Antibiotic resistance and Molecular characterization of Salmonella in diarrhoeal patients’ faeces in south-western Nigeria

Abstract

The study reports the prevalence of multiple antibiotic resistance (MAR) and molecular chacterization of resistance (BlaCTX and GyrA) genes in Salmonella recovered from stool samples of diarrhoeal patients in Ile-Ife, Osun state, Nigeria.

Salmonella was cultured on molten Salmonella and Shigella agar (Oxoid, Ltd, Bashingstoke, Hampshire, England) plate at 37⁰C. Susceptibility of isolates to antibiotics was done on Mueller Hinton (Himedia lab Ltd, Vadhani) by disk diffusion technique. Detection of plasmid DNA in multiple antibiotic resistant isolates was carried out by alkali lysis (TENS) method and resistance genes (BlaCTX and GyrA) were detected by the polymerase chain reaction. A total of 69 Salmonella (S.Typhimurium(82.6 %), S.Typhi(10.1 %) and S.ParatyphiA (7.3 %)) were cultured from 187 diarrhoeal stool samples analysed. Resistance was mostly to nitrofurantoin (100%), ceftriazone (97.2 %), and gentamicin (94.2 %) among others.  Sixty seven (97.1 %) of the Salmonella isolates were resistant to at least two different classes of antibiotics with 32 antibiotypes. Multiple plasmids of molecular weights (1.46 - 23.13 kbp) and resistance genes (GyrA-282 bp, blaCTX-480 bp) were detected in the representative MAR isolates. The prevalence of MAR Salmonella in diarrhoeal patients’ stool samples is high in the study area with attendant public health and economic loss consequences.

Keywords:Salmonella, diarrhoea, antibiotic resistance, plasmid, resistance genes