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 patterns of Vibrio cholerae 01 strains, which were isolated in two cholera epidemics 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 susceptibility pattern was determined, using Kirby Bauermethod.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 epidemic periods when tetracycline or erythromycin was used for treatment of patients with severe disease. Among the 94 V. cholerae Ol strains isolated in 1997; 98.6%, 93.6%, 83%, 81.9%, 36.2%, 35.5%, 3.2% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, nalidixic acid, chloramphenicol and trimethoprim/ sulphamethoxazole, respectively. Among the 87 V. cholerae 01 isolates collected in 1999, 100%, 58.6%, 46.0%, 46%, 47.1%, 19.5%, 3.4% were sensitive to ciprofloxacin, tetracycline, ampicillin, erythromycin, chloramphenicol, nalidixic acid and trimethoprim/sulphamethoxazole, respectively. Between 1997 and 1999, there was a significant increase in the proportion of V. cholerae 01 isolates resistant to tetracycline, ampicillin, nalidixic acid and to erythromycin but there was no change for susceptibility tociprofloxacin and trimethoprim/ sulphamethoxazole.Conclusion: Significant proportion of V. cholerae 0l strains in Dar es Salaam were resistant to commonly used antimicrobial agents during the two years of the study. Therefore, there is a great need to control the utilisation of antimicrobial agents in cholera control, in additionto continuing carrying out surveillance of antimicrobial resistance as a guide to choice of antimicrobial treatment. Rotational use of the available drugs with regular monitoring of susceptibility may contribute to continuing usefulness of such drugs