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Article in English | IMSEAR | ID: sea-163468


Citrobacter species have been reported to cause a wide spectrum of infections in humans and invasive infections are associated with a high mortality rate, with 33 to 48% of patients succumbing to Citrobacter bacteraemia. The high mortality rate associated with Citrobacter infections may be due in part to ineffective empirical antibiotic therapy. Citrobacter has been found to produce SHV and TEM derived Extended spectrum beta lactamases in addition to chromosomal inducible AmpC beta - lactamases which could be contributing to increasing drug resistance. The aims of the study were to detect the prevalence of Citrobacter infections with its associated risk factors, antibiotic susceptibility patterns and determination of beta-lactamase activity- both extended spectrum beta - lactamase and AmpC beta-lactamase activity among Citrobacter isolates. The isolates were identified by standard microbiological procedures. ESBL detection was by double disc diffusion method and AmpC beta-lactamase detection was done using Cefotaxime and Cefoxitin discs. C. braakii (33.3%) was the commonest genomospecies identified followed by C. freundii (21.3%) and C. amalonaticus (16.66 %) among 150 Citrobacter isolates. Diabetes mellitus was the major risk factor. Imipenem (100%)was most effective whereas 98% showed resistance to Ampicillin; carbapenems and fourth generation Cefipime showed better sensitivity than third generation cephalosporins. The study highlights the need for informed antibiotic treatment guided by routine antimicrobial susceptibility and knowledge of the ESBL status of the isolate, the outcome of which undoubtedly will be better patient care.

CITROBACTER --ISOLATION & , Citrobacter/microbiology , Enterobacteriaceae Infections/diagnosis , Enterobacteriaceae Infections/microbiology , Humans , beta-Lactamases/biosynthesis , beta-Lactamases/classification , beta-Lactamases/metabolism
Rev. argent. microbiol ; 45(3): 185-90, set. 2013.
Article in Spanish | LILACS, BINACIS | ID: biblio-1171786


Sixty-four colistin-resistant Klebsiella pneumoniae isolates recovered from clinical specimens from 57 patients admitted to Hospital de Clinicas Jose de San Martin during the period 2010-2012 were studied to describe the microbiological and epidemiological characteristics and factors associated with the emergence of colistin-resistance. Fifty-four colistin-susceptible K. pneumoniae isolates from the same period were also included in the study. The genetic relatedness among the isolates was studied by a PCR assay. Fifty percent of the resistant isolates were KPC-2 producers, 45.3

were ESBL producers and 4.7

only showed resistance to aminopenicilins. All KPC-producers (resistant and susceptible to colistin) were genotipically indistinguishable except for one, whereas the presence of 7 clonal types, which were different from the ones identified in the colistin-susceptible isolates, were detected among ESBL producers. The previous use of colistin was the main factor associated with the acquisition of resistance, and in the case of non-KPC producers the stay in ICU was another significant factor observed. Colistin resistance emerged in our hospital in the year 2010, reaching 3

in nosocomial isolates and maintaining this rate in successive years, due to the selection of resistant subpopulations in the epidemic clonal type in KPC-producers and due to the dispersion of colistin-resistant clonal types in non-KPC producing-isolates.

Colistin/pharmacology , Klebsiella pneumoniae/drug effects , Klebsiella pneumoniae/enzymology , Bacterial Proteins/biosynthesis , beta-Lactamases/biosynthesis , Drug Resistance, Bacterial , Female , Humans , Klebsiella Infections/epidemiology , Male , Bacterial Proteins/classification , beta-Lactamases/classification
Indian J Med Microbiol ; 2012 Oct-Dec; 30(4): 456-461
Article in English | IMSEAR | ID: sea-144010


Background: One leading factor responsible for resistance in Acinetobacter baumannii, an important opportunist in health care institutions globally, is the production of carbapenamases like metallo-β-lactamases (MBLs), which hydrolyze a variety of β-lactams including penicillin, cephalosporins and carbapenems. However, neither any standard guidelines are available nor any method has been found to be perfect for their detection. Various methods have shown discordant results, depending upon the employed methodology, β-lactamase substrate and MBL inhibitor used. This study aims to evaluate two phenotypic methods against PCR as gold standard among carbapenem resistant A. baumannii for identifying MBL producers. Materials and Methods: A total of 130 A. baumannii were screened for imipenem and meropenem resistance by Kirby-Bauer disc diffusion method. Phenotypic expression of MBL was detected by EDTA-imipenem-microbiological (EIM) assay and extended EDTA disc synergy (eEDS) test and presence of bla-IMP and bla-VIM was detected by PCR in all the carbapenem resistant isolates. Results: Of the 43 imipenem and/or meropenem resistant A. baumannii isolates, 4 (9.3%) were found to be MBL producers by EIM and 3 (6.97%) by eEDS. Only bla-VIM gene was detected in 7 (16.28%) by PCR. In addition EIM detected 14 (32.56%) carbapenem resistant non-metallo enzyme producers. Conclusion: Of the two MBL genes targeted, bla-VIM was only detected and that too in isolates resistant to both imipenem and meropenem. Further, EIM was useful in differentiating MBL from non-metalloenzymes producers.

Acinetobacter baumannii/metabolism , Acinetobacter baumannii/physiology , Biological Assay/methods , Microbial Sensitivity Tests/methods , Polymerase Chain Reaction/methods , beta-Lactamases/analysis , beta-Lactamases/classification , beta-Lactamases/genetics , beta-Lactams/physiology
Indian J Pathol Microbiol ; 2012 Jul-Sept 55(3): 357-360
Article in English | IMSEAR | ID: sea-142267


Aims: Carbapenems are usually the choice of antimicrobials in infections caused by Enterobacteriaceae bacteria-producing ESBL (extended spectrum β-lactamases) and Amp C. Resistance to carbapenems is mostly due to production of enzymes - Carbapenemases, which are divided into Ambler Classes A, B and D. Phenotypic detection and differentiation of types of Carbapenemases in carbapenem-resistant Enterobacteriaceae (CRE) is important for proper infection control and appropriate patient management. Materials and Methods: The present study done in a tertiary care hospital from North India differentiates Class A (KPC type) and B (MBL type) carbapenemases among Enterobacteriaceae isolates by simple phenotypic method that uses both the inhibitors EDTA and phenylboronic acid. Results: Total of 330 strains of Enterobacteriaceae were included in the study. Out of these 330 strains, 26 strains were resistant to carbapenems. The prevalence of CRE in our Institute is 7.87% (26/330). Conclusions: The prevalence of Enterobacteriaceae strains producing MBL type carbapenemase in our health care setup is 5.75% (19/330). None of the strains among the carbapenem-resistant bacterial isolates showed production of KPC enzyme. The need of the hour is simple, rapid and cost effective tests which will be able to identify and distinguish resistant pathogens for improved patient outcome, facilitating efficient infection control and reducing the escalation of resistance.

Anti-Bacterial Agents/pharmacology , Bacteriological Techniques/methods , Carbapenems/pharmacology , Enterobacteriaceae/drug effects , Enterobacteriaceae/enzymology , Humans , India , Prospective Studies , Tertiary Care Centers , beta-Lactam Resistance , beta-Lactamases/classification , beta-Lactamases/metabolism
Article in Spanish | LILACS | ID: lil-612944


Objective. To determine the frequency of enzymatic mechanisms associated with reduced sensitivity to broad-spectrum beta-lactam antibiotics in enterobacteria isolates obtained at hospital centers in Caracas, Venezuela.Methods. A cross-sectional study was conducted on enterobacteria isolated from patients at eight hospital centers in Caracas, Venezuela, from 15 October 2009 to 15 January 2010. The species were identified using conventional biochemical tests, and their susceptibility to antimicrobial drugs was assessed by antibiogram (Kirby-Bauer method), using the 2010 performance standards published by the Clinical and Laboratory Standards Institute. Beta-lactam-resistant genes were detected using an enhanced polymerase chain reaction assay.Results. Of 1 235 isolates, 207 (16.8%) exhibited resistance to third- and fourthgeneration cephalosporins, carbapenems, or both. They presented the following phenotypes: extended-spectrum beta-lactamase (ESBL), 93.8%; depressed AmpC, 4.3%; and carbapenemase, 1.9%. Further characterization of the first two phenotypes yielded the following breakdown of types: SHV, 36.7%; CTX-M-1 group, 22.3%; TEM, 21.7%; CTX-M-1 group with impermeability, 5.2%; two-enzyme combinations, 4.5%;CTX-M-2 group, 4.3%; PER, 3.4%; and KPC, 1.9%. The SHV type was predominant in the public hospital strains, whereas the CTX-M-1 group was most common in the strains from the private hospitals. Conclusions. Of the enzymatic mechanisms investigated, the SHV type was the most frequent, followed by the CTX-M-1 group and the TEM type. Also, a high percentageof type KPC was found. The research reported here is one of only a few multicenter studies that have been conducted in Venezuela to evaluate the frequency of this type of antimicrobial resistance mechanism, including phenotypical and molecular characterization...

Objetivo. Determinar la frecuencia de los mecanismos enzimáticos asociados a sensibilidad disminuida a los antibióticos betalactámicos de amplio espectro en aislados de enterobacteriasobtenidos de centros hospitalarios de Caracas, Venezuela. Métodos. Se realizó un estudio transversal con enterobacterias aisladas de pacientes de ocho centros hospitalarios de Caracas, Venezuela, desde el 15 de octubre de 2009 al 15 de enero de2010. La identificación se realizó mediante pruebas bioquímicas convencionales, y la susceptibilidada los antimicrobianos mediante antibiograma (Kirby-Bauer), según las normas de 2010 del Instituto de Estándares Clínicos y de Laboratorio. La detección de los genes de resistenciaa betalactámicos se realizó mediante amplificación por reacción en cadena de polimerasa. Resultados. De 1 235 aislados, 207 (16,8%) mostraron resistencia a cefalosporinas de terceray cuarta generación o a carbapenemes o a ambos. De esos, 93,8% presentaron fenotipo betalactamasa de espectro extendido (BLEE); 4,3%, fenotipo AmpC derreprimido, y 1,9%, fenotipocarbapenemasa. La caracterización de los dos primeros fenotipos determinó que 36,7% eran tipo SHV; 22,3%, grupo CTX-M-1; 21,7%, tipo TEM; 5,2%, grupo CTX-M-1 + impermeabilidad; 4,5%, combinación de dos enzimas; 4,3%, grupo CTX-M-2; 3,4%, tipo PER, y 1,9%, tipo KPC.Se observó un predominio del tipo SHV en las cepas obtenidas de hospitales públicos y del grupo CTX-M-1, en los privados. Conclusiones. De los mecanismos enzimáticos investigados, el tipo SHV fue el más frecuente,seguido del grupo CTX-M-1 y tipo TEM. Asimismo, se encontró un alto porcentaje de carbapenemasas tipo KPC. Este es uno de los pocos estudios multicéntricos realizados enVenezuela donde se evalúa la frecuencia de este tipo de mecanismo de resistencia a los antimicrobianos,incluida la caracterización fenotípica y molecular...

Humans , beta-Lactam Resistance , Bacterial Proteins/analysis , Drug Resistance, Multiple, Bacterial , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/drug effects , beta-Lactamases/analysis , Bacterial Proteins/genetics , Cross-Sectional Studies , Carbapenems/metabolism , Carbapenems/pharmacology , Cephalosporin Resistance/genetics , Cephalosporins/metabolism , Cephalosporins/pharmacology , Cross Infection/epidemiology , Cross Infection/microbiology , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae/enzymology , Enterobacteriaceae/genetics , Genes, Bacterial , Genotype , Hospitals, Urban/statistics & numerical data , Microbial Sensitivity Tests , Phenotype , Substrate Specificity , Venezuela/epidemiology , beta-Lactam Resistance/genetics , beta-Lactamases/classification , beta-Lactamases/genetics , beta-Lactamases/metabolism
Yonsei Medical Journal ; : 53-57, 2008.
Article in English | WPRIM | ID: wpr-98882


PURPOSE: Coexistence of different classes of beta-lactamases in a single bacterial isolate may pose diagnostic and therapeutic challenges. We investigated a spread of Klebsiella pneumoniae isolates co-producing an AmpC beta-lactamase and an extended-spectrum beta-lactamase (ESBL) in a university hospital. MATERIALS AND METHODS: Over a three-month period, a total of 11 K. pneumoniae isolates, which exhibited resistance to cefotaxime, aztreonam, and cefoxitin, were isolated. These isolates showed positive to ESBLs by double disk tests. Minimal inhibitory concentrations (MICs) were determined by broth microdilution testing. All isolates were examined by isoelectric focusing, PCR and sequence analysis to identify bla(SHV) and bla(DHA), and molecular typing by pulsed-field gel electrophoresis (PFGE). RESULTS: All 11 isolates were highly resistant (MIC, > or = 128microngram/ml) to ceftazidime, aztreonam, and cefoxitin, while they were susceptible (MIC, < or = 2microngram/ml) to imipenem. The bla(SHV-12) and bla(DHA-1) genes were detected by PCR and sequence analysis. PFGE revealed a similar pattern in 10 of the 11 strains tested. CONCLUSION: This is the first outbreak report of K. pneumoniae in Korea which co-produced SHV-12 and DHA-1 beta-lactamase, and we suggest a clonal spread of multidrug-resistant K. pneumoniae at a hospital.

Adult , Aged , Aged, 80 and over , Disease Outbreaks , Disease Susceptibility , Drug Resistance, Multiple, Bacterial , Female , Genotype , Hospitals , Humans , Klebsiella Infections/epidemiology , Klebsiella pneumoniae/classification , Korea , Male , Middle Aged , Phenotype , beta-Lactamases/classification
Article in Korean | WPRIM | ID: wpr-49540


BACKGROUND: The aim of this study was to compare the BD Phoenix (Beckton Dickinson Diagnostic Systems, USA) extended-spectrum beta-lactamase (ESBL) test with the Clinical and Laboratory Standards Institute (CLSI) ESBL phenotypic confirmatory test by disk diffusion (CLSI ESBL test) in Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis. METHODS: We tested 224 clinical isolates of E. coli, K. pneumoniae, K. oxytoca and P. mirabilis during May 2006 to March 2007. These isolates were examined by the Phoenix and the CLSI ESBL tests simultaneously. For the isolates showing discordant results between the two tests, boronic acid disk test was performed to differentiate AmpC beta-lactamase and ESBL. RESULTS: Among the 224 clinical isolates, 75 and 79 isolates were positive for ESBL by CLSI ESBL test and Phoenix test, respectively. Having detected 4 more isolates as ESBL-producers, Phoenix test showed a 98.2% agreement with a 100% sensitivity and 97.3% specificity compared with CLSI ESBL test. Among the four false positive isolates, three were AmpC-positive but ESBL-negative. CONCLUSIONS: The BD Phoenix ESBL test was sensitive and specific, and can be used as a rapid and reliable method to detect ESBL production in E. coli, Klebsiella species, and P. mirabilis.

Automation , Bacterial Proteins/classification , Disk Diffusion Antimicrobial Tests , Escherichia coli/drug effects , Humans , Klebsiella/enzymology , Klebsiella oxytoca/drug effects , Klebsiella pneumoniae/drug effects , Microbial Sensitivity Tests , Proteus mirabilis/drug effects , Reagent Kits, Diagnostic , Sensitivity and Specificity , beta-Lactamases/classification
Salud pública Méx ; 49(6): 415-421, nov.-dic. 2007. ilus, tab
Article in English | LILACS | ID: lil-470752


OBJECTIVE: In this work we report the molecular characterization of beta-lactam antibiotics resistance conferred by genes contained in plasmids from enterobacteria producing extended-spectrum beta-lactamases (ESBL). MATERIAL AND METHODS: Fourteen enterobacterial clinical isolates selected from a group of strains obtained from seven different hospitals in Mexico during 1990-1992 and 1996-1998 were analyzed at the Bacterial Resistance Laboratory (National Institute Public Health, Cuernavaca). Molecular characterization included PFGE, IEF of beta-lactamases, bacterial conjugation, PCR amplification and DNA sequencing, plasmid extraction and restriction. RESULTS: Isolates were genetically unrelated. ESBL identified were SHV-2 (5/14) and SHV-5 (9/14) type. Cephalosporin-resistance was transferable in 9 of 14 (64 percent) clinical isolates with only one conjugative plasmid, DNA finger printing showed a similar band pattern in plasmids. CONCLUSIONS: The dissemination of cephalosporin resistance was due to related plasmids carrying the ESBL genes.

OBJETIVO: En este trabajo se reporta la caracterización molecular de la resistencia a antibiótico beta-lactámicos conferida por genes contenidos en plásmidos de enterobacterias productoras de beta-lactamasas de espectro extendido (BLEEs). MATERIAL Y MÉTODOS: Catorce aislamientos clínicos de enterobacterias fueron seleccionados por conveniencia de un banco de cepas obtenidas de siete diferentes hospitales de México durante los periodos 1990-1992 y 1996-1998 y fueron procesados en el Laboratorio de Resistencia Bacteriana (Instituto Nacional de Salud Pública, Cuernavaca). En la caracterización se empleó PFGE, IEF para beta-lactamasas, conjugación bacteriana, amplificación por PCR y secuenciación de DNA, extracción y restricción de plásmidos. RESULTADOS: Las 14 cepas fueron no relacionadas genéticamente. Se identificaron BLEEs tipo SHV-2 (5/14) y SHV-5 (9/14). La resistencia a cefalosporinas fue transferida por conjugación en 9 de 14 (64 por ciento) aislamientos clínicos mediante un plásmido que mostró un patrón de restricción similar entre ellos. CONCLUSIÓN: Se sugiere que la diseminación de la resistencia a cefalosporinas fue debida a plásmidos relacionados que contienen los genes que codifican BLEEs.

Humans , Bacterial Proteins/genetics , Cross Infection/microbiology , Drug Resistance, Multiple, Bacterial/genetics , Escherichia coli Infections/microbiology , Escherichia coli/enzymology , Klebsiella Infections/microbiology , Klebsiella/enzymology , R Factors/genetics , beta-Lactam Resistance/genetics , beta-Lactamases/genetics , Bacterial Proteins/classification , Bacterial Proteins/isolation & purification , Cross Infection/epidemiology , DNA Fingerprinting , DNA, Bacterial/genetics , Escherichia coli Infections/epidemiology , Escherichia coli Proteins/classification , Escherichia coli Proteins/genetics , Escherichia coli Proteins/isolation & purification , Escherichia coli/drug effects , Escherichia coli/genetics , Klebsiella Infections/epidemiology , Klebsiella/drug effects , Klebsiella/genetics , Mexico/epidemiology , beta-Lactamases/classification , beta-Lactamases/isolation & purification
Rev. Hosp. Clin. Univ. Chile ; 16(2): 101-106, 2005. tab
Article in Spanish | LILACS | ID: lil-445734


Las Betalactamasas de espectro extendido (BLEE) son enzimas de configuración plasmídica producidas por bacterias que hidrolizan los antibióticos betalactámicos. La aparición de cepas bacterianas productoras de BLEE, constituye un problema de salud pública que afecta a todo tipo de instituciones y a la comunidad en general. Este estudio tiene como objetivo determinar las incidencia de BLEE en pacientes hospitalizados del Hospital Clínico de la Universidad de Chile. Se estudió un total de 238 cepas en el periodo julio-agosto 2004; de las cuales 184 correspondieron a de E. coli, 39 a K. pneumoniae y 15 a K. oxytoca, utilizándose el test confirmatorio de BLEE según estándar NCCLS 2004. Se encontró una incidencia de BLEE para E. coli de un 10.3 por ciento, para K. pneumoniae de 28.2 por ciento y de K. oxytoca de 20 por ciento, respectivamente. La distribución de los aislamientos de las cepas BLEE (+) en los distintos servicios del Hospital fue diversa: E. coli se encontró principalmente, en los servicios de medicina y cirugía, y K. pneumoniae en los servicios críticos. Los resultados del estudio permitieron conocer la incidencia y distribución de BLEEs en el Hospital Clínico de la Universidad de Chile y justificaron la implementación de esta técnica de diagnóstico como parte de la rutina del laboratorio de microbiología.

Humans , beta-Lactamases/isolation & purification , beta-Lactamases/analysis , Chile , Escherichia coli/isolation & purification , Enterobacteriaceae Infections/epidemiology , Klebsiella oxytoca/isolation & purification , Klebsiella pneumoniae/isolation & purification , beta-Lactamases/classification , beta-Lactamases/standards , beta-Lactamases/supply & distribution