Antimicrobial Resistance in Non-Typhoidal Salmonella Recovered from Selected Food Animals in Kenya

Abstract

Invasive Non-Typhoidal Salmonella (iNTS) are a major cause of serious bloodstream infections with a case fatality of 20-25%. NTS infection is often invasive in Sub-Saharan Africa (iNTS) and is implicated as a major cause of hospitalization and deaths among infants and HIV adults due to its invasive nature. NTS are non-spore forming bacillus in the Enterobacteriaceae family and the infection caused by iNTS is known as Salmonellosis. Food animals have been known as the main sources of NTS but recently humans have been implicated as potential reservoirs of these organisms. Enormous spread of iNTS in food animals and the environment have led to rise in its prevalence thus becoming a major concern in public health and global food chain. Antibiotic resistance iNTS is linked to more severe disease outcomes including bloodstream infections and hospitalization as a result of MDR. Continuous surveillance of resistance genes and their transferability would enable policy makers to develop effective treatment strategies. In addition, understanding resistant phenotypes would form important background to guide health and veterinary professionals in health care. This was a laboratory based cross-sectional study whose major objective was to determine the antimicrobial resistance in Non-Typhoidal Salmonella recovered from selected food animals (Cattle, Chicken and pigs) in Kenya. Ethical clearance was granted by KEMRI/ Scientific and Ethics Review Unit, study number KEMRI/CMR/P00058/SERU 3522. Antimicrobial susceptibility profiles of 289 iNTS archived isolates were determined using the Kirby-Bauer antibiotic sensitivity technique. The following antimicrobials were used with their respective concentrations; Ampicillin (AMP, 10µg), Ciprofloxacin (CIP, 5µg), Sulfamethoxazole/Trimethoprim (SXT, 1.25/23.75µg), Amoxicillin-clavulanic acid (AMC, 20/10µg), Nalidixic acid (NAL, 30µg), Ceftazidime (CAZ, 30µg), Cefotaxime (CTX, 30µg), Ceftriaxone (CRO, 30µg), Chloramphenicol (C, 30µg), Gentamicin (GEN, 10µg), Tetracycline (TET, 30 µg) and Azithromycin (AZM, 10 µg). Conjugation assay determined the transferability of multidrug resistant phenotypes. According to the study findings, high rates of resistance were against Ciprofloxacin (58%), which is a flouroquinolone for Salmonella. Resistance to Ampicillin drug was 45.8% followed Sulfamethoxazole/Trimethoprim 39.6%, Ceftriaxone 30% and then Chloramphenicol 24.3% drugs. 61% of S. enteritidis isolates were observed to exhibit resistance phenotype and the most common resistance phenotype was Ampicillin, Amoxycillin, Sulfamethoxazole/Trimethoprim, Chloramphenicol. 53% of S. typhimurium iNTS isolates were similarly observed to exhibit resistance with the most common resistance phenotype being Ampicillin, Amoxycillin, Sulfamethoxazole/Trimethoprim, Gentamycin. In conclusion, there is moderately high level of resistance in iNTS species against first line drugs and high level of resistance against 3rd generation Cephalosporins and fluoroquinolones. The study recommends appropriate measures such as rational use of antibiotics to help preserve the potency of antimicrobials and to improve successful treatment outcomes and also Molecular work also ought to be carried out to detect the genes transferred and mapping of the resistant phenotypes among isolates.