oa Molecular Diagnosis and Vaccines - Phenotypic and genotypic study of extended spectrum b-Lactamase producing isolates in nosocomial urinary tract infection
Extended spectrum ?-lactamase (ES?L) producing organisms are a problem in hospitalized patients suffering from nosocomial infections (UTI). Urinary tract infection is the most frequent nosocomial infection and catheterization is the most frequent risk factor. To study bacterial causes of nosocomial UTI, role of ES?L producing organisms and association between ES?L production and plasmid content of these organisms, we studied 70 catheterized patients (45 males and 25 females). Urine samples were cultivated on selective media with subsequent antimicrobial susceptibility tests for isolates. Screening for ES?L producing organisms was done using the modified three-dimensional method, E-test, disc diffusion method and plasmid profile analysis. Catheter associated infection was found in 42 (60%) cases, and was more prevalence among males than females. Infection was common among those with long catheter duration and hospital stay. Candida was the commonest organism causing infection followed by gram negative bacilli and Staph. aureus. The most effective antibiotics were Ceftazidime, Tobramycin, Amikacin, Cefotaxime and Vancomycin against E. coli, P. mirabilis, Ps. aeruginosa, K. pneumoniae and Staph aureus respectively. Among the infected cases, extended spectrum ? lactamase activity was present in 13 isolates (31%), and included E. coli (20%), P. mirabilis (30%) and Ps. aeruginosa (16.7%). Good agreement was found between the E. test and the three-dimensional method for detection of ES?Ls. Plasmids of different molecular weights were detected in 61.5% of ES?Ls. There was no particular association between plasmid content and ES?L activity in Proteus mirabilis and Pseudomonas aeruginosa isolates.
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