Salmonella is a gram negative bacteria which can cause a number of different diseases including gastroenteritis, bacteremia, and typhoid fever, with the most common being gastroenteritis, some serotypes of it are pathogenic and cause serious food poisoning in humans and major economic losses in both chicken and turkeys. The birds can be the reservoir of Salmonella species which cause food borne infections in human. Human get such infections by ingesting contaminated products. In poultry farms, Salmonella can be introduced by means of contaminated feeds, particularly those that contain animal raw materials.
Use of antibiotics in poultry has become a popular practice. Different antibiotics like tetracycline, streptomycin, trimethoprim etc. are given in poultry via water and feed for growth and protection against diseases. Extensive and uncontrolled use of antibiotics resulted in increased development of antibiotic resistant bacteria. Statistical data shows that Salmonella is resistant to many antibiotics especially tetracycline.
The goal of our study was Molecular characterization of tetracycline resistance genes in Salmonella spp. and to check the prevalence of tetracycline resistance genes in Salmonella isolates from poultry drinking water.
Total 50 water samples were collected from different poultry farms and poultry meat shops in Lahore district.Various biochemical tests were performed to confirm the isolated strains as Salmonella. Tetracycline resistance was examined against isolates. Plasmid DNA was extracted from these bacteria. Antibiotic resistant plasmid genes were amplified by PCR. After gel electrophoresis the resulting fragments were sequenced through genetic analyzer. After sequencing the sequence thus obtained was compared with the reported sequences of tet genes in Salmonella strains in NCBI.
It was found out that Salmonella isolates from the poultry drinking water are highly resistant to tetracycline, as 83% of the isolated Salmonella from poultry drinking water showed their resistance towards tetracycline.PCR amplification of tet genes indicated the presence of tetA gene in 100% of tetracycline resistant Salmonella, whereas 64% of the samples contained tetB gene. TetB gene was present only in combination with tetA gene. None of the sample contained tetC, tetD and tetGgene.
This study helped to find out the prevalence of antibiotic resistant genes in Salmonella isolated from poultry drinking water, which were potential threats to human being and this study will also help us in future to develop strategies to restrict the emergence of antibiotic resistant genes and their spread.