antibiotic stress through a population-based strategy and growth-controlled interphenotypic coordination. mBio 2014; 5:e00942-13. [PMID: 24520060 PMCID: PMC3950525 DOI: 10.1128/mbio.00942-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Heteroresistance refers to phenotypic heterogeneity of microbial clonal populations under antibiotic stress, and it has been thought to be an allocation of a subset of “resistant” cells for surviving in higher concentrations of antibiotic. The assumption fits the so-called bet-hedging strategy, where a bacterial population “hedges” its “bet” on different phenotypes to be selected by unpredicted environment stresses. To test this hypothesis, we constructed a heteroresistance model by introducing a blaCTX-M-14 gene (coding for a cephalosporin hydrolase) into a sensitive Escherichia coli strain. We confirmed heteroresistance in this clone and that a subset of the cells expressed more hydrolase and formed more colonies in the presence of ceftriaxone (exhibited stronger “resistance”). However, subsequent single-cell-level investigation by using a microfluidic device showed that a subset of cells with a distinguishable phenotype of slowed growth and intensified hydrolase expression emerged, and they were not positively selected but increased their proportion in the population with ascending antibiotic concentrations. Therefore, heteroresistance—the gradually decreased colony-forming capability in the presence of antibiotic—was a result of a decreased growth rate rather than of selection for resistant cells. Using a mock strain without the resistance gene, we further demonstrated the existence of two nested growth-centric feedback loops that control the expression of the hydrolase and maximize population growth in various antibiotic concentrations. In conclusion, phenotypic heterogeneity is a population-based strategy beneficial for bacterial survival and propagation through task allocation and interphenotypic collaboration, and the growth rate provides a critical control for the expression of stress-related genes and an essential mechanism in responding to environmental stresses. Heteroresistance is essentially phenotypic heterogeneity, where a population-based strategy is thought to be at work, being assumed to be variable cell-to-cell resistance to be selected under antibiotic stress. Exact mechanisms of heteroresistance and its roles in adaptation to antibiotic stress have yet to be fully understood at the molecular and single-cell levels. In our study, we have not been able to detect any apparent subset of “resistant” cells selected by antibiotics; on the contrary, cell populations differentiate into phenotypic subsets with variable growth statuses and hydrolase expression. The growth rate appears to be sensitive to stress intensity and plays a key role in controlling hydrolase expression at both the bulk population and single-cell levels. We have shown here, for the first time, that phenotypic heterogeneity can be beneficial to a growing bacterial population through task allocation and interphenotypic collaboration other than partitioning cells into different categories of selective advantage.
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Nosocomial Outbreak of Extensively and Pan Drug-Resistant Acinetobacter baumannii in Tertiary Hospital in Central Part of Iran. Jundishapur J Microbiol 2013. [DOI: 10.5812/jjm.9892] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Rezaee MA, Pajand O, Nahaei MR, Mahdian R, Aghazadeh M, Ghojazadeh M, Hojabri Z. Prevalence of Ambler class A β-lactamases and ampC expression in cephalosporin-resistant isolates of Acinetobacter baumannii. Diagn Microbiol Infect Dis 2013; 76:330-4. [PMID: 23726148 DOI: 10.1016/j.diagmicrobio.2013.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 03/14/2013] [Accepted: 04/09/2013] [Indexed: 01/31/2023]
Abstract
We examined the prevalence of various cephalosporins' resistance mechanisms in Acinetobacter baumannii clinical isolates. Phenotypic and molecular detection of Ambler classes A, B and D β-lactamases was performed on 75 isolates. Clonal relatedness was defined using Repetitive Extragenic Palindromic PCR. PCR mapping was used to examine the linkage of insertion sequences and the ampC gene, and ampC expression was analyzed by TaqMan reverse transcriptase-PCR. Twenty-six (37%) isolates carried at least one of the blaPER-1 or blaTEM-1. Sixty-nine (98.5%) out of 70 cephalosporin-resistant isolates had insertions upstream of the ampC gene, of which 48 (69%) and 6 (8%) were identified as ISAba1and ISAba125, respectively. Higher level of expression was obtained in resistant isolates lacking ISAba1/ampC combination in comparison with that in positive ones. The ability to up-regulate the expression of ampC gene in association with different insertion elements has become an important factor in A. baumannii resistance to cephalosporins.
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Affiliation(s)
- Mohammad Ahangarzadeh Rezaee
- Tabriz Research Center of Infectious and Tropical Diseases, Tabriz University of Medical Sciences, Tabriz 5163639888, Iran
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Virulence of Acinetobacter baumannii Exhibiting Phenotypic Heterogeneous Growth against Meropenem in a Murine Thigh Infection Model. Antibiotics (Basel) 2013; 2:73-82. [PMID: 27029293 PMCID: PMC4790299 DOI: 10.3390/antibiotics2010073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/16/2013] [Accepted: 03/01/2013] [Indexed: 11/17/2022] Open
Abstract
Acinetobacter baumannii may exhibit phenotypic heterogeneous growth under exposure to antibiotics. We investigated the in vitro characteristics of A. baumannii isolates grown heterogeneously in the presence of meropenem and their virulence evaluated in experimental infections treated with meropenem. Five clinical A. baumannii isolates and the respective heterogeneously grown subpopulations were tested by agar dilution minimum inhibitory concentration (MIC) testing, pulsed field gel electrophoresis (PFGE), population analysis using meropenem and growth curves. The virulence of isolates and the therapeutic efficacy of three meropenem dosing schemes was evaluated in a neutropenic murine thigh infection model. The clinical isolates were meropenem-susceptible (MICs 1 to 4 mg/liter) and exhibited three distinct PFGE patterns. In all clinical isolates, population analysis yielded heterogeneously grown colonies. After seven subcultures in antibiotic-free media, resistant MIC levels were retained in two isolates (heteroresistant), while three isolates were reversed to susceptible MICs (persisters). Clinical isolates and heterogeneous subpopulations had similar growth rates. The heterogeneously grown A. baumannii subpopulations had reduced virulence, killing considerably fewer animals than the respective clinical isolates without treatment. The meropenem treatment outcome was similar in infections caused by the clinical and the heterogeneous isolates, irrespective to their MICs. In vitro meropenem exposure induces phenotypic heterogeneous growth in A. baumannii. Compared with the parental clinical isolates, the heterogeneously grown subpopulations exhibited lower virulence, killing fewer mice and responding equally to meropenem treatment, despite their higher MICs.
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Epidemiological and clinical features associated with colonisation/infection by Acinetobacter baumannii with phenotypic heterogeneous resistance to carbapenems. Int J Antimicrob Agents 2012; 40:235-8. [DOI: 10.1016/j.ijantimicag.2012.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/16/2012] [Accepted: 05/04/2012] [Indexed: 11/17/2022]
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