Molecular Characterization of Antibiotic Resistance Genes in Non-typhoidal Salmonella Isolates from Human Samples in Bangui, Central African Republic (2019–2023)

Abstract

Bacteria of the genus Salmonella are motile, Gram-negative bacilli belonging to the Enterobacteriaceae family. In sub-Saharan Africa, foodborne illnesses caused by Salmonella result in approximately 680,000 deaths annually. Previous studies have been conducted in the Central African Republic, but these studies did not incorporate specific molecular biology techniques. It is in this context that this study was undertaken, with the aim of determining the antibiotic resistance genes of Salmonella non-Typhi isolates circulating in the Central African Republic (CAR).  This was a descriptive and analytical cross-sectional study conducted between 2019 and 2023. Serotyping and molecular characterization were partially performed on strains isolated from stool, urine, and blood samples from patients who came from different health facilities. A total of 72 Salmonella strains were selected, including 8.33% in blood, 15.28% in urine, and 76.39% in stool. The age of the patients ranged from 1 to 74 years, with an average of 30 years, the mode being 1 year with a standard deviation of 19.03. The 0-14 age group accounted for 30.56% and the >14 age group for 69.44%. Females were more represented, with a male/female sex ratio of 0.84. Salmonella enterica serotype Typhimurium was the most common, followed by Salmonella enterica serotype Enteritidis. The rate of resistance to chloramphenicol was high, followed by quinolones, B-lactams, and aminoglycosides. Molecular characterization of B-lactam resistance genes revealed a frequency of positivity for the blaCTX-M1, blaTEM, and blaSHV genes. The Salmonella enterica serotype Remo serotype showed a diversity of resistance genes for blaTEM, blaCTX-M1, and blaSHV. Molecular characterization of quinolone resistance genes revealed qnrB genes. BlaTEM genes were represented in the 0-14 age group. However, qnrB was detected in the >14 age group. blaTEM genes were detected in males, while blaCTX-M1 genes were detected in females. The results of this study showed that Salmonella strains possess qnrB genes for quinolone resistance and blaTEM, blaCTX-M1, and blaSHV genes for B-lactam resistance. Consequently, as these different antibiotic resistance genes are circulating in CAR, epidemiological investigations are needed to identify the link between the genes of isolates circulating in CAR and the food products consumed by the population, animals, and the environment, which could be sources of the emergence of salmonellosis.