frequency of extended spectrum beta lactamase and CTX M-I of Escherichia coli isolated from the urine tract infection of patients by phenotypic and PCR methods in the city of Khoy in Iran

The production of Extended Spectrum Beta Lactamases [ESBLs] by Escherichia coli is the main cause of resistance to Cephalosporins. In the past decade, CTX-M enzymes have become the most prevalent ESBLs in Europe, Canada, and Asia. In this study, the frequency of ESBL- producing E.coli and molecular detection of the CTX-M-I group was investigated. A total of 400 urine samples were collected from both hospitalized and out-patients in Khoy's hospitals between November 2009 and April 2010. Out of these samples, 188 were identified as E.coli by standard biochemical tests. The antibiotic Susceptibility tests to 10 antibiotics were performed by the-disk-agar diffusion [DAD] method. ESBL production was screened by phenotypic test that including disk diffusion agar and combined disk as recommended by the Clinical and Laboratory Standards Institute [CLSI] Screened isolates were investigated by PCR assay for detection of CTX-M-I group genes. The results show that out of 188 E.coli isolates identified, 56 [29.8%] were producing ESBls by phenotypic test. All isolates were sensitive to imipenem. Overall, 49 [87.5%] isolates were confirmed as CTX-M-I producer by PCR. The results of this study showed that about 30% of the identified E.coli were producing ESBL Therefore, we recommend to use molecular methods in such researches

[Synergistic effect polymyxin B sulphate and trimethoprim on yersinia enterocolotica and closely related species]

Previous studies have shown that polymyxin B sulfate and trimthoprim antibiotics are not individually effective on Yersinia enterocolitica and their closely related species. The aim of this study was to evaluate the synergistic effect of above antibiotics on Y. enterocolitica and their closely related species, from the clinical and the natural environment specimen collected in Iran, and compare them with the isolates that that were obtained from the Pasteur institute collection in France. In total, 73 species from Iran and 25 from the Pasteur institute in France were tested. The microdilution method was used for the MIC according to the standard protocol. The synergistic effect was seen in all tested samples. However, the human species from the Pasteur institute were more sensitive than the Iranian human and the environmental species were less sensitive than clinical specimens [1.6+16 micro gr, 0.4+4 micro gr in French Samples]. The Y. enterocolitica isolates were less sensitive than the related species such as Y. intermedia, Y. fredriksenii, and Y. kristensenii. The synergistic effect polymyxin B sulfate and trimthoprim were more evident on other closely related Yersinia species Y. enterocolitica