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.

Bacterial isolates in neutropenic febrile patients.

One hundred consecutive patients with documented bacteremia and neutrophil count of 0.5 x 10(9)/L or below were retrospectively studied to determine the pattern of infection at the Aga Khan University Hospital in Karachi. These included patients with primary haematologic malignancies presenting with low counts, and those patients with cancer who developed neutropenia as a result of chemotherapy. The gram negative organism pseudomonas aeruginosa was the most common bacterial organism isolated constituting 31% of all positive blood cultures. Gram positive organisms were frequently isolated comprising 24% of all isolates of which 15% were Staph.aureus. Staph. epidermidis was not isolated in this series. Salmonella species were isolated in 9 patients. The other gram negative rods included non-lactose fermenting organisms frequently isolated in a nosocomial setting including Serratia and Acinetobacter. Four patients had positive fungal blood cultures. A single positive anaerobic culture was obtained. Sensitivities of the Pseudomonas aeruginosa reflected the high frequency of resistance seen in nosocomial isolates and those from the community. More than half (54.8%) of the isolates were resistant to carbenicillin and 9.6% resistant to gentamicin. Although 3.2% were resistant to cefotaxime, none were resistant to ofloxacin or ceftazidime reflecting the relatively recent arrival of the latter. In contrast, 23% of Staph. aureus were still sensitive to penicillin. Methicillin (cloxacillin) resistant Staph. aureus did not occur. However 26.6% of the Staph. aureus were resistant to erythromycin. Knowledge of the prevailing pattern of infection permits the development of investigative and therapeutic approaches of optimal efficacy.

Quantitative tear lysozyme assay: a new technique for transporting specimens.

We have developed a method for assaying the concentration of tear lysozyme using eluates of tear fluid collected on filter paper discs. Specimens can be stored and transported to remote laboratories for assay. We have shown that the 'indirect' or eluate method gives statistically comparable results to the 'direct' method using fresh, neat tear fluid.