Molecular Identification of Genes Resistant to Antibiotics in Staphylococcus aureus Isolated from Sub-clinical Animals Affected by Mastitis

Abstract

Background and Aim: Mastitis is a prevalent and costly disease that significantly impacts the dairy industry, affecting both sheep's health and milk quality. In order to determine the bacterial causes of subclinical mastitis in Iraq and its susceptibility to antibiotics, the study aims to molecularly detect resistant Staphylococcus aureus isolated from sheep infected with mastitis. Methods: Molecular assay and phylogenetic study to detect Staph aureus isolates by using 16 Sr RNA and resistance virulence genes (aac-aph, tetk) by the conventional method of PCR. Two hundred samples were collected from the subclinical mastitis of infected ewes, Samples were reserved on an icebox and transported to the laboratories. Milk samples were cultured on Blood Agar and Mannitol Salt Agar (7.5%) plates. The culture plates were then incubated at 37°C for 24 hours. Results: The PCR assay revealed amplification of the 16S rRNA gene in all 20 isolates, amplification of the aac-aph gene in 19 isolates, and the tetK gene in all 20 isolates. The PCR products of 20 positive samples for (16 Sr RNA) target genes were sequenced, evaluated, and dropped on the Genbank-NCBI under the accession number, which became a reference to Iraq and the world. According to the current study, Staphylococcus aureus is commonly found in milk. To combat drug resistance, antimicrobial drug use should be normalized, and antimicrobial resistance surveillance should be conducted regularly. Conclusion: PCR-product of 8 positive samples for 16sr RNA target gene were sequenced, analyzed, and deposited on the Genbank-NCBI under the accession number and became a reference to Iraq and the Middle East and the world.