ACQUIRED TETRACYCLINE RESISTANCE GENES IN NOSOCOMIAL SALMONELLA-TYPHIMURIUM INFECTION IN A KENYAN HOSPITAL

Tetracyclines have been among the most widely used antibiotics worldwi de. Plasmid-mediated tetracycline resistance among hospital strains of bacteria has continued to rise and of major concern has been the tran sfer of resistance to pathogenic organisms. Bacteraemia due to hospita l acquired S. typhimurium has been a major cause of morbidity at Kenya tta National Hospital (KNH), hence the need to study drug susceptibili ty pattern of this organism. This study also characterized the tetracy cline resistance genes using oligonucleotide probes. Ninety seven S. t yphimurium strains isolated from patients at KNH were used. Agar dilut ion method was used to determine minimum inhibitory concentration (MIC ). Plasmids were isolated from each strain and the different plasmid p rofiles were grouped by their molecular weights into 6 patterns. Out o f 97, 87 (88%) strains were resistant. MIC ranged from 1 mug/ml to 128 mug/ml. Genes encoding for tetracycline resistance were located on pl asmids of molecular weights 65 MDa, 5.2 or both. Plasmid-encoded antim icrobial resistance is likely to spread to other pathogenic organisms, reduce our ability to treat the infection and increase the cost and d uration of treatment.