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Abstract
Class C β-lactamases or cephalosporinases can be classified into two functional groups (1, 1e) with considerable molecular variability (≤20% sequence identity). These enzymes are mostly encoded by chromosomal and inducible genes and are widespread among bacteria, including Proteobacteria in particular. Molecular identification is based principally on three catalytic motifs (64SXSK, 150YXN, 315KTG), but more than 70 conserved amino-acid residues (≥90%) have been identified, many close to these catalytic motifs. Nevertheless, the identification of a tiny, phylogenetically distant cluster (including enzymes from the genera Legionella, Bradyrhizobium, and Parachlamydia) has raised questions about the possible existence of a C2 subclass of β-lactamases, previously identified as serine hydrolases. In a context of the clinical emergence of extended-spectrum AmpC β-lactamases (ESACs), the genetic modifications observed in vivo and in vitro (point mutations, insertions, or deletions) during the evolution of these enzymes have mostly involved the Ω- and H-10/R2-loops, which vary considerably between genera, and, in some cases, the conserved triplet 150YXN. Furthermore, the conserved deletion of several amino-acid residues in opportunistic pathogenic species of Acinetobacter, such as A. baumannii, A. calcoaceticus, A. pittii and A. nosocomialis (deletion of residues 304-306), and in Hafnia alvei and H. paralvei (deletion of residues 289-290), provides support for the notion of natural ESACs. The emergence of higher levels of resistance to β-lactams, including carbapenems, and to inhibitors such as avibactam is a reality, as the enzymes responsible are subject to complex regulation encompassing several other genes (ampR, ampD, ampG, etc.). Combinations of resistance mechanisms may therefore be at work, including overproduction or change in permeability, with the loss of porins and/or activation of efflux systems.
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Liu S, Huang N, Zhou C, Lin Y, Zhang Y, Wang L, Zheng X, Zhou T, Wang Z. Molecular Mechanisms and Epidemiology of Carbapenem-Resistant Enterobacter cloacae Complex Isolated from Chinese Patients During 2004-2018. Infect Drug Resist 2021; 14:3647-3658. [PMID: 34522107 PMCID: PMC8434891 DOI: 10.2147/idr.s327595] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/02/2021] [Indexed: 12/17/2022] Open
Abstract
Background The emergence and spread of carbapenem-resistant Enterobacter cloacae complex (ECC) have posed a serious threat to human health worldwide. This study aimed to investigate the molecular mechanism of carbapenem resistance and its prevalence among ECC in China. Methods A total of 1314 ECC clinical isolates were collected from the First Affiliated Hospital of Wenzhou Medical University from 2004 to 2018. Sensitivity to antibiotics was determined using the agar dilution method. The production of carbapenemases and the prevalence of resistance-associated genes were investigated using PCR. The expression of outer membrane porin (OMP) genes (ompC/ompF) and cephalosporinase gene ampC was analyzed by quantitative real-time PCR. The effect of efflux pump mechanism on carbapenem resistance was tested. ECC was typed by multilocus sequence typing (MLST). Results In this study, 113 carbapenem-nonsusceptible ECC strains were identified. The prevalence rates of carbapenemase genes bla KPC-2 and bla NDM were 12.4% (14/113) and 17.7% (20/113), and that of the extended-spectrum β-lactamase (ESBL) genes bla CTX-M, bla TEM, and bla SHV were 28.3% (32/113), 27.4% (31/113), and 14.2% (16/113), respectively. Among 67 carbapenem-nonsusceptible ECC isolates producing non-carbapenemase, low expression of ompC/ompF and overexpression of ampC were found in 46 and 40 strains, respectively. In addition, the carbapenem resistance was related to the overexpression of the efflux pump in the study. Finally, the 113 carbapenem-nonsusceptible ECC strains were categorized into 39 different sequence types using MLST. Conclusion Carbapenem-nonsusceptible ECC strains producing non-carbapenemase were predominant. The low expression of OMP with the overexpression of cephalosporinase or production of ESBLs and overexpression of efflux pump might contribute to the resistance to carbapenem for carbapenem-nonsusceptible ECC strains producing non-carbapenemase. The bla NDM and bla KPC comprised the principal resistance mechanism of carbapenemase-producing ECC in the hospital, causing a threat to public health. Therefore, monitoring programs to prevent the emergence and further spread of antibiotic resistance are urgently needed.
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Affiliation(s)
- Shixing Liu
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Na Huang
- 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
| | - Yishuai Lin
- School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Ying Zhang
- School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Lingbo Wang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
| | - Xiangkuo Zheng
- Department of Clinical Laboratory, The First Affiliated Hospital of 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
| | - Zhongyong Wang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, People's Republic of China
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Khalifa SM, Abd El-Aziz AM, Hassan R, Abdelmegeed ES. β-lactam resistance associated with β-lactamase production and porin alteration in clinical isolates of E. coli and K. pneumoniae. PLoS One 2021; 16:e0251594. [PMID: 34014957 PMCID: PMC8136739 DOI: 10.1371/journal.pone.0251594] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/28/2021] [Indexed: 12/23/2022] Open
Abstract
β-lactam resistance represents a worldwide problem and a serious challenge for antimicrobial treatment. Hence this research was conducted to recognize several mechanisms mediating β-lactam resistance in E. coli and K. pneumoniae clinical isolates collected from Mansoura University hospitals, Egypt. A total of 80 isolates, 45 E. coli and 35 K. pneumoniae isolates, were collected and their antibiotic susceptibility was determined by the Disc diffusion method followed by phenotypic and genotypic detection of extended-spectrum β-lactamases (ESBLs), AmpC β-lactamase, carbapenemase enzymes. The outer membrane protein porins of all isolates were analyzed and their genes were examined using gene amplification and sequencing. Also, the resistance to complement-mediated serum killing was estimated. A significant percentage of isolates (93.8%) were multidrug resistance and showed an elevated resistance to β-lactam antibiotics. The presence of either ESBL or AmpC enzymes was high among isolates (83.75%). Also, 60% of the isolated strains were carbapenemase producers. The most frequently detected gene of ESBL among all tested isolates was blaCTX-M-15 (86.3%) followed by blaTEM-1 (81.3%) and blaSHV-1 (35%) while the Amp-C gene was present in 83.75%. For carbapenemase-producing isolates, blaNDM1 was the most common (60%) followed by blaVIM-1 (35%) and blaOXA-48 (13.8%). Besides, 73.3% and 40% of E. coli and K. pneumoniae isolates respectively were serum resistant. Outer membrane protein analysis showed that 93.3% of E. coli and 95.7% of K. pneumoniae isolates lost their porins or showed modified porins. Furthermore, sequence analysis of tested porin genes in some isolates revealed the presence of frameshift mutations that produced truncated proteins of smaller size. β-lactam resistance in K. pneumoniae and E. coli isolates in our hospitals is due to a combination of β-lactamase activity and porin loss/alteration. Hence more restrictions should be applied on β-lactams usage to decrease the emergence of resistant strains.
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Affiliation(s)
- Sara M. Khalifa
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Abeer M. Abd El-Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
- * E-mail: ,
| | - Ramadan Hassan
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Eman S. Abdelmegeed
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
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Pfaendler HR, Schmidt HU, Freidank H. The Novel CarbaLux Test for Carbapenemases and Carbapenem Deactivating AmpC Beta-Lactamases. Front Microbiol 2020; 11:588887. [PMID: 33329464 PMCID: PMC7719632 DOI: 10.3389/fmicb.2020.588887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
Objectives To evaluate the rapid phenotypic CarbaLux test for routine diagnostics in the medical laboratory in a proof of concept study. Methods isolates of Gram-negative bacteria suspicious for carbapenem resistance including Enterobacterales (67), Pseudomonas (10), Acinetobacter (5), and Stenotrophomonas (1) species, collected between 2016 and 2018 from in-patients, were tested for carbapenemase activity using a novel fluorescent carbapenem. When subjected to extracted bacterial carbapenemases its fluorescence disappears. All bacteria to be tested were cultured on Columbia blood agar and few on other commercial media. MALDI TOF MS, molecular assays, automated MIC testing, and in part, agar diffusion tests served to characterize the isolates. For comparison, few selected bacteria were also investigated by prior phenotypic tests for carbapenemase detection. Results Under UV light, the CarbaLux test allowed a rapid detection of 39/39 carbapenemase-producing bacteria, including 15 isolates with OXA carbapenemases (e.g., OXA-23, OXA-24/40-like OXA-48-like or OXA-181). Several isolates had low MICs but still expressed carbapenemases. Among Enterobacter spp., it detected six strains with hyper-produced AmpC beta-lactamases, which deactivated carbapenems but were not detectable by prior rapid phenotypic assays. An unexpected high carbapenemase activity appeared with these enzymes. They were identified as AmpC variants by inhibition with cloxacillin. Conclusion Other than prior rapid phenotypic assessments for carbapenemases, which use secondary effects such as a change of pH, the inactivation of the fluorescent carbapenem substrate can be visualized directly under UV light. The new test works at 100 to 200-fold lower, therapy-like substrate concentrations. It takes advantage of the high substrate affinity to carbapenemases allowing also the detection of less reactive resistance enzymes via a trapping mechanism, even from bacteria, which might appear unsuspicious from initial antibiograms. The novel fluorescence method allows simple and safe handling, reliable readings, and documentation and is suitable for primary testing in the clinical laboratory.
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Affiliation(s)
| | | | - Heike Freidank
- Department of Medical Microbiology, München Klinik gGmbH, Munich, Germany
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Girlich D, Bonnin RA, Dortet L, Naas T. Genetics of Acquired Antibiotic Resistance Genes in Proteus spp. Front Microbiol 2020; 11:256. [PMID: 32153540 PMCID: PMC7046756 DOI: 10.3389/fmicb.2020.00256] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/03/2020] [Indexed: 01/30/2023] Open
Abstract
Proteus spp. are commensal Enterobacterales of the human digestive tract. At the same time, P. mirabilis is commonly involved in urinary tract infections (UTI). P. mirabilis is naturally resistant to several antibiotics including colistin and shows reduced susceptibility to imipenem. However higher levels of resistance to imipenem commonly occur in P. mirabilis isolates consecutively to the loss of porins, reduced expression of penicillin binding proteins (PBPs) PBP1a, PBP2, or acquisition of several antibiotic resistance genes, including carbapenemase genes. In addition, resistance to non-β-lactams is also frequently reported including molecules used for treating UTI infections (e.g., fluoroquinolones, nitrofurans). Emergence and spread of multidrug resistant P. mirabilis isolates, including those producing ESBLs, AmpC cephalosporinases and carbapenemases, are being more and more frequently reported. This review covers Proteus spp. with a focus on the different genetic mechanisms involved in the acquisition of resistance genes to multiple antibiotic classes turning P. mirabilis into a dreadful pandrug resistant bacteria and resulting in difficult to treat infections.
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Affiliation(s)
- Delphine Girlich
- EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", LabEx Lermit, Faculty of Medicine, Université Paris-Saclay, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance: Carbapenemase-producing Enterobacteriaceae, Le Kremlin-Bicêtre, France.,Evolution and Ecology of Resistance to Antibiotics Unit, Institut Pasteur - APHP - Université Paris-Saclay, Paris, France
| | - Rémy A Bonnin
- EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", LabEx Lermit, Faculty of Medicine, Université Paris-Saclay, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance: Carbapenemase-producing Enterobacteriaceae, Le Kremlin-Bicêtre, France.,Evolution and Ecology of Resistance to Antibiotics Unit, Institut Pasteur - APHP - Université Paris-Saclay, Paris, France
| | - Laurent Dortet
- EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", LabEx Lermit, Faculty of Medicine, Université Paris-Saclay, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance: Carbapenemase-producing Enterobacteriaceae, Le Kremlin-Bicêtre, France.,Evolution and Ecology of Resistance to Antibiotics Unit, Institut Pasteur - APHP - Université Paris-Saclay, Paris, France
| | - Thierry Naas
- EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", LabEx Lermit, Faculty of Medicine, Université Paris-Saclay, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance: Carbapenemase-producing Enterobacteriaceae, Le Kremlin-Bicêtre, France.,Evolution and Ecology of Resistance to Antibiotics Unit, Institut Pasteur - APHP - Université Paris-Saclay, Paris, France
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Palwe S, Khobragade K, Kharat AS. Preserving the Dwindling β-lactams-Based Empiric Therapy Options for Gram-Negative Infections in Challenging Resistance Scenario: Lessons Learned and Way Forward. Microb Drug Resist 2019; 26:637-651. [PMID: 31851576 DOI: 10.1089/mdr.2019.0195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Appropriate empiric therapy reduces mortality and morbidity associated with serious Gram-negative infections. β-lactams (BLs) owing to their safety, efficacy, and coverage spectrum are the most preferred agents for empiric use. Inappropriate use of older penicillins and cephalosporins led to selection and spread of resistant clones. As a result, these valuable agents have lost their reliability compelling clinicians to often use erstwhile last-line therapies such as carbapenems. Excessive carbapenems use imposed collateral damage by selecting difficult-to-treat carbapenem-resistant organisms. Lack of empiric therapeutic options amenable for use in infections caused by contemporary pathogens was realized by the pharmaceutical industry leading to intensive efforts in discovering novel antibiotics. These efforts led to the approval of newer β-lactams and β-lactamase inhibitor (BL-BLI) combination. This review elaborates the past trends in empirical use of BLs and ensuing patterns of resistance emergence in Gram-negatives. Furthermore, a critical appraisal of newer BL-BLIs has been presented to identify the appropriate clinical situations for their use to ensure clinical efficacy coupled with minimal resistance selection. These learning have been derived from past trends of clinical usage of older empiric therapies so that the therapeutic utility of newer agents is preserved for long in light of dwindling global antibiotics pipeline.
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Affiliation(s)
- Snehal Palwe
- Department of Environmental Science, SB College of Science, Aurangabad, India
| | - Kshama Khobragade
- Department of Environmental Science, SB College of Science, Aurangabad, India
| | - Arun S Kharat
- Laboratory of Microbiology, Jawaharlal Nehru University, New Delhi, India
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Davin-Regli A, Lavigne JP, Pagès JM. Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance. Clin Microbiol Rev 2019; 32:e00002-19. [PMID: 31315895 PMCID: PMC6750132 DOI: 10.1128/cmr.00002-19] [Citation(s) in RCA: 250] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The genus Enterobacter is a member of the ESKAPE group, which contains the major resistant bacterial pathogens. First described in 1960, this group member has proven to be more complex as a result of the exponential evolution of phenotypic and genotypic methods. Today, 22 species belong to the Enterobacter genus. These species are described in the environment and have been reported as opportunistic pathogens in plants, animals, and humans. The pathogenicity/virulence of this bacterium remains rather unclear due to the limited amount of work performed to date in this field. In contrast, its resistance against antibacterial agents has been extensively studied. In the face of antibiotic treatment, it is able to manage different mechanisms of resistance via various local and global regulator genes and the modulation of the expression of different proteins, including enzymes (β-lactamases, etc.) or membrane transporters, such as porins and efflux pumps. During various hospital outbreaks, the Enterobacter aerogenes and E. cloacae complex exhibited a multidrug-resistant phenotype, which has stimulated questions about the role of cascade regulation in the emergence of these well-adapted clones.
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Affiliation(s)
- Anne Davin-Regli
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
| | - Jean-Philippe Lavigne
- Department of Microbiology, U1047, INSERM, University Montpellier and University Hospital Nîmes, Nîmes, France
| | - Jean-Marie Pagès
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
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Davin-Regli A, Pagès JM. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment. Front Microbiol 2015; 6:392. [PMID: 26042091 PMCID: PMC4435039 DOI: 10.3389/fmicb.2015.00392] [Citation(s) in RCA: 300] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/16/2015] [Indexed: 12/14/2022] Open
Abstract
Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.
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Affiliation(s)
- Anne Davin-Regli
- Transporteurs Membranaires, Chimiorésistance et Drug Design, Facultés de Médecine et Pharmacie, UMR-MD1, IRBA - Aix-Marseille Université, Marseille France
| | - Jean-Marie Pagès
- Transporteurs Membranaires, Chimiorésistance et Drug Design, Facultés de Médecine et Pharmacie, UMR-MD1, IRBA - Aix-Marseille Université, Marseille France
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Chia J, Siu L, Su L, Lin H, Kuo A, Lee M, Wu T. Emergence of Carbapenem-ResistantEscherichia Coliin Taiwan: Resistance Due to Combined CMY-2 Production and Porin Deficiency. J Chemother 2013; 21:621-6. [DOI: 10.1179/joc.2009.21.6.621] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Dahmen S, Mansour W, Charfi K, Boujaafar N, Arlet G, Bouallègue O. Imipenem Resistance inKlebsiella pneumoniaeIs Associated to the Combination of Plasmid-Mediated CMY-4 AmpC β-Lactamase and Loss of an Outer Membrane Protein. Microb Drug Resist 2012; 18:479-83. [DOI: 10.1089/mdr.2011.0214] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Safia Dahmen
- Infections with Multiresistant Bacteria to Antibiotics (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
- Department of Bacteriology, University of Medicine Pierre and Marie Curie, Paris VI, Paris, France
| | - Wejdène Mansour
- Infections with Multiresistant Bacteria to Antibiotics (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
| | - Karama Charfi
- Infections with Multiresistant Bacteria to Antibiotics (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
| | - Noureddine Boujaafar
- Infections with Multiresistant Bacteria to Antibiotics (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
| | - Guillaume Arlet
- Department of Bacteriology, University of Medicine Pierre and Marie Curie, Paris VI, Paris, France
| | - Olfa Bouallègue
- Infections with Multiresistant Bacteria to Antibiotics (UR/29/04), Department of Microbiology, University Hospital of Sahloul, Sousse, Tunisia
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Papp-Wallace KM, Endimiani A, Taracila MA, Bonomo RA. Carbapenems: past, present, and future. Antimicrob Agents Chemother 2011; 55:4943-60. [PMID: 21859938 PMCID: PMC3195018 DOI: 10.1128/aac.00296-11] [Citation(s) in RCA: 877] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In this review, we summarize the current "state of the art" of carbapenem antibiotics and their role in our antimicrobial armamentarium. Among the β-lactams currently available, carbapenems are unique because they are relatively resistant to hydrolysis by most β-lactamases, in some cases act as "slow substrates" or inhibitors of β-lactamases, and still target penicillin binding proteins. This "value-added feature" of inhibiting β-lactamases serves as a major rationale for expansion of this class of β-lactams. We describe the initial discovery and development of the carbapenem family of β-lactams. Of the early carbapenems evaluated, thienamycin demonstrated the greatest antimicrobial activity and became the parent compound for all subsequent carbapenems. To date, more than 80 compounds with mostly improved antimicrobial properties, compared to those of thienamycin, are described in the literature. We also highlight important features of the carbapenems that are presently in clinical use: imipenem-cilastatin, meropenem, ertapenem, doripenem, panipenem-betamipron, and biapenem. In closing, we emphasize some major challenges and urge the medicinal chemist to continue development of these versatile and potent compounds, as they have served us well for more than 3 decades.
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Affiliation(s)
- Krisztina M. Papp-Wallace
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106
- Departments of Medicine
| | - Andrea Endimiani
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106
- Institute for Infectious Diseases, University of Bern 3010, Bern, Switzerland
- Departments of Medicine
| | | | - Robert A. Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106
- Departments of Medicine
- Pharmacology
- Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106
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Comparative evaluation of a chromogenic agar medium, the modified Hodge test, and a battery of meropenem-inhibitor discs for detection of carbapenemase activity in Enterobacteriaceae. J Clin Microbiol 2011; 49:1965-9. [PMID: 21430097 DOI: 10.1128/jcm.00203-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three phenotypic methods (modified Hodge test, chromogenic agar, and meropenem discs combined with specific inhibitors) used for the detection of carbapenemase activity were tested on a panel of characterized Enterobacteriaceae expressing various β-lactamase mechanisms. Overall, the meropenem-plus-inhibitor approach was more sensitive and specific than the other methods, despite its limitation of being unable to detect class D carbapenemases.
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Chia JH, Su LH, Lee MH, Kuo AJ, Shih NY, Siu LK, Wu TL. Development of High-Level Carbapenem Resistance inKlebsiella pneumoniaeAmong Patients with Prolonged Hospitalization and Carbapenem Exposure. Microb Drug Resist 2010; 16:317-25. [DOI: 10.1089/mdr.2009.0048] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ju-Hsin Chia
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan
| | - Lin-Hui Su
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan
| | - Ming-Hsun Lee
- Division of Infectious Diseases, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - An-Jing Kuo
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan
| | - Neng-Yao Shih
- Cancer Institute, National Health Research Institutes, Taipei, Taiwan
| | - Leung Kei Siu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan
- Unit of Infectious Diseases, Division of Clinical Research, National Health Research Institutes, Taipei, Taiwan
| | - Tsu-Lan Wu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan
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15
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Integron mobilization unit as a source of mobility of antibiotic resistance genes. Antimicrob Agents Chemother 2009; 53:2492-8. [PMID: 19332679 DOI: 10.1128/aac.00033-09] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Antibiotic resistance genes are spread mostly through plasmids, integrons (as a form of gene cassettes), and transposons in gram-negative bacteria. We describe here a novel genetic structure, named the integron mobilization unit (IMU), that has characteristics similar to those of miniature inverted transposable elements (MITEs). Two IMUs (288 bp each) were identified from a carbapenem-resistant Enterobacter cloacae isolate that formed a composite structure encompassing a defective class 1 integron containing the carbapenem resistance gene bla(GES-5). This beta-lactamase gene was located on a 7-kb IncQ-type plasmid named pCHE-A, which was sequenced completely. The plasmid pCHE-A was not self conjugative but was mobilizable, and it was successfully transferred from E. cloacae to Pseudomonas aeruginosa. The in silico analysis of the extremities of the IMU elements identified similarities with those of insertion sequence ISSod9 from Shewanella oneidensis MR-1. The mobilization of the IMU composite structure was accomplished by using the transposase activity of ISSod9 that was provided in trans. This is the first identification of MITE-type structures as a source of gene mobilization, implicating here a clinically relevant antibiotic resistance gene.
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Abstract
SUMMARY AmpC beta-lactamases are clinically important cephalosporinases encoded on the chromosomes of many of the Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and beta-lactamase inhibitor-beta-lactam combinations. In many bacteria, AmpC enzymes are inducible and can be expressed at high levels by mutation. Overexpression confers resistance to broad-spectrum cephalosporins including cefotaxime, ceftazidime, and ceftriaxone and is a problem especially in infections due to Enterobacter aerogenes and Enterobacter cloacae, where an isolate initially susceptible to these agents may become resistant upon therapy. Transmissible plasmids have acquired genes for AmpC enzymes, which consequently can now appear in bacteria lacking or poorly expressing a chromosomal bla(AmpC) gene, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Resistance due to plasmid-mediated AmpC enzymes is less common than extended-spectrum beta-lactamase production in most parts of the world but may be both harder to detect and broader in spectrum. AmpC enzymes encoded by both chromosomal and plasmid genes are also evolving to hydrolyze broad-spectrum cephalosporins more efficiently. Techniques to identify AmpC beta-lactamase-producing isolates are available but are still evolving and are not yet optimized for the clinical laboratory, which probably now underestimates this resistance mechanism. Carbapenems can usually be used to treat infections due to AmpC-producing bacteria, but carbapenem resistance can arise in some organisms by mutations that reduce influx (outer membrane porin loss) or enhance efflux (efflux pump activation).
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Genetic and structural insights into the dissemination potential of the extremely broad-spectrum class A beta-lactamase KPC-2 identified in an Escherichia coli strain and an Enterobacter cloacae strain isolated from the same patient in France. Antimicrob Agents Chemother 2008; 52:3725-36. [PMID: 18625772 DOI: 10.1128/aac.00163-08] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two clinical strains of Escherichia coli (2138) and Enterobacter cloacae (7506) isolated from the same patient in France and showing resistance to extended-spectrum cephalosporins and low susceptibility to imipenem were investigated. Both strains harbored the plasmid-contained bla(TEM-1) and bla(KPC-2) genes. bla(KLUC-2), encoding a mutant of the chromosomal beta-lactamase of Kluyvera cryocrescens, was also identified at a plasmid location in E. cloacae 7506, suggesting the ISEcp1-assisted escape of bla(KLUC) from the chromosome. Determination of the KPC-2 structure at 1.6 A revealed that the binding site was occupied by the C-terminal (C-ter) residues coming from a symmetric KPC-2 monomer, with the ultimate C-ter Glu interacting with Ser130, Lys234, Thr235, and Thr237 in the active site. This mode of binding can be paralleled to the inhibition of the TEM-1 beta-lactamase by the inhibitory protein BLIP. Determination of the 1.23-A structure of a KPC-2 mutant in which the five C-ter residues were deleted revealed that the catalytic site was filled by a citrate molecule. Structure analysis and docking simulations with cefotaxime and imipenem provided further insights into the molecular basis of the extremely broad spectrum of KPC-2, which behaves as a cefotaximase with significant activity against carbapenems. In particular, residues 104, 105, 132, and 167 draw a binding cavity capable of accommodating both the aminothiazole moiety of cefotaxime and the 6 alpha-hydroxyethyl group of imipenem, with the binding of the former drug being also favored by a significant degree of freedom at the level of the loop at positions 96 to 105 and by an enlargement of the binding site at the end of strand beta 3.
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18
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Identification of a novel multidrug efflux pump of Mycobacterium tuberculosis. Antimicrob Agents Chemother 2008; 52:2503-11. [PMID: 18458127 DOI: 10.1128/aac.00298-08] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The impermeability of the outer membrane in combination with drug efflux are major determinants of the natural drug resistance of mycobacteria. beta-Lactams are the most widely used antibiotics for treatment of bacterial infections. However, it is unknown how beta-lactams enter Mycobacterium tuberculosis and whether efflux pumps exist that can export these drugs out of the cell. To identify the molecular mechanisms of M. tuberculosis resistance to beta-lactams, a library of 7,500 transposon mutants was generated in the model organism Mycobacterium bovis BCG. Thirty-three unique insertion sites were determined that conferred medium or high-level (> or =2,000 microg/ml) resistance to ampicillin. Three mutants in sulfolipid synthesis or transport were highly resistant to ampicillin, indicating an indirect effect of the lipid composition on the outer membrane permeability of M. bovis BCG to ampicillin. Mutants with insertions in genes encoding surface molecules such as PPE proteins or lipoarabinomannan were also completely resistant to ampicillin, thus suggesting a lack of transport across the outer membrane. Insertion of the transposon in front of bcg0231 increased transcription of the gene and concomitantly the resistance of M. bovis BCG to ampicillin, streptomycin, and chloramphenicol by 32- to 64-fold. Resistance to vancomycin and tetracycline was increased four- to eightfold. Bcg0231 and Rv0194 are almost identical ATP-binding cassette transporters. Expression of rv0194 significantly reduced accumulation of ethidium bromide and conferred multidrug resistance to Mycobacterium smegmatis. Both effects were abrogated in the presence of the efflux pump inhibitor reserpine. These results demonstrate that Rv0194 is a novel multidrug efflux pump of M. tuberculosis.
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19
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Samra Z, Ofir O, Lishtzinsky Y, Madar-Shapiro L, Bishara J. Outbreak of carbapenem-resistant Klebsiella pneumoniae producing KPC-3 in a tertiary medical centre in Israel. Int J Antimicrob Agents 2007; 30:525-9. [DOI: 10.1016/j.ijantimicag.2007.07.024] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 07/31/2007] [Accepted: 07/31/2007] [Indexed: 10/22/2022]
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20
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Abstract
Carbapenems, such as imipenem and meropenem, are most often used to treat infections caused by enterobacteria that produce extended-spectrum beta-lactamases, and the emergence of enzymes capable of inactivating carbapenems would therefore limit the options for treatment. Carbapenem resistance in Enterobacteriaceae is rare, but class A beta-lactamases with activity against the carbapenems are becoming more prevalent within this bacterial family. The class A carbapenemases can phylogenetically be segregated into six different groups of which four groups are formed by members of the GES, KPC, SME, IMI/NMC-A enzymes, while SHV-38 and SFC-1 each separately constitute a group. The genes encoding the class A carbapenemases are either plasmid-borne or located on the chromosome of the host. The bla(GES) genes reside as gene cassettes on mainly class I integrons, whereas the bla(KPC) genes and a single bla(IMI-2) gene are flanked by transposable elements on plasmids. Class A carbapenemases hydrolyse penicillins, classical cephalosporins, monobactam, and imipenem and meropenem, and the enzymes are divided into four phenotypically different groups, namely group 2br, 2be, 2e and 2f, according to the Bush-Jacoby-Medeiros classification system. Class A carbapenemases are inhibited by clavulanate and tazobactam like other class A beta-lactamases.
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Affiliation(s)
- Jan Walther-Rasmussen
- Department of Clinical Microbiology, 9301, Rigshospitalet, National University Hospital, Copenhagen, Denmark.
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21
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Hakimelahi GH, Moosavi-Movahedi AA, Saboury AA, Osetrov V, Khodarahmi GA, Shia KS. Carbapenem-based prodrugs. Design, synthesis, and biological evaluation of carbapenems. Eur J Med Chem 2005; 40:339-49. [PMID: 15804533 DOI: 10.1016/j.ejmech.2004.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2004] [Accepted: 11/03/2004] [Indexed: 11/18/2022]
Abstract
Syntheses of racemic trans-3-hydroxycarbonyl-6-(phenylacetamido)carbapenem (13), trans-3-phosphono-6-(phenylacetamido)carbapenem (17), and beta-lactam based prodrugs 19 and 22 were accomplished. Carbapenem 13 was found to possess antibacterial activity, comparable with imipenem (+)-3, against Staphylococcus aureus FDA 209P, S. aureus 95, Escherichia coli ATCC 39188, Klebsiella pneumoniae NCTC 418, Pseudomonas aeruginosa 1101-75, P. aeruginosa 18S-H, and Xanthomonas maltophilia GN 12873. Like imipenem ((+)-3), carbapenem 13 was not stable to X. maltophilia oxyiminocephalosporinase type II. Its phosphonate analog 17, however, was neither a significant antibacterial agent nor a good beta-lactamase inhibitor. Chemical combinations of trans carbapenem 13 with cis carbapenem 6 (compound 19) as well as clavulanic acid (20) with cis carbapenem 6 (compound 22) via a tetrachloroethane linker exhibited remarkable activity against beta-lactamase producing microorganisms in vitro.
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22
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TavÃo MM, Perilli M, Vila J, Becerro P, Casañas L, Amicosante G, Teresa Jiménez de Anta M. Salicylate decreases production of AmpC type β-lactamases and increases susceptibility to β-lactams in a Morganella morganiiclinical isolate. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09748.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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23
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Bradford PA, Bratu S, Urban C, Visalli M, Mariano N, Landman D, Rahal JJ, Brooks S, Cebular S, Quale J. Emergence of Carbapenem-Resistant Klebsiella Species Possessing the Class A Carbapenem-Hydrolyzing KPC-2 and Inhibitor-Resistant TEM-30 -Lactamases in New York City. Clin Infect Dis 2004; 39:55-60. [PMID: 15206053 DOI: 10.1086/421495] [Citation(s) in RCA: 362] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Accepted: 02/07/2004] [Indexed: 11/04/2022] Open
Abstract
Nineteen isolates of carbapenem-resistant Klebsiella species were recovered from 7 hospitals in New York City. Most K. pneumoniae belonged to a single ribotype. Nucleotide sequencing identified KPC-2, a carbapenem-hydrolyzing beta -lactamase. In 3 strains, TEM-30, an inhibitor-resistant beta -lactamase, was detected. Carbapenem-resistant Klebsiella species possessing KPC-2 are endemic in New York City. This study documents the identification of an inhibitor-resistant TEM beta -lactamase in the United States.
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24
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Yigit H, Queenan AM, Rasheed JK, Biddle JW, Domenech-Sanchez A, Alberti S, Bush K, Tenover FC. Carbapenem-resistant strain of Klebsiella oxytoca harboring carbapenem-hydrolyzing beta-lactamase KPC-2. Antimicrob Agents Chemother 2003; 47:3881-9. [PMID: 14638498 PMCID: PMC296202 DOI: 10.1128/aac.47.12.3881-3889.2003] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2003] [Revised: 07/14/2003] [Accepted: 08/31/2003] [Indexed: 11/20/2022] Open
Abstract
We investigated a Klebsiella oxytoca isolate demonstrating resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The MICs of both imipenem and meropenem were 32 microg/ml. The beta-lactamase activity against imipenem and meropenem was inhibited in the presence of clavulanic acid. Isoelectric focusing studies demonstrated five beta-lactamases with pIs of 8.2 (SHV-46), 6.7 (KPC-2), 6.5 (unknown), 6.4 (probable OXY-2), and 5.4 (TEM-1). The presence of the bla(SHV) and bla(TEM) genes was confirmed by specific PCR assays and DNA sequence analysis. Transformation and conjugation studies with Escherichia coli showed that the beta-lactamase with a pI of 6.7, Klebsiella pneumoniae carbapenemase-2 (KPC-2), was encoded on an approximately 70-kb conjugative plasmid that also carried SHV-46, TEM-1, and the beta-lactamase with a pI of 6.5. The bla(KPC-2) determinant was cloned in E. coli and conferred resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The amino acid sequence of KPC-2 showed a single amino acid difference, S174G, when compared with KPC-1, another carbapenem-hydrolyzing beta-lactamase from K. pneumoniae 1534. Hydrolysis studies showed that purified KPC-2 hydrolyzed not only carbapenems but also penicillins, cephalosporins, and aztreonam. KPC-2 had the highest affinity for meropenem. The kinetic studies revealed that KPC-2 was inhibited by clavulanic acid and tazobactam. An examination of the outer membrane proteins of the parent K. oxytoca strain demonstrated that it expressed detectable levels of OmpK36 (the homolog of OmpC) and a higher-molecular-weight OmpK35 (the homolog of OmpF). Thus, carbapenem resistance in K. oxytoca 3127 is due to production of the Bush group 2f, class A, carbapenem-hydrolyzing beta-lactamase KPC-2. This beta-lactamase is likely located on a transposon that is part of a conjugative plasmid and thus has a very high potential for dissemination.
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Affiliation(s)
- Hesna Yigit
- Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, Connecticut 06492, USA
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25
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Steward CD, Mohammed JM, Swenson JM, Stocker SA, Williams PP, Gaynes RP, McGowan JE, Tenover FC. Antimicrobial susceptibility testing of carbapenems: multicenter validity testing and accuracy levels of five antimicrobial test methods for detecting resistance in Enterobacteriaceae and Pseudomonas aeruginosa isolates. J Clin Microbiol 2003; 41:351-8. [PMID: 12517872 PMCID: PMC149638 DOI: 10.1128/jcm.41.1.351-358.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
From January 1996 to May 1999, Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology) received 448 nonduplicate clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa that were reported to be imipenem intermediate or resistant. However, broth microdilution (BMD) confirmatory testing at the Project ICARE central laboratory confirmed this result in only 11 of 123 (8.9%) Enterobacteriaceae isolates and 241 of 325 (74.2%) P. aeruginosa isolates. To investigate this overdetection of imipenem resistance, we tested 204 selected isolates from the Project ICARE collection plus five imipenem-resistant challenge strains at the Centers for Disease Control and Prevention against imipenem and meropenem by agar dilution, disk diffusion, Etest (AB BIODISK North America, Inc., Piscataway, N.J.), two MicroScan WalkAway conventional panels (Neg MIC Plus 3 and Neg Urine Combo 3) (Dade MicroScan, Inc., West Sacramento, Calif.), and two Vitek cards (GNS-116 containing meropenem and GNS-F7 containing imipenem) (bioMérieux Vitek, Inc., Durham, N.C.). The results of each test method were compared to the results of BMD testing using in-house-prepared panels. Seven imipenem-resistant and five meropenem-resistant isolates of Enterobacteriaceae and 43 imipenem-resistant and 21 meropenem-resistant isolates of P. aeruginosa were identified by BMD. For Enterobacteriaceae, the imipenem and meropenem test methods produced low numbers of very major and major errors. All test systems in the study produced low numbers of very major and major errors when P. aeruginosa was tested against imipenem and meropenem, except for Vitek testing (major error rate for imipenem, 20%). Further testing conducted in 11 of the participating ICARE hospital laboratories failed to pinpoint the factors responsible for the initial overdetection of imipenem resistance. However, this study demonstrated that carbapenem testing difficulties do exist and that laboratories should consider using a second, independent antimicrobial susceptibility testing method to validate carbapenem-intermediate and -resistant results.
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Affiliation(s)
- Christine D Steward
- Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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26
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Essack SY. The development of beta-lactam antibiotics in response to the evolution of beta-lactamases. Pharm Res 2001; 18:1391-9. [PMID: 11697463 DOI: 10.1023/a:1012272403776] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
beta-Lactam antibiotics, viz., penicillin, penicillin derivatives, cephalosporins, cephamycins, carbapenems, monobactams. and monocarbams, are the most widely used of all antimicrobial classes by virtue of their high efficacy and specificity and the availability of several derivatives. The expression of one or several beta-lactamases (beta-lactam antibiotic-inactivating enzymes) represents the most widespread and the most clinically relevant resistance mechanism to these antibiotics. The development of beta-lactam antibiotics has thus been a continuous battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of beta-lactamases. This article traces antibiotic development in response to the evolution of beta-lactamases.
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Affiliation(s)
- S Y Essack
- School of Pharmacy and Pharmacology, University of Durban-Westville, South Africa.
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27
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Livermore DM, Carter MW, Bagel S, Wiedemann B, Baquero F, Loza E, Endtz HP, van Den Braak N, Fernandes CJ, Fernandes L, Frimodt-Moller N, Rasmussen LS, Giamarellou H, Giamarellos-Bourboulis E, Jarlier V, Nguyen J, Nord CE, Struelens MJ, Nonhoff C, Turnidge J, Bell J, Zbinden R, Pfister S, Mixson L, Shungu DL. In vitro activities of ertapenem (MK-0826) against recent clinical bacteria collected in Europe and Australia. Antimicrob Agents Chemother 2001; 45:1860-7. [PMID: 11353638 PMCID: PMC90558 DOI: 10.1128/aac.45.6.1860-1867.2001] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ertapenem (MK-0826, L-749,345) is a 1-beta-methyl carbapenem with a long serum half-life. Its in vitro activity was determined by broth microdilution against 3,478 bacteria from 12 centers in Europe and Australia, with imipenem, cefepime, ceftriaxone, and piperacillin-tazobactam used as comparators. Ertapenem was the most active agent tested against members of the family Enterobacteriaceae, with MICs at which 90% of isolates are inhibited (MIC(90)s) of < or =1 microg/ml for all species. Ertapenem also was more active than imipenem against fastidious gram-negative bacteria and Moraxella spp.; on the other hand, ertapenem was slightly less active than imipenem against streptococci, methicillin-susceptible staphylococci, and anaerobes, but its MIC(90)s for these groups remained < or =0.5 microg/ml. Acinetobacter spp. and Pseudomonas aeruginosa were also much less susceptible to ertapenem than imipenem, and most Enterococcus faecalis strains were resistant. Ertapenem resistance, based on a provisional NCCLS MIC breakpoint of > or =16 microg/ml, was seen in only 3 of 1,611 strains of the family Enterobacteriaceae tested, all of them Enterobacter aerogenes. Resistance was also seen in 2 of 135 anaerobes, comprising 1 Bacteroides fragilis strain and 1 Clostridium difficile strain. Ertapenem breakpoints for streptococci have not been established, but an unofficial susceptibility breakpoint of < or =2 microg/ml was adopted for clinical trials to generate corresponding clinical response data for isolates for which MICs were as high as 2 microg/ml. Of 234 Streptococcus pneumoniae strains tested, 2 required ertapenem MICs of 2 microg/ml and one required an MIC of 4 microg/ml, among 67 non-Streptococcus pyogenes, non-Streptococcus pneumoniae streptococci, single isolates required ertapenem MICs of 2 and 16 microg/ml. These streptococci also had diminished susceptibilities to other beta-lactams, including imipenem as well as ertapenem. The Etest and disk diffusion gave susceptibility test results in good agreement with those of the broth microdilution method for ertapenem.
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Affiliation(s)
- D M Livermore
- Antibiotic Resistance Monitoring & Reference Laboratory, Central Public Health Laboratory, London, United Kingdom.
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28
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Yigit H, Queenan AM, Anderson GJ, Domenech-Sanchez A, Biddle JW, Steward CD, Alberti S, Bush K, Tenover FC. Novel carbapenem-hydrolyzing beta-lactamase, KPC-1, from a carbapenem-resistant strain of Klebsiella pneumoniae. Antimicrob Agents Chemother 2001; 45:1151-61. [PMID: 11257029 PMCID: PMC90438 DOI: 10.1128/aac.45.4.1151-1161.2001] [Citation(s) in RCA: 1197] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2000] [Accepted: 01/23/2001] [Indexed: 01/20/2023] Open
Abstract
A Klebsiella pneumoniae isolate showing moderate to high-level imipenem and meropenem resistance was investigated. The MICs of both drugs were 16 microg/ml. The beta-lactamase activity against imipenem and meropenem was inhibited in the presence of clavulanic acid. The strain was also resistant to extended-spectrum cephalosporins and aztreonam. Isoelectric focusing studies demonstrated three beta-lactamases, with pIs of 7.2 (SHV-29), 6.7 (KPC-1), and 5.4 (TEM-1). The presence of bla(SHV) and bla(TEM) genes was confirmed by specific PCRs and DNA sequence analysis. Transformation and conjugation studies with Escherichia coli showed that the beta-lactamase with a pI of 6.7, KPC-1 (K. pneumoniae carbapenemase-1), was encoded on an approximately 50-kb nonconjugative plasmid. The gene, bla(KPC-1), was cloned in E. coli and shown to confer resistance to imipenem, meropenem, extended-spectrum cephalosporins, and aztreonam. The amino acid sequence of the novel carbapenem-hydrolyzing beta-lactamase, KPC-1, showed 45% identity to the pI 9.7 carbapenem-hydrolyzing beta-lactamase, Sme-1, from Serratia marcescens S6. Hydrolysis studies showed that purified KPC-1 hydrolyzed not only carbapenems but also penicillins, cephalosporins, and monobactams. KPC-1 had the highest affinity for meropenem. The kinetic studies also revealed that clavulanic acid and tazobactam inhibited KPC-1. An examination of the outer membrane proteins of the parent K. pneumoniae strain demonstrated that the strain does not express detectable levels of OmpK35 and OmpK37, although OmpK36 is present. We concluded that carbapenem resistance in K. pneumoniae strain 1534 is mainly due to production of a novel Bush group 2f, class A, carbapenem-hydrolyzing beta-lactamase, KPC-1, although alterations in porin expression may also play a role.
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Affiliation(s)
- H Yigit
- Hospital Infections Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
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29
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Bush K. New beta-lactamases in gram-negative bacteria: diversity and impact on the selection of antimicrobial therapy. Clin Infect Dis 2001; 32:1085-9. [PMID: 11264037 DOI: 10.1086/319610] [Citation(s) in RCA: 249] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2000] [Revised: 11/30/2000] [Indexed: 11/03/2022] Open
Abstract
Of the 340 discrete beta-lactamases that have been identified, the most important groups of enzymes that are continuing to proliferate include the plasmid-encoded cephalosporinases, the metallo-beta-lactamases, and the extended-spectrum beta-lactamases. Resistance to specific beta-lactam-containing antimicrobial agents frequently can be traced to a single beta-lactamase, but this task is becoming more difficult for the clinical microbiology laboratory. Other factors, such as multiple beta-lactamase production, transferable multidrug-resistance genes, alterations in outer-membrane porins, and possible antibiotic efflux, all may contribute to a resistance phenotype. Appreciation of these factors may help the physician make a more informed decision when choosing therapy to try to avoid selection of even more pathogenic strains.
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Affiliation(s)
- K Bush
- The R. W. Johnson Pharmaceutical Research Institute, Raritan, NJ, 08869, USA.
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30
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Matsumura N, Minami S, Araki H, Hori R, Ogake N, Watanabe Y. Determination of intracellular and extracellular beta-lactamase activities of Pseudomonas aeruginosa after exposure to beta-lactams in vitro and in vivo. J Infect Chemother 2000; 6:200-5. [PMID: 11810566 DOI: 10.1007/s101560070003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2000] [Accepted: 08/09/2000] [Indexed: 11/25/2022]
Abstract
Beta-lactamase production in Pseudomonas aeruginosa was determined in in-vitro models and in rat pouch infection models after exposure to ceftazidime, imipenem, and piperacillin. Exposure of 28 P. aeruginosa strains to 1/4 minimum inhibitory concentration (MIC) of ceftazidime, imipenem, and piperacillin for 24 h enhanced intracellular beta-lactamase activities in 14, 22, and 6 strains, respectively, of the 28 clinical strains tested, and enhanced extracellular beta-lactamase activities which were not detected without exposure to antibiotics, in 7, 23, and 1 of the 28 strains, respectively. Extracellular beta-lactamase activity from P. aeruginosa S-1278, producing an inducible beta-lactamase, scarcely increased after exposure to ceftazidime and piperacillin 24 h after incubation, while the activity increased after exposure to imipenem over the range of 1/8 to 8 MIC. In the rat granuloma pouch models infected with P. aeruginosa S-1278, ceftazidime and piperacillin, after single administration (20 mg/kg) and serial administration (20 mg/kg per day x 3 days), did not enhance extracellular beta-lactamase activities. However, the activities were enhanced with single and serial administrations of imipenem, and levels over 10 mU/ml were detected until the third day. The beta-lactamase activity, similar to the activity found in rat pouches after serial administration of imipenem, inactivated various cephalosporins. In conclusion, extracellular beta-lactamase activity was detected both in vitro and in vivo after exposure to a good inducer, and extracellular beta-lactamase remained at infection site at levels that could inactivate cephalosporins.
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Affiliation(s)
- N Matsumura
- Third Research Department, Research Laboratories, Toyama Chemical Co., Ltd., 2-4-1 Shimookui, Toyama 930-8508, Japan. NAOKI
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31
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Hakimelahi GH, Moosavi-Movahedi AA, Tsay SC, Tsai FY, Wright JD, Dudev T, Hakimelahi S, Lim C. Design, synthesis, and SAR of novel carbapenem antibiotics with high stability to Xanthomonas maltophilia oxyiminocephalosporinase type II. J Med Chem 2000; 43:3632-40. [PMID: 11020277 DOI: 10.1021/jm000213z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Racemic cis-6-(phenylacetamido)carbapenem (21), 2-hydroxycarbonyl-cis-6-(phenylacetamido)carbapenem (22), 2-methoxycarbonyl-cis-6-(phenylacetamido)carbapenem (30), 2-methoxycarbomethyl-cis-6-(phenylacetamido)carbapenem (33), 2-hydroxyethyl-cis-6-(phenylacetamido)carbapenem (34), and 2-acetoxyethyl-cis-6-(phenylacetamido)carbapenem (35) were synthesized. Formation of the carbapenem nuclei in 21, 22, and 30 involved dehydrophosphonation of the corresponding 2-diphenylphosphono-6-(phenylacetamido)carbapenam precursors 14, 15, and 28 using trimethylsilyl triflate and 1,8-diazabicyclo[5.4.0]undec-7-ene in THF. Syntheses of carbapenems 33-35 involved a Wittig reaction of carbapenam 14 with methyl glyoxylate in the presence of lithium 2,2,6,6-tetramethylpiperidine in THF. For the antibacterial activities against Staphylococcus aureus FDA 209P, S. aureus 95, Escherichia coli ATCC 39188, Klebsiellapneumoniae NCTC 418, Pseudomonas aeruginosa 1101-75, and P. aeruginosa 18S-H, carbapenems (+/-)-21, (+/-)-22, (+/-)-30, and (+/-)-33-35 were found comparable with imipenem ((+)-3), yet they were notably more potent than (+)-3 against Xanthomonas maltophilia GN 12873. On the other hand, unlike (+)-3, carbapenems (+/-)-21, (+/-)-22, (+/-)-30, and (+/-)-33-35 were stable to X. maltophilia oxyiminocephalosporinase type II. Their beta-lactamase inhibitory properties, however, were found to be more comparable with those of penicillin G ((+)-4) than to those of imipenem ((+)-3). A combination of imipenem ((+)-3) with (+/-)-21, (+/-)-22, (+/-)-30, and (+/-)-33-35 resulted in synergistic antibacterial activity against X. maltophilia GN 12873. Results from the biological tests were correlated with the distribution of the electron density at C(2)=C(3) of carbapenems upon reaction with transpeptidases or beta-lactamases.
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Affiliation(s)
- G H Hakimelahi
- Institute of Chemistry and Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan 115, Republic of China.
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32
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Chevalier J, Malléa M, Pagès JM. Comparative aspects of the diffusion of norfloxacin, cefepime and spermine through the F porin channel of Enterobacter cloacae. Biochem J 2000; 348 Pt 1:223-7. [PMID: 10794735 PMCID: PMC1221057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
In Enterobacteriaceae, the permeability of the outer membrane to hydrophilic antibiotics is associated with the presence of pore-forming proteins. We tested the diffusion of the fluoroquinolone norfloxacin in four Enterobacter cloacae strains: a clinical isolate and three derivatives variously producing or lacking the D and F porins. We analysed the entry of norfloxacin into E. cloacae cells in the presence of either the polyamine spermine or the recently developed cefepime, which are known to penetrate through the Escherichia coli OmpF porin. Uptake of the fluoroquinolone was decreased in both cases; the initial rate of penetration decreased as more spermine blocked the channel. Our results indicate that, like beta-lactam molecules, fluoroquinolones translocate through the outer membrane via the F porin and that cefepime and norfloxacin entries are polyamine-sensitive. This suggests that the closure of the F porin channel by polyamines might modulate the susceptibility of E. cloacae to both fluoroquinolone and cephalosporin antibiotics.
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Affiliation(s)
- J Chevalier
- CJF 9606 INSERM, Faculté de Médecine, Université de la Méditerranée, Marseille Cedex 05, France
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33
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Cornaglia G, Mazzariol A, Fontana R, Satta G. Diffusion of carbapenems through the outer membrane of enterobacteriaceae and correlation of their activities with their periplasmic concentrations. Microb Drug Resist 2000; 2:273-6. [PMID: 9158772 DOI: 10.1089/mdr.1996.2.273] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Scarce information is available on the real mechanism by which carbapenemes penetrate in Enterobacteriaceae, although a considerable amount of evidence suggests that in many species of this family the lack of certain outer membrane proteins is associated with the acquisition of resistance to these antibiotics. The existance of specific pathways for the carbapenems has never been demonstrated, although at times it has been postulated in both wild and mutant strains, on the basis of evident discordances between permeability patterns and suceptibility data. By using the Zimmerman and Rosselet technique, which requires the strain under investigation to harbor a suitable beta-lactamase, the permeability of intact Escherichia coli and Enterobacter cloacae cells to meropenem and imipenem was investigated by transferring a constructed vector carrying the carbapenem hydrolyzing CphA metallo-beta-lactamase gene into the parental strains and their porin-deficient mutants. Reduced amounts of nonspecific porins significantly reduced the penetration of both carbapenems. The virtual absence of porins caused the MICs of meropenem to increase, mostly in Enterobacter cloacae, while it did not affected the MICs of imipenem. No evidence of specific porin pathways of the type described in Pseudomonas aeruginosa was found.
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Affiliation(s)
- G Cornaglia
- Institute of Microbiology, University of Verona, Italy
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34
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Martínez-Martínez L, Pascual A, Hernández-Allés S, Alvarez-Díaz D, Suárez AI, Tran J, Benedí VJ, Jacoby GA. Roles of beta-lactamases and porins in activities of carbapenems and cephalosporins against Klebsiella pneumoniae. Antimicrob Agents Chemother 1999; 43:1669-73. [PMID: 10390220 PMCID: PMC89341 DOI: 10.1128/aac.43.7.1669] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of beta-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC beta-lactamase types, by studying the effect of an increased inoculum, and by evaluating interactions with beta-lactamase inhibitors. The contribution of porin deficiency was investigated by restoring a functional ompK36 gene on a plasmid. Plasmids encoding AmpC-type beta-lactamases provided resistance to imipenem (up to 64 microg/ml) and meropenem (up to 16 microg/ml) in strains deficient in porins. Carbapenem resistance showed little inoculum effect, was not affected by clavulanate but was blocked by BRL 42715, and was diminished if OmpK36 porin was restored. Plasmids encoding TEM- and SHV-type ESBLs conferred resistance to cefepime and cefpirome, as well as to earlier oxyimino-beta-lactams. This resistance was magnified with an increased inoculum, was blocked by clavulanate, and was also lowered by OmpK36 porin restoration. In addition, SHV-2 beta-lactamase had a small effect on carbapenem resistance (imipenem MIC, 4 microg/ml, increasing to 16 microg/ml with a higher inoculum) when porins were absent. In K. pneumoniae porin loss can thus augment resistance provided either by TEM- or SHV-type ESBLs or by plasmid-mediated AmpC enzymes to include the latest oxyimino-beta-lactams and carbapenems.
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Affiliation(s)
- L Martínez-Martínez
- Department of Microbiology, School of Medicine, University of Seville, Seville, Spain.
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35
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Stapleton PD, Shannon KP, French GL. Carbapenem resistance in Escherichia coli associated with plasmid-determined CMY-4 beta-lactamase production and loss of an outer membrane protein. Antimicrob Agents Chemother 1999; 43:1206-10. [PMID: 10223937 PMCID: PMC89134 DOI: 10.1128/aac.43.5.1206] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three cefoxitin-resistant Escherichia coli isolates from stool specimens of a patient with leukemia were either resistant, intermediate, or sensitive to imipenem. Conjugation experiments showed that cefoxitin resistance, but not imipenem resistance, was transferable. All isolates were shown by isoelectric focusing to produce two beta-lactamases with isoelectric points of 5.4 (TEM-1, confirmed by sequencing of a PCR product) and >8.5 (consistent with a class C beta-lactamase). The gene coding for the unknown beta-lactamase was cloned and sequenced and revealed an enzyme which had 99.9% sequence identity with the plasmid-determined class C beta-lactamase CMY-2. The cloned beta-lactamase gene differed from blaCMY-2 at one nucleotide position that resulted in an amino acid change, tryptophan to arginine at position 221. We propose that this enzyme be designated CMY-4. Both the imipenem-resistant and -intermediate isolates lacked a 38-kDa outer membrane protein (OMP) that was present in the imipenem-sensitive isolate. The lack of an OMP alone did not explain the difference in carbapenem susceptibilities observed. However, measurement of beta-lactamase activities (including measurements under conditions where TEM-1 beta-lactamase was inhibited) indicated that the imipenem-intermediate isolate expressed six- to eightfold less beta-lactamase than did the other isolates. This study illustrates that carbapenem resistance in E. coli can arise from high-level expression of plasmid-mediated class C beta-lactamase combined with an OMP deficiency. Furthermore, in the presence of an OMP deficiency, the level of expression of a plasmid-mediated class C beta-lactamase is an important factor in determining whether E. coli isolates are fully resistant to carbapenems.
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Affiliation(s)
- P D Stapleton
- Department of Microbiology, UMDS, St. Thomas' Hospital, London, United Kingdom.
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36
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Jyothisri K, Deepak V, Rajeswari MR. Purification and characterization of a major 40 kDa outer membrane protein of Acinetobacter baumannii. FEBS Lett 1999; 443:57-60. [PMID: 9928952 DOI: 10.1016/s0014-5793(98)01679-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Acinetobacter baumannii, an opportunistic pathogen, is well known to cause a wide spectrum of nosocomial infections particularly in intensive care units. The major outer membrane (OM) protein, OmpAb, of 40 kDa from A. baumannii has been identified and purified to homogeneity from cultures grown at 30 degrees C and 100 mM NaCl. The synthesis of OM proteins of A. baumannii is thermoregulated and osmoregulated. The pore forming ability of the purified OmpAb and the diffusion of uncharged solutes in proteoliposomes has been demonstrated by following the liposomal swelling assay. The trimeric OmpAb is characterized as a porin with a pore size of 1.3 nm and is found to be similar to the OmpF of Escherichia coli and can possibly be classified as a general diffusion pore. It appears that OmpAb plays an important role in the diffusion properties of the outer membrane of A. baumannii.
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Affiliation(s)
- K Jyothisri
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi
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37
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Lakaye B, Dubus A, Lepage S, Groslambert S, Frère JM. When drug inactivation renders the target irrelevant to antibiotic resistance: a case story with beta-lactams. Mol Microbiol 1999; 31:89-101. [PMID: 9987113 DOI: 10.1046/j.1365-2958.1999.01150.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
By challenging the efficiency of some of our most useful antimicrobial weapons, bacterial antibiotic resistance is becoming an increasingly worrying clinical problem. A good antibiotic is expected to exhibit a high affinity for its target and to reach it rapidly, while escaping chemical modification by inactivating enzymes and elimination by efflux mechanisms. A study of the behaviour of a beta-lactamase-overproducing mutant of Enterobacter cloacae in the presence of several penicillins and cephalosporins showed that the minimum inhibitory concentration (MIC) values for several compounds were practically independent of the sensitivity of the target penicillin binding protein (PBP), even for poor beta-lactamase substrates. This apparent paradox was explained by analysing the equation that relates the antibiotic concentration in the periplasm to that in the external medium. Indeed, under conditions that are encountered frequently in clinical isolates, the factor characterizing the PBP sensitivity became negligible. The conclusions can be extended to all antibiotics that are sensitive to enzymatic inactivation and efflux mechanisms and must overcome permeability barriers. It would be a grave mistake to neglect these considerations in the design of future antibacterial chemotherapeutic agents.
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Affiliation(s)
- B Lakaye
- Centre d'Ingénierie des Protéines, Université de Liège, Belgium
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38
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Namias N, Harvill S, Ball S, McKenney MG, Salomone JP, Sleeman D, Civetta JM. Empiric therapy of sepsis in the surgical intensive care unit with broad-spectrum antibiotics for 72 hours does not lead to the emergence of resistant bacteria. THE JOURNAL OF TRAUMA 1998; 45:887-91. [PMID: 9820698 DOI: 10.1097/00005373-199811000-00008] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND It is our practice to treat suspected sepsis with imipenem/cilastatin and gentamicin (IMP/GENT) for 72 hours while awaiting culture results. We wanted to determine if this practice engenders antimicrobial resistance. METHODS Review of prospectively collected data regarding use of IMP/GENT and microbial sensitivity to imipenem/cilastatin during the first and last 7 months of a 19-month study period (October 1, 1995, to April 30, 1997). RESULTS The susceptibility of appropriate organisms to imipenem/cilastatin was 76% in the early period and 80% in the late period (p = 0.42). Pseudomonas aeruginosa was more susceptible in the late period (88 vs. 62%; p = 0.007). Resistance to gentamicin (30% early vs. 21% late; p = 0.02) and representative cephalosporins (cefoxitin, 52% early vs. 61% late; p = 0.35; ceftazidime, 26% early vs. 23% late; p = 0.76) did not develop during the study period. The incidence of fungemia was the same in both periods (4 of 467 admissions vs. 3 of 599 admissions; p = 0.48). CONCLUSION This protocol did not lead to the emergence of resistant bacteria.
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Affiliation(s)
- N Namias
- University of Miami School of Medicine, Jackson Memorial Hospital, FL 33101, USA
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39
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Ardanuy C, Liñares J, Domínguez MA, Hernández-Allés S, Benedí VJ, Martínez-Martínez L. Outer membrane profiles of clonally related Klebsiella pneumoniae isolates from clinical samples and activities of cephalosporins and carbapenems. Antimicrob Agents Chemother 1998; 42:1636-40. [PMID: 9660996 PMCID: PMC105658 DOI: 10.1128/aac.42.7.1636] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Fifteen isolates of Klebsiella pneumoniae producing extended-spectrum beta-lactamases (ESBLs) isolated during a nosocomial outbreak were studied. The strains belonged to the same clonal type, as shown by pulsed-field gel electrophoretic analysis of chromosomal DNA. All the isolates were resistant to extended-spectrum cephalosporins, aztreonam, gentamicin, and fluoroquinolones and were susceptible to carbapenems, tobramycin, netilmicin, and amikacin. None of the isolates expressed the OmpK36 porin. Eight isolates, for which the MICs of cefoxitin were > or = 64 micrograms/ml, showed a diminished level or no expression of a 35-kDa porin. The MICs of meropenem, cefotaxime, and cefpirome were three to eight times higher for porin-deficient isolates than for isolates expressing the 35-kDa porin, but the MICs of imipenem increased two times for porin-deficient isolates compared to those for isolates expressing the porin. This MIC increase reverted to a level similar to that for the parental strain when porin-deficient isolates were transformed with the gene coding for the K. pneumoniae porin OmpK36. It is concluded that the high level of resistance to cefoxitin and the increase in the MICs of meropenem, cefotaxime, and cefpirome for the ESBL-producing K. pneumoniae isolates studied are associated with porin deficiency.
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Affiliation(s)
- C Ardanuy
- Servicio de Microbiología, Hospital de Bellvitge, Universidad de Barcelona, Spain.
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40
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Eltahawy AT. Gram-negative bacilli isolated from patients in intensive care unit: prevalence and antibiotic susceptibility. J Chemother 1997; 9:403-10. [PMID: 9491839 DOI: 10.1179/joc.1997.9.6.403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The surveillance of 100 gram-negative bacilli that were recovered from patients in the intensive care unit (ICU) at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia showed that Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Enterobacter species, in this order, were the most frequently isolated organisms. The most common sites were respiratory tract (34%), wounds (24%), urinary tract (18%), and blood (11%). The resistance patterns towards different antimicrobial agents were determined by the minimal inhibitory concentration (MIC) using the E test. Imipenem, ciprofloxacin and amikacin were the most active agents against the isolates. Of the gram-negative isolates, 31% were resistant to at least two of the four major antibiotic groups (e.g. aminoglycosides, fluoroquinolones, third generation cephalosporins, and carbapenems), and 6% to three of the groups. Twenty-nine percent of the gram-negative bacilli were resistant to ceftazidime. Ceftazidime-resistant bacteria were frequently resistant to monobactams, piperacillin/tazobactam and gentamicin.
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Affiliation(s)
- A T Eltahawy
- King Abdulaziz University Hospital, Jeddah, Saudi Arabia
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41
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Mainardi JL, Mugnier P, Coutrot A, Buu-Hoï A, Collatz E, Gutmann L. Carbapenem resistance in a clinical isolate of Citrobacter freundii. Antimicrob Agents Chemother 1997; 41:2352-4. [PMID: 9371332 PMCID: PMC164127 DOI: 10.1128/aac.41.11.2352] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Carbapenem resistance was studied in two sets of Citrobacter freundii strains: (i) strain CFr950, resistant to imipenem (MIC, 16 microg/ml) and isolated in vivo during imipenem therapy, and strain CFr950-Rev, the spontaneous, imipenem-susceptible revertant of CFr950 selected in vitro, and (ii) strains CFr801 and CFr802, two imipenem-resistant mutants selected in vitro from the susceptible clinical isolate CFr800. In all strains, whether they were imipenem-susceptible or -resistant strains, production of the cephalosporinase was derepressed and their Km values for cephaloridine were in the range of 128 to 199 microM. No carbapenemase activity was detected in vitro. The role of cephalosporinase overproduction in the resistance was demonstrated after introduction of the ampD gene which decreased the level of production of cephalosporinase at least 250-fold and resulted in an 8- to 64-fold decrease in the MICs of the carbapenems. The role of reduced permeability in the resistance was suggested by the absence, in CFr950 and CFr802, of two outer membrane proteins (the 42- and 40-kDa putative porins whose levels were considerably decreased in CFr801) and the reappearance of the 42-kDa protein in imipenem-susceptible strain CFr950-Rev. This role was confirmed after introduction of the ompF gene of Escherichia coli into the CFr strains, which resulted in 8- to 16-fold decreases in the MICs of carbapenems for CFr802 and CFr950. We infer from these results that the association of reduced, porin-mediated permeability with high-level cephalosporinase production, observed previously in other gram-negative bacteria, may also confer carbapenem resistance on C. freundii.
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Affiliation(s)
- J L Mainardi
- Service de Microbiologie Clinique, Hôpital Saint-Joseph, Paris, France
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42
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Kar AK, Ghosh AS, Chauhan K, Ahamed J, Basu J, Chakrabarti P, Kundu M. Involvement of a 43-kilodalton outer membrane protein in beta-lactam resistance of Shigella dysenteriae. Antimicrob Agents Chemother 1997; 41:2302-4. [PMID: 9333070 PMCID: PMC164115 DOI: 10.1128/aac.41.10.2302] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A beta-lactam-sensitive strain (C152) of Shigella dysenteriae showed two major outer membrane proteins (OMPs) with M(r)s of 43,000 and 38,000, while the clinical isolate M2 lacked the 43,000-Mr OMP, which acted as a channel for beta-lactam antibiotics. Permeability of beta-lactams across the outer membrane (OM) of M2 was lower than that across the OM of C152. Mutants deficient in the 43-kDa OMP could be selected in vitro from strain C152 in the presence of cefoxitin. All beta-lactam-resistant strains were sensitive to imipenem.
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Affiliation(s)
- A K Kar
- Department of Chemistry, Bose Institute, Calcutta, India
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43
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Bradford PA, Urban C, Mariano N, Projan SJ, Rahal JJ, Bush K. Imipenem resistance in Klebsiella pneumoniae is associated with the combination of ACT-1, a plasmid-mediated AmpC beta-lactamase, and the foss of an outer membrane protein. Antimicrob Agents Chemother 1997; 41:563-9. [PMID: 9055993 PMCID: PMC163751 DOI: 10.1128/aac.41.3.563] [Citation(s) in RCA: 322] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Six Escherichia coli and 12 Klebsiella pneumoniae isolates from a single hospital expressed a common beta-lactamase with a pI of approximately 9.0 and were resistant to cefoxitin and cefotetan (MIC ranges, 64 to > 128 and 16 to > 128 micrograms/ml, respectively). Seventeen of the 18 strains produced multiple beta-lactamases. Most significantly, three K. pneumoniae strains were also resistant to imipenem (MICs, 8 to 32 micrograms/ml). Spectrophotometric beta-lactamase assays with purified enzyme indicated hydrolysis of cephamycins, in addition to cephaloridine and benzylpenicillin. The 4ene encoding the pI 9.0 beta-lactamase (designated ACT-1 for AmpC type) was cloned and sequenced, which revealed an ampC-type beta-lactamase gene that originated from Enterobacter cloacae and that had 86% sequence homology to the P99 beta-lactamase and 94% homology to the partial sequence of MIR-1. Southern blotting revealed that the gene encoding ACT-1 was on a large plasmid in some of the K. pneumoniae strains as well as on the chromosomes of all of the strains, suggesting that the gene is located on an easily mobilized element. Outer membrane protein profiles of the K. pneumoniae strains revealed that the three imipenem-resistant strains were lacking a major outer membrane protein of approximately 42 kDa which was present in the imipenem-susceptible strains. ACT-1 is the first plasmid-mediated AmpC-type beta-lactamase derived from Enterobacter which has been completely sequenced. This work demonstrates that in addition to resistance to cephamycins, imipenem resistance can occur in K. pneumoniae when a high level of the ACT-1 beta-lactamase is produced in combination with the loss of a major outer membrane protein.
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Affiliation(s)
- P A Bradford
- Wyeth-Ayerst Research, Pearl River, New York 10965, USA.
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44
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Charrel RN, Pagès JM, De Micco P, Mallea M. Prevalence of outer membrane porin alteration in beta-lactam-antibiotic-resistant Enterobacter aerogenes. Antimicrob Agents Chemother 1996; 40:2854-8. [PMID: 9124854 PMCID: PMC163635 DOI: 10.1128/aac.40.12.2854] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We evaluated the prevalence of impermeability as a mechanism associated with resistance against beta-lactam antibiotics in members of the family Enterobacteriaceae. During a 1-year period, 80 strains were selected from 3,110 routinely isolated strains according to their noticeable cross-resistance pattern to cephalosporins. They were tested for (i) outer membrane nonspecific porins involved in the entry of small hydrophilic molecules; (ii) the MICs of cefepime, cefotaxime, imipenem, and moxalactam; and (iii) beta-lactamase production. Immunological investigations using specific probes showed that 23 of 80 strains presented an alteration of the porin content, most of them expressing an additional resistance mechanism. The prevalence of this porin-deficient phenotype is especially high in Enterobacter aerogenes and concerns 6.4% of the clinical isolates.
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Affiliation(s)
- R N Charrel
- Enveloppe et perméation chez les entérobactéries, UPR 9027, I.F.R.I, Centre National de la Recherche Scientifique, Marseille, France
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45
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Lee EH, Collatz E, Podglajen I, Gutmann L. A rob-like gene of Enterobacter cloacae affecting porin synthesis and susceptibility to multiple antibiotics. Antimicrob Agents Chemother 1996; 40:2029-33. [PMID: 8878575 PMCID: PMC163467 DOI: 10.1128/aac.40.9.2029] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A chromosomal gene of Enterobacter cloacae affecting the synthesis of major outer membrane proteins in E. cloacae and Escherichia coli was cloned by using selection for resistance to cefoxitin in E. coli. The presence of the gene, when plasmid-borne, led to a decrease in the amount of porin F in E. cloacae and the amount of OmpF in E. coli and caused 2- to 32-fold increases in the MICs of chloramphenicol, tetracycline, quinolones, and beta-lactam antibiotics. The gene encoded a 33-kDa protein, similar (83% identity) to the protein Rob involved in the initiation of DNA replication in E. coli, which was called RobA(EC1) by analogy. RobA from E. cloacae was found to inhibit ompF expression at the posttranscriptional level via activation of micF, a gene also apparently present in E. cloacae, as detected by PCR. As with its homolog from E. coli, RobA(EC1) is related to the XylS-AraC class of positive transcriptional regulators, along with MarA and SoxS, which also cause a micF-mediated decrease in the level of ampF expression.
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Affiliation(s)
- E H Lee
- Laboratoire de Recherche Moléculaire sur les Antibiotiques, Université Paris VI, France
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46
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Abstract
beta-Lactamases are the commonest single cause of bacterial resistance to beta-lactam antibiotics. Numerous chromosomal and plasmid-mediated types are known and may be classified by their sequences or phenotypic properties. The ability of a beta-lactamase to cause resistance varies with its activity, quantity, and cellular location and, for gram-negative organisms, the permeability of the producer strain. beta-Lactamases sometimes cause obvious resistance to substrate drugs in routine tests; often, however, these enzymes reduce susceptibility without causing resistance at current, pharmacologically chosen breakpoints. This review considers the ability of the prevalent beta-lactamases to cause resistance to widely used beta-lactams, whether resistance is accurately reflected in routine tests, and the extent to which the antibiogram for an organism can be used to predict the type of beta-lactamase that it produces.
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Affiliation(s)
- D M Livermore
- Department of Medical Microbiology, London Hospital Medical College, United Kingdom
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47
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Wiseman LR, Wagstaff AJ, Brogden RN, Bryson HM. Meropenem. A review of its antibacterial activity, pharmacokinetic properties and clinical efficacy. Drugs 1995; 50:73-101. [PMID: 7588092 DOI: 10.2165/00003495-199550010-00007] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The parenteral carbapenem meropenem is relatively stable to inactivation by human renal dehydropeptidase (DHP-1) and does not require concomitant administration of a DHP-1 inhibitor such as cilastatin. It has a broad spectrum of antibacterial activity in vitro, the majority of Gram-negative, Gram-positive and anaerobic pathogens being highly susceptible to the drug. Meropenem has shown clinical and bacteriological efficacy in the treatment of a wide range of serious infections in adults and children which is at least comparable with that of currently available treatment options. Its clinical and bacteriological efficacy is similar to that of imipenem/cilastatin, clindamycin plus tobramycin and cefotaxime plus metronidazole in the treatment of intraabdominal infections; cefotaxime or ceftriaxone in the treatment of meningitis; imipenem/cilastatin, and ceftazidime with or without an aminoglycoside, in lower respiratory tract infections; and imipenem/cilastatin or ceftazidime in the treatment of urinary tract infections. Satisfactory clinical and bacteriological response rates have also been achieved in patients with skin and skin structure infections, obstetric and gynaecological infections or septicaemia, and in immunocompromised patients with febrile episodes. Preliminary findings also indicate efficacy in the treatment of respiratory tract infections in patients with cystic fibrosis. The tolerability profile of meropenem is generally similar to that of comparator agents, although it is associated with a lower incidence of adverse gastrointestinal effects (nausea and vomiting) than imipenem/cilastatin. Importantly, the incidence of seizures in patients with meningitis is not increased following administration of meropenem. Thus, meropenem is an effective broad spectrum antibacterial drug for the treatment of a wide range of infections including polymicrobial infections in both adults and children, with comparable efficacy to imipenem/cilastatin and various other treatment regimens. Meropenem is likely to be of greatest value as empiric monotherapy in the treatment of serious infections for those caused by multiply-resistant pathogens. Further clinical experience is necessary, however, to ultimately define its place in therapy.
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Affiliation(s)
- L R Wiseman
- Adis International Limited, Auckland, New Zealand
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48
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Malléa M, Simonet V, Lee EH, Gervier R, Collatz E, Gutmann L, Pagès JM. Biological and immunological comparisons of Enterobacter cloacae and Escherichia coli porins. FEMS Microbiol Lett 1995; 129:273-9. [PMID: 7541759 DOI: 10.1111/j.1574-6968.1995.tb07592.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Bacteriocin susceptibilities indicate that during cloacin DF13 uptake the F porin of Enterobacter cloacae plays a similar role to that reported for the OmpF porin of Escherichia coli during colicin A entry. The translocatory activities of these two porins during the bacteriocin uptake can be substituted by the porins D and OmpC, respectively, under conditions not requiring the receptor binding step. Using anti-peptide antibodies, a peptide located in the internal loop L3 of the Escherichia coli OmpF porin was identified in the D and F porins of Enterobacter cloacae. The results demonstrated the existence of a close relationship between porins in terms of both antigenic determinants and bacteriocin susceptibilities.
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Affiliation(s)
- M Malléa
- Enveloppe et perméation chez les entérobactéries, UPR 9027, IFRC1, Centre National de la Recherche Scientifique, Marseille, France
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49
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Raimondi A, Pessina A, Neri MG. Loss of porins following carbapenem-resistance selection and adherence modification in enterobacteria. J Chemother 1995; 7:171-4. [PMID: 7562008 DOI: 10.1179/joc.1995.7.3.171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The acquired resistance to the carbapenems is frequently joined to modified expression of porins or other outer membrane (OM) structures, thus bacterial adherence, that also depends on the presence of peculiar surface structures, might theoretically be influenced. In this study the ability to adhere to Hep-2 and I-407 eukaryotic cell monolayers was assayed for two susceptible strains of Serratia marcescens, one strain of Enterobacter cloacae and one of Providencia rettgeri in comparison with that of isogenic resistant mutants selected either by carbapenems or by cephalosporins. The mutants appeared slightly less adherent than the wild type strains, however, due to the high variability of this kind of assay, the differences observed in most cases could not be considered statistically significant. The data suggest that adherence, among the factors affecting the pathogenicity of the strains, remains probably unmodified in the resistant bacterial population possibly selected by a carbapenem treatment.
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Affiliation(s)
- A Raimondi
- Institute of Medical Microbiology, University of Milano, Italy
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50
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Maurin M, Musso D, Charrel R, Perez R, n'Guyen A, Dumon H, de Micco P. Résistance aux antibiotiques des bactéries hospitalières (bacilles à Gram négatif aérobies). Situation 1992 à Marseille. Med Mal Infect 1995. [DOI: 10.1016/s0399-077x(05)80734-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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