Isolation of Staphylococcus Aureus and factors for colonization at a selected animal clinic in Kampala, Uganda

Abstract

Background: Staphylococcus aureus (S. aureus) colonizes numerous body sites and is one of the most frequently isolated bacteria associated with nosocomial infections worldwide. Treatment with antibiotics remains the cornerstone for control of these infections but this has been hampered by the emergence of resistant S. aureus which are shared pathogens of both medical and veterinary importance. Whereas comprehensive data on dynamics of body site colonization and antibiotic-resistant strains in animals and humans is available elsewhere, related information is very limited in sub-Saharan Africa including Uganda. Methods: A total of 303 swabs (156 swabs from out-patient dogs, 122 swabs from humans and 25 swabs from environmental surfaces) were collected and cultured for S. aureus. The isolates were subjected to a panel of 9 antibiotics and the drug resistance patterns determined. The isolates were then tested for the presence of the mec A and tet M genes using a conventional PCR. Results: The overall prevalence of S. aureus was 11.9% (36/303). Prevalence as per sample type was reported as 10.9% (17/156), 11.5% (14/122) and 20.0% (5/25) in pets, humans and the environment respectively. There was no significant difference in the prevalence of S. aureus isolated from pets, humans and the clinic environment. Nevertheless, monthly pet house cleaning frequency was a significantly associated with S. aureus prevalence in dogs (p=0.001). The highest resistance was observed against penicillin (100%), followed by resistance against tetracycline (70.6% to 100%). There was no resistance observed against gentamicin. The overall burden of MDR S. aureus was 75.0% (27/36). The tet M gene was detected in 47.2% (17/36) S. aureus isolates. Conclusion: Dogs had the highest prevalence of S. aureus compared to humans and the environment. There was no resistance observed against gentamycin making it the best drug of choice of drug to deal with S. aureus isolates in the event that there was an infection. Multidrug-resistant S. aureus colonizes both animate and inanimate surfaces and therefore these can be means of sharing MDR S. aureus. Resistance gene tet M was detected from S. aureus isolated irrespective of their phenotypic resistance and therefore care should be taken on use of antibiotics to avoid development of induced resistance. Lastly monthly pet house cleaning frequency was the only significant factor for colonization with S. aureus, suggesting that infections could be escalated by poor cleaning practices.