| Abstract: |
Nosocomial infections have sharply increased in the past two decades. These nosocomial infections consititute a significant problem for clinicians, the health serives and above all, the patients. These infections represent a leading cause of death and an important health care cost. The urinary tract infection is the most frequent site of nosocomial infections, accounting for approximatly 40 % of all NCls. Catheterization is the most risk factors that predipose for such UTI. This work aims to:• To diagnose the risk factors associated with catheter related infections and detecting the prevalent organisms.• Study the antimicrobial susceptibility patterns of the isolated bacteria to evaluate the efficacy of routinely used methods.• Detection of Extended spectrum B-Iactamases (ESBLs) in the isolated bacteria.• Evaluate the susceptibility patterns of ESBL positive isolates (for ceftazidime) by a commerically used E-test versus routinely used methods (disc diffusion and agar dilution methods).• Study the association between ESBL producing organismsand their plasm ids by plasmid profile techinque.This study was carried out on 348 catheterized patients from different hospital wards (surgery, orthopedic, nurology, urology, Ganyacology & Obestatric and intensive care unite) during the period from June 1998 to June 2000, at Microbiology & Immunology Department, Faculty of Medicine, Zagazig UniversityUrine samples were taken from the catheter and isolated on CLEO and Sabouraud’s agar media. Standard bacteriological identification was done for all isolates by microscopical, conventional cultural media and biochmical methods using 10 RAPID KIT. Disc diffusion method was used to determine susceptibility of bacterial isolates to various antibiotics. Detection of ESBLs by using 3-dimentional method was done for all isolated organisms. Susceptibility tests by E-test (using ceftazidime strip) were done for ESBL positive organisms and the results were compared with that obtained by both disc diffusion and agar dilution methods. Plasmid profile analysis of ESBL positive isolates was done according to Birnboim and doly (1979) with slight modification according to Becker et aI., (1990).Two hunderd sixty-six strains (76 %) out of 348 patients were isolated. Two hunderd and twelve cases (80 %) out of 266 were identified as NCls, 54 cases (20 0/0) were identified as community acquired infection. Two hunderd-two cases (76 0!c» out of 266 were caused by gram negative bacilli, 32 cases (12 0/0) by S. aureus and 32 cases (12 %) by candida isolates. The isolated organisms were more common in NCls than that in Community acquired infections. The most common isolated pathogens of NCls were candida (84 %), S. aureus (84 %) and P. mirabilis (84 %) followed by E. coli (80 %) and P. vulgaris (80 %). Nosocomial infections were higher in the urology ward than in any other ward involved in the study.The most effective antibiotic against S. aureus was vancomycin (100 %). For gram negative bacilli, the most effictive antibiotics were amikacin (for E. call), tobramycin (for P. mirabilis), cefotaxime (for K. pneumoniae) and ceftazidime (for P. vulgaris and E. cloacae). High level of antimicrobial resistance was noticed among P. aeruginosa, the most active antibiotic was amikacin.ESBL production was nearly the same in both NCI and community acquired infection, and it was highly prevalent among isolates of P. mirabilis (26 %), followed by E. coli (8 %). Other isolates showed no ESBL activity. Rough comparison of susceptibility results of E-test (ceftazidime strip) with that of disc diffusion and agar dilution methods give priority of E-test above both disc diffusion and agar dilution methods in detection of the susceptibility test of the organisms to the antibiotic used.As regard the plasmid profile, it seemed that there is no particular association between the plasmid content and ESBL activity of the isolated nosocomial strains of both E.coli and P. mirabilis to explain intra or interspecies relationship
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