Prevalence and Characterization of Staphylococcus aureus Isolated from Bulk Tank Milk Dairy Cow Farms in West Bank-Palestine

Aims: The current study aimed to characterize and document the occurrence of Methicillin-sensitive S. aureus (MSSA) and Methicillin-resistant S. aureus (MRSA) in bulk tank milk (BTM) samples, farm workers and the environmental surfaces from bovine dairy farms, antibiotic resistance rate, and genetic characterization of clones for both MSSA and MRSA using Enterobacterial Repetitive Intergenic (ERIC-PCR) and Staphylococcal protein A (spA) gene typing.

Methodology: A total of 57 bovine BTM samples, 45 samples from farm environmental surfaces and 16 nasal swab samples from farm workers, were collected from 12 bovine dairy farms in the Jenin district in northern West Bank-Palestine, between September and October, 2017.

Results: Results of this research showed that 83.3% of farms had at least one BTM sample contaminated with Staphylococcus aureus. Also, 75% and 58.3% of farms had contaminated environmental surfaces and farm worker carriers with S. aureus, respectively. Also, it showed that 58.3% of farms had at least one BTM sample contaminated with MRSA, while 50% of farms had MRSA contaminated environmental surfaces and MRSA farm worker carriers. Results of the current study also showed that 68.4% and 45.6% of bovine BTM samples were contaminated with S. aureus and MRSA, respectively. S. aureus recovered from different sources showed a high level of resistance to many different antibiotics. Also, results of this study showed that 100% and 69.2% of MRSA and MSSA strains, respectively, isolated from BTM samples were multi-drug resistant (MDR). ERIC-PCR profile and spa typing showed that some strains of the same clone had been isolated from diverse sources from different farms. This evidence suggested that these strains of the same clone or spa type could be circulated between cattle, environment, and humans.

Conclusion: Results of this study showed that Palestine BTM samples are a common source of MRSA. The presence of MRSA isolates in BTM may present a potential public health risk. Therefore, careful monitoring of the resistance status of S. aureus in cattle, farm workers, and dairy environmental surfaces is required due to some clones that circulate among them and play a major threat to farm workers who are in close contact with cattle.