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Perera V, Silva ND, Jayatilleke K, Silva SD, Corea E. Performance of Phenotypic Tests to Detect β-Lactamases in a Population of β-Lactamase Coproducing Enterobacteriaceae Isolates. J Lab Physicians 2023; 15:117-125. [PMID: 37064978 PMCID: PMC10104725 DOI: 10.1055/s-0042-1760399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Abstract
Objectives This study aimed to evaluate the performance of routinely used phenotypic tests to detect β-lactamase production in isolates coproducing multiple β-lactamase types.
Methods Commonly used phenotypic tests for the detection of extended spectrum β-lactamases (ESBL), AmpC β-lactamase, and carbapenemases were compared with detection and sequencing of β-lactamase genes (as the reference test) in 176 uropathogenic Enterobacteriaceae coproducing multiple β-lactamases from two hospitals in the Western Province of Sri Lanka.
Results Majority of the isolates (147/176, 83.5%) carried β-lactamase genes with (90/147, 61%) harboring multiple genes. The Clinical and Laboratory Standards Institute screening method using cefotaxime (sensitivity [Se], 97; specificity [Sp], 93; accuracy [Ac], 94) and ceftriaxone (Se, 97; Sp, 91; Ac, 93) was the most effective to detect ESBLs. The modified double disc synergy test (Se, 98; Sp, 98; Ac, 97) and combined disc test (Se, 94; Sp, 98; Ac, 96) showed good specificity for confirmation of ESBLs. Cefoxitin resistance (Se, 97; Sp, 73; Ac, 85) and the AmpC disc test (Se, 96; Sp, 82; Ac, 86) were sensitive to detect AmpC β-lactamase producers coproducing other β-lactamases but showed low specificity, probably due to coproduction of carbapenemases. Meropenem was useful to screen for New Delhi metallo β-lactamases and OXA-48-like carbapenemases (Se, 97; Sp, 96; Ac, 96). The modified carbapenem inactivation method showed excellent performance (Se, 97; Sp, 98; Ac, 97) in identifying production of both types of carbapenemases and was able to distinguish this from carbapenem resistance due to potential mutations in the porin gene.
Conclusions Microbiology laboratories that are still depend on phenotypic tests should utilize tests that are compatible with the types of β-lactamase prevalent in the region and those that are least affected by coexisting resistance mechanisms.
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Affiliation(s)
- Vindya Perera
- Faculty of Medicine, Department of Microbiology, University of Colombo, Sri Lanka
- Faculty of Medicine, Department of Microbiology, Sabaragamuwa University of Sri Lanka, Ratnapura, Sri Lanka
| | - Nelun de Silva
- Faculty of Medicine, Department of Microbiology, Sabaragamuwa University of Sri Lanka, Ratnapura, Sri Lanka
- Neville Fernando Teaching Hospital, Malabe, Sri Lanka
| | | | - Sara de Silva
- Sri Jayewardenapura General Hospital, Nugegoda, Sri Lanka
| | - Enoka Corea
- Faculty of Medicine, Department of Microbiology, University of Colombo, Sri Lanka
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Martins-Oliveira I, Pérez-Viso B, Silva-Dias A, Gomes R, Peixe L, Novais Â, Cantón R, Pina-Vaz C. Rapid Detection of Plasmid AmpC Beta-Lactamases by a Flow Cytometry Assay. Antibiotics (Basel) 2022; 11:antibiotics11081130. [PMID: 36009999 PMCID: PMC9405432 DOI: 10.3390/antibiotics11081130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 12/02/2022] Open
Abstract
Plasmidic AmpC (pAmpC) enzymes are responsible for the hydrolysis of extended-spectrum cephalosporins but they are not routinely investigated in many clinical laboratories. Phenotypic assays, currently the reference methods, are cumbersome and culture dependent. These methods compare the activity of cephalosporins with and without class C inhibitors and the results are provided in 24–48 h. Detection by molecular methods is quicker, but several genes should be investigated. A new assay for the rapid phenotypic detection of pAmpC enzymes of the Enterobacterales group-I (not usually AmpC producers) based on flow cytometry technology was developed and validated. The technology was evaluated in two sites: FASTinov, a spin-off of Porto University (Portugal) where the technology was developed, and the Microbiology Department of Ramón y Cajal University Hospital in Madrid (Spain). A total of 100 strains were phenotypically screened by disk diffusion for the pAmpC with the new 2 h assay. Molecular detection of the pAmpC genes was also performed on discrepant results. Forty-two percent of the strains were phenotypically classified as pAmpC producers using disk diffusion. The percentage of agreement of the flow cytometric assay was 93.0%, with 95.5% sensitivity and 91.1% specificity. Our proposed rapid assay based on flow cytometry technology can, in two hours, accurately detect pAmpC enzymes.
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Affiliation(s)
- Inês Martins-Oliveira
- FASTinov: S.A., 4450-676 Matosinhos, Portugal
- Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - Blanca Pérez-Viso
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ana Silva-Dias
- FASTinov: S.A., 4450-676 Matosinhos, Portugal
- CINTESIS-Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, 4200-450 Porto, Portugal
| | | | - Luísa Peixe
- UCIBIO-Applied Molecular Biosciences Unit, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Ângela Novais
- UCIBIO-Applied Molecular Biosciences Unit, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Rafael Cantón
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: (R.C.); (C.P.-V.); Tel.: +34-913368832 (R.C.); +351-924393147 (C.P.-V.)
| | - Cidália Pina-Vaz
- FASTinov: S.A., 4450-676 Matosinhos, Portugal
- Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
- CINTESIS-Center for Health Technology and Services Research, Faculty of Medicine, University of Porto, 4200-450 Porto, Portugal
- Correspondence: (R.C.); (C.P.-V.); Tel.: +34-913368832 (R.C.); +351-924393147 (C.P.-V.)
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Parra-Flores J, Holý O, Acuña S, Lepuschitz S, Pietzka A, Contreras-Fernández A, Chavarría-Sepulveda P, Cruz-Córdova A, Xicohtencatl-Cortes J, Mancilla-Rojano J, Castillo A, Ruppitsch W, Forsythe S. Genomic Characterization of Cronobacter spp. and Salmonella spp. Strains Isolated From Powdered Infant Formula in Chile. Front Microbiol 2022; 13:884721. [PMID: 35722296 PMCID: PMC9201451 DOI: 10.3389/fmicb.2022.884721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/04/2022] [Indexed: 11/14/2022] Open
Abstract
This study characterized five Cronobacter spp. and six Salmonella spp. strains that had been isolated from 155 samples of powdered infant formula (PIF) sold in Chile and manufactured in Chile and Mexico in 2018–2020. Two strains of Cronobacter sakazakii sequence type (ST) ST1 and ST31 (serotypes O:1 and O:2) and one strain of Cronobacter malonaticus ST60 (O:1) were identified. All Salmonella strains were identified as Salmonella Typhimurium ST19 (serotype O:4) by average nucleotide identity, ribosomal multilocus sequence typing (rMLST), and core genome MLST (cgMLST). The C. sakazakii and C. malonaticus isolates were resistant to cephalothin, whereas the Salmonella isolates were resistant to oxacillin and ampicillin. Nineteen antibiotic resistance genes were detected in the C. sakazakii and C. malonaticus isolates; the most prevalent were mcr-9.1, blaCSA, and blaCMA. In Salmonella, 30 genes encoding for aminoglycoside and cephalosporin resistance were identified, including aac(6′)-Iaa, β-lactamases ampH, ampC1, and marA. In the Cronobacter isolates, 32 virulence-associated genes were detected by WGS and clustered as flagellar proteins, outer membrane proteins, chemotaxis, hemolysins, invasion, plasminogen activator, colonization, transcriptional regulator, survival in macrophages, use of sialic acid, and toxin-antitoxin genes. In the Salmonella strains, 120 virulence associated genes were detected, adherence, magnesium uptake, resistance to antimicrobial peptides, secretion system, stress protein, toxin, resistance to complement killing, and eight pathogenicity islands. The C. sakazakii and C. malonaticus strains harbored I-E and I-F CRISPR-Cas systems and carried Col(pHHAD28) and IncFIB(pCTU1) plasmids, respectively. The Salmonella strains harbored type I-E CRISPR-Cas systems and carried IncFII(S) plasmids. The presence of C. sakazakii and Salmonella in PIF is a health risk for infants aged less than 6 months. For this reason, sanitary practices should be reinforced for its production and retail surveillance.
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Affiliation(s)
- Julio Parra-Flores
- Department of Nutrition and Public Health, Universidad del Bío-Bío, Chillán, Chile
| | - Ondřej Holý
- Science and Research Centre, Faculty of Health Sciences, Palacký University Olomouc, Olomouc, Czechia
| | - Sergio Acuña
- Department of Food Engineering, Universidad del Bío-Bío, Chillán, Chile
| | - Sarah Lepuschitz
- Austrian Agency for Health and Food Safety, Institute for Medical Microbiology and Hygiene, Vienna, Austria
| | - Ariane Pietzka
- Austrian Agency for Health and Food Safety, Institute for Medical Microbiology and Hygiene, Vienna, Austria
| | | | | | - Ariadnna Cruz-Córdova
- Intestinal Bacteriology Research Laboratory, Hospital Infantil de México Federico Gómez, Mexico City, Mexico
| | - Juan Xicohtencatl-Cortes
- Intestinal Bacteriology Research Laboratory, Hospital Infantil de México Federico Gómez, Mexico City, Mexico
| | - Jetsi Mancilla-Rojano
- Intestinal Bacteriology Research Laboratory, Hospital Infantil de México Federico Gómez, Mexico City, Mexico.,Faculty of Medicine, Biological Sciences Graduate Program, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alejandro Castillo
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX, United States
| | - Werner Ruppitsch
- Austrian Agency for Health and Food Safety, Institute for Medical Microbiology and Hygiene, Vienna, Austria
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Rodríguez-Guerrero E, Callejas-Rodelas JC, Navarro-Marí JM, Gutiérrez-Fernández J. Systematic Review of Plasmid AmpC Type Resistances in Escherichia coli and Klebsiella pneumoniae and Preliminary Proposal of a Simplified Screening Method for ampC. Microorganisms 2022; 10:microorganisms10030611. [PMID: 35336186 PMCID: PMC8954824 DOI: 10.3390/microorganisms10030611] [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: 02/14/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 02/01/2023] Open
Abstract
Beta-lactamase (BL) production is a major public health problem. Although not the most frequent AmpC type, AmpC-BL is increasingly isolated, especially plasmid AmpC-BL (pAmpC-BL). The objective of this study was to review information published to date on pAmpC-BL in Escherichia coli and Klebsiella pneumoniae, and on the epidemiology and detection methods used by clinical microbiology laboratories, by performing a systematic review using the MEDLINE PubMed database. The predictive capacity of a screening method to detect AmpC-BL using disks with cloxacillin (CLX) was also evaluated by studying 102 Enterobacteriaceae clinical isolates grown in CHROMID ESBL medium with the addition of cefepime (FEP), cefoxitin (FOX), ertapenem (ETP), CLX, and oxacillin with CLX. The review, which included 149 publications, suggests that certain risk factors (prolonged hospitalization and previous use of cephalosporins) are associated with infections by pAmpC-BL-producing microorganisms. The worldwide prevalence has increased over the past 10 years, with a positivity rate ranging between 0.1 and 40%, although AmpC was only detected when sought in a targeted manner. CMY-2 type has been the most prevalent pAmpC-BL-producing microorganism. The most frequently used phenotypic method has been the double-disk synergy test (using CLX disks or phenyl-boronic acid and cefotaxime [CTX] and ceftazidime) and the disk method combined with these inhibitors. In regard to screening methods, a 1-µg oxacillin disk with CLX showed 88.9% sensitivity, 100% specificity, 100% positive predictive value (PPV), 98.9% negative predictive value (NPV), and 98.9% validity index (VI). This predictive capacity is reduced with the addition of extended-spectrum beta-lactamases, showing 62.5% sensitivity, 100% specificity, 100% PPV, 93.5% NPV, and 94.1% VI. In conclusion, there has been a worldwide increase in the number of isolates with pAmpC-BL, especially in Asia, with CMY-2 being the most frequently detected pAmpC-BL-producing type of microorganism. Reduction in its spread requires routine screening with a combination of phenotypic methods (with AmpC inhibitors) and genotypic methods (multiplex PCR). In conclusion, the proposed screening technique is an easy-to-apply and inexpensive test for the detection of AmpC-producing isolates in the routine screening of multidrug-resistant microorganisms.
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Affiliation(s)
- Enrique Rodríguez-Guerrero
- Laboratory of Microbiology, Virgen de las Nieves University Hospital & ibs.Granada—Instituto de Investigación Biosanitaria de Granada, Avda. de las Fuerzas Armadas 2, 18014 Granada, Spain; (E.R.-G.); (J.M.N.-M.)
| | - Juan Carlos Callejas-Rodelas
- Department of Microbiology, School of Medicine, University of Granada & ibs.Granada—Instituto de Investigación Biosanitaria de Granada, Avenida de la Investigación 11, 18016 Granada, Spain;
| | - José María Navarro-Marí
- Laboratory of Microbiology, Virgen de las Nieves University Hospital & ibs.Granada—Instituto de Investigación Biosanitaria de Granada, Avda. de las Fuerzas Armadas 2, 18014 Granada, Spain; (E.R.-G.); (J.M.N.-M.)
| | - José Gutiérrez-Fernández
- Laboratory of Microbiology, Virgen de las Nieves University Hospital & ibs.Granada—Instituto de Investigación Biosanitaria de Granada, Avda. de las Fuerzas Armadas 2, 18014 Granada, Spain; (E.R.-G.); (J.M.N.-M.)
- Department of Microbiology, School of Medicine, University of Granada & ibs.Granada—Instituto de Investigación Biosanitaria de Granada, Avenida de la Investigación 11, 18016 Granada, Spain;
- Correspondence:
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5
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Joji RM, Al-Mahameed AE, Jishi TA, Fatani DI, Saeed NK, Jaradat A, Ezzat H, Bindayna KM. Molecular detection of plasmid-derived AmpC β-lactamase among clinical strains of Enterobacteriaceae in Bahrain. Ann Thorac Med 2021; 16:287-293. [PMID: 34484445 PMCID: PMC8388573 DOI: 10.4103/atm.atm_523_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/10/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Enterobacteriaceae with AmpC β-lactamase are multidrug-resistant organisms and represent a significant challenge to patient care. This study aims to determine the prevalence of plasmid-derived AmpC β-lactamase among extended spectrum β-lactamases (ESBL)-producing Enterobacteriaceae strains in Bahrain. METHODS It was a cross-sectional study. A total of 185 ESBL-producing Enterobacteriaceae isolates were recovered from clinically significant specimens from January 2018 to December 2019. The samples underwent initial screen for cefoxitin resistance by disc diffusion test and subsequent phenotypic confirmation of AmpC production with phenyl boronic acid assays as well as genotypic analysis by multiplex polymerase chain reactions for AmpC subtypes. Drug-resistant features of these clinical isolates were also examined. RESULTS Twenty-nine ESBL-producing Enterobacteriaceae isolates were cefoxitin resistant. Phenotypic and genotypic analyses confirmed that 8 and 12 cefoxitin-resistant isolates are AmpC positive, respectively. These AmpC producers are multidrug resistant, and Escherichia coli is the dominant strain among them. CONCLUSIONS Plasmid-mediated spread of AmpC is present in clinically relevant Enterobacteriaceae species in Bahrain. Rational antimicrobial therapy against these multidrug-resistant organisms and continued surveillance of antimicrobial resistance mechanisms among the clinical isolates are recommended for optimal patient care.
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Affiliation(s)
- Ronni Mol Joji
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Ali Ebrahim Al-Mahameed
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Thamer Al Jishi
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Dania Ismail Fatani
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Nermin K Saeed
- Department of Pathology, Salmaniya Medical Complex, Ministry of Health, Manama, Kingdom of Bahrain
| | - Ahmed Jaradat
- Department of Community Medicine, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Hicham Ezzat
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
| | - Khalid Mubarak Bindayna
- Departments of Microbiology, Immunology and Infectious Diseases, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
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6
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Pfaendler HR, Schmidt HU, Freidank H. The Novel CarbaLux Test for Carbapenemases and Carbapenem Deactivating AmpC Beta-Lactamases. Front Microbiol 2020; 11:588887. [PMID: 33329464 PMCID: PMC7719632 DOI: 10.3389/fmicb.2020.588887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
Objectives To evaluate the rapid phenotypic CarbaLux test for routine diagnostics in the medical laboratory in a proof of concept study. Methods isolates of Gram-negative bacteria suspicious for carbapenem resistance including Enterobacterales (67), Pseudomonas (10), Acinetobacter (5), and Stenotrophomonas (1) species, collected between 2016 and 2018 from in-patients, were tested for carbapenemase activity using a novel fluorescent carbapenem. When subjected to extracted bacterial carbapenemases its fluorescence disappears. All bacteria to be tested were cultured on Columbia blood agar and few on other commercial media. MALDI TOF MS, molecular assays, automated MIC testing, and in part, agar diffusion tests served to characterize the isolates. For comparison, few selected bacteria were also investigated by prior phenotypic tests for carbapenemase detection. Results Under UV light, the CarbaLux test allowed a rapid detection of 39/39 carbapenemase-producing bacteria, including 15 isolates with OXA carbapenemases (e.g., OXA-23, OXA-24/40-like OXA-48-like or OXA-181). Several isolates had low MICs but still expressed carbapenemases. Among Enterobacter spp., it detected six strains with hyper-produced AmpC beta-lactamases, which deactivated carbapenems but were not detectable by prior rapid phenotypic assays. An unexpected high carbapenemase activity appeared with these enzymes. They were identified as AmpC variants by inhibition with cloxacillin. Conclusion Other than prior rapid phenotypic assessments for carbapenemases, which use secondary effects such as a change of pH, the inactivation of the fluorescent carbapenem substrate can be visualized directly under UV light. The new test works at 100 to 200-fold lower, therapy-like substrate concentrations. It takes advantage of the high substrate affinity to carbapenemases allowing also the detection of less reactive resistance enzymes via a trapping mechanism, even from bacteria, which might appear unsuspicious from initial antibiograms. The novel fluorescence method allows simple and safe handling, reliable readings, and documentation and is suitable for primary testing in the clinical laboratory.
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Affiliation(s)
| | | | - Heike Freidank
- Department of Medical Microbiology, München Klinik gGmbH, Munich, Germany
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7
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Coolen JPM, den Drijver EPM, Kluytmans JAJW, Verweij JJ, Lamberts BA, Soer JACJ, Verhulst C, Wertheim HFL, Kolwijck E. Development of an algorithm to discriminate between plasmid- and chromosomal-mediated AmpC β-lactamase production in Escherichia coli by elaborate phenotypic and genotypic characterization. J Antimicrob Chemother 2020; 74:3481-3488. [PMID: 31504559 PMCID: PMC7183348 DOI: 10.1093/jac/dkz362] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 07/18/2019] [Accepted: 07/19/2019] [Indexed: 01/14/2023] Open
Abstract
OBJECTIVES AmpC-β-lactamase production is an under-recognized antibiotic resistance mechanism that renders Gram-negative bacteria resistant to common β-lactam antibiotics, similar to the well-known ESBLs. For infection control purposes, it is important to be able to discriminate between plasmid-mediated AmpC (pAmpC) production and chromosomal-mediated AmpC (cAmpC) hyperproduction in Gram-negative bacteria as pAmpC requires isolation precautions to minimize the risk of horizontal gene transmission. Detecting pAmpC in Escherichia coli is challenging, as both pAmpC production and cAmpC hyperproduction may lead to third-generation cephalosporin resistance. METHODS We tested a collection of E. coli strains suspected to produce AmpC. Elaborate susceptibility testing for third-generation cephalosporins, WGS and machine learning were used to develop an algorithm to determine ampC genotypes in E. coli. WGS was applied to detect pampC genes, cAmpC hyperproducers and STs. RESULTS In total, 172 E. coli strains (n=75 ST) were divided into a training set and two validation sets. Ninety strains were pampC positive, the predominant gene being blaCMY-2 (86.7%), followed by blaDHA-1 (7.8%), and 59 strains were cAmpC hyperproducers. The algorithm used a cefotaxime MIC value above 6 mg/L to identify pampC-positive E. coli and an MIC value of 0.5 mg/L to discriminate between cAmpC-hyperproducing and non-cAmpC-hyperproducing E. coli strains. Accuracy was 0.88 (95% CI=0.79-0.94) on the training set, 0.79 (95% CI=0.64-0.89) on validation set 1 and 0.85 (95% CI=0.71-0.94) on validation set 2. CONCLUSIONS This approach resulted in a pragmatic algorithm for differentiating ampC genotypes in E. coli based on phenotypic susceptibility testing.
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Affiliation(s)
- Jordy P M Coolen
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Evert P M den Drijver
- Department of Infection Control, Amphia Ziekenhuis, Breda, The Netherlands.,Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands
| | - Jan A J W Kluytmans
- Department of Infection Control, Amphia Ziekenhuis, Breda, The Netherlands.,Laboratory for Microbiology, Microvida, Location Breda, The Netherlands.,Julius Center for Health Sciences and Primary Care, UMCU, Utrecht, The Netherlands
| | - Jaco J Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-Tweesteden Hospital, Tilburg, The Netherlands
| | - Bram A Lamberts
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joke A C J Soer
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carlo Verhulst
- Department of Infection Control, Amphia Ziekenhuis, Breda, The Netherlands.,Laboratory for Microbiology, Microvida, Location Breda, The Netherlands
| | - Heiman F L Wertheim
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eva Kolwijck
- Department of Medical Microbiology and Radboudumc Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
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8
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Aruhomukama D. Review of phenotypic assays for detection of extended-spectrum β-lactamases and carbapenemases: a microbiology laboratory bench guide. Afr Health Sci 2020; 20:1090-1108. [PMID: 33402954 PMCID: PMC7751514 DOI: 10.4314/ahs.v20i3.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Background Infections caused by gram-negative antibiotic-resistant bacteria continue to increase. Despite recommendations by the Clinical Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) with regards to detection of antibiotic degrading enzymes secreted by these bacteria, the true prevalence of extended-spectrum β-lactamase (ESBL) and carbapenemase producers remains a difficult task to resolve. Describing of previously designed phenotypic detection assays for ESBLs and carbapenemases in a single document avails a summary that allows for multiple testing which increases the sensitivity and specificity of detection. Methods and aims This review, therefore, defined and classified ESBLs and carbapenemases, and also briefly described how the several previously designed phenotypic detection assays for the same should be performed. Conclusion Extended-spectrum β-lactamase and carbapenemase detection assays, once performed correctly, can precisely discriminate between bacteria producing these enzymes and those with other mechanisms of resistance to β-lactam antibiotics.
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Affiliation(s)
- Dickson Aruhomukama
- Department of Medical Microbiology, College of Health Sciences, Makerere University, Kampala, Uganda
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10
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Hosuru Subramanya S, Bairy I, Nayak N, Amberpet R, Padukone S, Metok Y, Bhatta DR, Sathian B. Detection and characterization of ESBL-producing Enterobacteriaceae from the gut of healthy chickens, Gallus gallus domesticus in rural Nepal: Dominance of CTX-M-15-non-ST131 Escherichia coli clones. PLoS One 2020; 15:e0227725. [PMID: 32469888 PMCID: PMC7259619 DOI: 10.1371/journal.pone.0227725] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 05/11/2020] [Indexed: 11/24/2022] Open
Abstract
The surge in the prevalence of drug-resistant bacteria in poultry is a global concern as it may pose an extended threat to humans and animal health. The present study aimed to investigate the colonization proportion of extended-spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacteriaceae (EPE and CPE, respectively) in the gut of healthy poultry, Gallus gallus domesticus in Kaski district of Western Nepal. Total, 113 pooled rectal swab specimens from 66 private household farms and 47 commercial poultry farms were collected by systematic random sampling from the Kaski district in western Nepal. Out of 113 pooled samples, 19 (28.8%) samples from 66 backyard farms, and 15 (31.9%) from 47 commercial broiler farms were positive for EPE. Of the 38 EPE strains isolated from 34 ESBL positive rectal swabs, 31(81.6%) were identified as Escherichia coli, five as Klebsiella pneumoniae (13.2%), and one each isolate of Enterobacter species and Citrobacter species (2.6%). Based on genotyping, 35/38 examined EPE strains (92.1%) were phylogroup-1 positive, and all these 35 strains (100%) had the CTX-M-15 gene and strains from phylogroup-2, and 9 were of CTX-M-2 and CTX-M-14, respectively. Among 38 ESBL positive isolates, 9 (23.7%) were Ambler class C (Amp C) co-producers, predominant were of DHA, followed by CIT genes. Two (6.5%) E. coli strains of ST131 belonged to clade C, rest 29/31 (93.5%) were non-ST131 E. coli. None of the isolates produced carbapenemase. Twenty isolates (52.6%) were in-vitro biofilm producers. Univariate analysis showed that the odd of ESBL carriage among commercial broilers were 1.160 times (95% CI 0.515, 2.613) higher than organically fed backyard flocks. This is the first study in Nepal, demonstrating the EPE colonization proportion, genotypes, and prevalence of high-risk clone E. coli ST131 among gut flora of healthy poultry. Our data indicated that CTX-M-15 was the most prevalent ESBL enzyme, mainly associated with E. coli belonging to non-ST131clones and the absence of carbapenemases.
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Affiliation(s)
| | - Indira Bairy
- Melaka Manipal Medical College, Manipal Academy of Higher Education, Manipal, India
| | | | - Rajesh Amberpet
- Melaka Manipal Medical College, Manipal Academy of Higher Education, Manipal, India
- Jawaharlal Institute of Postgraduate Medical Education & Research, Pondicherry, India
| | - Shashiraj Padukone
- Jawaharlal Institute of Postgraduate Medical Education & Research, Pondicherry, India
- Bangalore Medical College and Research Institute, Bengaluru, India
| | - Yang Metok
- Manipal College of Medical Sciences, Pokhara, Nepal
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Rizi KS, Mosavat A, Youssefi M, Jamehdar SA, Ghazvini K, Safdari H, Amini Y, Farsiani H. High prevalence of bla CMY AmpC beta-lactamase in ESBL co-producing Escherichia coli and Klebsiella spp. clinical isolates in the northeast of Iran. J Glob Antimicrob Resist 2020; 22:477-482. [PMID: 32247080 DOI: 10.1016/j.jgar.2020.03.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 03/02/2020] [Accepted: 03/07/2020] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE The production of β-lactamase enzymes such as AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) is among the main mechanisms for resistance to expanded-spectrum cephalosporins. The present study was conducted to investigate the prevalence and molecular epidemiology of plasmid-mediated AmpC beta (β)-lactamase in ESBL co-producing Escherichia coli (E. coli) and Klebsiella spp. (Klebsiella pneumoniae and Klebsiella oxytoca) clinical isolates in the northeast of Iran. METHODS A total of 602 E. coli and Klebsiella spp. clinical isolates were collected from three hospitals in Mashhad (northeast of Iran). A combination disk test (CDT) was performed for the phenotypic detection of ESBLs. Screening for the detection of AmpC β-lactamases was performed by a susceptibility test to a cefoxitin disc among ESBL producing isolates. A confirmatory test for AmpC β-lactamases was performed using the Mast® D68C test. Identification of plasmid-mediated AmpC cluster genes was done by multiplex polymerase chain reaction (PCR). RESULTS Among 336 ESBL-producing strains, 230 (68.4%) isolates were resistant to cefoxitin. Results of the Mast® D68C test showed that 30% (69/230) of cefoxitin-resistant isolates simultaneously exhibited ESBL and AmpC activity and 22% (51/230) of isolates probably showed multi-drug resistant (MDR) phenotype. Results of multiplex PCR among ESBL-positive isolates showed that, 16.7% (56/336) of isolates were positive for plasmid-borneampC cluster genes, and CMY (38%) was the most frequent genotype of plasmid mediated AmpC. CONCLUSION Findings of the study revealed that an increase in the prevalence of ESBL and AmpC co-producer in E. coli and Klebsiella spp. strains may become an important public health issue. Therefore, there is a vital need for surveillance of spread of these clinical isolates.
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Affiliation(s)
- Kobra Salimiyan Rizi
- Department of Microbiology and Virology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Arman Mosavat
- Blood Borne Infections Research Center, Academic Center for Education, Culture and Research, Mashhad, Razavi Khorasan, Iran
| | - Masoud Youssefi
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Saeid Amel Jamehdar
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Kiarash Ghazvini
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hadi Safdari
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Yousef Amini
- Infectious Disease and Tropical Medicine Research Center, Resistant Tuberculosis Institute, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Hadi Farsiani
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
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Böhm ME, Razavi M, Flach CF, Larsson DGJ. A Novel, Integron-Regulated, Class C β-Lactamase. Antibiotics (Basel) 2020; 9:antibiotics9030123. [PMID: 32183280 PMCID: PMC7148499 DOI: 10.3390/antibiotics9030123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/26/2022] Open
Abstract
AmpC-type β-lactamases severely impair treatment of many bacterial infections, due to their broad spectrum (they hydrolyze virtually all β-lactams, except fourth-generation cephalosporins and carbapenems) and the increasing incidence of plasmid-mediated versions. The original chromosomal AmpCs are often tightly regulated, and their expression is induced in response to exposure to β-lactams. Regulation of mobile ampC expression is in many cases less controlled, giving rise to constitutively resistant strains with increased potential for development or acquisition of additional resistances. We present here the identification of two integron-encoded ampC genes, blaIDC-1 and blaIDC-2 (integron-derived cephalosporinase), with less than 85% amino acid sequence identity to any previously annotated AmpC. While their resistance pattern identifies them as class C β-lactamases, their low isoelectric point (pI) values make differentiation from other β-lactamases by isoelectric focusing impossible. To the best of our knowledge, this is the first evidence of an ampC gene cassette within a class 1 integron, providing a mobile context with profound potential for transfer and spread into clinics. It also allows bacteria to adapt expression levels, and thus reduce fitness costs, e.g., by cassette-reshuffling. Analyses of public metagenomes, including sewage metagenomes, show that the discovered ampCs are primarily found in Asian countries.
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Affiliation(s)
- Maria-Elisabeth Böhm
- Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden; (M.-E.B.); (M.R.); (C.-F.F.)
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Mohammad Razavi
- Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden; (M.-E.B.); (M.R.); (C.-F.F.)
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Carl-Fredrik Flach
- Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden; (M.-E.B.); (M.R.); (C.-F.F.)
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - D. G. Joakim Larsson
- Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden; (M.-E.B.); (M.R.); (C.-F.F.)
- Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
- Correspondence:
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Hosuru Subramanya S, Bairy I, Nayak N, Padukone S, Sathian B, Gokhale S. Low rate of gut colonization by extended-spectrum β-lactamase producing Enterobacteriaceae in HIV infected persons as compared to healthy individuals in Nepal. PLoS One 2019; 14:e0212042. [PMID: 30779752 PMCID: PMC6380550 DOI: 10.1371/journal.pone.0212042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/25/2019] [Indexed: 12/12/2022] Open
Abstract
A worldwide increase in the gastrointestinal colonization by extended-spectrum β-lactamase (ESBL)-producing bacteria has been observed. Their prevalence amongst Healthy People Living with HIV (HPLWH) has not been investigated adequately. The aim of this study was to determine and compare the rates of and risk factors for intestinal carriage and acquisition of extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-E) and carbapenemase-producing Enterobacteriaceae (CPE) among healthy people living with HIV (HPLWH) and healthy HIV negative population in the community. A cross-sectional study was conducted. Rectal swabs from HPLWH (n = 119) and HIV negative individuals (n = 357) from the community were screened for ESBL and CPE. Phenotypically confirmed ESBL-E strains were genotyped by multiplex PCR. The risk factors associated with ESBL-E colonization were analyzed by a multivariable conditional logistic regression analysis. Specimen from 357 healthy volunteers (213 female and 144 male) and 119 HPLWH (82 female and 37 male) with a median age of 30 [IQR 11–50] years were included in the study. ESBL colonization were found in 45 (37.82% [CI 29.09, 47.16]) and 246 (68.91% [CI 63.93, 73.49]), HPLWH and healthy HIV negative participants respectively. HPLWH had lower ESBL carriage rate (odds ratio 0.274 [CI 0.178, 0.423]) compared to healthy HIV negative subject’s (p<0.01). In this study, no carbapenemase-producing bacteria were isolated.CTX-M-15 type was the most predominant genotype in both groups. Livestock contact and over-the-counter medications were significantly associated with a higher ESBL-E carriage rate among healthy subjects. This is the first study in Nepal that has demonstrated a high rate of gut colonization by ESBL-E in the community, predominantly of blaCTX-M-15 genotype. This study divulges the low fecal carriage rate of ESBL producing bacteria in HPLWH group compared to healthy individuals in western Nepal. The factors responsible for this inverse relationship of HIV status and gut colonization by ESBL-E are unidentified and require further large-scale study.
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Affiliation(s)
| | - Indira Bairy
- Melaka Manipal Medical College, Manipal Academy of Higher Education, Manipal, India
- * E-mail: (IB); (SHS)
| | | | - Shashiraja Padukone
- Melaka Manipal Medical College, Manipal Academy of Higher Education, Manipal, India
- Jawaharlal Institute of Postgraduate Medical Education & Research, Puducherry, India
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Kazi M, Ajbani K, Tornheim JA, Shetty A, Rodrigues C. Multiplex PCR to detect pAmpC β-lactamases among enterobacteriaceae at a tertiary care laboratory in Mumbai, India. MICROBIOLOGY (READING, ENGLAND) 2019; 165:246-250. [PMID: 30543509 PMCID: PMC7003648 DOI: 10.1099/mic.0.000748] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/02/2018] [Indexed: 12/18/2022]
Abstract
Drug-resistance due to AmpC β-lactamases represents a growing problem worldwide. In this study, a previously collected sample of 108 cefoxitin-resistant clinical isolates was assessed for AmpC β-lactamase production through routine phenotypic testing and double-disc cefoxitin/cloxcallin (DD-CC), cefoxitin/phenylboronic acid (CDT-PBA) and AmpC disc tests. The same isolates were characterized by a novel multiplex polymerase chain reaction molecular assay to detect the presence of blaACT, blaDHA, blaCIT, blaFOX, blaMIR and blaMOX. By phenotypic analysis, 56%, 55% and 48 % were detected as being AmpC β-lactamase producers by the CDT-PBA, DD-CC and AmpC disc tests, respectively. By molecular analysis, 57 % were determined to be AmpC β-lactamase producers, including 34 % blaFOX, 8 % blaCIT and 1.6 % blaDHAas mono-AmpC producers. The production of multiple AmpC molecular types was common, including 30 % with both blaCIT+FOX and 1.6 % each of blaCIT+DHA, blaACT+MIR, blaACT+FOX, blaACT+DHA and blaMIR+FOX. Molecular characterization of AmpC would help detect the prevalence of AmpC β-lactamase producers, facilitate proper patient management and implement infection control practices.
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Affiliation(s)
- Mubin Kazi
- Department of Microbiology, P. D. Hinduja Hospital and Medical Research Centre, Veer Sarvarkar Marg, Mahim, Mumbai, India
| | - Kanchan Ajbani
- Department of Microbiology, P. D. Hinduja Hospital and Medical Research Centre, Veer Sarvarkar Marg, Mahim, Mumbai, India
| | - Jeffrey A. Tornheim
- Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Anjali Shetty
- Department of Microbiology, P. D. Hinduja Hospital and Medical Research Centre, Veer Sarvarkar Marg, Mahim, Mumbai, India
| | - Camilla Rodrigues
- Department of Microbiology, P. D. Hinduja Hospital and Medical Research Centre, Veer Sarvarkar Marg, Mahim, Mumbai, India
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Correa-Martínez CL, Idelevich EA, Sparbier K, Kostrzewa M, Becker K. Rapid Detection of Extended-Spectrum β-Lactamases (ESBL) and AmpC β-Lactamases in Enterobacterales: Development of a Screening Panel Using the MALDI-TOF MS-Based Direct-on-Target Microdroplet Growth Assay. Front Microbiol 2019; 10:13. [PMID: 30733710 PMCID: PMC6353820 DOI: 10.3389/fmicb.2019.00013] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/07/2019] [Indexed: 11/13/2022] Open
Abstract
Introduction: Antibiotic resistant bacteria are a growing concern worldwide. Extended-spectrum β-lactamases (ESBL) represent the most common resistance mechanism of Gram-negative bacteria against β-lactams, underlining the need for adequate diagnostic methods that provide reliable information in the shortest time possible. AmpC, a less prevalent but increasingly relevant class of β-lactamases, pose an additional challenge as their detection is complex. Here, we present an ESBL and AmpC screening panel employing the MALDI-TOF MS-based direct-on-target microdroplet growth assay (DOT-MGA). Materials and Methods: Four reference strains recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) were used to develop the panel, which was further validated on 50 clinical Enterobacterales isolates resistant to third generation cephalosporins. The panel relies on the synergistic effect between ESBL and/or AmpC β-lactamase inhibitors and cephalosporins, which indicates β-lactamase production. Microdroplets containing the tested microorganism, cephalosporins in different concentrations and inhibitors were pipetted onto an MBT Biotarget and incubated for 3 or 4 h at 35 ± 1°C. Afterward, the liquid medium was removed and the material adhered to the spots was analyzed by MALDI-TOF MS. Synergy was detected by determining and comparing the minimum inhibitory concentrations of the tested cephalosporins with and without β-lactamase inhibitors. Data were interpreted following a diagnostic algorithm proposed by EUCAST in order to establish a final diagnosis. In comparison, PCR, broth microdilution (BMD) and combination disk tests (CDT) were performed. Results: Compared to the PCR results, the following positive and negative percent agreement values (PPA/NPA) were obtained for each resistance mechanism: ESBL, 94.44/100%; AmpC, 94.44/93.75% and ESBL+AmpC, 100/100%. These results, obtained after 4 h of incubation, were comparable with those of BMD and showed a higher accuracy than CDT. Discussion: We propose a novel phenotypic method for detection of ESBL and AmpC β-lactamases in Enterobacterales that provides reliable results in a short time, representing a promising alternative to the diagnostic techniques currently available. This easy-to-perform approach has potential for being implemented in routine laboratories, contributing to the further diversification of mass spectrometry technology into other fields such as antibiotic resistance testing.
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Affiliation(s)
| | - Evgeny A Idelevich
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | | | | | - Karsten Becker
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
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16
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den Drijver E, Verweij JJ, Verhulst C, Oome S, Soer J, Willemsen I, Schrauwen EJA, Kluytmans—van den Bergh MFQ, Kluytmans JAJW. Decline in AmpC β-lactamase-producing Escherichia coli in a Dutch teaching hospital (2013-2016). PLoS One 2018; 13:e0204864. [PMID: 30273375 PMCID: PMC6166941 DOI: 10.1371/journal.pone.0204864] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 09/14/2018] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE The objective of this study is to determine the prevalence of rectal carriage of plasmid- and chromosome-encoded AmpC β-lactamase-producing Escherichia coli and Klebsiella spp. in patients in a Dutch teaching hospital between 2013 and 2016. METHODS Between 2013 and 2016, hospital-wide yearly prevalence surveys were performed to determine the prevalence of AmpC β-lactamase-producing E. coli and Klebsiella spp. rectal carriage. Rectal swabs were taken and cultured using an enrichment broth and selective agar plates. All E. coli and Klebsiella spp. isolates were screened for production of AmpC β-lactamase using phenotypic confirmation tests and for the presence of plasmid-encoded AmpC (pAmpC) genes. E. coli isolates were screened for chromosome-encoded AmpC (cAmpC) promoter/attenuator alterations. RESULTS Fifty (2.4%) of 2,126 evaluable patients were identified as rectal carrier of AmpC β-lactamase-producing E. coli. No carriage of AmpC β-lactamase producing Klebsiella spp. was found. Nineteen (0.9%) patients harboured isolates with pAmpC genes and 30 (1,4%) patients harboured isolates with cAmpC promoter/attenuator alterations associated with AmpC β-lactamase overproduction. For one isolate, no pAmpC genes or cAmpC promotor/attenuator alterations could be identified. During the study period, a statistically significant decline in the prevalence of rectal carriage with E. coli with cAmpC promotor/attenuator alterations was found (p = 0.012). The prevalence of pAmpC remained stable over the years. CONCLUSIONS The prevalence of rectal carriage of AmpC-producing E. coli and Klebsiella spp. in patients in Dutch hospitals is low and a declining trend was observed for E. coli with cAmpC promotor/attenuator alterations.
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Affiliation(s)
- Evert den Drijver
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Laboratory for Medical Microbiology and Immunology, Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
- * E-mail:
| | - Jaco J. Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
| | - Carlo Verhulst
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
| | - Stijn Oome
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Avans Academy for Technology of Health & Environment, AVANS University of Applied Sciences, Breda, The Netherlands
| | - Joke Soer
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Avans Academy for Technology of Health & Environment, AVANS University of Applied Sciences, Breda, The Netherlands
| | - Ina Willemsen
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
| | - Eefje J. A. Schrauwen
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Avans Academy for Technology of Health & Environment, AVANS University of Applied Sciences, Breda, The Netherlands
| | - Marjolein F. Q. Kluytmans—van den Bergh
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Amphia Academy Infectious Disease Foundation, Amphia Hospital, Breda, The Netherlands
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Jan A. J. W. Kluytmans
- Laboratory for Microbiology and Infection Control, Amphia Hospital, Breda, The Netherlands
- Laboratory for Medical Microbiology and Immunology, Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
- Julius Center for Health Sciences and Primary Care, UMC Utrecht, Utrecht University, Utrecht, the Netherlands
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Pereckaite L, Tatarunas V, Giedraitiene A. Current antimicrobial susceptibility testing for beta-lactamase-producing Enterobacteriaceae in clinical settings. J Microbiol Methods 2018; 152:154-164. [PMID: 30063958 DOI: 10.1016/j.mimet.2018.07.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 07/16/2018] [Accepted: 07/27/2018] [Indexed: 11/17/2022]
Abstract
The worldwide prevalence of beta-lactamase-producing Enterobacteriaceae (BL-E) is increasing. Bacterial infections involving ESBLs can be more difficult to treat because of antibiotic resistance, as there are fewer effective antibiotics left to be used. Moreover, treatment failure is often observed. Thus, quick and accurate identification of β-lactamases is imperative to minimize it. This review article describes most commonly used phenotypic techniques and molecular methods for the detection of ESBLs, acquired AmpC β-lactamases, and carbapenemases produced by Enterobacteriaceae. Phenotypic detection tests remain useful and relevant in clinical laboratories while molecular diagnostic methods are less affordable, more technically demanding, and not standardized. Molecular methods could be used to speed up results of bacterial antibiotic resistance or to clarify the results of phenotypic β-lactamases confirmation tests.
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Affiliation(s)
- Laura Pereckaite
- Department of Laboratory Medicine, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Vacis Tatarunas
- Institute of Cardiology, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Agne Giedraitiene
- Institute of Microbiology and Virology, Lithuanian University of Health Sciences, Kaunas, Lithuania.
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18
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Frickmann H, Köller T, Hagen RM, Ebert KP, Müller M, Wenzel W, Gatzer R, Schotte U, Binder A, Skusa R, Warnke P, Podbielski A, Rückert C, Kreikemeyer B. Molecular Epidemiology of Multidrug-Resistant Bacteria Isolated from Libyan and Syrian Patients with War Injuries in Two Bundeswehr Hospitals in Germany. Eur J Microbiol Immunol (Bp) 2018; 8:1-11. [PMID: 29760959 PMCID: PMC5944420 DOI: 10.1556/1886.2018.00002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 01/31/2018] [Indexed: 12/16/2022] Open
Abstract
Introduction We assessed the molecular epidemiology of multidrug-resistant bacteria colonizing or infecting war-injured patients from Libya and Syria who were treated at the Bundeswehr hospitals Hamburg and Westerstede, Germany. Methods Enterobacteriaceae and Gram-negative rod-shaped nonfermentative bacteria with resistance against third-generation methoxyimino cephalosporins or carbapenems as well as methicillin-resistant Staphylococcus aureus (MRSA) from war-injured patients from Libya and Syria were assessed by molecular typing, i.e., spa typing for MRSA strains and rep-PCR and next-generation sequencing (NGS) for Gram-negative isolates. Results A total of 66 isolates were assessed – comprising 44 Enterobacteriaceae, 16 nonfermentative rod-shaped bacteria, and 6 MRSA from 22 patients – and 8 strains from an assessment of the patient environment comprising 5 Enterobacteriaceae and 3 nonfermentative rod-shaped bacteria. Although 24 out of 66 patient strains were isolated more than 3 days after hospital admission, molecular typing suggested only 7 likely transmission events in the hospitals. Identified clonal clusters primarily suggested transmission events in the country of origin or during the medical evacuation flights. Conclusions Nosocomial transmissions in hospital can be efficiently prevented by hygiene precautions in spite of heavy colonization. Transmission prior to hospital admission like on evacuation flights or in crises zones needs further assessment.
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Affiliation(s)
- Hagen Frickmann
- Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Hamburg, Hamburg, Germany.,Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Thomas Köller
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Ralf Matthias Hagen
- Department of Preventive Medicine, Bundeswehr Medical Academy, Munich, Germany
| | - Klaus-Peter Ebert
- Hygiene Department, Bundeswehr Hospital Westerstede, Westerstede, Germany
| | - Martin Müller
- Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Berlin, Berlin, Germany
| | - Werner Wenzel
- Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Hamburg, Hamburg, Germany.,Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Berlin, Berlin, Germany
| | - Renate Gatzer
- Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Berlin, Berlin, Germany
| | - Ulrich Schotte
- Laboratory Department II, Central Institute of the Bundeswehr Kiel, Kiel-Kronshagen, Germany
| | - Alfred Binder
- Laboratory Department II, Central Institute of the Bundeswehr Kiel, Kiel-Kronshagen, Germany
| | - Romy Skusa
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Philipp Warnke
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Andreas Podbielski
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Christian Rückert
- Centrum for Biotechnology (CeBiTec), University Bielefeld, Bielefeld, Germany
| | - Bernd Kreikemeyer
- Institute of Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
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Zerr DM, Weissman SJ, Zhou C, Kronman MP, Adler AL, Berry JE, Rayar J, Myers J, Haaland WL, Burnham CAD, Elward A, Newland J, Selvarangan R, Sullivan KV, Zaoutis T, Qin X. The Molecular and Clinical Epidemiology of Extended-Spectrum Cephalosporin- and Carbapenem-Resistant Enterobacteriaceae at 4 US Pediatric Hospitals. J Pediatric Infect Dis Soc 2017; 6:366-375. [PMID: 28339623 PMCID: PMC5907845 DOI: 10.1093/jpids/piw076] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 11/10/2016] [Indexed: 12/31/2022]
Abstract
OBJECTIVE In this report, we aim to describe the epidemiology of extended-spectrum cephalosporin-resistant (ESC-R) and carbapenem-resistant (CR) Enterobacteriaceae infections in children. METHODS ESC-R and CR Enterobacteriaceae isolates from normally sterile sites of patients aged <22 years from 4 freestanding pediatric medical centers were collected along with the associated clinical data. RESULTS The overall frequencies of ESC-R and CR isolates according to hospital over the 4-year study period ranged from 0.7% to 2.8%. Rates of ESC-R or CR Escherichia coli and Klebsiella pneumoniae varied according to hospital and ranged from 0.75 to 3.41 resistant isolates per 100 isolates (P < .001 for any differences). E coli accounted for 272 (77%) of the resistant isolates; however, a higher rate of resistance was observed in K pneumoniae isolates (1.78 vs 1.27 resistant isolates per 100 same-species isolates, respectively; P = .005). One-third of the infections caused by ESC-R or CR E coli were community-associated. In contrast, infections caused by ESC-R or CR K pneumoniae were more likely than those caused by resistant E coli to be healthcare- or hospital-associated and to occur in patients with an indwelling device (P ≤ .003 for any differences, multivariable logistic regression). Nonsusceptibility to 3 common non-β-lactam agents (ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole) occurred in 23% of the ESC-R isolates. The sequence type 131-associated fumC/fimH-type 40-30 was the most prevalent sequence type among all resistant E coli isolates (30%), and the clonal group 258-associated allele tonB79 was the most prevalent allele among all resistant K pneumoniae isolates (10%). CONCLUSIONS The epidemiology of ESC-R and CR Enterobacteriaceae varied according to hospital and species (E coli vs K pneumoniae). Both community and hospital settings should be considered in future research addressing pediatric ESC-R Enterobacteriaceae infection.
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Affiliation(s)
- Danielle M Zerr
- Departments of Pediatrics University of Washington, Seattle,Seattle Children’s Research Institute, Washington,Correspondence: D. M. Zerr, MD, MPH, Seattle Children’s Hospital, 4800 Sand Point Way, NE, Seattle, WA 98105 ()
| | - Scott J Weissman
- Departments of Pediatrics University of Washington, Seattle,Seattle Children’s Research Institute, Washington
| | - Chuan Zhou
- Departments of Pediatrics University of Washington, Seattle,Seattle Children’s Research Institute, Washington
| | - Matthew P Kronman
- Departments of Pediatrics University of Washington, Seattle,Seattle Children’s Research Institute, Washington
| | | | | | | | - Jeff Myers
- Seattle Children’s Research Institute, Washington
| | | | - Carey-Ann D Burnham
- Departments of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri,Department of Pediatrics, St. Louis Children’s Hospital, Missouri
| | - Alexis Elward
- Department of Pediatrics, St. Louis Children’s Hospital, Missouri,Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Jason Newland
- Department of Pediatrics, University of Missouri, Kansas City, Missouri,Children’s Mercy, Kansas City, Missouri
| | - Rangaraj Selvarangan
- Children’s Mercy, Kansas City, Missouri,Department of Pathology and Laboratory Medicine, University of Missouri, Kansas City, Missouri
| | - Kaede V Sullivan
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia,Children’s Hospital of Philadelphia, Pennsylvania
| | - Theoklis Zaoutis
- Children’s Hospital of Philadelphia, Pennsylvania,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia
| | - Xuan Qin
- Seattle Children’s Research Institute, Washington,Departments of Laboratory Medicine, University of Washington, Seattle
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Phenotypic and genotypic characteristics of ESBL and AmpC producing organisms associated with bacteraemia in Ho Chi Minh City, Vietnam. Antimicrob Resist Infect Control 2017; 6:105. [PMID: 29046783 PMCID: PMC5644090 DOI: 10.1186/s13756-017-0265-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/09/2017] [Indexed: 01/22/2023] Open
Abstract
Background Broad-spectrum antimicrobials are commonly used as empirical therapy for infections of presumed bacterial origin. Increasing resistance to these antimicrobial agents has prompted the need for alternative therapies and more effective surveillance. Better surveillance leads to more informed and improved delivery of therapeutic interventions, potentially leading to better treatment outcomes. Methods We screened 1017 Gram negative bacteria (excluding Pseudomonas spp. and Acinetobacter spp.) isolated between 2011 and 2013 from positive blood cultures for susceptibility against third generation cephalosporins, ESBL and/or AmpC production, and associated ESBL/AmpC genes, at the Hospital for Tropical Diseases in Ho Chi Minh City. Results Phenotypic screening found that 304/1017 (30%) organisms were resistance to third generation cephalosporins; 172/1017 (16.9%) of isolates exhibited ESBL activity, 6.2% (63/1017) had AmpC activity, and 0.5% (5/1017) had both ESBL and AmpC activity. E. coli and Aeromonas spp. were the most common organisms associated with ESBL and AmpC phenotypes, respectively. Nearly half of the AmpC producers harboured an ESBL gene. There was no significant difference (p > 0.05) between the antimicrobial resistance phenotypes of the organisms associated with community and hospital-acquired infections. Conclusion AmpC and ESBL producing organisms were commonly associated with bloodstream infections in this setting, with antimicrobial resistant organisms being equally distributed between infections originating from the community and healthcare settings. Aeromonas spp., which was associated with bloodstream infections in cirrhotic/hepatitis patients, were the most abundant AmpC producing organism. We conclude that empirical monotherapy with third generation cephalosporins may not be optimum in this setting. Electronic supplementary material The online version of this article (10.1186/s13756-017-0265-1) contains supplementary material, which is available to authorized users.
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21
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Teethaisong Y, Evans K, Nakouti I, Tiamyom K, Ketudat-Cairns JR, Hobbs G, Eumkeb G. The performance of a resazurin chromogenic agar plate with a combined disc method for rapid screening of extended-spectrum-β-lactamases, AmpC β-lactamases and co-β-lactamases in Enterobacteriaceae. Microbiol Immunol 2017; 61:297-304. [PMID: 28685856 DOI: 10.1111/1348-0421.12499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/12/2017] [Accepted: 07/03/2017] [Indexed: 11/28/2022]
Abstract
A promising means of rapid screening of extended-spectrum-β-lactamase (ESBL), AmpC β-lactamase, and co-production of ESBL and AmpC that combines resazurin chromogenic agar (RCA) with a combined disc method is here reported. Cefpodoxime (CPD) discs with and without clavulanic acid (CA), cloxacillin (CX) and CA+CX were evaluated against 86 molecularly confirmed β-lactamase-producing Enterobacteriaceae, including 15 ESBLs, 32 AmpCs, nine co-producers of ESBL and AmpC and 30 carbapenemase producers. The CA and CX synergy test successfully detected all ESBL producers (100% sensitivity and 98.6% specificity) and all AmpC producers (100% sensitivity and 96.36% specificity). This assay also performed well in screening for co-existence of ESBL and AmpC (88.89% sensitivity and 100% specificity). The RCA assay is simple and inexpensive and provides results within 7 hr. It can be performed in any microbiological laboratory, in particular, in geographic regions in which ESBL, AmpC or co-β-lactamase-producing Enterobacteriaceae are endemic.
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Affiliation(s)
- Yothin Teethaisong
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
- School of Preclinic, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Katie Evans
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Ismini Nakouti
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Kanokwan Tiamyom
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - James R Ketudat-Cairns
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Glyn Hobbs
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Griangsak Eumkeb
- School of Preclinic, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
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Chuong LV, Prachayasittikul V, Isarankura Na Ayudhya C, Lawung R. Multiplex PCR scheme for variant plasmid mediated class C β-lactamase typing. J Clin Lab Anal 2017; 32. [PMID: 28718958 DOI: 10.1002/jcla.22298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2017] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND An increasing of prevalence and diversification of plasmid-mediated AmpC (pAmpC) has been emerged worldwide. The incidence of pAmpC resulted in increasing β-lactamase production and conferred resistance to almost all β-lactam antibiotics excluding carbapenems. The lack of standard method for pAmpC identification and classification exert a challenge in epidemiological surveillance and infection control practices. METHODS A robust, single tube multiplex PCR has been developed to classify six different pAmpC groups including CIT (CMY-2 like, LAT and CFE), ECB (ACT, MIR), MOX & CMY-1 like, DHA, ACC, and FOX. The developed method was optimized and validated by testing of sensitivity and specificity. RESULTS Developed method can detect crude extracted DNA template at nano-scale (2.5 ηg) and has high discriminatory power as compared to phenotypic and commercial genotypic method. CONCLUSION The developed method can be utilized for tracking the changes of clinically important resistance patterns and further investigation of occurrence and distribution of plasmid-mediated AmpC types.
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Affiliation(s)
- Le Van Chuong
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand.,Department of Microbiology, Faculty of Medicine, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam
| | - Virapong Prachayasittikul
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
| | | | - Ratana Lawung
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
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Tuerena I, Williams NJ, Nuttall T, Pinchbeck G. Antimicrobial-resistant Escherichia coli in hospitalised companion animals and their hospital environment. J Small Anim Pract 2017; 57:339-47. [PMID: 27385621 DOI: 10.1111/jsap.12525] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 04/26/2016] [Accepted: 05/06/2016] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Antimicrobial resistance is a growing concern with implications for animal health. This study investigated the prevalence of antimicrobial resistance among commensal and environmental Escherichia coli isolated from animals sampled in referral hospitals in the UK. MATERIALS AND METHODS Resistant Escherichia coli isolated from animal faeces and practice environments were tested for susceptibility to antimicrobial agents. PCR and sequencing techniques were used to identify extended spectrum beta-lactamase and AmpC-producer genotypes. RESULTS In total, 333 faecal and 257 environmental samples were collected. Multi-drug resistant Escherichia coli were found in 13·1% of faecal and 8·9% of environmental samples. Extended spectrum beta-lactamase and AmpC genes were identified 14% and 7·7% of faecal samples and 8·6% and 8·6% of environmental samples, respectively. The most common extended spectrum beta-lactamase gene type detected was blaCTX-M -15 , although blaTEM-158 was detected in faecal and environmental samples from one practice. CLINICAL SIGNIFICANCE Escherichia coli resistant to key antimicrobials were isolated from hospitalised animals and the practice environment. We identified the emergence of the inhibitor resistant and extended spectrum beta-lactamase blaTEM-158 in companion animals. Further investigation to determine risk factors for colonisation with antimicrobial-resistant bacteria is needed to provide evidence for antimicrobial stewardship and infection control programmes.
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Affiliation(s)
- I Tuerena
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Neston, CH64 7TE
| | - N J Williams
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Neston, CH64 7TE
| | - T Nuttall
- School of Veterinary Science, Faculty of Health and Life Sciences, University of Liverpool, Neston, CH64 7TE
| | - G Pinchbeck
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Neston, CH64 7TE
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Detection and epidemiology of plasmid-mediated AmpC β-lactamase producing Escherichia coli in two Irish tertiary care hospitals. J Glob Antimicrob Resist 2016; 3:242-246. [PMID: 27842867 DOI: 10.1016/j.jgar.2015.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/01/2015] [Accepted: 06/10/2015] [Indexed: 11/24/2022] Open
Abstract
This study determined the prevalence and distribution of plasmid-mediated AmpC (pAmpC) β-lactamases in Irish Escherichia coli isolates. Clinical E. coli isolates (n=95) that were intermediate or resistant to cefoxitin and/or flagged by VITEK® 2 as potential AmpC-producers underwent confirmation using a MASTDISCS™ ESBL and AmpC Detection Kit. Multiplex PCR capable of detecting family-specific plasmid ampC genes was performed to detect the presence of these genes. Five PCR-negative isolates were selected for promoter analysis. PFGE and MLST were performed on E. coli isolates that harboured a plasmid ampC gene to determine their clonal relatedness. Plasmid ampC genes were detected in 19% (18/95) of phenotypic AmpC producing E. coli isolates. The CIT group was the most common plasmid family type (n=14); DHA (n=3) and ACC (n=1) groups were also detected. Promoter analysis showed that four isolates had multiple point mutations and one had a 1 bp insertion in the -10 box. PFGE demonstrated a polyclonal pattern for E. coli isolates. Furthermore, with the exception of two isolates with an identical sequence type (ST720), MLST analysis revealed that these isolates were not clonally related. This study revealed that there was a marked prevalence of pAmpC E. coli among phenotypic AmpC producing E. coli isolates but no evidence of cross-transmission of a single strain. Establishing the prevalence and clonality of these organisms is important in order to implement evidence-based infection control measures that reduce the spread of pAmpC β-lactamase resistance in the hospital environment.
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Frickmann H, Wiemer D, Frey C, Hagen RM, Hinz R, Podbielski A, Köller T, Warnke P. Low Enteric Colonization with Multidrug-Resistant Pathogens in Soldiers Returning from Deployments- Experience from the Years 2007-2015. PLoS One 2016; 11:e0162129. [PMID: 27598775 PMCID: PMC5012679 DOI: 10.1371/journal.pone.0162129] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/17/2016] [Indexed: 11/24/2022] Open
Abstract
This assessment describes the enteric colonization of German soldiers 8–12 weeks after returning from mostly but not exclusively subtropical or tropical deployment sites with third-generation cephalosporin-resistant Enterobacteriaceae, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA). Between 2007 and 2015, 828 stool samples from returning soldiers were enriched in nonselective broth and incubated on selective agars for Enterobacteriaceae expressing extended-spectrum beta-lactamases (ESBL), VRE and MRSA. Identification and resistance testing of suspicious colonies was performed using MALDI-TOF-MS, VITEK-II and agar diffusion gradient testing (bioMérieux, Marcy-l’Étoile, France). Isolates with suspicion of ESBL were characterized by ESBL/ampC disc-(ABCD)-testing and molecular approaches (PCR, Sanger sequencing). Among the returnees, E. coli with resistance against third-generation cephalosporins (37 ESBL, 1 ESBL + ampC, 1 uncertain mechanism) were found in 39 instances (4.7%). Associated quinolone resistance was found in 46.2% of these isolates. Beta-lactamases of the blaCTX-M group 1 predominated among the ESBL mechanisms, followed by the blaCTX-M group 9, and blaSHV. VRE of vanA-type was isolated from one returnee (0.12%). MRSA was not isolated at all. There was no clear trend regarding the distribution of resistant isolates during the assessment period. Compared with colonization with resistant bacteria described in civilians returning from the tropics, the colonization in returned soldiers is surprisingly low and stable. This finding, together with high colonization rates found in previous screenings on deployment, suggests a loss of colonization during the 8- to 12-week period between returning from the deployments and assessment.
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Affiliation(s)
- Hagen Frickmann
- Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Hamburg, Germany
- Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
- * E-mail:
| | - Dorothea Wiemer
- Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Hamburg, Germany
| | - Claudia Frey
- Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Hamburg, Germany
| | - Ralf Matthias Hagen
- Deployment Health Surveillance Capability, NATO Center of Excellence for Military Medicine, Munich, Germany
| | - Rebecca Hinz
- Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Hamburg, Germany
| | - Andreas Podbielski
- Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Thomas Köller
- Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - Philipp Warnke
- Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
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Previous Antibiotic Exposure Increases Risk of Infection with Extended-Spectrum-β-Lactamase- and AmpC-Producing Escherichia coli and Klebsiella pneumoniae in Pediatric Patients. Antimicrob Agents Chemother 2016; 60:4237-43. [PMID: 27139486 DOI: 10.1128/aac.00187-16] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/27/2016] [Indexed: 12/24/2022] Open
Abstract
The objective of this study was to determine whether antibiotic exposure is associated with extended-spectrum-beta-lactamase- or AmpC-producing Escherichia coli or Klebsiella pneumoniae infections in children. We collected extended-spectrum-beta-lactamase- or AmpC-producing E. coli or K. pneumoniae isolates and same-species susceptible controls from normally sterile sites of patients aged ≤21 years, along with associated clinical data, at four free-standing pediatric centers. After controlling for potential confounders, the relative risk of having an extended-spectrum-beta-lactamase-producing isolate rather than a susceptible isolate was 2.2 times higher (95% confidence interval [CI], 1.49 to 3.35) among those with antibiotic exposure in the 30 days prior to infection than in those with no antibiotic exposure. The results were similar when analyses were limited to exposure to third-generation cephalosporins, other broad-spectrum beta-lactams, or trimethoprim-sulfamethoxazole. Conversely, the relative risk of having an AmpC-producing versus a susceptible isolate was not significantly elevated with any antibiotic exposure in the 30 days prior to infection (adjusted relative risk ratio, 1.12; 95% CI, 0.65 to 1.91). However, when examining subgroups of antibiotics, the relative risk of having an AmpC-producing isolate was higher for patients with exposure to third-generation cephalosporins (adjusted relative risk ratio, 4.48; 95% CI, 1.75 to 11.43). Dose-response relationships between antibiotic exposure and extended-spectrum-beta-lactamase-producing or AmpC-producing isolates were not demonstrated. These results reinforce the need to study and implement pediatric antimicrobial stewardship strategies, and they indicate that epidemiological studies of third-generation cephalosporin-resistant E. coli and K. pneumoniae isolates should include resistance mechanisms when possible.
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27
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Occurrence of SHV, TEM and CTX-M β-Lactamase Genes Among Enteropathogenic Escherichia coli Strains Isolated From Children With Diarrhea. Jundishapur J Microbiol 2015. [DOI: 10.5812/jjm.15620.8(4)2015.15620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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28
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Memariani M, Najar Peerayeh S, Zahraei Salehi T, Shokouhi Mostafavi SK. Occurrence of SHV, TEM and CTX-M β-Lactamase Genes Among Enteropathogenic Escherichia coli Strains Isolated From Children With Diarrhea. Jundishapur J Microbiol 2015; 8:e15620. [PMID: 26034531 PMCID: PMC4449847 DOI: 10.5812/jjm.8(4)2015.15620] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 12/20/2013] [Accepted: 12/28/2013] [Indexed: 12/02/2022] Open
Abstract
Background: Antibiotic resistance is widespread among diarrheagenic Escherichia coli in developing countries, where the overuse of antibiotics is common. Information regarding β-lactamases, especially Extended-Spectrum β-Lactamases (ESBLs) in diarrheagenic pathogens should be considered in clinical management when an optimal treatment is needed. Objectives: The main objective of this study was to investigate the prevalence of blaCTX-M, blaSHV and blaTEM β-lactamase genes among enteropathogenic E. coli (EPEC) isolates in Tehran, Iran. Materials and Methods: Stool specimens were collected from children with diarrhea during a 17-month period from 2011 to 2013. Routine biochemical tests were performed for identification of E. coli isolates. The isolates were further examined by PCR for the presence of eae, stx1, stx2 and bfp genes. EPEC isolates have been screened for different β-lactamase genes. Genotyping EPEC isolates harboring blaCTX-M15 gene was performed through Multi-Locus VNTR Analysis (MLVA). Results: Of 42 EPEC, eight isolates carried the blaCTX-M1. None of the isolates carried blaCTX-M2 and blaCTX-M9. The blaCTX-M15 variant was identified in all of blaCTX-M1-positive isolates. Furthermore, blaSHV and blaTEM genes were detected in 40.5% (n = 17) and 19% (n = 8) of all EPEC isolates, respectively. No significant association was observed between the existence of bfp gene and presence of those β-lactamase genes (P > 0.05). MLVA analysis revealed high genetic diversity among blaCTX-M15-positive isolates. Conclusions: Our study emphasized the increasing role of ESBL genes, especially blaCTX-M15 in EPEC isolates.
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Affiliation(s)
- Mojtaba Memariani
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
| | - Shahin Najar Peerayeh
- Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
- Corresponding author: Shahin Najar Peerayeh, Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran. Tel: +98-2182883870, Fax: +98-2182884555, E-mail:
| | - Taghi Zahraei Salehi
- Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, IR Iran
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Micheel V, Hogan B, Rakotoarivelo RA, Rakotozandrindrainy R, Razafimanatsoa F, Razafindrabe T, Rakotondrainiarivelo JP, Crusius S, Poppert S, Schwarz NG, May J, Frickmann H, Hagen RM. Identification of nasal colonization with β-lactamase-producing Enterobacteriaceae in patients, health care workers and students in Madagascar. Eur J Microbiol Immunol (Bp) 2015; 5:116-25. [PMID: 25908994 DOI: 10.1556/eujmi-d-15-00001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 01/07/2015] [Indexed: 12/21/2022] Open
Abstract
This study assesses the nasal occurrence of β-lactamase-producing Enterobacteriaceae both in patients in a hospital department of infectious diseases at admission and in healthy Madagascan students and health care workers. Nasal swabs from 681 students, 824 health care workers, and 169 patients were obtained in Antananarivo, Madagascar, and transferred to Germany. Screening for β-lactamase (ESBL, ampC) producing Enterobacteriaceae was performed by cultural and molecular approaches, comprising Brilliance ESBL agar, E-testing, ABCD-testing, and commercial hyplex ESBL and SuperBug ID PCR. Regarding ESBL-positive strains and strains with resistance against at least three out of the four tested bactericidal antibiotic drugs, 0.3% (five out of 1541) of the students and health care workers group showed nasal colonization, whereas colonization was observed in 7.1% (12 out of 169) of the hospitalized patients at admission. No appreciably reduced detection rates after sample storage and intercontinental transport were observed. A considerable proportion of nasal colonization with cephalosporin-resistant Enterobacteriaceae was demonstrated in Madagascan hospital patients at admission, posing a risk of developing future endogenous infections. The nasal colonization of healthy individuals was negligible. Good storage and transport stability of Enterobacteriaceae will allow for future studies even in areas difficult to access.
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The MAST® D68C test: an interesting tool for detecting extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. Eur J Clin Microbiol Infect Dis 2015; 34:975-83. [PMID: 25586825 DOI: 10.1007/s10096-014-2305-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 12/14/2014] [Indexed: 10/24/2022]
Abstract
The Mast® D68C test is a phenotypical test that allows the detection of extended-spectrum β-lactamase (ESBL) production, even in AmpC-producing Enterobacteriaceae. We assessed its detection accuracy against a large collection of 106 Enterobacteriaceae isolates producing a wide diversity of well-characterized β-lactamases (53 ESBL producers, 25 Amp. producers, seven AmpC and ESBL producers, five carbapenemase producers, three carbapenemase and ESBL producers, one AmpC, carbapenemase, and ESBL producer, three TEM-1 producers, three SHV-1 producers, three OXA-1 producers, and one hyperOXY producer, ATCC 35218, ATCC 25922 [a β-lactamase-negative control strain]). The results were compared with those of the double disk test and the Clinical and Laboratory Standards Institute (CLSI) confirmatory test for the detection of ESBL. The sensitivity was 90.6 % for the synergy test, 87.5 % for the CLSI method, and only 73.1 % for D68C, which, however, reached 92.1 % if the strains for which supplementary investigations were recommended and the complex mutant TEM (CMT)-producing strains were excluded versus 94.1 % and 88.2 % for the other methods. The specificity was 90.2 % for the synergy test and 100 % for the CLSI method and D68C. D68C was also efficient in detecting AmpC-overproducing strains (sensitivity = 97 %, specificity = 95.9 %): among the 74 strains belonging to natural AmpC-producing species, the sensitivity and specificity were 100 and 94.8 %, respectively. The Mast® D68C-test is a promising method that is easy to perform for the detection of current ESBLs and could also be useful for the detection of plasmid-encoded AmpC enzymes (sensitivity = 100 %).
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Japoni-Nejad A, Ghaznavi-Rad E, van Belkum A. Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods. Osong Public Health Res Perspect 2014; 5:333-8. [PMID: 25562041 PMCID: PMC4281629 DOI: 10.1016/j.phrp.2014.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/17/2014] [Accepted: 09/23/2014] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVES Plasmid-mediated AmpC β-lactamases (PMABLs) and carbapenemases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test performance of various phenotypic methods for detection of these enzymes in Iran. METHODS A total of 100 K. pneumoniae isolates were collected from clinical specimens obtained in Valiasr Hospital. AmpC production in all isolates was determined using the AmpC disk test, the cephamycin Hodge test, the AmpC Etest, and the boronic acid combined-disk test. In addition, carbapenemase production was determined using the modified Hodge test, the EDTA disk synergy test, and the boronic acid combined-disk test. The performances of various phenotypic methods were evaluated by the comparison of their results with polymerase chain reaction (PCR) method as the gold standard. RESULTS Of the 100 isolates, 19 (19%) were demonstrated to harbor the PMABL-resistance gene by the multiplex PCR method. The PCR result indicated the presence of carbapenemase genes in 12 isolates. The performance of various phenotypic tests carried out for detection of carbapenemase-producing isolates varied widely, ranging in sensitivity from 30% to 100% and in specificity from 90.8% to 100%. CONCLUSION This is the first report of MOX-type AmpC β-lactamase and bla GES in K. pneumoniae in Iran. A comparison of the phenotypic methods showed that a combination of cefoxitin plus boronic acid is optimal for detecting plasmid-mediated AmpC enzymes in K. pneumoniae, whereas the implementation of molecular methods is often complex, requires specially trained personnel, and is associated with higher costs.
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Affiliation(s)
| | - Ehsanollah Ghaznavi-Rad
- Department of Medical Microbiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran
| | - Alex van Belkum
- Erasmus MC, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands ; bioMérieux, La Balme-les-Grottes, Isère, France
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Philbey AW, Mather HA, Gibbons JF, Thompson H, Taylor DJ, Coia JE. Serovars, bacteriophage types and antimicrobial sensitivities associated with salmonellosis in dogs in the UK (1954-2012). Vet Rec 2013; 174:94. [PMID: 24277916 DOI: 10.1136/vr.101864] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Serovars and bacteriophage (phage) types were determined for 442 isolates of Salmonella enterica from dogs in the UK submitted to the Scottish Salmonella Reference Laboratory from 1954 to 2012. The most frequent serovars were Salmonella Typhimurium (196 isolates; 44.3 per cent), Dublin (40 isolates; 9.0 per cent), Enteritidis (28 isolates; 6.3 per cent), Montevideo (19 isolates; 4.3 per cent), Virchow (10 isolates; 2.3 per cent), Heidelberg (8 isolates; 1.8 per cent) and Derby (8 isolates; 1.8 per cent), along with 55 other recognised serovars among 127 other isolates, and six incompletely classified isolates. Serovars were frequently represented by strains commonly associated with poultry, cattle or pigs and their products. Among 196 Salmonella Typhimurium isolates from dogs, the most frequent phage types (definitive types) were the multiple antimicrobial-resistant strains DT104 (62 isolates), DT204c (18 isolates) and DT193 (8 isolates), along with antimicrobial sensitive wild finch strains DT40 (13 isolates) and DT56 variant (8 isolates). Eleven of 28 isolates of Salmonella Enteritidis were phage type 4. S enterica was frequently recovered from faecal or intestinal samples of dogs with diarrhoea, although many dogs had concurrent infection with other enteric pathogens. Salmonella Dublin was recovered from the brain and/or cerebrospinal fluid of two dogs with meningoencephalitis. Salmonella Kedougou was isolated from the joint fluid of a dog with septic arthritis. Salmonella Typhimurium and Salmonella Dublin were each recovered from the vaginas of bitches that had aborted. Isolates of Salmonella Enteritidis phage types 1, 4 and 8, Salmonella Typhimurium DT104, Salmonella Dublin and Salmonella Indiana were isolated from clinically healthy dogs in households where the same strains were recovered from human beings with diarrhoea. The pattern ampicillin-chloramphenicol-spectinomycin-streptomycin-sulfamethoxazole-tetracycline (ACSpSSuT) was the most frequent resistance phenotype and was observed in 44 (13.3 per cent) of 330 isolates. Dogs in the UK are exposed to a wide variety of serovars of S enterica, sometimes associated with clinical disease, and represent a zoonotic risk.
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Affiliation(s)
- A W Philbey
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Edinburgh EH25 9RG, UK
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Luk S, Wong WK, Ng TK, To WK, Lo TH. Detection of plasmid-mediated AmpC β-lactamases in isolates of Klebsiella pneumoniae in a regional laboratory in Hong Kong, China. Diagn Microbiol Infect Dis 2013; 76:252-3. [DOI: 10.1016/j.diagmicrobio.2013.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 12/21/2012] [Accepted: 02/11/2013] [Indexed: 10/27/2022]
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Detection of AmpC beta-lactamases using sodium salicylate. J Microbiol Methods 2012; 91:354-7. [PMID: 23059062 DOI: 10.1016/j.mimet.2012.09.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 09/22/2012] [Accepted: 09/29/2012] [Indexed: 11/24/2022]
Abstract
AmpC β-lactamases are enzymes that hydrolyze all β-lactam antibiotics except cefipime and imipenem. Currently, there is no standard phenotypic method for detection of such enzymes. This study aims to report the use of sodium salicylate for AmpC β-lactamases detection and to compare its sensitivity and specificity to other commonly known inhibitors. A total of 135 clinical isolates were used to test the effectiveness of sodium salicylate in detection of plasmid- as well as chromosomally encoded AmpC β-lactamases. All isolates were tested by multiplex PCR testing as well as inhibitor-based methods using cloxacillin, phenylboronic acid and sodium salicylate for the detection of AmpC enzymes. Four isolates were confirmed as producers of plasmid-encoded AmpC β-lactamase and a single isolate was confirmed to have both plasmid and chromosomal genes. Cloxacillin and phenylyboronic acid failed to detect most of the plasmid-encoded enzymes. Sodium salicylate was able to detect the Escherichia coli isolates with plasmid-encoded enzymes in addition to few other isolates that were chromosomally mediated. The sensitivity and specificity of sodium salicylate was 50% and 93%, respectively, higher than those of other known inhibitors. We thus conclude that sodium salicylate can be reliably used as an inhibitor in the detection of plasmid-encoded AmpC enzymes in E. coli.
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Evaluation of four phenotypic methods to detect plasmid-mediated AmpC β-lactamases in clinical isolates. Eur J Clin Microbiol Infect Dis 2012; 31:2037-43. [PMID: 22278294 DOI: 10.1007/s10096-011-1537-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/21/2011] [Indexed: 10/14/2022]
Abstract
Four phenotypic methods (three dimensional test, AmpC test, cloxacillin synergy test and cefotetan/cefotetan-cloxacillin E-test) to detect plasmid-mediated AmpC β-lactamases (pAmpC) were compared in 125 clinical Enterobacteriaceae isolates with AmpC profile: 74 E. coli (bla (CMY-2): 70; bla (DHA-1): 4), five K. pneumoniae (bla (CMY-2): 2; bla (DHA-1): 3), six P. mirabilis (bla (CMY-2): 6) and 40 negative isolates for pAmpC β-lactamases. All evaluated methods showed a good sensitivity (>95%) but low values of specificity (<60%) in E. coli, explained by an increase of AmpC expression caused by chromosomal ampC promoter/attenuator mutations (-42, -18, -1, +58, predominantly). The cefotetan/cefotetan-cloxacillin or cloxacillin synergy test may be advocated as phenotypic screening test, and the AmpC test as confirmatory test for detection of pAmpC in isolates that lack or minimally express chromosomally encoded AmpC β-lactamases. In the case of E. coli, the phenotypic evaluated tests were not able to differentiate between chromosomal ampC overexpression or acquisition of plasmid-encoded ampC genes.
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