PREVALENCE AND ANTIBIOTIC SUSCEPTIBILITY OF SALMONELLA SPECIES ISOLATED FROM ASYMPTOMATIC FOOD HANDLERS IN WESTLANDS DIVISION, NAIROBI, KENYA

Abstract

Salmonella are Gram-negative facultative intracellular anaerobic bacteria that cause a wide range of diseases in diverse hosts ranging from gastroenteritis, enteric fever and bacteraemia. These infections can lead to a convalescent lifetime carrier status/asymptomatic carriers. The antimicrobials that are currently widely regarded as most favourable for the management of Salmonella infections by the World Health Organisation (WHO) in adults is the fluoroquinolone group of antibiotics while in young children the third generation cephalosporin is used for serious infections. However, the occurrence of emerging resistant strains is evident. The aim of this study was to isolate, characterize and determine the antibiotic susceptibility of the Salmonella isolates. Being an epidemiological study, a cross sectional laboratory based design was employed, involving stratified random sampling. This study was based at the Kenya Medical Research Institute microbiology centre for microbiology research (CMR) laboratories in Nairobi Kenya. A total of 400 stool samples were used and the study was run for a period of four months. The samples were cultured in Xylose Lysine Deoxycholate agar (XLD) and Mac Conkey agar both are selective and differential media for isolation of Salmonella sp; serotyping and biochemical test was conducted for the confirmation of the isolated bacterial strains. The Kirby-Bauer disc diffusion method was used to test susceptibility of the isolated Salmonella to antibiotics commonly used in animal and human health. Data was analyzed using analysis of variance (ANOVA) and descriptive statistical methods were used for statistical analysis. A total of 6 serotypes were isolated with a total prevalence of 2%, namely; Salmonella paratyphi A, S. paratyphi B, S. enteritidis with a percentage of 0.5%, S. typhimurium, S. typhisuis both with a percentage of 0.25%. Among the isolates, a significant variation in inhibition zone sizes of salmonella under the commonly used drugs was observed F=19.48 while p≤0.05, thus significant difference in their effectiveness. A drug susceptibility of 81.8% was observed. Multi-drug resistance of 37.5% was observed with 4 antimicrobial resistance profiles. Ampicillin and Amox-clav showed more resistance among the Salmonella isolates. Although a prevalence of 2% can be considered an insignificant figure, it indicates a probability of Salmonella infection being passed to the food consumers by the asymptomatic handlers. Furthermore, should there be a case of infection by asymptomatic food handler to consumer, and the chances of the consumer being infected by the drug resistant Salmonella serotypes will be high. Therefore, the ministry of public health should make it mandatory for hotel owners to employ certified food handlers to break this cycle of infections.