Identification of bla-CTX-M β-lactamase in Klebsiella pnumoniae clinical isolates by polymerase chain reaction

The incidence of extended-spectrum β- lactamase- producing bacteria has been increased worldwide. The most common cause of resistance to extended-Spectrum cephalosporins in Klebsiella pneumoniae is the production of extended-spectrum beta lactamases (ESBLs). In the past decade، CTX-M enzymes have become the most prevalent ESBLs in Europe، Canada and Asia. The aim of this study was to find the prevalence of ESBL-producing K. pneumoniae and molecular detection of CTX-M group in these bacteria. In the descriptive study، 100 K. pneumoniae isolates were detected by standard biochemical tests between April 2012 and September 2012، in Besat and Imam Reza hospitals of Tehran، Iran. Susceptibility to antimicrobial agents was tested for 10 antibiotics by the disk agar diffusion (DAD) method. Also، ESBL production was screened by combined disk diffusionas recommended by the Clinical and Laboratory Standards Institute (CLSI). Then، Screened isolates were assayed by PCR for detection of CTX-M-1 group genes. Of 100 K. pneumonia isolates، 26 isolates produced ESBLs، and also 42 isolates were CTX-M-1 producer using PCR method. According to the differences between the results of phenotypic and genotypic tests، it seems that molecular detection of drug-resistance genes is necessary. Further investigations are needed to determine the epidemiology of ESBL producing K. pneumoniae in Iran.