Prevalence of CTX-M-Type and PER Extended-Spectrum β-Lactamases Among Klebsiella spp. Isolated From Clinical Specimens in the Teaching Hospital of Kashan, Iran

BACKGROUND: Extended-spectrum β-lactamases (ESBLs) is one of the most important mechanisms of resistance to β-lactams especially among Enterobacteriaceae family including Klebsiella spp. Different types of extended-spectrum β-lactamases including CTX-M-type and PER enzymes are identified among gram negative bacteria. OBJECTIVES: The current study aimed to determine the prevalence of CTX-M-type and PER extended-spectrum β-lactamases among Klebsiella spp. isolated from clinical specimens in the teaching hospital of Kashan, Iran. PATIENTS AND METHODS: One hundred Klebsiella spp. were isolated from clinical specimens of hospitalized patients at Shahid-Beheshti hospital from December 2012 to November 2013. Disk diffusion method was used to determine the susceptibility of these isolates to 14 different antimicrobial agents; disks were purchased from MAST company (United Kingdom). The phenotypic double disk synergy confirmatory test was used to screen the isolates to produce extended-spectrum β-lactamase. DNAs of isolates were extracted using boiling method and PCR assay was used to characterize the bla(CTX-M) type and bla(PER) genes. The purified PCR products were sent to Macrogen research company (Korea) for sequencing. RESULTS: Of the total 100 Klebsiella isolates, %93 was susceptible to imipenem. Resistance to ampicillin, ceftazidime, ceftriaxone, aztreonam and cefotaxime was (92%), (67%), (65%), (64%) and (59%), respectively. The phenotypic confirmatory test (PCT) confirmed that 35% (n = 35) of the isolates were ESBL-producing Klebsiella strains. The prevalence of bla(CTX-M) type and bla(RER) genes among Klebsiella isolates were 28% (n = 28) and 9% (n = 9), respectively. CONCLUSIONS: The prevalence of ESBL-producing Klebsiella strains in Shahid-Beheshti hospital in Kashan has increased. The study concluded that there was a high prevalence of the bla(CTX-M) type gene among ESBL positive isolates.