Antimicrobial Sensitivity in Enterobacteria from AIDS Patients, Zambia

James Mwansa, Kabanga Mutela, University of Zambia School of Medicine, University Teaching Hospital, Lusaka, Zambia; Isaac Zulu, University of Zambia School of Medicine, University Teaching Hospital, Lusaka, Zambia and St. Bartholomew's & Royal London School of Medicine, London, United Kingdom; Beatrice Amadi, University of Zambia School of Medicine, University Teaching Hospital, Lusaka, Zambia; Paul Kelly University of Zambia School of Medicine, University Teaching Hospital, Lusaka, Zambia and St. Bartholomew's & Royal London School of Medicine, London, United Kingdom

Disclosures

Emerging Infectious Diseases. 2002;8(1) 

In This Article

The Study

To determine the prevalence of infection in adults and children, cultures were performed by standard techniques on fecal samples from several groups of adults and children, all residents of Lusaka, the capital of Zambia. Group A was 124 adults and 105 children, all HIV-seropositive patients with persistent diarrhea, studied from 1995 to 1999 during three clinical trials of antiprotozoal or nutritional therapies. The average number of samples tested was 2.1 for each adult and 2.8 for each child. Group B was 216 adults enrolled in a longitudinal study of intestinal infection in a cohort of adults in a representative urban community in Lusaka; this group was studied to provide an estimate of asymptomatic carriage rates.

To define the profile of antimicrobial sensitivity, isolates from Group A were analyzed together with additional isolates of nontyphoidal salmonellae, Shigella dysenteriae, and S. flexneri from a third source (Group C): routine stool or blood cultures from AIDS patients in the University Teaching Hospital from 1995 to 1999. All isolates were cultured and tested for antimicrobial susceptibility by using standard antimicrobial discs (Oxoid Ltd, Basingstoke, UK) on Mueller-Hinton agar. Zones of growth inhibition were compared with standard tables[4], and control organisms of known sensitivity were tested beside clinical isolates for verification.

Of 124 adults with persistent diarrhea in Group A, 6 (5%) were infected with nontyphoidal Salmonella spp. and 9 (7%) with S. flexneri or S. dysenteriae. Of 105 children with persistent diarrhea, also in Group A, 21 (20%) were infected with nontyphoidal Salmonella spp. and 3 (3%) with S. flexneri or S. dysenteriae. In Group B, 7 (4%) of 174 adults had one or more fecal samples positive for nontyphoidal Salmonella spp. in one year (1999), and 10 (6%) had one or more positive for S. flexneri or S. dysenteriae. As each adult submitted samples approximately monthly (for a total of 1,440 samples), the point prevalence in these asymptomatic adults was <1% for either infection.

Studies of patients with HIV-related persistent diarrhea in other countries in Africa have found the prevalence of enterobacterial infection to be higher. In Rwanda and Kenya, prevalences of nontyphoidal salmonellae were 11% and 16%, respectively, and of shigellae were 22% and 4%, respectively[5,6]. In recent years, HIV seroprevalence in Lusaka has been estimated to be 22% to 30%[7], and the overall rate of HIV-related diarrhea is high[8].

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