Tetracycline Resistance Genes in Salmonella enterica Serovars With Animal and Human Origin

Tetracycline is one of the important antibacterial agents which is used against various bacterial infections. Different bacterial species and strains convey various tetracycline resistance (tetr ) genes. The present study was conducted to evaluate the occurrence of five tetr genes (tetA, tetB, tetC, tetD, and tetM) among Salmonella serovars obtained from humans and animals. A total of 60 different Salmonella strains previously recovered from humans, poultry, and animals were subjected to polymerase chain reaction (PCR) and sequence analysis of the genes. In total, 6 strains were positive for the presence of tetA gene; three serotypes were also positive for the presence of tetC gene. The sequence analysis and phylogenetic tree showed similarities between the sequences of serovars in the present study and other Salmonella serovars and some other bacteria species in GenBank data. The results showed the great distribution of tetracycline resistance genes among Salmonella serovars with different sources which could be the effect of widespread use of the antibiotic particularly in the animals breeding farms.