Prevalence and Ecology of Zoonotic Methicillin Resistant S. aureus and its Relation to Biofilm Formation

Abstract

The high zoonotic importance of Staphylococcus aureus and the increasing rates of isolation of methicillin resistant traits from both clinical and subclinical cases pose a major threat to human health and animal industry. The aim of this study was to monitor methicillin-resistant isolates of S. aureus recovered from milk, human and environmental samples in a small holder dairy unit, detection of their antibiotic resistance and their relation to biofilm formation. Seventy-five milk samples besides 150 different environmental samples including (bulk milk tank swabs, water trough swabs, feeding manager swabs, milk machine swabs, and bedding) and 50 nasal and attendants' hand swabs from animal attendants were collected using stratified random sampling technique. Samples were aseptically cultured for isolation of S. aureus that was confirmed using molecular assays. Antibiotic sensitivity pattern and biofilm formation using disc diffusion and Congo red method, respectively were detected. Resistant isolates were screened for Mec A and Ica A genes. The highest isolation percentage (64.0%) was obtained from manager followed by milk machine swabs (60.0%). All strains showed complete resistance to cefoxitin and ampicillin (100.0% each) and varying degrees of resistance to other used antibiotics. Mec A gene was detected in 5 out of 6 examined isolates meanwhile Ica A gene was detected in all the tested isolates. It can be concluded that the environment considered the link between animal and human infections through poor standards of hygiene and a possible cross relation between antibiotic resistance particularly to methicillin and biofilm formation was also observed.