Preliminary screening of cloxacillin susceptibility in staphylococcal species isolated from healthy dogs presented to Veterinary Teaching Hospital, University of Peradeniya, Sri Lanka

Staphylococcus spp are part of the normal flora of the skin of dogs where it is also found as an opportunistic pathogen. Antimicrobial resistance is changing over time and is generally rising steadily for those antimicrobials that are frequently used. The cloxacillin susceptibility of staphylococcus isolates from 30 healthy dogs, presented to the Veterinary Teaching Hospital, University of Peradeniya, Sri Lanka was investigated in this study. Samples collected from both the ear canals and the skin of each dog were initially grown on nutrient agar identified using conventional biochemical methods. Out of the 64 Staphylococci isolates, 36(56.25%) were obtained from the skin surface and 28 (43.75%) isolates from the ear canals. The susceptibility of 64 isolates to cloxacillin was examined by cloxacillin-added agar medium (5μg/ml). Out of 64 isolates, 14 isolates (21.87%) of Staphylococcus spp were resistant to cloxacillin and 7 (50%) of them were S. aureus which was confirmed by biochemical tests. Out of 28 isolates of Staphylococcus spp from the ear canal, 2 (7.14%) isolates were resistant to cloxacillin, and out of 36 isolates from the skin, 12 (33.34%) isolates were resistant to cloxacillin. A high number of cloxacillin-resistant Staphylococci isolated from dogs reflects the emergence of cloxacillin-resistant strains of Staphylococcus spp. This signals the need for antibiotic susceptibility testing in order to choose antimicrobial agents to treat diseases caused by resistant Staphylococcus spp and also paves the way for future studies paying more attention regarding development of cross-resistance to other antibiotics by these resistant strains.