Isolation of Bacteria from the Respiratory Tract and Abscesses of Livestock to Test their Antibiotic Sensitivity

This study aimed to identify and classify the bacterial species from various animal body fluids and assess their susceptibility. The research involved the isolation and identification of bacteria from different body fluids (including the mouth and abscesses) of cows and sheep, followed by the evaluation of bacterial susceptibility to drugs conducted after biochemical tests, alongside phenotypic and microscopic diagnostic methods. The 16S rRNA gene was then employed as a molecular technique to confirm the diagnosis. Fifty samples were collected from body fluids between October 2023 and February 2024. Using cotton swabs, animals suffering from abscesses and respiratory infections were used to generate the isolates. The samples were transported to the microbiology laboratory of the College of Education, Qurna, where they were grown on blood agar and MacConkey medium. The samples were incubated at 37°C for 24–48 h. Then, the samples were processed to isolate the bacteria. First, a phenotypic diagnostic methodology was applied. Second, the traditional method relied on biochemical tests targeting bacterial enzymes. Third, the molecular method was based on the 16S rRNA gene, because it is present in all types of bacteria and has nine variable regions that allow the sequence to be compared with the reference sequence in GenBank. The molecular diagnosis showed that the bacteria isolated from the mouth were Staphylococcus microti and Rothia aerolata; for the abscesses, Serratia marcescens and Escherichia coli were identified. According to the study, the samples were compared with sequences available in GenBank to verify the degree of similarity. The isolated bacteria were pathogenic to animals. The isolates demonstrated strong resistance to erythromycin, tetracycline and amoxicillin.