Changing pattern of antimicrobial susceptibility of organisms causing community acquired urinary tract infections.

OBJECTIVE: To assess common organisms causing Urinary Treat Infection (UTI) in this community and to see antimicrobial susceptibility pattern of these isolates.

DESIGN: Prospective study on urine samples.

SETTING: Tertiary care hospital in Karachi.

METHODS: Over a period of 8 years (1990-97) 9,892 urine samples grew significant bacteriuria for various organisms. All Gram negative rods and entercocci was identified by using API 20E and API 32 strips respectively. Staphylococci were identified by catalase, coagulase and D'Nase tests. Antimicrobial sensitivity testing of all isolates was performed on Diagnostic Sensitivity Test plates by Kerby Bauer method. The discs used were ampicillin, trimethoprim-sulfamethoxazole, cefotaxime, ceftriaxone, aztreonam, ofloxacin, carbenicillin, amikacin, gentamicin, penicillin, clindamycin, methicillin, vancomycin, ceftazidime, cefuroxime, Nalidixic acid, pipemedic acid and Nitrofurantoin.

RESULTS: Our results indicate that E. coli and Klebsiella aerogenes are the most common organisms causing UTI in this community. Other organisms involved are Pseudomonas aeroginosa, Enterobacter species, Enterococcus, Proteus mirabillus, Staphylococcus aureus and Staphylococcus saprophyticus. Organisms resistant to various antimicrobial agents such as gentamicin, Amikacin, Ofloxacin, Cefotaxime and Ceftazidime are increasing.

CONCLUSION: In conclusion, E. coli and Klebsiella aerogenes are the most common organisms causing UTI in this community. Pattern of antibiotic susceptibility to first line antibiotics is changing. Antimicrobial susceptibility testing of all isolates is crucial for the treatment of UTI.