Journal of Bioanalysis & Biomedicine

Phylogenetic Analysis of the Antibiotic Resistance Genes in Salmonella Species in silico.

Abstract

Nusrat Nahar* and Ridwan Bin Rashid

Antibiotic resistance is an emerging problem in both developed and developing countries. It has been responsible for 700,000 deaths worldwide. Some genotypes of bacteria are sensitive to certain antibiotics than others. Hence by conducting phylogenetic analysis of bacteria and detecting the presence of resistance genes in each genotype, we can select the antibiotic that would be most effective for the bacteria in that certain genotype. A total of forty-five Salmonella species were investigated for the presence of antibiotic resistance genes through in silico PCR (polymerase chain reaction) amplification and PFGE (pulsed-field gel electrophoresis) analysis was conducted to assess the phylogenetic relationship. Total twenty-eight antibiotic resistance genes were selected for screening the isolates and seventeen antibiotic resistance genes among the Salmonella strains were found. Almost all the isolates (n=43) exhibited PCR amplification product for gyrA genes while fluoroquinolone resistance gyrB (66.67%), parC (68.89%) and parE (15.56%) genes were also present. About 15.56% and 11.11% isolates were found to harbor adenylyltransferase gene, aadA1 and aadA2, respectively while phosphotransferase gene was detected in only one isolate. Two isolates expressed both chloramphenicol acetyltransferase genes, cat1 and cat2. Three isolates (6.67%) harbored chloramphenicol resistance gene cmlA gene while two isolates (4.44%) expressed florfenicol resistance gene, floR. Tetracycline resistance gene, tetA was more prevalent (8.89%) than tetG genes (2.22%). Salmonella harbored all three sulfonamide resistance genes while sulII was more prevalent (17.78%). Genotype 2 contained fifteen antibiotic resistance genes while genotype 3 contained only one antibiotic resistance genes. These investigations used a computer aided approach to genotype isolates and assess the difference in antibiotic resistance profile of Salmonella species based on genotype. This data helps to predict antibiotic resistance genes that might be present for an isolate of known genotype and select antibiotic for the treatment of Salmonella infections based on their phylogenetic group.