Patterns and antimicrobial susceptibility of bacterial isolates causing pyogenic infections at Muhimbili National Hospital, Dar es Salaam, Tanzania

Abstract

In order to determine the patterns and antimicrobial susceptibility of bacterial isolate causing pyogenic infections, a cross sectional study was done at the Muhimbili National Hospital, Dar. es Salaam from 1St to 31st of September, 1999. Consecutive 209 pus isolates from infected umbilical cord stumps, wounds, post-surgery wounds, ears, eyes and abscesses were collected. The pattern and causative agents of superficial pyogenic infections, characteristics of patients by age and sex, antimicrobial susceptibility patterns of the isolates, comparison of resistance patterns among inpatients and outpatients and relation between antibiotic use and susceptibility patterns were studied. S. aureus was the commonest isolate (22.5%), of which 87.2% and 2.1% were resistant to penicillin, and methicillin respectively. Among the Gram-negative rods, Proteus spp was the most prevalent isolate (12.4%). A significant proportion of Gram-negative bacteria was resistant to ampicillin, doxycycline, amoxycillin/ clavulanic acid and chloramphenicol. Pseudomonads were sensitive to all antimicrobials tested. There was no influence of age, sex or patient status in the distribution of the antimicrobial resistant isolates.

Vlll The relationship between antimicrobial utilization and resistance was not clearly demonstrated. The resistance to erythromycin among S.aureus had increased from 2% in 1979 to 34% in the present study, while tetracycline resistance among S.aureus declined from 44% in 1978 to 29.8% in the current study. It was recommended that ampicilin and penicillin should not be used in staphylococcal infections, while tetracycline, trimethoprim/ sulphamethaxazole, amoxycilin/ clavulanic acid and erythromycin should be used cautiously basing on sensitivity testing. There is a need to establish a surveillance system to monitor antimicrobial resistance.