Antimicrobial Susceptibility Profiles of Non-Typhoidal Salmonella Isolates Obtained from Food Animals in Selected Sites in Kenya

Abstract

The organisms Salmonella are known to be facultative intracellular pathogens that can survive in the host macrophages. The Strains of Non-Typhoidal Salmonella (NTS) are a major cause of serious bloodstream infections with a case fatality of 20-25%. In most cases, the clinical presentations include: gastroenteritis, bacteremia, focal infection and enteric fever. In other continents of the world, NTS are associated with other clinical presentations but not majorly diarrhea. This study aims to determine the antimicrobial susceptibility profiles and resistance genes transferability of Non Typhoidal Salmonella isolates obtained from food animals (Cattle, Chicken and Pigs) and the environment in selected sites in Kenya at the Center for Microbiology Research (CMR) Institute. During this study, some of the laboratory methods that were carried out included antimicrobial susceptibility testing using the disk diffusion technique for all commonly used antimicrobials and Conjugation Assay to determine Transferable Resistance determinants. This study yielded relevant findings concerning the increasing rate of Salmonellosis in this country. The study first of all agrees with other studies that there is a high rate of NTS in food animals and this has a great connection with the increased population of these organisms in the environment. The high rate in continuous usage of antibiotics for treatment of infections in food animals and also to increase products production especially in chicken has led to the rise of resistance cases to commonly used antibiotics. Conjugation studies carried out revealed that resistant genes transferability from one bacterial species to the other is common.  A total of 289 isolates used in this study, A total of 289 NTS samples were analyzed. Among the 289 samples, 134 (46%; 95% C.I: 40.3%-51.8%) were chicken isolates, 45 (16%; 95% C.I: 11.2%-20.3%) were cow isolates, 27 (9%; 95% C.I: 5.7%-12.3%) were pig isolates, 3 (1%; 95% C.I: -0.15%-2.15%) were isolates from goats and environmental isolates were 80 (28%; 95% C.I: 22.8%-33.2. The highest levels of resistance were against Ampicillin 42.7% had the highest resistance level followed by Sulfamethoxazole/Trimethoprim 38.2% and then Chloramphenicol 22.2%. The proportion of isolates resistant against Gentamicin was 9.4%. Environmental isolates showed a higher resistance profile against Ceftazidime 2.4%, Ceftriaxone 2.4%, Sulfamethoxazole/Trimethoprim 40.2% and Chloramphenicol 25.6% compared to food animal isolates. %). It is of importance that there be strict control on the use of antibiotics in animal production to prevent the emergence of antibiotic resistance in Non-Typhoidal Salmonella.

Keywords: Invasive Non-Typhoidal Salmonella, antimicrobial resistance, conjugation, resistance genes transferability, MDRs

DOI: 10.7176/JBAH/9-2-06