Investigation of Antibiotic Susceptibility Patterns in Bacteria Isolated During a Male Sheep Castration Surgery

There are different antibiotic resistance profiles among Yersinia spp. This pathogenic bacterium causes yersiniosis worldwide, requiring testing the organism's susceptibility in the local environment. An antibiotic susceptibility profile of a Yersinia spp. isolated from a castration surgical site were analyzed to provide insight into selecting appropriate antibiotics to treat Yersinia spp. infections while addressing antibiotic resistance issues effectively. The surgical site was swabbed before castration and cultures were performed. Samples of the surgical site were taken after the procedure, cultured, and then incubated. CLSI ۲۰۲۰ guidelines were followed for interpreting antibiotic susceptibility tests. The Kirby-Bauer disk diffusion method was applied to understand antibiotic susceptibility and resistance patterns better, and a zone of inhibition measurement was used to determine the zone of inhibition. Staining and microscopic examination of swab samples after surgery revealed a single colony of gram-negative bacteria. Laboratory tests confirmed that the isolated Gram-negative bacilli were indeed Yersinia spp. Methyl Red and Voges-Proskauer tests showed negative results, while Citrate utilization testing demonstrated a positive effect. A positive impact was obtained for Yersinia spp. in the glucose fermentation test. Specifically, nitrofurantoin showed a significant zone of inhibition of over ۱۷ mm, and gentamicin showed a more than ۲۷ mm zone. However, resistance to ampicillin (۱۱ mm), ceftriaxone, and cefazolin was observed. Due to the observed resistance to antibiotics, our results indicate that nitrofurantoin and gentamicin are likely to be the best options for treating Yersinia spp., in contrast to ampicillin, cefazolin, and ceftriaxone, which may be unsuitable because of resistance.

Keywords:

Ampicillin , Antibiotic Susceptibility , Bacterial identification , Drug resistance , Yersinia spp