Prevalence and Characterization of Bacteria of Genus Salmonella in Retail Pork and Raw Vegetables, Busia County

Abstract

Salmonellosis is a major global threat to public health and causes emergence and spread of antimicrobial-resistant strains. This study aimed to determine the prevalence and characterization of Salmonella species (spp.) in retail pork and raw vegetables commonly known as Kachumbari( tomatoes, onions, pepper, dhania, avocados) served alongside cooked pork in Busia County, Kenya. Samples collected from selected butcheries were 451 consisting of 262 raw pork, 108 cooked pork and 81 side salads served alongside cooked pork. Samples were cultured in Salmonella selective media in Busia ILRI laboratories. Isolated Salmonella spp. were afterwards identified using genus antiserum at the UoN laboratories . Serotyping was done using Kauffmann- Whyte scheme and antimicrobial sensitivity was determined using disc diffusion method. The overall Salmonella prevalence of retail pork was 32.59% (147/451 95% CI 32.40% - 32.80%). Raw pork recorded the highest prevalence of 49.24% (129/262 95% CI 48.86% - 49.61%), followed by raw vegetables with 19.75% (16/81 95% CI 18.79% - 20.72%) and cooked pork recorded the least with 1.85% (2/108 95% CI 1.65% - 2.10%). Salmonella-positive isolates were highly resistant to the antibiotics used with an overall resistance of 135/147 (91.84%). 67/147 (45.58%) of the samples had multidrug resistance while 99/147 (67.35%) had extended drug resistance. Overall, the isolates had the highest resistance to Gentamicin (63.94%) followed by Ampicillin (59.86%). The highest intermediate resistance was found in ciprofloxacin (76.19%) and nalidixic acid (74.15%). Seven isolates were resistant to third-generation cephalosporins, ceftriaxone. This study highlights a risk of exposure to Salmonella spp. from retail pork and raw vegetables sold at pork butcheries in Busia. This is evidenced by the high prevalence of Salmonella spp. from the raw pork and raw vegetables served alongside cooked pork from butcheries in the four subxv counties in Busia that were being investigated. In this setting, cooking of pork mitigated much of the risk of exposure to Salmonella spp. from pork, though the practice of plating pork with raw vegetable side-salads (Kachumbari) with a high prevalence of Salmonella spp. is thought to reintroduce the exposure risk. This study is not able to determine if the vegetables entered the butcheries while contaminated or whether they were cross-contaminated within the butchery setting. This is the first study reporting on salmonella prevalence in retail pork in this country. Worryingly the majority of the isolates were resistant to one or more antimicrobials tested and more than half of them had multidrug-resistant to three or more classes of antimicrobials tested, creating an additional potential health burden. This study highlights risks that may be present in other butchers in the country where hygiene and sanitation are not strictly followed hence necessitating more investigation and action to be taken.