Widely distributed and predominant CTX-M type extented spectrum ß lactamase (ESBL) in enterobacteriaceae isolates

Extended-spectrum beta-lactamase (ESBL)-producing members of the Enterobacteriaceae family are important nosocomial pathogens. CTX-M type extended-spectrum beta-lactamases (ESBLs) are now the most important cause of resistance to beta-lactam antibiotics in E. coli and are reported worldwide with increasing frequency. Dominant CTX-M genotype varies geographically. CTX-M 15 dominates in many countries including the UK and India whereas CTX-M 2 is the most common genotype in Latin America and CTX-M 9 and CTX-M -14 in Spain and the Far East.In this study; a total of 100 consecutive ESBL positive nosocomial isolates of Enterobacteriaceae collected from Afyon Kocatepe University Hospital were screened for production of ESBLs by double disk synergy test and determined the susceptibility to antibiotics. Then this results confirmed by Phoenix® (Bekton Dickinson Diagnostics) and MicroScan® (Dade Behring Inc.).Among 100 ESBL positive strains 65 were positive for CTX-M by PCR with universal primers. However when group specific primers were used 61 strains were positive for CTX-M 1 (61.0%), 1 strain was positive CTX-M 9 (1%) and 1 strain was positive for CTX-M 2 (1%). Polymerase chain reaction detected bla(CTX-M) in 50/82 (60,97%) Escherichia coli, 12/14 (85,71%) Klebsiella pneumoniae, and 1/2 (50,0 %) Citrobacter freundii isolates with the ESBL phenotype. But there was no positive isolate detected in Morganella morganii and Enterobacter cloacae. Amplicons were sequenced to determine the CTX-M types and sequences were compared to gene bank. Among CTX-M 1 positive strains sequence results showed higher homology to CTX-M 15 (31 strains), CTX-M 28 (17 strains), CTX-M 3 (9 strains), CTX-M 22 (2 strains), CTX-M 33 (2 strains), CTX-M 42 (2 strains).As a result; The most common CTX-M type was CTX-M 15, the second common CTX-M type was CTX-M 28 related among strains isolated in Afyonkarahisar Turkey. Further studies will be necessary to confirm our finding.