Background: There are numerous types of extended spectrum &beta-lactamase, such as TEM and SHV, are predominant among Klebsiella strains. The aim of this study was to determine the frequency of TEM and SHV in the extended-spectrum beta-lactamase producing Klebsiella isolate from urinary tract infections in Karaj city.

Materials and methods: Totally, 100 isolates of Klebsiella were collected from some hospitals and clinical laboratories in Karaj city. Isolates were screened for ESBLs production by phenotypic confirmatory test (PCT). Extracted DNA samples were analyzed using specific primers for SHV and TEM genes by PCR method.

Results: By disk diffusion test, resistance to ceftazidime and cefotaxime were observed in 24% of the isolates. The phenotypic confirmatory test (PCT) detected 25 isolates (25%) as ESBL producers. Of them, 23 (92%) were Klebsiella pneumoniae and 2 isolate (8%) were Klebsiella oxytoca. The frequency of bla_TEM and bla_SHV among these isolates was 80% (n=20) and 88% (n=22), respectively.

Conclusion: SHV is the dominant enzyme among the ESBL-producing strains of Klebsiella. The high rate of resistance to ceftazidime, cefotaxime and ceftriaxone in strain that harbored bla_TEM and bla_SHV genes, is a matter of concern and treatment requires further attention to the results of susceptibility tests.

Keywords: Klebsiella, Antibiotic resistance, UTI, ESBLs, TEM, SHV.