Auxotypes, serovars, and trends of antimicrobial resistance of Neisseria gonorrhoeae in Kigali, Rwanda (1985-93).

OBJECTIVE: To investigate the in vitro antimicrobial susceptibility and the auxotype/serovar distribution of Neisseria gonorrhoeae in Kigali, Rwanda, during 1985-93. METHODS: As part of a monitoring programme the in vitro susceptibility of 1604 isolates of N gonorrhoeae was determined by agar dilution. Auxo- and serotyping was performed on 1350 and 1313 isolates respectively. RESULTS: The prevalence of penicillinase producing N gonorrhoeae (PPNG) remained stable at a rate of 39% during 1985-91 and increased to 61% in 1992-3. Chromosomal resistance to penicillin was common among non-PPNG and resistance to thiamphenicol and tetracycline was common among both PPNG and non-PPNG. High level, plasmid mediated resistance to tetracycline (TRNG) was observed for the first time at the end of 1989 and increased from 2% of the isolates in 1990 to 50% by 1993. A trend for increasing resistance to norfloxacin and ofloxacin was observed during 1985-90 but disappeared in 1991-93. Five isolates with high level resistance to norfloxacin (MIC 2 mg/l) were observed in 1990. Resistance to trimethoprim-sulphamethoxazole (TMP-SMZ) emerged at the end of 1990 and was observed among 10% of the isolates during 1991-3. All strains remained susceptible to ofloxacin, ciprofloxacin, spectinomycin, and ceftriaxone. Overall, 75% of the isolates were prototrophic or required proline for their growth and 62% belonged to serovars IA-6 and IB-1. The prevalence of serovar IB-4 increased strongly during the last 3 years of the study. CONCLUSION: Resistance to penicillin, thiamphenicol, and tetracycline was common in N gonorrhoeae during 1985-1993. The rapid spread of TRNG after 1989 and the steep increase of PPNG during 1992-3 were the most striking facts of the study period. The auxotype and serovar distribution was comparable with findings from other African countries.

Antimicrobial resistance and serotypes of Shigella isolates in Kigali, Rwanda (1983 to 1993): increasing frequency of multiple resistance.

The serotype distribution and susceptibility to nine antibiotics was determined for 2491 Shigella isolates cultured in the medical laboratory of the Centre Hospitalier de Kigali, Rwanda, during 1983 to 1993. Overall, Shigella flexneri was the most frequent species, ranking before Shigella sonnei, Shigella boydii, and Shigella dysenteriae. However, the relative frequency of the different Shigella spp. showed an important variability over time. S flexneri increased from 40% in 1983 to 68% of the isolates in 1993 whereas S. dysenteriae Type 1 decreased gradually from 30 to 0.5% of the isolates in 1992. After the outbreak of severe civil unrest, which caused the displacement of many people to the capital, a new epidemic of dysentery started in the Kigali area and S. dysenteriae Type 1 accounted again for 24% of the isolates in 1993. In 1983, resistance to tetracycline, streptomycin, and sulfonamides was common among the endemic Shigella spp. Resistance to chloramphenicol was observed in 17% (30/182) of the isolates. Only 10% were resistant to ampicillin and an equal proportion to trimethoprim, whereas 5% of the isolates showed resistance to both products. By 1993, 66% (195/295) of the isolates were resistant to chloramphenicol (for comparison with 1983, p < 0.001), 70% (207/295) to ampicillin (p < 0.001), 67% to trimethoprim (p < 0.001), and 58% had combined resistance to the latter two drugs (p < 0.001). Resistance patterns differed strongly by species, S. flexneri being more frequently resistant than S. sonnei. In 1983, all S. dysenteriae Type 1 isolates were resistant to ampicillin, chloramphenicol, tetracycline, and sulfonamides. Trimethoprim resistance increased from 31% (25/80) in 1983 to 96% (26/27) of the isolates in 1986 (p < 0.001). After the introduction of nalidixic acid as an alternative for trimethoprim-sulfamethoxazole, trimethoprim resistance decreased to 87%, during 1987 to 1992, and subsequently to 68% of the isolates in 1993. However, 20% of the isolates became resistant to nalidixic acid in 1993. Ampicillin and trimethoprim-sulfamethoxazole are no longer useful for the empirical treatment of shigellosis in Rwanda.