Dissemination of CTX-M-15 β-lactamase genes carried on inc FI and FII plasmids among clinical isolates of escherichia coli in a university hospital in Istanbul, Turkey

The CTX-M-1 group was found in 86.8% of the Escherichia coli isolates from Istanbul. A subset study revealed all isolates carrying blaCTX-M-15 genes flanked by the insertion element ISEcp1. Plasmid typing of transconjugates carrying blaCTX-M-15 showed that most isolates belonged to the Inc/rep FII group but that one isolate also belonged to the FI group

Investigation of metallo-beta-lactamase producing strains of Pseudomonas aeruginosa and Acinetobacter baumannii by E-test, disk synergy and PCR

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 blaIMP/VIM related genes or imipenemase activity were detected although E-test found all strains as MBL-positive. Disk synergy tests with 0.5M EDTA determined 63.6-100%, while those with 0.1M 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, 0.1M EDTA seems to be acceptable

Molecular characterization of Salmonella Typhimurium and Salmonella Enteritidis by plasmid analysis and pulsed-field gel electrophoresis

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 Salmonella enterica 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. (C) 2007 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved

Carbapenem-hydrolyzing oxacillinase, OXA-48, persists in Klebsiella pneumoniae in Istanbul, Turkey

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. Copyright (c) 2008 S. Karger AG, Basel

Resistance to newer beta-Lactams and related ESBL types in gram-negative nosocomial isolates in Turkish hospitals: Results of the multicentre HITIT study

Aktas, Zerrin/0000-0002-5998-0440; Ogunc, Dilara/0000-0001-6669-6811; ERAC, BAYRI/0000-0002-6343-2519WOS: 000260856700001PubMed: 19149074Increasing resistance due to extended-spectrum beta-lactamases (ESBLs) and multiple resistance mechanisms in gram-negative hospital isolates restrict the role of R-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 baumannii (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 R-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

Dissemination of CTX-M-15 beta-lactamase genes carried on inc FI and FII plasmids among clinical isolates of Escherichia coli in a university hospital in Istanbul, Turkey

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 blaCTX-M-15 showed that most isolates belonged to the Inc/rep FII group but that one isolate also belonged to the FI group

Dissemination of CTX-M-15 β-Lactamase Genes Carried on Inc FI and FII Plasmids among Clinical Isolates of Escherichia coli in a University Hospital in Istanbul, Turkey▿

The CTX-M-1 group was found in 86.8% of the Escherichia coli isolates from Istanbul. A subset study revealed all isolates carrying blaCTX-M-15 genes flanked by the insertion element ISEcp1. Plasmid typing of transconjugates carrying blaCTX-M-15 showed that most isolates belonged to the Inc/rep FII group but that one isolate also belonged to the FI group

VANCOMYCIN-RESISTANT ENTEROCOCCUS FAECIUM INFECTIONS ON PEDIATRIC WARDS

Nosocomial infections with vancomycin-resistant enterococci (VRE) have been reported with increasing frequency in recent years, and are associated with an increase in mortality. Isolates of VRE were first detected in our hospital between September 2006 and January 2007. In this study, we analyzed the phenotypic and genotypic characteristics underlying that resistance and clonal relationships amongst VRE isolated from six patients at pediatric wards. All isolates were identified as Enterococcus faecium and showed resistance to both vancomycin and teicoplanin by disk diffusion and E-test methods. The resistance patterns fbr other anti-microbials were similar, indicating that the isolates might belong to the same clone. The genes responsible for resistance were identified in the isolates by multiplex polymerase chain reaction (PCR). Four isolates from patients on the same pediatric ward showed the same random amplification of polymorphic DNA (RAPD) pattern, suggesting clonal dissemination of a single strain

RESISTANCE TO NEWER BETA-LACTAMS AND RELATED ESBL TYPES IN GRAM-NEGATIVE NOSOCOMIAL ISOLATES IN TURKISH HOSPITALS: RESULTS OF THE MULTICENTRE HITIT STUDY

Increasing resistance due to extended-spectrum beta-lactamases (ESBLs) and multiple resistance mechanisms in gram-negative hospital isolates restrict the role of R-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 baumannii (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 R-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