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Updated: Apr 19, 2026
Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus
Published on: March 10, 2017
Transmission through air as a possible route of exposure for MRSA
Marian E H Bos1, Koen M Verstappen2, Brigitte A G L van Cleef3,4
1Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
Abstract:
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pigs and veal calves. The environment and air in pig and veal calf barns is often contaminated with LA-MRSA, and can act as a transmission source for humans. This study explores exposure-response relationships between sequence type 398 (ST398) MRSA air exposure level and nasal ST398 MRSA carriage in people working and/or living on farms. Samples and data were used from three longitudinal field studies in pig and veal calf farm populations. Samples consisted of nasal swabs from the human participants and electrostatic dust fall collectors capturing airborne settled dust in barns. In both multivariate and mutually adjusted analyses, a strong association was found between nasal ST398 MRSA carriage in people working in the barns for >20 h per week and MRSA air levels. In people working in the barns < 20 h per week there was a strong association between nasal carriage and number of working hours. Exposure to ST398 MRSA in barn air seems to be an important determinant for nasal carriage, especially in the highly exposed group of farmers, next to duration of contact with animals. Intervention measures should therefore probably also target reduction of ST398 MRSA air levels.
Insights
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in farm environments poses risks to humans. Reducing airborne LA-MRSA levels is crucial for preventing nasal carriage in farm workers.
Area of Science:
- Veterinary Microbiology
- Public Health
- Environmental Health
Background:
- Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is common in pigs and veal calves.
- Contaminated barn environments and air can transmit LA-MRSA to humans.
- Sequence type 398 (ST398) is a prevalent strain in livestock.
Purpose of the Study:
- To investigate the relationship between airborne ST398 MRSA exposure and nasal carriage in farm personnel.
- To identify risk factors for ST398 MRSA nasal carriage in individuals working or living on farms.
Main Methods:
- Utilized data from three longitudinal field studies involving pig and veal calf farms.
- Collected nasal swabs from human participants and airborne settled dust samples using electrostatic dust fall collectors.
- Performed multivariate and mutually adjusted analyses to assess exposure-response relationships.
Main Results:
- A significant association was found between higher airborne ST398 MRSA levels and nasal carriage in individuals working >20 hours/week in barns.
- For those working <20 hours/week, nasal carriage was strongly associated with the number of working hours.
- Airborne ST398 MRSA exposure is a key factor for nasal carriage, particularly for highly exposed farm workers.
Conclusions:
- Airborne ST398 MRSA exposure is an important determinant of nasal carriage in farm workers.
- Duration of contact with animals and airborne exposure levels are critical factors.
- Intervention strategies should focus on reducing airborne ST398 MRSA levels in farm environments.
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