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.