Extended-spectrum beta-lactamase (ESBL)-producing isolates of Klebsiella pneumoniae have been increasingly recognized in the hospital settings in Iran as well as throughout the world. The aim of this study was to detect and determine the genes encoding the ESBLs including bla(TEM), bla(SHV), and bla(CTX-M) groups among the K. pneumoniae isolates at Labbafinejad Hospital by polymerase chain reaction (PCR) and characterize them by direct sequencing of PCR products. Eighty-nine isolates were isolated from patients at different wards during March 2008-March 2009. They were identified as K. pneumoniae using biochemical tests. Susceptibility of isolates to 17 different antimicrobial agents was determined using agar disk diffusion method. The phenotypic confirmatory test was used to screen the isolates for production of ESBLs. To amplify the bla(SHV) the template DNA was extracted by boiling method. Plasmid DNA was extracted using minipreparation kit and used as template in PCR for detection of bla(TEM) and bla(CTX-M). The selected PCR products were sequenced and analyzed. All 89 strains were susceptible to imipenem. The rates of resistance to different antibiotics were in the following order: aztronam (79.7%), cefexime (67.4%), cefpodoxime (66.2%), cefotaxime (65.1%), ceftazidime (61.7%). The phenotypic confirmatory test detected 62 isolates (69.7%) as ESBL-producing K. pneumoniae. The prevalence of genes encoding ESBLs were as follows: bla(TEM) 54% (n = 48), bla(SHV) 67.4% (n = 60), bla(CTX-M-I) 46.51% (n = 40), and bla(CTX-M-III) 29% (n = 25). The bla(CTX-M-II) and bla(CTX-M-IV) were not detected. All bla(TEM) types were characterized as bla(TEM-1) and all bla(CTX-M-I) were identified as bla(CTX-M-15). The SHV types were characterized as SHV-5, SHV-11, and SHV-12. The rate of ESBL at Labbafinejad Hospital was 25% increase in a 4-year study that ended in March 2009. It appears that bla(TEM-1), bla(SHV-5), bla(SHV-11), bla(SHV-12), and bla(CTX-M-15) are the dominant ESBLs among the resistant strains of K. pneumoniae in Iran.

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Background: Klebseilla pneumoniae causes urinary tract infections, nosocomial pneumonia and intra-abdominal infections. Capsular antigens are considered to be the ultimate virulence determinants. Among 77 capsular serotypes of K. pneumoniae, serotypes K1 and K2 are the most virulent ones in humans. Objectives: We designed a PCR method for detection of capsular serotypes K1 and K2 of K. pneumoniae using genes cps cluster wzc and orf10 which are required for biosynthesis of capsular polysaccharides in K1 and K2 types, respectively. Materials and Methods: We collected 89 K. pneumoniae clinical isolates from the patients of Labafinejad Hospital located in Tehran. Clinical isolates were mostly chosen from urine. We used PCR technique to detect isolates possessing K1 and K2 capsular polysaccharides based on the wzc and orf10 genes which are required for biosynthesis of capsular polysaccharide in K1 and K2 types, respectively. The results of PCR were compared with those obtained by capsular serotyping using Quellung test. Results: Of 89 isolates of K. pneumoniae tested by both techniques, 10 (11.2%) belonged to K1 and 13 (14.6%) belonged to K2 serotypes, respectively. Conclusions: We found that these serotypes are probably important in clinical specimens. PCR was a simple and inexpensive tool for identification of K. pneumoniae clinical isolates of K1 and K2 geno-serotypes.