Background: Salmonella spp. are recognized as some of the most common causes of enteritis worldwide. This study aimed to identify clinically isolated S. Typhimurium in western Kenya and to assess antimicrobial resistance profiles and strain inter-relatedness. Methods: The study was performed in rural Maseno, Nyanza province in Kenya, between February 2004 and June 2005. Sixty-three patients with diarrhoea and fever were recruited. S. Typhimurium isolates were confirmed using serotyping, biochemical testing, and 16S rRNA sequencing. Susceptibility to 20 antimicrobials was determined and specific resistance genes were identified by polymerase chain reaction (PCR). Strain diversity was further analyzed using pulsed-field gel electrophoresis (PFGE), fluorescence amplified fragment length polymorphism (fAFLP), and multi-locus-variable-number-tandem regions (MLVNTR). Results: Twenty S. Typhimurium strains were isolated in the course of the study and their identity was confirmed by 16S rRNA gene sequencing. All 20 S. Typhimurium strains were resistant to ampicillin, streptomycin and sulfamethoxazole; ciprofloxacin resistance and phage DT104 were not detected. PFGE, plasmid profiling, and analysis of selected VNTR loci revealed further heterogeneity among the strains in the study. Conclusion: S. Typhimurium was commonly isolated from patients with diarrhoea and fever in Maseno. Considerable phenotypic and genotypic diversity was observed among isolates, suggesting that strains belonging to multiple lineages are responsible for disease in the study region. Multiple resistance was common and mediated by a variety of resistance genes but not by phage DT104.

The study compares Escherichia coli recovered from human, fish products, domesticated animals and the environment within the Lake Victoria basin on the basis of their antimicrobial susceptibility profiles. A total of 134 E. coli isolates were isolated from the collected samples. 52.2% of the E. coli isolates were found to be resistant to at least one antibiotic. Isolates originating from fish and soil showed the highest levels of resistance (100%). Based on the discriminant analysis (DA), most of the fish isolates were misclassified into soil category, probably due to the groups displaying similar Multiple Antibiotic Resistance (MAR) profiles. On the other hand, human isolates had the highest score of 0.55. The findings suggest that soil may be an important source of bacterial contamination of fish. Similarly resistance to antibiotics is widely prevalent among human, environment and domesticated animals within the Lake Victoria basin.