Antibiotic Susceptibility Profile and Molecular Detection of tetA Genes in Tetracycline Resistant Salmonella Species Isolated from Different Water Sources in Keffi, Nasarawa State, Nigeria

Abstract

This study was carried out to determine the antibiotics susceptibility profile and molecular detection of tetA genes in tetracycline resistant Salmonella species isolated from different water sources in Keffi, Central Nigeria. A total of 100 water samples, 25 each of well, public borehole, tap and sachet water were collected from different locations within the Metropolis and analysed using standard microbiological techniques. Of which 38(38.0%) of the samples were contaminated with Salmonella species with well water having the highest contamination rate, 18(72.0%) and sachet water having the least, 3(12.0%). The antibiotic susceptibility of the isolates revealed varying degree of susceptibility in which isolates were susceptible to Ciprofloxacin (100.0%), Gentamicin (84.2%) and Chloramphenicol (76.3%). Susceptibility of the isolates to the other antibiotics tested is as follows; Vancomycin (47.4%), Ceftriaxone (44.7%), Amoxicillin/Clavulanic acid (39.5%), Tetracycline (36.8%), Sulfamethoxazole /Trimethoprim (31.6%) and Erythromycin (15.9%). They also exhibited different antibiotic resistance phenotypes: E, TE, SXT; AMC, E, SXT, TE, CRO, VA; TE, AMC, SXT, E; CRO, E, SXT, TE, AMC and E, AMC, SXT, TE, CRO which expresses a resistance frequency of 2(5.3%) respectively. The isolates were multiple antibiotics resistant with MAR index of 0.6 as the peak and 0.2 as the least. MAR index of 0.3 was the most encountered indices with an occurrence of 8(21.1%). Similarly, of the 38 total isolates, only 21(55.3%) were cured indicating that resistance were plasmid-mediated. Molecular detection of Tetracycline resistant plasmid gene (tetA) was conducted by Polymerase Chain Reaction method while agarose gel electrophoresis showed that the tetA genes were on the 282bp band. Therefore, water in Keffi should be properly treated before consumption while boreholes and wells should be dug far away from latrines and septic tanks so as to avoid cross-contamination by faecal materials and indiscriminate use of antibiotics should be discouraged.