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 d etermined for 2491 Shigella isolates cultured in the medical laborator y of the Centre Hospitalier de Kigali, Rwanda, during 1983 to 1993. Ov erall, 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 import ant variability over time. S. flexneri increased from 40% in 1983 to 6 8% of the isolates in 1993 whereas S. dysenteriae Type I decreased gra dually 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 t he capital, a new epidemic of dysentery started in the Kigali area and S. dysenteriae Type I 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 chloramphenic ol was observed in 17% (30/182) of the isolates. Only 10% were resista nt to ampicillin and an equal proportion to trimethoprim, whereas 5% o f the isolates showed resistance to both products. By 1993, 66% (195/2 95) 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 latt er two drugs (p < 0.001). Resistance patterns differed strongly by spe cies, S. flexneri being more frequently resistant than S. sonnei. In 1 983, all S. dysenteriae Type 1 isolates were resistant to ampicillin, chloramphenicol, tetracycline, and sulfonamides. Trimethoprim resistan ce increased from 31% (25/80) in 1983 to 96% (26/27) of the isolates i n 1986 (p < 0.002). After the introduction of nalidixic acid as an alt ernative for trimethoprim-sulfamethoxazole, trimethoprim resistance de creased to 87%, during 1987 to 1992, and subsequently to 68% of the is olates in 1993. However, 20% of the isolates became resistant to nalid ixic acid in 1993. Ampicillin and trimethoprim-sulfamethoxazole ave no longer useful for the empirical treatment of shigellosis in Rwanda. ( C) 1997 Elsevier Science Inc.