Phenotypic Resistance of Staphylococcus aureus to Antibiotics in Dogs of Tamale Metropolis, Ghana

Introduction: Staphylococcus aureus is an important bacterium which induces a wide range of diseases. Its presence in dogs and resistance to antibiotics is a threat to public health due to the close association of humans with dogs. The objective of the present study was to determine the phenotypic resistance of Staphylococcus aureus (S. aureus) to antibiotics in dogs without any clinical manifestation of diseases in Tamale Metropolis, Ghana. The current study also examined microbial load in these dogs. Materials and methods: A total of 120 samples from various parts of dogs, including the mouth, nose, anus, inner ear, and outer ear, were examined. Isolation and antibiotic resistance of S. aureus were determined using the USA Bacteriological Analytical Manual and the Disc Diffusion method, respectively. Results: The presence of S. aureus in the dogs ranged from 8.3% (anus) to 58.3% (nose), averaging 40%. The microbial load also ranged from 2.9 log cfu/cm2 (mouth) to 3.4 log cfu/cm2 (outer ear) with an average of 3.2 log cfu/cm2. There were significant differences among the examined samples regarding the presence of S. aureus, but not the microbial load. The overall resistance, intermediate resistance, and susceptibility of S. aureus were 46.2%, 12.9%, and 42.2%, respectively. The S. aureus was highly resistant to teicoplanin (88.0%) and susceptible to chloramphenicol (72.0%). The multiple antibiotic indexes ranged from 0 to 0.9, and 89.1% of the isolates exhibited multidrug resistance. Conclusion: The findings of the current study revealed that healthy dogs in Tamale Metropolis, Ghana, were carriers of S. aureus as well as other bacteria, and the S. aureus exhibited different resistance patterns to antibiotics.