Antimicrobial susceptibility pattern of Vibrio cholerae 01 strains during two cholera outbreaks in Dar es Salaam, Tanzania

Objective: To determine and compare the antimicrobial susceptibility patter ns of Vibrio cholerae 01 strains, which were isolated in two cholera epidem ics in 1997 and 1999 in Dar es Salaam, Methods: V. cholerae 01 strains isolated from patients with cholera in Dar es Salaam city during 1997 (94 isolates) and 1999 (87 isolates) were stored on nutrient agar slants at room temperature and antimicrobial susceptibili ty pattern was determined, using Kirby Bauer method. Setting Department of Microbiology and Immunology, Muhimbili Medical Centre , Dar es Salaam, Tanzania, Results: A total of 181 V. cholerae 01 strains were studied during two epid emic periods when tetracycline or erythromycin was used for treatment of pa tients with severe disease. Among the 94 V. cholerae 01 strains isolated in 1997: 98.6%, 93.6%, 83%, 81.9%, 36.2%, 35.5%, 3.2% were sensitive to cipro floxacin, tetracycline, ampicillin, erythromycin, nalidixic acid, chloramph enicol and trimethoprim/ sulphamethoxazole, respectively. Among the 87 V. c holerae 01 isolates collected in 1999, 100%, 58.6%, 46.0%, 46%, 47.1%, 19.5 %, 3.4% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythrom ycin, chloramphenicol, nalidixic acid and trimethoprim/sulphamethoxazole, r espectively. Between 1997 and 1999, there was a significant increase in the proportion of V. cholerae 01 isolates resistant to tetracycline, ampicilli n, nalidixic acid and to erythromycin but there was no change for susceptib ility to ciprofloxacin and trimethoprim/ sulphamethoxazole, Conclusion: Significant proportion of V. cholerae 01 strains in Dar es Sala am were resistant to commonly used antimicrobial agents during the two year s of the study. Therefore, there is a great need to control the utilisation of antimicrobial agents in cholera control, in addition to continuing carr ying out surveillance of antimicrobial resistance as a guide to choice of a ntimicrobial treatment. Rotational use of the available drugs with regular monitoring of susceptibility may contribute to continuing usefulness of suc h drugs.