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Yang J, Zhang K, Ding C, Wang S, Wu W, Liu X. Exploring multidrug-resistant Klebsiella pneumoniae antimicrobial resistance mechanisms through whole genome sequencing analysis. BMC Microbiol 2023; 23:245. [PMID: 37660028 PMCID: PMC10474722 DOI: 10.1186/s12866-023-02974-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/08/2023] [Indexed: 09/04/2023] Open
Abstract
BACKGROUND Antibiotic-resistant Klebsiella pneumoniae has emerged as a critical public health threat worldwide. Understanding the antimicrobial resistance mechanisms of multidrug-resistant K. pneumoniae (MDR-Kp) and its prevalence in time and space would provide clinical significance for managing pathogen infection. METHODS Eighteen clinical MDR-Kp strains were analyzed by whole genome sequencing (WGS), and the antimicrobial resistance genes and associated resistance mechanisms were compared with results obtained from the conventional microbiological test (CMT). The sequence homology across strains in our study and those previously collected over time from a wide geographical region was assessed by phylogenetic analysis. RESULTS MDR-Kp strains were collected from eighteen patients who had received empirical treatment before strain collection, with sputum (83.3%, 15/18) being the primary source of clinical samples. The commonly received treatments include β-lactamase inhibitors (55.6%, 10/18) and carbapenems (50%, 9/18). Using CMT, we found that all 18 strains were resistant to aztreonam and ciprofloxacin, while 14 (77.8%) showed resistance to carbapenem. Polymyxin B and tigecycline were the only antibiotics to which MDR-Kp strains were sensitive. A total of 42 antimicrobial resistance mechanisms were identified by WGS, surpassing the 40 detected by the conventional method, with 25 mechanisms shared between the two techniques. Despite a 100% accuracy rate of WGS in detecting penicillin-resistant strains, the accuracy in detecting cephalosporin-resistant strains was only at 60%. Among all resistance genes identified by WGS, Klebsiella pneumoniae carbapenemase-2 (KPC-2) was present in all 14 carbapenem-resistant strains. Phenotypic analysis indicated that sequence type (ST) 11 isolates were the primary cause of these MDR-Kp infections. Additionally, phylogenic clustering analysis, encompassing both the clinical and MDR-Kp strains previously reported in China, revealed four distinct subgroups. No significant difference was observed in the sequence homology between K. pneumoniae strains in our study and those previously collected in East China over time. CONCLUSION The application of WGS in identifying potential antimicrobial-resistant genes of MDR-Kp has demonstrated promising clinical significance. Comprehensive genomic information revealed by WGS holds the promise of guiding treatment decisions, enabling surveillance, and serving as a crucial asset in understanding antibiotic resistance.
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Affiliation(s)
- Jing Yang
- Xuzhou Medical University, Xuzhou, 221004, Jiangsu, China
| | - Kai Zhang
- Clinical Laboratory, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, No. 269, Daxue Road, Tongshan District, Xuzhou, 221002, Jiangsu, China
| | - Chen Ding
- Xuzhou Central Hospital, Xuzhou, 221009, Jiangsu, China
| | - Song Wang
- Dinfectome Inc, Nanjing, 210000, Jiangsu, China
| | - Weiwei Wu
- Dinfectome Inc, Nanjing, 210000, Jiangsu, China
| | - Xiangqun Liu
- Department of Respiratory and Critical Care Medicine, The Affiliated Xuzhou Municipal Hospital of Xuzhou Medical University, No. 269, Daxue Road, Tongshan District, Xuzhou, 221002, Jiangsu, China.
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Vuillemin X, Da Silva M, Bour M, Landon C, Plésiat P, Jeannot K. Cefiderocol activity is compromised by acquired extended-spectrum oxacillinases in Pseudomonas aeruginosa. Int J Antimicrob Agents 2023; 62:106917. [PMID: 37429451 DOI: 10.1016/j.ijantimicag.2023.106917] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 06/16/2023] [Accepted: 07/04/2023] [Indexed: 07/12/2023]
Abstract
OBJECTIVES Cefiderocol has an excellent in vitro activity on clinical strains of Pseudomonas aeruginosa (P. aeruginosa). However, the resistance of some isolates has been associated with the production of some β-lactamases. Whether some acquired extended-spectrum oxacillinases (ES-OXA) common in this species may compromise the susceptibility of P. aeruginosa to cefiderocol has not been evaluated so far. METHODS Eighteen genes encoding OXA belonging to the major subgroups identified in P. aeruginosa OXA-1 (n = 3); - 2 (n = 5); - 10 (n = 8), and - 46 (n = 2) were cloned into pUCP24 shuttle vector and transferred into reference strain PAO1. RESULTS Although production of the OXA-1 subgroup enzymes did not alter cefiderocol MICs, the β-lactamases of OXA-2, OXA-46, and four variants of the OXA-10 subgroup resulted in an 8-fold to 32-fold decrease in susceptibility in the PAO1 background. Interestingly, point mutations Ala149Pro and Asp150Gly in OXA-2 subgroup, Trp154Cys and Gly157Asp in OXA-10 subgroup (all located in the Ω loop), and the duplication of a Thr206 and a Gly207 in the β5-β6 loop of OXA-10 subgroup were related to decreased susceptibility to cefiderocol. We also showed that some ES-OXA, including the most frequent ES-OXA in P. aeruginosa strains, OXA-19 (derived from OXA-10 subgroup), significantly compromised activity of cefiderocol in addition to ceftazidime, ceftolozane/tazobactam, and ceftazidime/avibactam in clinical strains. CONCLUSION This work shows that several ES-OXA have a significant effect on cefiderocol susceptibility. Of concern are the Trp154Cys and Gly157Asp mutations that occur in some of these β-lactamases, as they are associated with a decreased activity of the most recent cephalosporins introduced to combat P. aeruginosa infections.
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Affiliation(s)
- Xavier Vuillemin
- Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, Besançon, France; Laboratoire Associé au Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, Besançon, France; Chrono-environnement, Université Bourgogne-Franche Comté, Besançon, France
| | - Maëlle Da Silva
- Laboratoire Associé au Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Maxime Bour
- Laboratoire Associé au Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | | | - Patrick Plésiat
- Chrono-environnement, Université Bourgogne-Franche Comté, Besançon, France
| | - Katy Jeannot
- Laboratoire de Bactériologie, Centre Hospitalier Universitaire de Besançon, Besançon, France; Laboratoire Associé au Centre National de Référence de la Résistance aux Antibiotiques, Centre Hospitalier Universitaire de Besançon, Besançon, France; Chrono-environnement, Université Bourgogne-Franche Comté, Besançon, France.
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3
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Barbu IC, Gheorghe-Barbu I, Grigore GA, Vrancianu CO, Chifiriuc MC. Antimicrobial Resistance in Romania: Updates on Gram-Negative ESCAPE Pathogens in the Clinical, Veterinary, and Aquatic Sectors. Int J Mol Sci 2023; 24:7892. [PMID: 37175597 PMCID: PMC10178704 DOI: 10.3390/ijms24097892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Multidrug-resistant Gram-negative bacteria such as Acinetobacter baumannii, Pseudomonas aeruginosa, and members of the Enterobacterales order are a challenging multi-sectorial and global threat, being listed by the WHO in the priority list of pathogens requiring the urgent discovery and development of therapeutic strategies. We present here an overview of the antibiotic resistance profiles and epidemiology of Gram-negative pathogens listed in the ESCAPE group circulating in Romania. The review starts with a discussion of the mechanisms and clinical significance of Gram-negative bacteria, the most frequent genetic determinants of resistance, and then summarizes and discusses the epidemiological studies reported for A. baumannii, P. aeruginosa, and Enterobacterales-resistant strains circulating in Romania, both in hospital and veterinary settings and mirrored in the aquatic environment. The Romanian landscape of Gram-negative pathogens included in the ESCAPE list reveals that all significant, clinically relevant, globally spread antibiotic resistance genes and carrying platforms are well established in different geographical areas of Romania and have already been disseminated beyond clinical settings.
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Affiliation(s)
- Ilda Czobor Barbu
- Microbiology-Immunology Department, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
- The Research Institute of the University of Bucharest, 050095 Bucharest, Romania
| | - Irina Gheorghe-Barbu
- Microbiology-Immunology Department, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
- The Research Institute of the University of Bucharest, 050095 Bucharest, Romania
| | - Georgiana Alexandra Grigore
- Microbiology-Immunology Department, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
- The Research Institute of the University of Bucharest, 050095 Bucharest, Romania
- National Institute of Research and Development for Biological Sciences, 060031 Bucharest, Romania
| | - Corneliu Ovidiu Vrancianu
- Microbiology-Immunology Department, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
- The Research Institute of the University of Bucharest, 050095 Bucharest, Romania
| | - Mariana Carmen Chifiriuc
- Microbiology-Immunology Department, Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania
- The Research Institute of the University of Bucharest, 050095 Bucharest, Romania
- Academy of Romanian Scientists, 050044 Bucharest, Romania
- Romanian Academy, 010071 Bucharest, Romania
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4
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Furniss RCD, Kaderabkova N, Barker D, Bernal P, Maslova E, Antwi AA, McNeil HE, Pugh HL, Dortet L, Blair JM, Larrouy-Maumus GJ, McCarthy RR, Gonzalez D, Mavridou DA. Breaking antimicrobial resistance by disrupting extracytoplasmic protein folding. eLife 2022; 11:57974. [PMID: 35025730 PMCID: PMC8863373 DOI: 10.7554/elife.57974] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 01/11/2022] [Indexed: 11/24/2022] Open
Abstract
Antimicrobial resistance in Gram-negative bacteria is one of the greatest threats to global health. New antibacterial strategies are urgently needed, and the development of antibiotic adjuvants that either neutralize resistance proteins or compromise the integrity of the cell envelope is of ever-growing interest. Most available adjuvants are only effective against specific resistance proteins. Here, we demonstrate that disruption of cell envelope protein homeostasis simultaneously compromises several classes of resistance determinants. In particular, we find that impairing DsbA-mediated disulfide bond formation incapacitates diverse β-lactamases and destabilizes mobile colistin resistance enzymes. Furthermore, we show that chemical inhibition of DsbA sensitizes multidrug-resistant clinical isolates to existing antibiotics and that the absence of DsbA, in combination with antibiotic treatment, substantially increases the survival of Galleria mellonella larvae infected with multidrug-resistant Pseudomonas aeruginosa. This work lays the foundation for the development of novel antibiotic adjuvants that function as broad-acting resistance breakers. Antibiotics, like penicillin, are the foundation of modern medicine, but bacteria are evolving to resist their effects. Some of the most harmful pathogens belong to a group called the 'Gram-negative bacteria', which have an outer layer – called the cell envelope – that acts as a drug barrier. This envelope contains antibiotic resistance proteins that can deactivate or repel antibiotics or even pump them out of the cell once they get in. One way to tackle antibiotic resistance could be to stop these proteins from working. Proteins are long chains of building blocks called amino acids that fold into specific shapes. In order for a protein to perform its role correctly, it must fold in the right way. In bacteria, a protein called DsbA helps other proteins fold correctly by holding them in place and inserting links called disulfide bonds. It was unclear whether DsbA plays a role in the folding of antibiotic resistance proteins, but if it did, it might open up new ways to treat antibiotic resistant infections. To find out more, Furniss, Kaderabkova et al. collected the genes that code for several antibiotic resistance proteins and put them into Escherichia coli bacteria, which made the bacteria resistant to antibiotics. Furniss, Kaderabkova et al. then stopped the modified E. coli from making DsbA, which led to the antibiotic resistance proteins becoming unstable and breaking down because they could not fold correctly. Further experiments showed that blocking DsbA with a chemical inhibitor in other pathogenic species of Gram-negative bacteria made these bacteria more sensitive to antibiotics that they would normally resist. To demonstrate that using this approach could work to stop infections by these bacteria, Furniss, Kaderabkova et al. used Gram-negative bacteria that produced antibiotic resistance proteins but could not make DsbA to infect insect larvae. The larvae were then treated with antibiotics, which increased their survival rate, indicating that blocking DsbA may be a good approach to tackling antibiotic resistant bacteria. According to the World Health Organization, developing new treatments against Gram-negative bacteria is of critical importance, but the discovery of new drugs has ground to a halt. One way around this is to develop ways to make existing drugs work better. Making drugs that block DsbA could offer a way to treat resistant infections using existing antibiotics in the future.
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Affiliation(s)
| | - Nikol Kaderabkova
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - Declan Barker
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Patricia Bernal
- Department of Microbiology, Universidad de Sevilla, Seville, Spain
| | - Evgenia Maslova
- Department of Life Sciences, Brunel University London, London, United Kingdom
| | - Amanda Aa Antwi
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Helen E McNeil
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Hannah L Pugh
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Laurent Dortet
- Department of Bacteriology-Hygiene, Paris-Sud University, Paris, France
| | - Jessica Ma Blair
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | | | - Ronan R McCarthy
- Department of Life Sciences, Brunel University London, London, United Kingdom
| | - Diego Gonzalez
- Department of Biology, University of Neuchatel, Neuchatel, Switzerland
| | - Despoina Ai Mavridou
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
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Abstract
Class D β-lactamases are composed of 14 families and the majority of the member enzymes are included in the OXA family. The genes for class D β-lactamases are frequently identified in the chromosome as an intrinsic resistance determinant in environmental bacteria and a few of these are found in mobile genetic elements carried by clinically significant pathogens. The most dominant OXA family among class D β-lactamases is superheterogeneous and the family needs to have an updated scheme for grouping OXA subfamilies through phylogenetic analysis. The OXA enzymes, even the members within a subfamily, have a diverse spectrum of resistance. Such varied activity could be derived from their active sites, which are distinct from those of the other serine β-lactamases. Their substrate profile is determined according to the size and position of the P-, Ω- and β5-β6 loops, assembling the active-site channel, which is very hydrophobic. Also, amino acid substitutions occurring in critical structures may alter the range of hydrolysed substrates and one subfamily could include members belonging to several functional groups. This review aims to describe the current class D β-lactamases including the functional groups, occurrence types (intrinsic or acquired) and substrate spectra and, focusing on the major OXA family, a new model for subfamily grouping will be presented.
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Affiliation(s)
- Eun-Jeong Yoon
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
| | - Seok Hoon Jeong
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
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6
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Arca-Suárez J, Lasarte-Monterrubio C, Rodiño-Janeiro BK, Cabot G, Vázquez-Ucha JC, Rodríguez-Iglesias M, Galán-Sánchez F, Beceiro A, González-Bello C, Oliver A, Bou G. Molecular mechanisms driving the in vivo development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR Pseudomonas aeruginosa infections. J Antimicrob Chemother 2021; 76:91-100. [PMID: 33083833 DOI: 10.1093/jac/dkaa396] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/25/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The development of resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of Pseudomonas aeruginosa infections is concerning. OBJECTIVES Characterization of the mechanisms leading to the development of OXA-10-mediated resistance to ceftolozane/tazobactam and ceftazidime/avibactam during treatment of XDR P. aeruginosa infections. METHODS Four paired ceftolozane/tazobactam- and ceftazidime/avibactam-susceptible/resistant isolates were evaluated. MICs were determined by broth microdilution. STs, resistance mechanisms and genetic context of β-lactamases were determined by genotypic methods, including WGS. The OXA-10 variants were cloned in PAO1 to assess their impact on resistance. Models for the OXA-10 derivatives were constructed to evaluate the structural impact of the amino acid changes. RESULTS The same XDR ST253 P. aeruginosa clone was detected in all four cases evaluated. All initial isolates showed OprD deficiency, produced an OXA-10 enzyme and were susceptible to ceftazidime, ceftolozane/tazobactam, ceftazidime/avibactam and colistin. During treatment, the isolates developed resistance to all cephalosporins. Comparative genomic analysis revealed that the evolved resistant isolates had acquired mutations in the OXA-10 enzyme: OXA-14 (Gly157Asp), OXA-794 (Trp154Cys), OXA-795 (ΔPhe153-Trp154) and OXA-824 (Asn143Lys). PAO1 transformants producing the evolved OXA-10 derivatives showed enhanced ceftolozane/tazobactam and ceftazidime/avibactam resistance but decreased meropenem MICs in a PAO1 background. Imipenem/relebactam retained activity against all strains. Homology models revealed important changes in regions adjacent to the active site of the OXA-10 enzyme. The blaOXA-10 gene was plasmid borne and acquired due to transposition of Tn6746 in the pHUPM plasmid scaffold. CONCLUSIONS Modification of OXA-10 is a mechanism involved in the in vivo acquisition of resistance to cephalosporin/β-lactamase inhibitor combinations in P. aeruginosa.
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Affiliation(s)
- Jorge Arca-Suárez
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | - Cristina Lasarte-Monterrubio
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | - Bruno-Kotska Rodiño-Janeiro
- Prof. Martin Polz Laboratory, University of Vienna, Department for Microbiology and Ecosystem Science, Division of Microbial Ecology, Vienna, Austria
| | - Gabriel Cabot
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdiSBA), Palma de Mallorca, Spain
| | - Juan Carlos Vázquez-Ucha
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | - Manuel Rodríguez-Iglesias
- Servicio de Microbiología and Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Hospital Universitario Puerta del Mar; Departamento de Biomedicina, Biotecnología y Salud Pública, Universidad de Cádiz, Cádiz, Spain
| | - Fátima Galán-Sánchez
- Servicio de Microbiología and Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Hospital Universitario Puerta del Mar; Departamento de Biomedicina, Biotecnología y Salud Pública, Universidad de Cádiz, Cádiz, Spain
| | - Alejandro Beceiro
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | - Concepción González-Bello
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdiSBA), Palma de Mallorca, Spain
| | - Germán Bou
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
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Bergšpica I, Kaprou G, Alexa EA, Prieto M, Alvarez-Ordóñez A. Extended Spectrum β-Lactamase (ESBL) Producing Escherichia coli in Pigs and Pork Meat in the European Union. Antibiotics (Basel) 2020; 9:E678. [PMID: 33036406 PMCID: PMC7600538 DOI: 10.3390/antibiotics9100678] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 02/06/2023] Open
Abstract
The aim of this article is to review the fast and worldwide distribution of ESBL enzymes and to describe the role of the pork production chain as a reservoir and transmission route of ESBL-producing Escherichia coli and ESBLs in the European Union (EU). The use of β-lactam antibiotics in swine production and the prevalence of ESBL producing E. coli in fattening pigs and pork meat across Europe is analyzed. Overall, an increasing trend in the prevalence of presumptive ESBL producing E. coli in fattening pigs in the EU has been observed in the last decade, although with major differences among countries, linked to different approaches in the use of antimicrobials in pork production within the EU. Moreover, the various dissemination pathways of these bacteria along the pork production chain are described, along with factors at farm and slaughterhouse level influencing the risk of introducing or spreading ESBL producing bacteria throughout the food chain.
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Affiliation(s)
- Ieva Bergšpica
- Department of Food Hygiene and Technology, Universidad de León, 24007 León, Spain; (G.K.); (E.A.A.); (M.P.)
- Institute of Food Safety, Animal Health and Environment BIOR, LV-1076 Riga, Latvia
| | - Georgia Kaprou
- Department of Food Hygiene and Technology, Universidad de León, 24007 León, Spain; (G.K.); (E.A.A.); (M.P.)
| | - Elena A. Alexa
- Department of Food Hygiene and Technology, Universidad de León, 24007 León, Spain; (G.K.); (E.A.A.); (M.P.)
| | - Miguel Prieto
- Department of Food Hygiene and Technology, Universidad de León, 24007 León, Spain; (G.K.); (E.A.A.); (M.P.)
- Institute of Food Science and Technology, Universidad de León, 24007 León, Spain
| | - Avelino Alvarez-Ordóñez
- Department of Food Hygiene and Technology, Universidad de León, 24007 León, Spain; (G.K.); (E.A.A.); (M.P.)
- Institute of Food Science and Technology, Universidad de León, 24007 León, Spain
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8
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Chen Q, Zhou W, Qian C, Shen K, Zhu X, Zhou D, Sun Z, Lu W, Liu H, Li K, Xu T, Bao Q, Lu J. OXA-830, a Novel Chromosomally Encoded Extended-Spectrum Class D β-Lactamase in Aeromonas simiae. Front Microbiol 2019; 10:2732. [PMID: 31849884 PMCID: PMC6902050 DOI: 10.3389/fmicb.2019.02732] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/11/2019] [Indexed: 12/04/2022] Open
Abstract
The diversity of class D β-lactamases mediating resistance to β-lactams has been increasingly reported recently. In this study, a novel class D oxacillinase named OXA-830 was identified in a fully sequenced Aeromonas simiae strain, which was isolated from sewage discharged from a farm in southern China. OXA-830 shares the highest amino acid identity of 79.3% with an OXA-12-like variant named OXA-725. When expressed in E. coli DH5α, OXA-830 conferred resistance to penicillins and selected β-lactamase inhibitors but not to cephalosporins and carbapenems. Kinetic analysis of OXA-830 revealed a broad substrate profile including penicillins, cefazolin, cefoxitin, and ceftazidime but not carbapenems. The hydrolytic activity was significantly inhibited by sulbactam, followed by tazobactam, but was less effectively inhibited by clavulanic acid. The blaOXA–830 gene was located on the A. simiae A6 chromosome and the blaOXA–830-related region was bracketed by a pair of perfect inverted repeats.
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Affiliation(s)
- Qianqian Chen
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Wangxiao Zhou
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Changrui Qian
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Kai Shen
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Xinyi Zhu
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Danying Zhou
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Zhewei Sun
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Wei Lu
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Hongmao Liu
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Kewei Li
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Teng Xu
- Tongji University School of Medicine, Shanghai, China.,Institute of Translational Medicine, Baotou Central Hospital, Baotou, China
| | - Qiyu Bao
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China
| | - Junwan Lu
- School of Laboratory Medicine and Life Science/Institute of Biomedical Informatics, Wenzhou Medical University, Wenzhou, China.,School of Medical and Health, Lishui University, Lishui, China
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9
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Liapis E, Bour M, Triponney P, Jové T, Zahar JR, Valot B, Jeannot K, Plésiat P. Identification of Diverse Integron and Plasmid Structures Carrying a Novel Carbapenemase Among Pseudomonas Species. Front Microbiol 2019; 10:404. [PMID: 30886610 PMCID: PMC6409357 DOI: 10.3389/fmicb.2019.00404] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/15/2019] [Indexed: 12/20/2022] Open
Abstract
A novel carbapenem-hydrolyzing beta-lactamase, called IMP-63, was identified in three clonally distinct strains of Pseudomonas aeruginosa and two strains of Pseudomonas putida isolated within a 4 year timeframe in three French hospitals. The blaIMP–63 gene that encodes this carbapenemase turned out to be located in the variable region of four integrons (In1297, In1574, In1573, and In1572) and to coexist with novel or rare gene cassettes (fosM, gcu170, gcuF1) and insertion elements (ISPsp7v, ISPa16v). All these integrons except one (In1574) were flanked by a copy of insertion sequence ISPa17 next to the orf6 putative gene, and were carried by non-conjugative plasmids (pNECK1, pROUSS1, pROUSS2, pROUE1). These plasmids exhibit unique modular structures and partial sequence homologies with plasmids previously identified in various non-fermenting environmental Gram-negative species. Lines of evidence suggest that ISPa17 promoted en bloc the transposition of IMP-63-encoding integrons on these different plasmids. As demonstrated by genotyping experiments, isolates of P. aeruginosa harboring the 28.9-kb plasmid pNECK1 and belonging to international “high-risk” clone ST308 were responsible for an outbreak in one hospital. Collectively, these data provide an insight into the complex and unpredictable routes of diffusion of some resistance determinants, here blaIMP–63, among Pseudomonas species.
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Affiliation(s)
- Eleni Liapis
- Centre National de Référence de la Résistance aux Antibiotiques, CHRU Jean Minjoz, Besançon, France.,CNRS, UMR 6249 Chrono-Environnement, Besançon, France
| | - Maxime Bour
- Centre National de Référence de la Résistance aux Antibiotiques, CHRU Jean Minjoz, Besançon, France
| | - Pauline Triponney
- Centre National de Référence de la Résistance aux Antibiotiques, CHRU Jean Minjoz, Besançon, France
| | - Thomas Jové
- INSERM UMR 1092, Université de Limoges, CHU Limoges, Limoges, France
| | - Jean-Ralph Zahar
- Département de Microbiologie Clinique, AP-HP, CHU Avicenne, Bobigny, France
| | - Benoît Valot
- CNRS, UMR 6249 Chrono-Environnement, Besançon, France
| | - Katy Jeannot
- Centre National de Référence de la Résistance aux Antibiotiques, CHRU Jean Minjoz, Besançon, France.,CNRS, UMR 6249 Chrono-Environnement, Besançon, France
| | - Patrick Plésiat
- Centre National de Référence de la Résistance aux Antibiotiques, CHRU Jean Minjoz, Besançon, France.,CNRS, UMR 6249 Chrono-Environnement, Besançon, France
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10
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Characterization of the First OXA-10 Natural Variant with Increased Carbapenemase Activity. Antimicrob Agents Chemother 2018; 63:AAC.01817-18. [PMID: 30397053 DOI: 10.1128/aac.01817-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 10/26/2018] [Indexed: 12/25/2022] Open
Abstract
While carbapenem resistance in Gram-negative bacteria is mainly due to the production of efficient carbapenemases, β-lactamases with a narrower spectrum may also contribute to resistance when combined with additional mechanisms. OXA-10-type class D β-lactamases, previously shown to be weak carbapenemases, could represent such a case. In this study, two novel OXA-10 variants were identified as the sole carbapenem-hydrolyzing enzymes in meropenem-resistant enterobacteria isolated from hospital wastewater and found by next-generation sequencing to express additional β-lactam resistance mechanisms. The new variants, OXA-655 and OXA-656, were carried by two related IncQ1 broad-host-range plasmids. Compared to the sequence of OXA-10, they both harbored a Thr26Met substitution, with OXA-655 also bearing a leucine instead of a valine in position 117 of the SAV catalytic motif. Susceptibility profiling of laboratory strains replicating the natural bla OXA plasmids and of recombinant clones expressing OXA-10 and the novel variants in an isogenic background indicated that OXA-655 is a more efficient carbapenemase. The carbapenemase activity of OXA-655 is due to the Val117Leu substitution, as shown by steady-state kinetic experiments, where the k cat of meropenem hydrolysis was increased 4-fold. In contrast, OXA-655 had no activity toward oxyimino-β-lactams, while its catalytic efficiency against oxacillin was significantly reduced. Moreover, the Val117Leu variant was more efficient against temocillin and cefoxitin. Molecular dynamics indicated that Val117Leu affects the position 117-Leu155 interaction, leading to structural shifts in the active site that may alter carbapenem alignment. The evolutionary potential of OXA-10 enzymes toward carbapenem hydrolysis combined with their spread by promiscuous plasmids indicates that they may pose a future clinical threat.
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11
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Sheu CC, Lin SY, Chang YT, Lee CY, Chen YH, Hsueh PR. Management of infections caused by extended-spectrum β-lactamase-producing Enterobacteriaceae: current evidence and future prospects. Expert Rev Anti Infect Ther 2018; 16:205-218. [PMID: 29402125 DOI: 10.1080/14787210.2018.1436966] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION The spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has become a major public health threat worldwide. Area covered: A thorough systematic literature review describing the current evidence and future prospects of therapeutic options for infections caused by ESBL-producing Enterobacteriaceae. Expert commentary: The methods of detecting ESBLs have been evolving. The Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing lowered the MIC breakpoints of cephalosporins against ESBL-producing Enterobacteriaceae in 2010. Phenotypic testing for ESBLs is no longer recommended. Instead, the selection of appropriate antimicrobial agents largely depends on the report of minimum inhibitory concentrations (MICs). To date, therapeutic options for these multidrug-resistant organisms remain limited. The clinical efficacy of piperacillin/tazobactam and cefepime on in vitro-susceptible ESBL-producing Enterobacteriaceae remains a concern. Many studies found an in vitro-in vivo discordance based on current breakpoints. Carbapenems are the most reliable antibiotics for severe infections caused by ESBL-producing Enterobacteriaceae. However, their overuse has led to a serious problem of increasing drug resistance. Recently, ceftolozane/tazobactam and ceftazidime/avibactam have been approved for the treatment of complicated urinary tract infections and complicated intra-abdominal infections. The introduction of these new β-lactam/β-lactamase inhibitor combinations offers new carbapenem-sparing options for the treatment of ESBL infections.
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Affiliation(s)
- Chau-Chyun Sheu
- a Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine , Kaohsiung Medical University Hospital , Kaohsiung , Taiwan.,b School of Medicine, Sepsis Research Institute, Graduate Institute of Medicine, College of Medicine , Kaohsiung Medical University , Kaohsiung , Taiwan
| | - Shang-Yi Lin
- b School of Medicine, Sepsis Research Institute, Graduate Institute of Medicine, College of Medicine , Kaohsiung Medical University , Kaohsiung , Taiwan.,c Division of Infectious Disease, Department of Internal Medicine , Kaohsiung Medical University Hospital , Kaohsiung , Taiwan
| | - Ya-Ting Chang
- b School of Medicine, Sepsis Research Institute, Graduate Institute of Medicine, College of Medicine , Kaohsiung Medical University , Kaohsiung , Taiwan.,c Division of Infectious Disease, Department of Internal Medicine , Kaohsiung Medical University Hospital , Kaohsiung , Taiwan
| | - Chun-Yuan Lee
- b School of Medicine, Sepsis Research Institute, Graduate Institute of Medicine, College of Medicine , Kaohsiung Medical University , Kaohsiung , Taiwan.,c Division of Infectious Disease, Department of Internal Medicine , Kaohsiung Medical University Hospital , Kaohsiung , Taiwan
| | - Yen-Hsu Chen
- b School of Medicine, Sepsis Research Institute, Graduate Institute of Medicine, College of Medicine , Kaohsiung Medical University , Kaohsiung , Taiwan.,c Division of Infectious Disease, Department of Internal Medicine , Kaohsiung Medical University Hospital , Kaohsiung , Taiwan.,d Department of Biological Science and Technology , College of Biological Science and Technology, National Chiao Tung University , Hsin Chu , Taiwan
| | - Po-Ren Hsueh
- e Department of Laboratory Medicine , National Taiwan University Hospital, College of Medicine, National Taiwan University , Taipei , Taiwan.,f Department of Internal Medicine , National Taiwan University Hospital, College of Medicine, National Taiwan University , Taipei , Taiwan
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12
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Molecular Docking and Molecular Dynamics Studies to Identify Potential OXA-10 Extended Spectrum β-Lactamase Non-hydrolysing Inhibitors for Pseudomonas aeruginosa. Cell Biochem Biophys 2016; 74:141-55. [DOI: 10.1007/s12013-016-0735-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 05/18/2016] [Indexed: 01/17/2023]
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13
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Abstract
The OXA β-lactamases were among the earliest β-lactamases detected; however, these molecular class D β-lactamases were originally relatively rare and always plasmid mediated. They had a substrate profile limited to the penicillins, but some became able to confer resistance to cephalosporins. From the 1980s onwards, isolates of Acinetobacter baumannii that were resistant to the carbapenems emerged, manifested by plasmid-encoded β-lactamases (OXA-23, OXA-40, and OXA-58) categorized as OXA enzymes because of their sequence similarity to earlier OXA β-lactamases. It was soon found that every A. baumannii strain possessed a chromosomally encoded OXA β-lactamase (OXA-51-like), some of which could confer resistance to carbapenems when the genetic environment around the gene promoted its expression. Similarly, Acinetobacter species closely related to A. baumannii also possessed their own chromosomally encoded OXA β-lactamases; some could be transferred to A. baumannii, and they formed the basis of transferable carbapenem resistance in this species. In some cases, the carbapenem-resistant OXA β-lactamases (OXA-48) have migrated into the Enterobacteriaceae and are becoming a significant cause of carbapenem resistance. The emergence of OXA enzymes that can confer resistance to carbapenems, particularly in A. baumannii, has transformed these β-lactamases from a minor hindrance into a major problem set to demote the clinical efficacy of the carbapenems.
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14
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Potron A, Poirel L, Nordmann P. Emerging broad-spectrum resistance in Pseudomonas aeruginosa and Acinetobacter baumannii: Mechanisms and epidemiology. Int J Antimicrob Agents 2015; 45:568-85. [PMID: 25857949 DOI: 10.1016/j.ijantimicag.2015.03.001] [Citation(s) in RCA: 451] [Impact Index Per Article: 50.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/05/2015] [Indexed: 02/07/2023]
Abstract
Multidrug resistance is quite common among non-fermenting Gram-negative rods, in particular among clinically relevant species including Pseudomonas aeruginosa and Acinetobacter baumannii. These bacterial species, which are mainly nosocomial pathogens, possess a diversity of resistance mechanisms that may lead to multidrug or even pandrug resistance. Extended-spectrum β-lactamases (ESBLs) conferring resistance to broad-spectrum cephalosporins, carbapenemases conferring resistance to carbapenems, and 16S rRNA methylases conferring resistance to all clinically relevant aminoglycosides are the most important causes of concern. Concomitant resistance to fluoroquinolones, polymyxins (colistin) and tigecycline may lead to pandrug resistance. The most important mechanisms of resistance in P. aeruginosa and A. baumannii and their most recent dissemination worldwide are detailed here.
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Affiliation(s)
- Anaïs Potron
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Laurent Poirel
- Emerging Antibiotic Resistance Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland.
| | - Patrice Nordmann
- Emerging Antibiotic Resistance Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland; HFR - Hôpital Cantonal de Fribourg, Fribourg, Switzerland
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15
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Antunes NT, Fisher JF. Acquired Class D β-Lactamases. Antibiotics (Basel) 2014; 3:398-434. [PMID: 27025753 PMCID: PMC4790369 DOI: 10.3390/antibiotics3030398] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/31/2014] [Accepted: 08/08/2014] [Indexed: 12/21/2022] Open
Abstract
The Class D β-lactamases have emerged as a prominent resistance mechanism against β-lactam antibiotics that previously had efficacy against infections caused by pathogenic bacteria, especially by Acinetobacter baumannii and the Enterobacteriaceae. The phenotypic and structural characteristics of these enzymes correlate to activities that are classified either as a narrow spectrum, an extended spectrum, or a carbapenemase spectrum. We focus on Class D β-lactamases that are carried on plasmids and, thus, present particular clinical concern. Following a historical perspective, the susceptibility and kinetics patterns of the important plasmid-encoded Class D β-lactamases and the mechanisms for mobilization of the chromosomal Class D β-lactamases are discussed.
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Affiliation(s)
- Nuno T Antunes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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16
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First Report of OXA-4, an ESBL Isolated from Pseudomonas aeruginosa a South Indian Strain. Indian J Microbiol 2014; 53:308-14. [PMID: 24426128 DOI: 10.1007/s12088-012-0326-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 03/22/2010] [Indexed: 10/27/2022] Open
Abstract
The OXA-type β-lactamases are so named because of their oxacillin-hydrolyzing abilities. In this study we characterize an extended spectrum β-lactamase, designated OXA-4, produced by a clinical isolate of Pseudomonas aeruginosa. ESBL production was detected by double disk synergy test. The P. aeruginosa isolate was obtained from endotracheal suction tip of 84 years old male patient diagnosed with CVA and hypertension. ESBL producing OXA β-lactamases was detected by PCR with primers specific to the conserved regions of the coding genes. Iso electric focusing was done to confirm the significance, sequencing the amplified product was also done. In the phenotypic identification, the strain was highly resistant to third generation cephalosporins and also to imipenem. The PCR amplified product for OXA β-lactamase was viewed at 919 bp. The pI point for the same was identified at 7.2. With the help of sequencing the amplified OXA β-lactamase was identified as OXA-4 gene. Here we report P. aeruginosa producing OXA-4 ESBL for the first time in the Indian subcontinent.
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17
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Morita Y, Tomida J, Kawamura Y. Primary mechanisms mediating aminoglycoside resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7. MICROBIOLOGY-SGM 2012; 158:1071-1083. [PMID: 22282519 DOI: 10.1099/mic.0.054320-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The multiresistant taxonomic outlier Pseudomonas aeruginosa PA7 possesses the conserved efflux genes, mexXY; however these are linked to a unique gene encoding an outer membrane channel, dubbed oprA, that is absent in most P. aeruginosa strains. Using genetic knockouts and single copy chromosomal complementation, we showed that aminoglycoside resistance in PA7 is mediated in part by the MexXY-OprA pump, and intriguingly that MexXY in this strain can utilize either the OprA or OprM outer membrane channel, linked to the mexAB efflux genes. We also identified a small portion of the oprA gene immediately downstream of the mexY gene in PAO1, suggesting that non-PA7 P. aeruginosa strains might have possessed, but lost, the intact mexXY-oprA efflux pump locus. Consistent with this, most of a panel of serotype strains possessed the truncated oprA but the serotype O12 isolate had an intact mexXY-oprA locus, similar to PA7 and the related strain DSM 1128. We also showed that the mexZ repressor gene upstream of mexXY-oprA in PA7 is mutated, leading to overexpression of mexXY-oprA, using sequencing, homologous replacement and real-time quantitative reverse transcriptase PCR. Finally we assessed the contribution of MexXY and aminoglycoside modifying enzymes AAC together to resistance in PA7 and the AAC(6')-Iae-mediated amikacin-resistant clinical isolate IMCJ2.S1, concluding that the effect of the modifying enzymes is enhanced by functional efflux, especially in the presence of divalent cations, to develop high-level aminoglycoside resistance in P. aeruginosa.
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Affiliation(s)
- Yuji Morita
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Junko Tomida
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Yoshiaki Kawamura
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
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18
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Hocquet D, Colomb M, Dehecq B, Belmonte O, Courvalin P, Plésiat P, Meziane-Cherif D. Ceftazidime-hydrolysing β-lactamase OXA-145 with impaired hydrolysis of penicillins in Pseudomonas aeruginosa. J Antimicrob Chemother 2011; 66:1745-50. [PMID: 21665906 DOI: 10.1093/jac/dkr187] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVES To describe a novel extended-spectrum oxacillinase, named OXA-145, differing from narrow-spectrum OXA-35 (from the OXA-10 group) by deletion of residue Leu-165. The genetic environment of bla(OXA-145) and the biochemical properties of OXA-145 are reported. We also assessed the impact of the Leu-165 deletion on the hydrolysis spectrum of the ancestor OXA-10. METHODS Extended-spectrum β-lactamase OXA-145 was identified in the multidrug-resistant clinical Pseudomonas aeruginosa 08-056, and characterized by isoelectric focusing, PCR and DNA sequencing. Antibiotic susceptibility tests were performed by agar dilution. The resistance profiles conferred by cloned bla(OXA-10), bla(OXA-35), bla(OXA-145) and a bla(OXA-10) derivative obtained by site-directed mutagenesis were determined in Escherichia coli. Kinetic parameters of OXA-35 and OXA-145 were established after purification of His-tagged proteins. RESULTS The sequence of OXA-145, encoded by a class 1 integron-borne gene in strain 08-056, differed from that of narrow-spectrum penicillinase OXA-35 by a single amino acid deletion (Leu-165) located in the highly conserved omega loop. Deletion of Leu-165 from OXA-35 (yielding OXA-145) or OXA-10 (the progenitor of OXA-35) extended the hydrolysis spectrum to third-generation cephalosporins and to monobactams, while reducing that for penicillins. OXA-145 showed biphasic hydrolysis curves for all the substrates tested. Its activity against nitrocefin was 10-fold higher in the presence of sodium hydrogen carbonate. CONCLUSIONS OXA-145 is a new extended-spectrum β-lactamase from the OXA-10 group. The deletion of Leu-165 is responsible for a shift in the hydrolysis spectrum from penicillins to third-generation cephalosporins, as well as monobactams. The loss of penicillin hydrolysis was due to a non-carboxylated Lys-73.
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Affiliation(s)
- Didier Hocquet
- Centre National de Référence de Résistance aux Antibiotiques, Laboratoire associé Pseudomonas aeruginosa, Centre Hospitalier Universitaire, Besançon, France
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19
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Strain-tailored double-disk synergy test detects extended-spectrum oxacillinases in Pseudomonas aeruginosa. J Clin Microbiol 2011; 49:2262-5. [PMID: 21450950 DOI: 10.1128/jcm.02585-10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The prevalence of class D extended-spectrum oxacillinases (ES-OXAs) in ceftazidime-resistant strains of Pseudomonas aeruginosa is often underestimated by double-disk synergy tests (DDST) using clavulanate. A DDST with a customized distance between a disk of ceftazidime or cefepime and inhibitors (clavulanate and imipenem) detected 14 out of 15 different ES-OXAs.
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20
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Abstract
Aminoglycosides have been an essential component of the armamentarium in the treatment of life-threatening infections. Unfortunately, their efficacy has been reduced by the surge and dissemination of resistance. In some cases the levels of resistance reached the point that rendered them virtually useless. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevalent in the clinical setting. Aminoglycoside modifying enzymes catalyze the modification at different -OH or -NH₂ groups of the 2-deoxystreptamine nucleus or the sugar moieties and can be nucleotidyltransferases, phosphotransferases, or acetyltransferases. The number of aminoglycoside modifying enzymes identified to date as well as the genetic environments where the coding genes are located is impressive and there is virtually no bacteria that is unable to support enzymatic resistance to aminoglycosides. Aside from the development of new aminoglycosides refractory to as many as possible modifying enzymes there are currently two main strategies being pursued to overcome the action of aminoglycoside modifying enzymes. Their successful development would extend the useful life of existing antibiotics that have proven effective in the treatment of infections. These strategies consist of the development of inhibitors of the enzymatic action or of the expression of the modifying enzymes.
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21
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Zhao WH, Hu ZQ. β-Lactamases identified in clinical isolates ofPseudomonas aeruginosa. Crit Rev Microbiol 2010; 36:245-58. [DOI: 10.3109/1040841x.2010.481763] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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22
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Cholley P, Hocquet D, Alauzet C, Cravoisy-Popovic A, Talon D, Aissa N, Plésiat P, Bertrand X. Hospital outbreak of Pseudomonas aeruginosa producing extended-spectrum oxacillinase OXA-19. J Med Microbiol 2010; 59:866-869. [PMID: 20299501 DOI: 10.1099/jmm.0.019364-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Pascal Cholley
- UMR 6249 Chrono-Environnement, Université de Franche-Comté, Besançon, France.,Service d'Hygiène Hospitalière, Centre Hospitalier Universitaire Besançon, Besançon, France
| | - Didier Hocquet
- Centre National de Référence-Résistance chez P. aeruginosa, Centre Hospitalier Universitaire Besançon, Besançon, France.,Service de Bactériologie, Centre Hospitalier Universitaire Besançon, Besançon, France
| | - Corentine Alauzet
- Service de Bactériologie, Centre Hospitalier Universitaire Nancy, Nancy, France
| | | | - Daniel Talon
- Centre National de Référence-Résistance chez P. aeruginosa, Centre Hospitalier Universitaire Besançon, Besançon, France.,UMR 6249 Chrono-Environnement, Université de Franche-Comté, Besançon, France.,Service d'Hygiène Hospitalière, Centre Hospitalier Universitaire Besançon, Besançon, France
| | - Nejla Aissa
- Service de Bactériologie, Centre Hospitalier Universitaire Nancy, Nancy, France
| | - Patrick Plésiat
- Centre National de Référence-Résistance chez P. aeruginosa, Centre Hospitalier Universitaire Besançon, Besançon, France.,Service de Bactériologie, Centre Hospitalier Universitaire Besançon, Besançon, France
| | - Xavier Bertrand
- Centre National de Référence-Résistance chez P. aeruginosa, Centre Hospitalier Universitaire Besançon, Besançon, France.,UMR 6249 Chrono-Environnement, Université de Franche-Comté, Besançon, France.,Service d'Hygiène Hospitalière, Centre Hospitalier Universitaire Besançon, Besançon, France
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23
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Porto A, Ayala J, Gutkind G, Di Conza J. A novel OXA-10-like beta-lactamase is present in different Enterobacteriaceae. Diagn Microbiol Infect Dis 2009; 66:228-9. [PMID: 19833470 DOI: 10.1016/j.diagmicrobio.2009.09.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 09/01/2009] [Accepted: 09/09/2009] [Indexed: 11/19/2022]
Abstract
OXA 101, a novel OXA-10 like enzyme, was found forming part of a class 1 integron located in a conjugative plasmid in three different species of Enterobacteriaceae. This beta-lactamase is related to OXA-35 and OXA-56 and displays a narrow substrate hydrolysis profile.
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Affiliation(s)
- Ayelén Porto
- Cátedra de Microbiología General, Universidad Nacional del Litoral, Santa Fe, Argentina
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24
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Abstract
Class D beta-lactamase-mediated resistance to beta-lactams has been increasingly reported during the last decade. Those enzymes also known as oxacillinases or OXAs are widely distributed among Gram negatives. Genes encoding class D beta-lactamases are known to be intrinsic in many Gram-negative rods, including Acinetobacter baumannii and Pseudomonas aeruginosa, but play a minor role in natural resistance phenotypes. The OXAs (ca. 150 variants reported so far) are characterized by an important genetic diversity and a great heterogeneity in terms of beta-lactam hydrolysis spectrum. The acquired OXAs possess either a narrow spectrum or an expanded spectrum of hydrolysis, including carbapenems in several instances. Acquired class D beta-lactamase genes are mostly associated to class 1 integron or to insertion sequences.
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25
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Strateva T, Yordanov D. Pseudomonas aeruginosa - a phenomenon of bacterial resistance. J Med Microbiol 2009; 58:1133-1148. [PMID: 19528173 DOI: 10.1099/jmm.0.009142-0] [Citation(s) in RCA: 431] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is one of the leading nosocomial pathogens worldwide. Nosocomial infections caused by this organism are often hard to treat because of both the intrinsic resistance of the species (it has constitutive expression of AmpC beta-lactamase and efflux pumps, combined with a low permeability of the outer membrane), and its remarkable ability to acquire further resistance mechanisms to multiple groups of antimicrobial agents, including beta-lactams, aminoglycosides and fluoroquinolones. P. aeruginosa represents a phenomenon of bacterial resistance, since practically all known mechanisms of antimicrobial resistance can be seen in it: derepression of chromosomal AmpC cephalosporinase; production of plasmid or integron-mediated beta-lactamases from different molecular classes (carbenicillinases and extended-spectrum beta-lactamases belonging to class A, class D oxacillinases and class B carbapenem-hydrolysing enzymes); diminished outer membrane permeability (loss of OprD proteins); overexpression of active efflux systems with wide substrate profiles; synthesis of aminoglycoside-modifying enzymes (phosphoryltransferases, acetyltransferases and adenylyltransferases); and structural alterations of topoisomerases II and IV determining quinolone resistance. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. This review describes the known resistance mechanisms in P. aeruginosa to the most frequently administrated antipseudomonal antibiotics: beta-lactams, aminoglycosides and fluoroquinolones.
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Affiliation(s)
- Tanya Strateva
- Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria
| | - Daniel Yordanov
- Department of Microbiology, Medical University of Sofia, 2 Zdrave Street, 1431 Sofia, Bulgaria
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A plasmid-borne Shewanella algae Gene, qnrA3, and its possible transfer in vivo between Kluyvera ascorbata and Klebsiella pneumoniae. J Bacteriol 2008; 190:5217-23. [PMID: 18515416 DOI: 10.1128/jb.00243-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The plasmid-borne quinolone resistance gene qnrA1 is prevalent in multidrug-resistant Enterobacteriaceae. A chromosomally encoded homologue in Shewanella algae, qnrA3, has been described. We isolated two qnrA3-positive strains, one of Klebsiella pneumoniae (He96) and one of Kluyvera ascorbata (Kas96), from the feces of an immunocompromised outpatient. The qnrA3 allele was identical to that of S. algae except for 5 nucleotides and differed from qnrA1 by 29 nucleotides affecting three amino acids. The analysis of the qnrA3 genetic environment showed that qnrA3 was inserted downstream from an ISCR1 element at a recombination crossover site described for other resistance genes, including qnrA1, and immediately upstream from IS26, a situation not described before. IS26 preceded an incomplete class 1 integron which contained, among other genes, aac(6')-Ib-cr, another transferable quinolone resistance gene, and the beta-lactamase gene bla(OXA-1/30). The 10-kb fragment encompassing qnrA3 was compared to previously described qnrA1-containing plasmids and multidrug-resistant plasmids; it shares identical sequences with pC15a, pHSH2, pQR1, pQKp311H, and pSAL-1 but with rearrangements, deletions, and mutations. Conjugal transfer of qnrA3 was highly efficient (10(-2)) from K. pneumoniae He96 or K. ascorbata Kas96 to Escherichia coli J53 but less so (10(-5)) from either donor to a clinical strain of Enterobacter cloacae. This first description of a plasmid-borne copy and of the in vitro transfer of qnrA3 is taken to illustrate its likely in vivo transfer from S. algae to the Enterobacteriaceae.
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Kalai Blagui S, Achour W, Abbassi MS, Bejaoui M, Abdeladhim A, Ben Hassen A. Nosocomial outbreak of OXA-18-producing Pseudomonas aeruginosa in Tunisia. Clin Microbiol Infect 2007; 13:794-800. [PMID: 17610599 DOI: 10.1111/j.1469-0691.2007.01757.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Following systematic screening for ceftazidime-resistant (CAZ-R) Pseudomonas aeruginosa, 24 isolates producing extended-spectrum beta-lactamase (ESBL) were recovered during a 24-month period at the National Bone Marrow Transplant Centre of Tunisia. These isolates were from seven immunocompromised patients and from environmental swabs. ESBLs inhibited by clavulanic acid were detected by double-disk diffusion tests. Isoelectric focusing revealed that these isolates produced two to four beta-lactamases with pIs of 5.5, 6.1, 6.4, 7.6 or 8.2, and PCR detected the presence of bla(OXA-18), bla(SHV) and bla(TEM) genes in 24, 21 and two isolates, respectively. Pulsed-field gel electrophoresis defined two dominant genotypic groups: group A (16 isolates) and group B (four isolates). Sequencing of PCR products from representative isolates identified the bla(OXA-18) gene and revealed nucleotide sequences belonging to the bla(SHV-1) and bla(TEM-1) genes. Isolates producing OXA-18 belonged to genomic group A and were isolated from four immunocompromised patients in the haematology and graft units, and from two wash-basins in the graft unit. No immunocompromised patient harboured the clonal epidemic strain upon admission. This is the first report of the OXA-18-type ESBL in P. aeruginosa in Tunisia, and the first description of an outbreak caused by an OXA-18-producing strain of P. aeruginosa.
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Affiliation(s)
- S Kalai Blagui
- Unité de Recherche, Laboratoire de Bactériologie Médicale, Centre National de Greffe de Moelle Osseuse de Tunis, Tunis, Tunisia
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Depardieu F, Podglajen I, Leclercq R, Collatz E, Courvalin P. Modes and modulations of antibiotic resistance gene expression. Clin Microbiol Rev 2007; 20:79-114. [PMID: 17223624 PMCID: PMC1797629 DOI: 10.1128/cmr.00015-06] [Citation(s) in RCA: 246] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Since antibiotic resistance usually affords a gain of function, there is an associated biological cost resulting in a loss of fitness of the bacterial host. Considering that antibiotic resistance is most often only transiently advantageous to bacteria, an efficient and elegant way for them to escape the lethal action of drugs is the alteration of resistance gene expression. It appears that expression of bacterial resistance to antibiotics is frequently regulated, which indicates that modulation of gene expression probably reflects a good compromise between energy saving and adjustment to a rapidly evolving environment. Modulation of gene expression can occur at the transcriptional or translational level following mutations or the movement of mobile genetic elements and may involve induction by the antibiotic. In the latter case, the antibiotic can have a triple activity: as an antibacterial agent, as an inducer of resistance to itself, and as an inducer of the dissemination of resistance determinants. We will review certain mechanisms, all reversible, that bacteria have elaborated to achieve antibiotic resistance by the fine-tuning of the expression of genetic information.
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Affiliation(s)
- Florence Depardieu
- Unité des Agents Antibactériens, Institut Pasteur, 75724 Paris Cedex 15, France
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29
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Bonomo RA, Szabo D. Mechanisms of multidrug resistance in Acinetobacter species and Pseudomonas aeruginosa. Clin Infect Dis 2006; 43 Suppl 2:S49-56. [PMID: 16894515 DOI: 10.1086/504477] [Citation(s) in RCA: 478] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Acinetobacter species and Pseudomonas aeruginosa are noted for their intrinsic resistance to antibiotics and for their ability to acquire genes encoding resistance determinants. Foremost among the mechanisms of resistance in both of these pathogens is the production of beta -lactamases and aminoglycoside-modifying enzymes. Additionally, diminished expression of outer membrane proteins, mutations in topoisomerases, and up-regulation of efflux pumps play an important part in antibiotic resistance. Unfortunately, the accumulation of multiple mechanisms of resistance leads to the development of multiply resistant or even "panresistant" strains.
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Affiliation(s)
- Robert A Bonomo
- Louis Stokes Cleveland Dept. of Veterans Affairs Medical Center, Section of Infectious Diseases, Cleveland, Ohio 44106, USA.
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Aktaş Z, Poirel L, Salcioğlu M, Ozcan PE, Midilli K, Bal C, Anğ O, Nordmann P. PER-1- and OXA-10-like beta-lactamases in ceftazidime-resistant Pseudomonas aeruginosa isolates from intensive care unit patients in Istanbul, Turkey. Clin Microbiol Infect 2005; 11:193-8. [PMID: 15715716 DOI: 10.1111/j.1469-0691.2004.01067.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The presence of PER-1- and OXA-10-like beta-lactamases was investigated by PCR in 49 ceftazidime-resistant Pseudomonas aeruginosa isolates from patients hospitalised in the 24-bed general intensive care unit of the Istanbul Faculty of Medicine during a 12-month period between February 1999 and February 2000. The clonal relatedness of the isolates was investigated by random amplified polymorphic DNA (RAPD) analysis, and the sequences of the PER-1 and OXA genes from all isolates were determined. The rates of resistance of the isolates to imipenem, aztreonam and cefepime were 98%, 92% and 96%, respectively, and to piperacillin and piperacillin-tazobactam were 41% and 37%, respectively. Using the double-disk synergy test, 37% (18/49) of the isolates were identified as extended-spectrum beta-lactamase producers. The PER-1 gene was identified in 86% (42/49) and the OXA-10 gene in 55% (27/49) of the ceftazidime-resistant isolates. Of isolates carrying the PER-1 gene, 48% (20/42) also carried the OXA-10 gene. The respective nucleotide sequences were identical for each isolate. Sixteen RAPD patterns were detected among the PER-1-positive isolates, but 60% (25/42) of the PER-1-positive isolates belonged to two distinct patterns, while the remainder exhibited a wide clonal diversity. The results indicated that the prevalence of PER-1- and OXA-10-like beta-lactamases remains high among ceftazidime-resistant P. aeruginosa isolates in Turkey.
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Affiliation(s)
- Z Aktaş
- Department of Microbiology and Clinical Microbiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
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Affiliation(s)
- Keith Poole
- Department of Microbiology & Immunology, Rm. 737 Botterell Hall, Queen's University, Kingston, ON K7L 3N6, Canada.
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Abstract
The understanding of microbial resistance to the beta-lactam class of antibiotics in the form of beta-lactamases has come a long way since the early discoveries of narrow-spectrum penicillinases. Integron-borne beta-lactamases co-occurring with a wide array of non-beta-lactam resistance genes, particularly pose an increasing threat to the nosocomial environment, giving rise to multi-drug resistant microbes with complex resistance patterns. Selection of potent beta-lactamases through the use of non-beta-lactam agents may be possible through integron-mediated resistance. It has become imperative that we should continuously strive to understand these complex mechanisms of antimicrobial resistance, not only to overcome them, but to avoid them from evolving further.
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Affiliation(s)
- Gerhard F Weldhagen
- Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria and National Health Laboratory Service, P.O. Box 2034, Pretoria 0001, South Africa.
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Stürenburg E, Mack D. Extended-spectrum β-lactamases: implications for the clinical microbiology laboratory, therapy, and infection control. J Infect 2003; 47:273-95. [PMID: 14556752 DOI: 10.1016/s0163-4453(03)00096-3] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Extended-spectrum beta-lactamase (ESBL) producing gram-negative bacilli are a growing concern in human medicine today. When producing these enzymes, organisms (mostly K. pneumoniae and E. coli) become highly efficient at inactivating the newer third-generation cephaloporins (such as cefotaxime, ceftazidime, and ceftriaxone). In addition, ESBL-producing bacteria are frequently resistant to many classes of non-beta-lactam antibiotics, resulting in difficult-to-treat infections. This review gives an introduction into the topic and is focused on various aspects of ESBLs; it covers the current epidemiology, the problems of ESBL detection and the clinical relevance of infections caused by ESBL-producing organisms. Therapeutic options and potential strategies for dealing with this growing problem are also discussed in this article.
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Affiliation(s)
- Enno Stürenburg
- Institut für Infektionsmedizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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Cagatay AA, Kocagoz T, Eraksoy H. Dio-Sensimedia: a novel culture medium for rapid detection of extended spectrum beta-lactamases. BMC Infect Dis 2003; 3:22. [PMID: 14511397 PMCID: PMC222987 DOI: 10.1186/1471-2334-3-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2003] [Accepted: 09/25/2003] [Indexed: 12/15/2022] Open
Abstract
Background Resistance to contemporary broad-spectrum β-lactams, mediated by extended-spectrum β-lactamases (ESBL), is an increasing problem worldwide. Many of the emerging antimicrobial resistance problems of this decade have been characterized by difficulty in the recognition of resistance in the laboratory, particularly by rapid susceptibility test methods. The plasmid-encoded ESBL represent such a resistance phenomenon that is difficult to recognize. We compared Dio-Sensimedia-ES (DSM-ES; Diomed, Istanbul, Turkey) and Mueller-Hinton (MH) agar in the double-disk synergy test (DDST) as a novel rapid system for detecting ESBL directly from bacterial culture. Methods Sixty ESBL-producing Klebsiella pneumoniae isolates cultured from blood (30), endotracheal aspirates (20), urine (5) and pus (5), as well as 40 Escherichia coli isolates cultured from endotracheal aspirates (15), urine (10), blood (8) and pus (7) were studied. Isolates positive for ESBL by the combined disk tests were tested with the DDST using MH and DSM-ES agar to detect ESBL-mediated resistance in K. pneumoniae and E. coli. DSM-ES agar was also used to determine the susceptibility of Enterobacteriaceae and staphylococci. Results Among 60 ESBL-producing K. pneumoniae isolates, 59 (98.3%) were identified as ESBL-positive by the DDST using MH, and 58 (96.6%), using DSM-ES agar. Of 40 ESBL-producing E. coli isolates, 38 (95%) were ESBL-positive by the DDST on MH agar, and 37 (92.5%), on DSM-ES agar. The average incubation period required for ESBL detection by the DDST on DSM-ES agar was 4 hours. Conclusions Since the DDST results were available within 4 hours when DSM-ES agar was used, the use of this media may significantly lower the length of hospital stay, the total cost for patient care and even the mortality rate by fascilitating early treatment against ESBL-producing organisms.
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Affiliation(s)
- Atahan A Cagatay
- Department of Infectious Diseases and Clinical Microbiology, Istanbul University, Istanbul Faculty of Medicine, Capa, Istanbul, Turkey
| | - Tanil Kocagoz
- Department of R&D, DIOMED Inc. and Acibadem Health Group, Istanbul Turkey
| | - Haluk Eraksoy
- Department of Infectious Diseases and Clinical Microbiology, Istanbul University, Istanbul Faculty of Medicine, Capa, Istanbul, Turkey
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Correia M, Boavida F, Grosso F, Salgado MJ, Lito LM, Cristino JM, Mendo S, Duarte A. Molecular characterization of a new class 3 integron in Klebsiella pneumoniae. Antimicrob Agents Chemother 2003; 47:2838-43. [PMID: 12936982 PMCID: PMC182612 DOI: 10.1128/aac.47.9.2838-2843.2003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Klebsiella pneumoniae FFUL 22K was isolated in April 1999 from the urine of an intensive care unit patient in Portugal. The strain showed an extended-spectrum cephalosporin resistance profile. A typical synergistic effect between cefotaxime or cefepime and clavulanic acid was observed. An Escherichia coli transformant displayed a similar resistance phenotype and harbored a ca. 9.4-kb plasmid (p22K9). Cloning experiments revealed that the extended-spectrum beta-lactamase was encoded by bla(GES-1), previously described in class 1 integrons from K. pneumoniae ORI-1 and Pseudomonas aeruginosa Pa695. Further sequence analysis demonstrated that the bla(GES-1) gene cassette was located on a new class 3 integron. The integron was 2863 bp long and consisted of an intI3 integrase gene, an attI3 recombination site, two promoter regions, and two gene cassettes. The IntI3 integrase was 98.8% identical to that of Serratia marcescens AK9373. The bla(GES-1) gene cassette was inserted at the attI3 site. The second gene cassette was the result of a fusion event between bla(OXA-10)-type and aac(6')-Ib gene cassettes and conferred resistance to kanamycin. This is the second class 3 integron reported and the first time that the bla(GES-1) gene cassette has been found on an integron belonging to this class, highlighting the considerable heterogeneity of their genetic environment and the spread of gene cassettes among different classes of integrons.
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Affiliation(s)
- Mário Correia
- Laboratory of Microbiology, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
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36
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Casin I, Hanau-Berçot B, Podglajen I, Vahaboglu H, Collatz E. Salmonella enterica serovar Typhimurium bla(PER-1)-carrying plasmid pSTI1 encodes an extended-spectrum aminoglycoside 6'-N-acetyltransferase of type Ib. Antimicrob Agents Chemother 2003; 47:697-703. [PMID: 12543680 PMCID: PMC151738 DOI: 10.1128/aac.47.2.697-703.2003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have studied the aminoglycoside resistance gene, which confers high levels of resistance to both amikacin and gentamicin, that is carried by plasmid pSTI1 in the PER-1 beta-lactamase-producing strain of Salmonella enterica serovar Typhimurium previously isolated in Turkey. This gene, called aac(6')-Ib(11), was found in a class 1 integron and codes for a protein of 188 amino acids, a fusion product between the N-terminal moiety (8 amino acids) of the signal peptide of the beta-lactamase OXA-1 and the acetyltransferase. The gene lacked a plausible Shine-Dalgarno (SD) sequence and was located 45 nucleotides downstream from a small open reading frame, ORF-18, with a coding capacity of 18 amino acids and a properly spaced SD sequence likely to direct the initiation of aac(6')-Ib(11) translation. AAC(6')-Ib(11) had Leu118 and Ser119 as opposed to Gln and Leu or Gln and Ser, respectively, which were observed in all previously described enzymes of this type. We have evaluated the effect of Leu or Gln at position 118 by site-directed mutagenesis of aac(6')-Ib(11) and two other acetyltransferase gene variants, aac(6')-Ib(7) and -Ib(8), which naturally encode Gln118. Our results show that the combination of Leu118 and Ser119 confers an extended-spectrum aminoglycoside resistance, with the MICs of all aminoglycosides in clinical use, including gentamicin, being two to eight times higher for strains with Leu118 and Ser119 than for those with Gln118 and Ser119.
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Affiliation(s)
- Isabelle Casin
- Service de Microbiologie, Hôpital Saint-Louis, INSERM EMI-U 0004-LRMA, Université Paris VI, France.
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37
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De Champs C, Poirel L, Bonnet R, Sirot D, Chanal C, Sirot J, Nordmann P. Prospective survey of beta-lactamases produced by ceftazidime- resistant Pseudomonas aeruginosa isolated in a French hospital in 2000. Antimicrob Agents Chemother 2002; 46:3031-4. [PMID: 12183264 PMCID: PMC127436 DOI: 10.1128/aac.46.9.3031-3034.2002] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In 2000, at the Université d'Auvergne teaching hospital in Clermont-Ferrand, France, 44 (6.2%) strains of Pseudomonas aeruginosa were found to be resistant to ceftazidime. After genotyping, 34 strains were selected. Nine had an additional beta-lactamase: OXA-21 (n = 6), PSE-1 (CARB-2) (n = 2), or PER-1 (n = 1). Ceftazidime resistance was related solely to the overproduction of the cephalosporinase in 30 strains. Sequencing of five bla(AmpC) genes encoding cephalosporinases with different pIs showed 99% identity with the ampC gene of P. aeruginosa PAO1.
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Affiliation(s)
- Christophe De Champs
- Service de Bactériologie, Faculté de Médecine, Université d'Auvergne, 63001 Clermont-Ferrand, France.
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38
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Crowley D, Daly M, Lucey B, Shine P, Collins JJ, Cryan B, Moore JE, Murphy P, Buckley G, Fanning S. Molecular epidemiology of cystic fibrosis-linked Burkholderia cepacia complex isolates from three national referral centres in Ireland. J Appl Microbiol 2002; 92:992-1004. [PMID: 11972706 DOI: 10.1046/j.1365-2672.2002.01612.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS Burkholderia cepacia is a Gram-negative bacterium associated with increasing morbidity and mortality and is readily transmitted among infected cystic fibrosis (CF) patients. The B. cepacia complex consists of five distinct subgroups, termed genomovars. A collection of 17 presumptive B. cepacia isolates, obtained from three national CF referral centres located in different geographical regions in Ireland, was studied. The aim of this study was to investigate these isolates using molecular subtyping protocols for evidence of genetic relationships and for the presence of antibiotic resistance-encoding class 1 integron structures. METHODS AND RESULTS Genomovar classifications were assigned to each isolate based on HaeIII enzyme profiles of their recA locus. Genetic relationships among this collection were also assessed after restriction fragment length polymorphism (RFLP)-mediated analysis of the 16S rDNA locus and DNA amplification fingerprinting (DAF). The surface expression of the cable pilus gene (cblA) may facilitate an early step in the infection process. All isolates were tested by amplification strategies for this marker. Burkholderia cepacia is known to be resistant to several antimicrobial agents. Resistance typing showed that the majority were resistant to three or more common antimicrobial agents. Five of the 17 isolates were resistant to sulphonamide, a characteristic linked with the presence of class 1 integrons. Gene cassettes containing beta-lactamase (oxa) and aminoglycoside acetyltransferase (aac(6')-1a) encoding genes were identified by polymerase chain reaction amplification. CONCLUSIONS Most of the isolates in this study were classified as genomovar III and were indistinguishable based on their corresponding 16S rDNA-RFLP profiles, whilst DAF further subtyped the collection. The cblA marker was identified in 47% of the isolates, many of which clustered in the genomovar III group. Class 1 integrons with recombined gene cassettes containing bla-OXA and aac(6')-1a genes were identified. SIGNIFICANCE AND IMPACT OF THE STUDY This study demonstrates the application of molecular methods to investigate B. cepacia, a well-recognized human pathogen, cultured from Irish CF patients. Genomovar III was the most common genomic type identified. DNA fingerprinting further subtyped the latter isolates, facilitating a more detailed description of the molecular epidemiology. Drug resistance in these organisms can be explained, at least in part, by the presence of class 1 integrons. Development of targeted infection control strategies could be facilitated using these applied methods.
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Affiliation(s)
- D Crowley
- Molecular Diagnostics Unit, Cork Institute of Technology, Bishopstown, Cork, Ireland
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Rejiba S, Limam F, Belhadj C, Belhadj O, Ben-Mahrez K. Biochemical characterization of a novel extended-spectrum beta-lactamase from Pseudomonas aeruginosa 802. Microb Drug Resist 2002; 8:9-13. [PMID: 12002654 DOI: 10.1089/10766290252913700] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa 802 was isolated at Rabta hospital in Tunis and was resistant to extended-spectrum cephalosporins and aztreonam. It produced a pI 7.6 extended-spectrum beta-lactamase (ESBL). The ESBL, named LBT 802, was purified to homogeneity by filtration on Sephadex G-75 followed by CM-Sepharose chromatography and high-performance liquid chromatography (HPLC) on a TSK-gel SP-5PW column. The LBT 802 enzyme had a molecular mass of 30 kDa. It showed a broad-substrate profile by hydrolyzing benzylpenicillin, ampicillin, cephalothin, cephaloridine, cefotaxime, ceftriaxone, and cefpirome but not ceftazidime, cefoxitin, imipenem, or aztreonam. The highest hydrolytic efficiency (Vmax/Km) was obtained for ampicillin, cephalothin, cephaloridine, and benzylpenicillin. Among extended-spectrum cephalosporins the best substrate was ceftriaxone followed by cefotaxime and cefpirome. LBT 802 activity was inhibited by clavulanic acid, sulbactam, imipenem, cefoxitin, and aztreonam. It showed its lowest Ki values for clavulanic acid, imipenem and sulbactam.
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Affiliation(s)
- Samia Rejiba
- Laboratoire de Biochimie et de Technobiologie, Faculté des Sciences de Tunis, Tunisia
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40
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Majiduddin FK, Materon IC, Palzkill TG. Molecular analysis of beta-lactamase structure and function. Int J Med Microbiol 2002; 292:127-37. [PMID: 12195735 DOI: 10.1078/1438-4221-00198] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The extensive and sometimes irresponsible use of beta-lactam antibiotics in clinical and agricultural settings has contributed to the emergence and widespread dissemination of antibiotic-resistant bacteria. Bacteria have evolved three strategies to escape the activity of beta-lactam antibiotics: 1) alteration of the target site (e.g. penicillin-binding protein (PBPs), 2) reduction of drug permeation across the bacterial membrane (e.g. efflux pumps) and 3) production of beta-lactamase enzymes. The beta-lactamase enzymes inactivate beta-lactam antibiotics by hydrolyzing the peptide bond of the characteristic four-membered beta-lactam ring rendering the antibiotic ineffective. The inactivation of the antibiotic provides resistance to the bacterium. Currently, there are over 300 beta-lactamase enzymes described for which numerous kinetic, structural, computational and mutagenesis studies have been performed. In this review, we discuss the recent work performed on the four different classes (A, B, C, and D) of beta-lactamases. These investigative advances further expand our knowledge about these complex enzymes, and hopefully, will provide us with additional tools to develop new inhibitors and antibiotics based on structural and rational designs.
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Affiliation(s)
- Fahd K Majiduddin
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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41
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Leotard S, Poirel L, Leblanc PE, Nordmann P. In vivo selection of oxacillinase-mediated ceftazidime resistance in Pseudomonas aeruginosa. Microb Drug Resist 2002; 7:273-5. [PMID: 11759089 DOI: 10.1089/10766290152652828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ceftazidime-susceptible and -resistant Pseudomonas aeruginosa strains were isolated from pulmonary specimens following a treatment with ceftazidime in a patient who developed a nosocomial pneumonia. The ceftazidime-susceptible and -resistant strains were clonally related and harbored a self-transferable approximately 155-kb plasmid. These isolates expressed two OXA-10-like oxacillinases, the narrow-spectrum OXA-35 and the expanded-spectrum OXA-19, respectively, differing by one amino acid substitution. This is the first example of in vivo selection of an extended-spectrum oxacillinase from a restricted-spectrum oxacillinase.
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Affiliation(s)
- S Leotard
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Faculté de Médecine Paris-Sud, France
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42
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Poirel L, Gerome P, De Champs C, Stephanazzi J, Naas T, Nordmann P. Integron-located oxa-32 gene cassette encoding an extended-spectrum variant of OXA-2 beta-lactamase from Pseudomonas aeruginosa. Antimicrob Agents Chemother 2002; 46:566-9. [PMID: 11796380 PMCID: PMC127075 DOI: 10.1128/aac.46.2.566-569.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa clinical isolate CY-1, which was resistant to ceftazidime, harbored a conjugative ca. 250-kb plasmid that contained a class 1 integron with two gene cassettes encoding OXA-32, an OXA-2- type beta-lactamase, and the aminoglycoside acetyltransferase AAC(6')Ib(9). OXA-32 differed from OXA-2 by an Leu169Ile amino acid substitution (class D numbering). Site-directed mutagenesis established that Ile169 is responsible for resistance to ceftazidime but not to cefotaxime.
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Affiliation(s)
- Laurent Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre, France
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43
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Bradford PA. Extended-spectrum beta-lactamases in the 21st century: characterization, epidemiology, and detection of this important resistance threat. Clin Microbiol Rev 2001; 14:933-51, table of contents. [PMID: 11585791 PMCID: PMC89009 DOI: 10.1128/cmr.14.4.933-951.2001] [Citation(s) in RCA: 1568] [Impact Index Per Article: 68.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Beta-lactamases continue to be the leading cause of resistance to beta-lactam antibiotics among gram-negative bacteria. In recent years there has been an increased incidence and prevalence of extended-spectrum beta-lactamases (ESBLs), enzymes that hydrolyze and cause resistance to oxyimino-cephalosporins and aztreonam. The majority of ESBLs are derived from the widespread broad-spectrum beta-lactamases TEM-1 and SHV-1. There are also new families of ESBLs, including the CTX-M and OXA-type enzymes as well as novel, unrelated beta-lactamases. Several different methods for the detection of ESBLs in clinical isolates have been suggested. While each of the tests has merit, none of the tests is able to detect all of the ESBLs encountered. ESBLs have become widespread throughout the world and are now found in a significant percentage of Escherichia coli and Klebsiella pneumoniae strains in certain countries. They have also been found in other Enterobacteriaceae strains and Pseudomonas aeruginosa. Strains expressing these beta-lactamases will present a host of therapeutic challenges as we head into the 21st century.
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Affiliation(s)
- P A Bradford
- Wyeth-Ayerst Research, Pearl River, New York 10965, USA.
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Pernot L, Frénois F, Rybkine T, L'Hermite G, Petrella S, Delettré J, Jarlier V, Collatz E, Sougakoff W. Crystal structures of the class D beta-lactamase OXA-13 in the native form and in complex with meropenem. J Mol Biol 2001; 310:859-74. [PMID: 11453693 DOI: 10.1006/jmbi.2001.4805] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The therapeutic problems posed by class D beta-lactamases, a family of serine enzymes that hydrolyse beta-lactam antibiotics following an acylation-deacylation mechanism, are increased by the very low level of sensitivity of these enzymes to beta-lactamase inhibitors. To gain structural and mechanistic insights to aid the design of new inhibitors, we have determined the crystal structure of OXA-13 from Pseudomonas aeruginosa in the apo form and in complex with the carbapenem meropenem. The native form consisted of a dimer displaying an overall organisation similar to that found in the closely related enzyme OXA-10. In the acyl-enzyme complex, the positioning of the antibiotic appeared to be ensured mainly by (i) the covalent acyl bond and (ii) a strong salt-bridge involving the carboxylate moiety of the drug. Comparison of the structures of OXA-13 in the apo form and in complex with meropenem revealed an unsuspected flexibility in the region of the essential serine 115 residue, with possible consequences for the catalytic properties of the enzyme. In the apo form, the Ser115 side-chain is oriented outside the active site, whereas the general base Lys70 adopts a conformation that seems to be incompatible with the activation of the catalytic water molecule required for the deacylation step. In the OXA-13:meropenem complex, a 3.5 A movement of the backbone of the 114-116 loop towards the side-chain of Lys70 was observed, which seems to be driven by a displacement of the neighbouring 91-104 loop and which results in the repositioning of the side-chain hydroxyl group of Ser115 toward the catalytic centre. Concomitantly, the side-chain of Lys70 is forced to curve in the direction of the deacylating water molecule, which is then strongly bound and activated by this residue. However, a distance of ca 5 A separates the catalytic water molecule from the acyl carbonyl group of meropenem, a structural feature that accounts for the inhibition of OXA-13 by this drug. Finally, the low level of penicillinase activity revealed by the kinetic analysis of OXA-13 could be related to the specific presence in position 73 of a serine residue located close to the general base Lys70, which results in a decrease of the number of hydrogen-bonding interactions stabilising the catalytic water molecule.
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Affiliation(s)
- L Pernot
- Laboratoire de Recherche Moléculaire sur les Antibiotiques (LRMA), Facultés de Médecine Pitié-Salpêtrière and Broussais-Hôtel Dieu, Université Pierre et Marie Curie, 91 bd de l'Hôpital, Paris cedex 13, 75634, France
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Danel F, Frère JM, Livermore DM. Evidence of dimerisation among class D beta-lactamases: kinetics of OXA-14 beta-lactamase. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1546:132-42. [PMID: 11257516 DOI: 10.1016/s0167-4838(01)00133-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OXA-14 enzyme, a class D beta-lactamase, gave biphasic kinetics with all penicillin and cephalosporin substrates tested, such that the catalytic rate declined more swiftly than was explicable by substrate depletion. This biphasic behaviour was independent of temperature or extraneous protein but was lost if the enzyme was diluted to occupy almost the total assay volume before addition of a small amount of concentrated substrate. The presence of substrate could partially protect the enzyme against conversion to the less active form, with protection greatest at substrate concentration above the K(m). These observations are compatible with the hypothesis that the biphasic kinetics depended on the enzyme existing as a highly active dimer at high concentration and as a less active monomer at low concentration. Direct evidence supporting this hypothesis came from the observation that gel exclusion chromatography indicated a higher molecular weight for concentrated enzyme than for dilute. Biphasic kinetics are not so universal for different substrates amongst beta-lactamases (OXA-10, -11, -13, -16 and -17) that differ from OXA-14 by only one to two amino acid substitutions. It may be that the monomer:dimer equilibrium is more rapidly achieved with these enzymes than with OXA-14, or that the kinetic properties of the dimers and monomers of these enzymes are similar, masking any biphasic trait.
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Affiliation(s)
- F Danel
- Department of Medical Microbiology, St. Bartholomew's and the Royal London School of Medicine and Dentistry, Turner Street, London E1 2AD, UK.
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Abstract
Infection caused by organisms resistant to conventional antimicrobial therapy is an emerging problem of global proportions. This article describes the epidemiology of infections caused by resistant organisms in chronically critically ill patients and explores factors and mechanisms that lead to the development of resistance. Specific organisms and strategies for the treatment and control of these resistance organisms are discussed.
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Affiliation(s)
- D D Poutsiaka
- Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts, USA
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Poirel L, Girlich D, Naas T, Nordmann P. OXA-28, an extended-spectrum variant of OXA-10 beta-lactamase from Pseudomonas aeruginosa and its plasmid- and integron-located gene. Antimicrob Agents Chemother 2001; 45:447-53. [PMID: 11158739 PMCID: PMC90311 DOI: 10.1128/aac.45.2.447-453.2001] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa ED-1, isolated from a pulmonary brush of a patient hospitalized in a suburb of Paris, France, was resistant to ceftazidime and of intermediate susceptibility to ureidopenicillins and to cefotaxime. Cloning and expression of the beta-lactamase gene content of this isolate in Escherichia coli DH10B identified a novel OXA-10 variant, OXA-28, with a pI value of 8.1 and a molecular mass of 29 kDa. It differed from OXA-10 by 10 amino acid changes and from OXA-13 and OXA-19 by 2 amino acid changes, including a glycine instead of tryptophan at position 164, which is likely involved in its resistance to ceftazidime. Like OXA-11, -14, -16, and -19 and as opposed to OXA-17, OXA-28 predominantly compromised ceftazidime and had only marginal effect on the MICs of aztreonam and cefotaxime in P. aeruginosa. Once expressed in E. coli, OXA-28 raised the MIC of ceftazidime to a much higher level than those of amoxicillin, cephalothin, and cefotaxime (128, 16, 8, and 4 microg/ml, respectively). OXA-28 beta-lactamase had a broad spectrum of activity, including ceftazidime. Its activity was partially antagonized by clavulanic acid (50% inhibitory concentration, 10 microM) and NaCl addition. The oxa28 gene cassette was inserted in the variable region of a class 1 integron, In57, immediately downstream of an amino 6'-N-acetyltransferase gene cassette, aac(6')Ib. The structures of the integrons carrying either oxa28, oxa13, or oxa19 gene cassettes were almost identical, suggesting that they may have derived from a common ancestor as a result of the common European origin of the P. aeruginosa isolates. In57 was located on a self-transferable plasmid of ca. 150 kb that was transferred from P. aeruginosa to P. aeruginosa.
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Affiliation(s)
- L Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre, France
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48
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Abstract
Pseudomonas aeruginosa is responsible for a variety of nosocomial infections associated with high morbidity and mortality, involving the immunocompromised and immunocompetent host. There are several groups of antipseudomonal antibiotics available today: antipseudomonal penicillins (carboxy and ureido penicillins), antipseudomonal cephalosporins, monobactams, quinolones, aminoglycosides, and carbapenems. This article reviews the newer antipseudomonal compounds and focuses on recent and important pieces of information for older compounds. Antibacterial spectrum, with particular emphasis on contemporary resistance mechanisms, and recent global resistance surveillance reports, pharmacokinetics, in vitro combination studies and in vivo interactions, and adverse effects and dosage schedules are described in an effort to approach the clinicians' needs.
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Affiliation(s)
- H Giamarellou
- Department of Internal Medicine, Athens University Medical School, Sismanoglio General Hospital, Athens, Greece
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Maveyraud L, Golemi D, Kotra LP, Tranier S, Vakulenko S, Mobashery S, Samama JP. Insights into class D beta-lactamases are revealed by the crystal structure of the OXA10 enzyme from Pseudomonas aeruginosa. Structure 2000; 8:1289-98. [PMID: 11188693 DOI: 10.1016/s0969-2126(00)00534-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND beta-lactam antibiotic therapies are commonly challenged by the hydrolytic activities of beta-lactamases in bacteria. These enzymes have been grouped into four classes: A, B, C, and D. Class B beta-lactamases are zinc dependent, and enzymes of classes A, C, and D are transiently acylated on a serine residue in the course of the turnover chemistry. While class A and C beta-lactamases have been extensively characterized by biochemical and structural methods, class D enzymes remain the least studied despite their increasing importance in the clinic. RESULTS The crystal structure of the OXA10 class D beta-lactamase has been solved to 1.66 A resolution from a gold derivative and MAD phasing. This structure reveals that beta-lactamases from classes D and A, despite very poor sequence similarity, share a similar overall fold. An additional beta strand in OXA10 mediates the association into dimers characterized by analytical ultracentrifugation. Major differences are found when comparing the molecular details of the active site of this class D enzyme to the corresponding regions in class A and C beta-lactamases. In the native structure of the OXA10 enzyme solved to 1.8 A, Lys-70 is carbamylated. CONCLUSIONS Several features were revealed by this study: the dimeric structure of the OXA10 beta-lactamase, an extension of the substrate binding site which suggests that class D enzymes may bind other substrates beside beta-lactams, and carbamylation of the active site Lys-70 residue. The CO2-dependent activity of the OXA10 enzyme and the kinetic properties of the natural OXA17 mutant protein suggest possible relationships between carbamylation, inhibition of the enzyme by anions, and biphasic behavior of the enzyme.
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Affiliation(s)
- L Maveyraud
- Groupe de Cristallographie Biologique IPBS-CNRS, Toulouse, France
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Thomson KS, Smith Moland E. Version 2000: the new beta-lactamases of Gram-negative bacteria at the dawn of the new millennium. Microbes Infect 2000; 2:1225-35. [PMID: 11008112 DOI: 10.1016/s1286-4579(00)01276-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
beta-lactamases of Gram-negative bacteria are evolving dynamically. New developments include the production of enzymes with novel substrate profiles, reduced susceptibility to beta-lactamase inhibitors, and the simultaneous production of multiple types of beta-lactamases. The changes represent evolutionary upgrades which provide modern pathogens with a greater potential to resist beta-lactam antibiotics and cause formidable therapeutic, infection control, and diagnostic challenges. This review is a clinically oriented outline of recent developments in the beta-lactamase production of Gram-negative bacteria.
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Affiliation(s)
- K S Thomson
- Center for Research in Anti-Infectives and Biotechnology, Creighton University School of Medicine, Omaha, Nebraska 68178, USA
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