بررسي روشهاي مختلف تايپينگ براي تشخيص و افتراق سويه هاي اشرشياكلي جداشده از موارد عفونت هاي دستگاه ادراري

The Study of Different Methods of Typing for Diagnosis and Differentiation of E.coli Strains Isolated From Urinary Tract Infections

Introduction: Urinary Tract Infections are among the most common infections of human. E.coli causes 90% of these infections. Aim: We compared various typing methods (serotyping, resistotyping and plasmid profiles analysis) as epidemiological tools for the differentiation and identification of E.coli strains isolated from UTI. Materials and Methods: In spring of 2004, 44 strains isolated in north of Iran were studied. Serotyping was performed by using a special kit and O2 antiserum produced by Razi Institute and resistotyping by Kirby & Bauer method. Plasmids were extracted by modified Birnboim & Doly method and isolates with similar plasmid profiles were digested by EcoRI. Results: 16 strains were serotyped in 4 groups which were O2, C>6, Oig and O25. Strains showed 24 different resistance patterns. The most common pattern was ampicillin/tetracycline. All isolates were sensitive to Imipenem. Four strains had no plasmid. Forty four strains showed 1-10 plasmids. All of these had a 9.9 MDa plasmid. 85% of these strains were resistant to ampicillin. Using EcoRI showed heterology in some cases. Conclusion: 06 and O2 serotypes were among the most observed serotypes, that showed, many cases of UTIs, may be produced by a limited number of E.coli strains that usually belong to special serogroups. High resistance to ampicillin/tetracycline probably was due to uncontrolled use of these antibiotics. Presence of 9.9 MDa plasmids in most strains showed that the UPEC isolates may be epidemiologically related. In this study plasmid profile distinguished more strains than did serotyping and resistotyping.