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.

Oxacillin resistance was present in 99 of 277 (36%) consecutive Staphylococcus aureus isolates collected from hospital patients in Tehran during a 15-month period (January 2004-March 2005). The majority of isolates (77/99 = 78%) had been cultured from wounds or blood. The staphylococcal cassette chromosome mec (SCCmec) types and antimicrobial susceptibility patterns of 99 methicillin-resistant S. aureus (MRSA) strains were determined. Disk diffusion and agar dilution methods were used to determine the susceptibility of isolates to antimicrobial agents as instructed by Clinical and Laboratory Standards Institute. The presence of mecA and SCCmec types was determined by PCR and multiplex PCR. All MRSA isolates were susceptible to vancomycin (MIC90

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Objective: The objective of the study was to investigate the prevalence of vancomycin-resistant Staphylococcus aureus (VRSA). Materials and Methods: Three hundred and fifty-six S. aureus isolates from the Imam Khomeini hospital in Tehran, Iran, were evaluated for methicillin and decreased vancomycin susceptibility by the microbroth dilution method. The mecA, vanAand vanB genes were targeted by polymerase chain reaction. Results: Of the 356 isolates, 149 (41.85%) S. aureus strains were resistant to methicillin. Two strains of methicillin-resistant S. aureus were VRSA strains. One isolate, Teaching Hospital-1 (TEH-1), had a vancomycin minimum inhibitory concentration (MIC) of 64 µg/ml and was susceptible to teicoplanin while the other isolate (TEH-2) had a vancomycin and teicoplanin MIC of 512 and >256 µg/ml, respectively, and was positive for the vanA gene. Conclusion: This report shows that the emergence of VRSA in Iran warrants active microbiological surveillance and careful monitoring of vancomycin therapy.

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Diarrhoea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. To investigate the incidence, antimicrobial resistance and genetic relationships of enteropathogenic Escherichia coli (EPEC) in children with diarrhoea, a total of 612 stool specimens were collected in Tehran, Iran, and cultured to isolate strains of EPEC. The disc diffusion method was used to determine the susceptibility of the isolates according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of eae, stx and bfp-A genes was determined by PCR. The genetic relationships between EPEC isolates were determined by pulsed-field gel electrophoresis (PFGE). Out of the 412 strains of E. coli obtained from 612 diarrhoeal stool specimens, 23 (5.6 %) were identified as EPEC, of which seven (30.4 %) were classified as typical strains of EPEC and 16 (69.6 %) were classified as atypical. Out of the 23 EPEC isolates, 69.5 % were resistant to ampicillin, 39.1 % were resistant to tetracycline and cotrimoxazole, 30.4 % were resistant to cefpodoxime, ceftazidime, ceftriaxone and aztreonam, and 26.1 % were resistant to imipenem. The isolates were classified into 21 pulsotypes by PFGE profiles. The present study shows that typical and atypical EPEC isolates displayed considerable heterogeneity in PFGE profiles and EPEC infections were only sporadic in Tehran. Overall 69 % of isolates were resistant to at least one of the antibiotics tested. INTRODUCTIONEnteropathogenic Escherichia coli (EPEC) is one of the major causes of diarrhoea among children in developing countries (Hernandes et al., 2009;Moura et al., 2009). The pathogenesis of EPEC depends on the locus of enterocyte effacement (LEE), a chromosomal pathogenicity island. The LEE contains a number of different genes, including eae, which has an essential role in inducing a characteristic lesion formation in the intestinal epithelium, termed an attaching and effacing (A/E) lesion (Elliott et al., 1998;Vallance & Finlay 2000;Kaper et al., 2004). The eae gene encodes intimin, a 94 kDa outer-membrane protein that is responsible for the intimate adherence between bacterial and enterocyte membranes (Vallance & Finlay, 2000;Trabulsi et al., 2002). EPEC strains are classified as typical or atypical, according to the presence or absence of the E. coli adherence factor plasmid (EAF) that carries the bfpA gene, which encodes the bundle-forming pili (Hernandes et al., 2009). The most typical EPEC strains belong to the classic O : H serotypes and are eae-and bfpA-positive (Ochoa et al., 2008). The atypical EPEC isolates are eaepositive and bfpA-and stx (the gene encoding shiga-like toxin)-negative. EPEC are among the most important pathogens infecting children under 2 years of age in the developing world (Ochoa et al., 2008). Recent studies indicate that atypical EPEC is more prevalent than typical Abbreviations: EPEC, enteropathogenic Escherichia coli; LEE, locus of enterocyte effacement; PFGE, pulsed-field gel electrophore...

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