Characterization of AmpC, CTX-M and MBLs types of β-lactamases in clinical isolates of Klebsiella pneumoniae and Escherichia coli producing Extended Spectrum β-lactamases in Kerman, Iran

BACKGROUND Extended spectrum β-lactamases (ESBLs) and AmpC β-lactamases enzyme are major sources of resistance to β-lactam antibiotics especially in Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae. Increasing frequency of the co-existence of ESBLs with AmpC-β-lactamases in bacteria is a serious threat for treating bacterial infections. OBJECTIVES The aim of this study was to determine the presence of AmpC and CTX-M types of β-lactamases in clinical isolates of E. coli and K. pneumoniae producing ESBLs. MATERIALS AND METHODS Resistance to different antibiotics was determined using the standard disk diffusion method. ESBLs, MBLs and AmpC-β-lactamases were detected by the combination double disk test (CDDT) method and polymerase chain reaction (PCR) was used to determine bla CTX -M genes in the ESBLs and AmpC positive isolates. RESULTS The prevalence of ESBLs and AmpC-β-lactamase producer isolates was 181 (43.8%) and 133 (37.2%), respectively. The prevalence of bla CTX -M among isolates was 61 (14.7%). CONCLUSIONS Outbreak of isolates co-expressing AmpC-β-lactamases and ESBLs can cause serious problems in the future, regarding the treatment of infections caused by these common enteric pathogens.