Resistance Evaluation, Gene Sequence and Plasmid Profile of Salmonella typhi Isolated from Human Anal Swab

Abstract

Antibiotic resistance in Enterobacteriaceae are of great global concern. Salmonella Sp. is widespread in the environment, but the main reservoir is the intestinal tract of livestock animals and particularly pig, poultry, and cattle and can be transmitted to humans through the food chain. Ten rectal swab samples were collected from five (5) male and five (5) females.  One organism of clinical importance amongst the isolates was identified as Salmonella typhi through colonial, morphological and biochemical tests carried out following standard procedures. The identified isolate was investigated for its antibiotic resistance profile, Multiple Antibiotic Resistance index (MARi), pathogenicity status and its resistance genes were determined through molecular means using plasmid amplification and primers. Primers used include. ermB, BlaTem, qnrB genes. Result obtained showed Salmonella typhi to have α heamolysis. It was sensitive to 25% of the tested antibiotics, especially to all classes of Cephalosporin used. The Multiple antibiotic resistance index (MARi) was 0.66. The plasmid profiling revealed Salmonella to have low molecular weight plasmid and the molecular investigation using gene primers ermB,  BlaTem,  and  qnrB genes showed Salmonella typhi to have resistance genes for macrolides (ermB gene) and betalactam (BlaTem) but no resistance gene quinolones (qnrB gene). The high antibiotic resistance of Salmonella typhi to antibiotics is a cause for concern and alternative means of intervention into the treatment of Salmonella associated infection should be investigated as a matter of urgency. Identifying and monitoring resistance in Salmonella isolates from human-related environments are of clinical and epidemiological significance in battling antimicrobial resistance.