RESUMEN
The CTX-M-1 group was found in 86.8% of the Escherichia coli isolates from Istanbul. A subset study revealed all isolates carrying bla(CTX-M-15) genes flanked by the insertion element ISEcp1. Plasmid typing of transconjugates carrying bla(CTX-M-15) showed that most isolates belonged to the Inc/rep FII group but that one isolate also belonged to the FI group.
Asunto(s)
Conjugación Genética , Escherichia coli/enzimología , Factor F/genética , Hospitales Universitarios , Plásmidos/genética , beta-Lactamasas/genética , Antibacterianos/farmacología , Cefotaxima/farmacología , Ceftazidima/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/microbiología , Proteínas de Escherichia coli/genética , Humanos , Pruebas de Sensibilidad Microbiana , Reacción en Cadena de la Polimerasa , Prevalencia , Técnica del ADN Polimorfo Amplificado Aleatorio , Turquía/epidemiología , Resistencia betalactámicaRESUMEN
BACKGROUND: Two OXA-48-producing Klebsiella pneumoniae isolates (KP-4936 and KP-154488) were analyzed. METHOD: Minimum inhibitory concentrations were determined using agar dilution and E-test, beta-lactamase production by phenotypic tests (E-test MBL and ESBL, isoelectric focusing, and bioassay) and molecular methods (PCR, RAPD-PCR, sequencing, plasmid analysis, and conjugation). RESULTS: Isolates were resistant to all beta-lactams, including carbapenems. PCR and sequencing identified bla(OXA-48) in both isolates and the transconjugant. KP-4936 harbored bla(TEM-1) (pI 5.4) and bla(CTX-M-15) genes (pI 8.6), while KP-154488 was positive for bla(TEM-1) (pI 5.4), bla(CTX-M-15) (pI 8.9), and bla(SHV2a) (pI 7.6), in addition. The enzyme with a pI of 7.2 hydrolyzed imipenem according to a bioassay result. Plasmids (70 and 140 kb) from KP-4936 were transferred by conjugation. RAPD-PCR found no clonal relationship between the two strains. CONCLUSION: Carbapenem resistance may spread among Enterobacteriaceae via the transferable enzyme OXA-48.
Asunto(s)
Carbapenémicos/farmacología , Klebsiella pneumoniae/enzimología , Resistencia betalactámica/efectos de los fármacos , Resistencia betalactámica/genética , beta-Lactamasas/química , Carbapenémicos/uso terapéutico , Humanos , Hidrólisis , Infecciones por Klebsiella/tratamiento farmacológico , Infecciones por Klebsiella/enzimología , Infecciones por Klebsiella/epidemiología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/aislamiento & purificación , Turquía/epidemiología , beta-Lactamasas/biosíntesisRESUMEN
Increasing resistance due to extended-spectrum beta-lactamases (ESBLs) and multiple resistance mechanisms in gram-negative hospital isolates restrict the role of beta-lactam antibiotics in empirical treatment of serious infections. As the prevalence of ESBL producing strains and resistance rates to antimicrobial agents can vary in each center, local surveillance studies are required to guide therapy. In this study, in vitro rates of resistance to ceftriaxone, ceftazidime, cefepime, imipenem, cefoperazone/sulbactam and piperacillin/tazobactam were evaluated in 1196 gram-negative hospital isolates in a multicenter in vitro study with the participation of six different centers in Turkey between the period of June 2004-January 2005. The isolates included Escherichia coli (n= 457), Klebsiella pneumoniae (n= 390), Pseudomonas aeruginosa (n= 194) and Acinetobacter boumannii (n= 155). In addition, frequency of ESBL production and types of enzymes were determined in blood isolates of E. coli and K. pneumoniae. MICs and ESBL production were investigated by E-test (AB Biodisk, Solna) and the results were evaluated by using CLSI breakpoints. PCR analysis was used for typing of the ESBLs. In E. coli, 26% and in K. pneumoniae 32% of the isolates were ESBL producers. Among the blood isolates of E. coli and K. pneumoniae, 31.7% and 33.3% produced ESBLs, respectively. CTX-M (71.4%) was the most prevalent enzyme, followed by TEM (49.4%) and SHV (46.7%) derived enzymes. CTX-M-15 (69.4%) was the most frequent CTX-M type in blood isolates followed by CTX-M-3 (28.6%) and CTX-M-1 (2%). Resistance to imipenem was not observed in E. coli isolates, however it was 1.3% in K. pneumoniae, 28.9% in P. aeruginosa and 52.2% in A. baumannii strains. Resistance to cefoperazone/sulbactam was found as 6%, 17.7%, 27.9% and 41.3% in E. coli, K. pneumoniae, P. aeruginosa and A. baumannii isolates, respectively, whereas resistance rates to piperacillin/tazobactam were 10.2%, 22.3%, 22.7% and 78.7%, respectively. These results indicate that ESBL production and rates of resistance to beta-lactam antibiotics are high in hospital isolates of gram-negative bacteria in Turkey, however, they show variations in different hospitals and CTX-M enzymes are prevalent in these isolates.
Asunto(s)
Antibacterianos/farmacología , Infección Hospitalaria/microbiología , Bacterias Gramnegativas/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/microbiología , beta-Lactamasas/metabolismo , Acinetobacter baumannii/efectos de los fármacos , Bacteriemia/tratamiento farmacológico , Bacteriemia/microbiología , Infección Hospitalaria/tratamiento farmacológico , Farmacorresistencia Bacteriana Múltiple , Escherichia coli/efectos de los fármacos , Bacterias Gramnegativas/enzimología , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Humanos , Klebsiella pneumoniae/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , TurquíaRESUMEN
Forty-one paediatric isolates of Salmonella spp. from Cerrahpasa Faculty of Medicine, Istanbul, Turkey, between 2001 and 2004 were examined for susceptibility to various antibiotics and presence of antibiotic resistance genes. Pulsed-field gel electrophoresis and plasmid profiling were used to determine possible genetic relationships among Salmonellaenterica subsp. enterica clinical isolates. Plasmids from resistant strains were not transferred by conjugation to recipient Escherichia coli cells. Pulsed-field gel electrophoresis and restriction enzyme digestion analysis of DNA revealed that multidrug-resistant isolates belonged to the same clonal group, characterized by ACSSuT resistotype. Isolates of R-type ACSSuT were positive for the intI gene and possessed a single plasmid of 60 MDa.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Electroforesis en Gel de Campo Pulsado/métodos , Plásmidos/genética , Infecciones por Salmonella/epidemiología , Salmonella enteritidis/clasificación , Salmonella typhimurium/clasificación , Técnicas de Tipificación Bacteriana , Niño , ADN Bacteriano/análisis , Humanos , Pruebas de Sensibilidad Microbiana , Reacción en Cadena de la Polimerasa/métodos , Infecciones por Salmonella/microbiología , Salmonella enteritidis/efectos de los fármacos , Salmonella enteritidis/genética , Salmonella enteritidis/aislamiento & purificación , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/genética , Salmonella typhimurium/aislamiento & purificación , Serotipificación , Turquía/epidemiologíaRESUMEN
The purpose of this study was to investigate the prevalence and genetic mechanisms of erythromycin resistance in staphylococci. A total of 102 erythromycin resistant non-duplicate clinical isolates of staphylococci [78 coagulase negative stapylococci (CNS), 24 Staphylococcus aureus] were collected between October 2003 and August 2004 in Istanbul Faculty of Medicine in Turkey. The majority of the isolates were from blood and urine specimens. Antimicrobial susceptibilities were determined by the agar dilution procedure and the resistance phenotypes by the double disk induction test. A multiplex PCR was performed, using primers specific for erm(A), erm(B), erm(C), and msrA genes. Among the 78 CNS isolates, 57.8% expressed the MLSB-constitutive, 20.6% the MLSB-inducible, and 21.6% the MSB phenotypes. By PCR, 78.2% of these isolates harbored the erm(C) gene, 8.9% erm(A), 6.4% erm(B), and 11.5% msrA genes. In S. aureus, the constitutive MLSB (58.3%) was more common than the inducible phenotype (20.8%). erm(A) was detected in 50% and erm(C) in 62.5% of the isolates, while 37.5% contained both erm(A) and erm(C). erm(C)-associated macrolide resistance was the most prevalent in CNS, while erm(C) and erm(A, C) was the most prevalent in S. aureus.
Asunto(s)
Macrólidos/farmacología , Staphylococcus/efectos de los fármacos , Estreptograminas/farmacología , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/genética , Genes Bacterianos , Humanos , Lincosamidas , Pruebas de Sensibilidad Microbiana , Infecciones Estafilocócicas/microbiología , Staphylococcus/genética , Staphylococcus/aislamiento & purificación , TurquíaRESUMEN
Carbapenem non-susceptible Pseudomonas aeruginosa and Acinetobacter baumannii strains were tested for the presence of metallo-beta-lactamases (MBLs) by EDTA-synergy screening. Imipenem hydrolysis was investigated by a bioassay and IMP-/VIM-encoding genes by PCR. No bla(IMP/VIM) related genes or imipenemase activity were detected although E-test found all strains as MBL-positive. Disk synergy tests with 0.5 M EDTA determined 63.6-100%, while those with 0.1 M EDTA detected 0-7.7% of isolates as MBL producers. Most strains were susceptible to EDTA. In conclusion, for MBL-screening purposes, EDTA-synergy results change with molarity of EDTA, but even if some false positives are encountered, 0.1 M EDTA seems to be acceptable.