Antibiotic-Resistant Staphylococcus Strains Isolated from Ocular Samples of Healthy Calves

Healthy calves and cattle can also carry bacteria in their conjunctival flora. These bacteria may cause an infection when the immune system is compromised due to many reasons. The objective of this study was to assess the prevalence and antimicrobial resistance patterns of methicillin-resistant Staphylococcus strains isolated from ocular swabs of healthy calves. One hundred healthy calves were subjected to the collection of fresh ocular swab samples from both eyes. The bacteriological analysis was performed using the classical culture method and confirmation, and antimicrobial resistance of the isolates was done with the BD Phoenix identification system. Further characterization of the strains was completed by PCR analysis. Fifteen Staphylococcus strains (7.5%) were isolated and confirmed by the automatized system. The most common strain isolated in the current study was S. equorum (33.3%). The highest resistance rate against Staphylococcus strains was determined against erythromycin (73%) followed by tetracycline, and clindamycin (60%), whereas none of the strains was resistant to amikacin, daptomycin, linezolid, teicoplanin, and vancomycin. Although 46.7% and 53.3% of strains harbored tet(K) and erm(C) resistance genes, no virulence and mec genes were detected in the present study. The presence of antimicrobial-resistant strains in the ocular flora of healthy calves indicates that it could potentially act as a source of infection.