Livestock-Associated and Non-Livestock-Associated Staphylococcus aureus Carriage in Humans is Associated with Pig...

The distinction between livestock-associated and human-associated methicillin-resistant Staphylococcus aureus (MRSA) has become more and more blurred. This study aimed to reveal the transmission risk of livestock-associated and non-livestock-associated S. aureus (including MRSA and multidrug-resistant S. aureus [MDRSA]) by occupational pig exposure.

A total of 591 pig-exposed workers and 1178 non-exposed workers were enrolled in this study. All nasal S. aureus isolates were tested for antibiotic susceptibility and molecular characteristics. Logistic regression models were used to examine the dose-response relationships between occupational pig exposure and S. aureus carriage.

Pig-exposed workers had significantly higher carriage rates of MRSA (OR=6.29, 95% CI: 3.38~11.68) and MDRSA (OR=3.17, 95% CI: 2.03~4.96) than non-exposed workers. Notably, we found dose-response relationships between occupational pig exposure and MRSA or MDRSA carriage. Using genotypic and phenotypic markers for differentiating livestock-associated and non-livestock-associated S. aureus, we also revealed dose-response relationships occupational pig exposure and livestock-associated or non-livestock-associated S. aureus carriage.

Our findings provide sufficient epidemiological evidence for revealing the high transmission risk of livestock-associated S. aureus and the low transmission risk of non-livestock-associated S. aureus by occupational pig exposure.