Assessment and mitigation of airborne transmission of methicillin-resistant Staphylococcus Aureus in animal feeding operations and the outdoor environment

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) was originally recognized as a hospital acquired infection. However, it is now recognized that MRSA infections are frequently acquired in the community and agricultural settings as well. As epidemiological studies and surveillance of MRSA continued over the past decade, agricultural sources of MRSA have also been recognized. Although direct person-toperson transmission of MRSA has been recognized as a major known route of transmission, a preliminary study has shown that aerosol exposures may also be an important mechanism of transmission, both occupationally to workers inside animal feeding operations and environmentally via exhaust ventilation to the outside. In this study I aimed to 1) determine the concentration of viable MRSA inside and outside swine buildings known to be positive for MRSA, 2) determine the efficiency of the N-95 respirator for potentially protecting workers inside swine buildings, and 3) determine the efficiency of a biofilter unit for mitigating emissions of MRSA from a swine building. I hypothesize that remediation and control of airborne MRSA in animal feeding operations can be achieved by the appropriate use of N-95 respirators to protect workers and the addition of biofilters to the exhaust ventilation system to mitigate transmission of this emerging environmental contaminant to the outdoor environment. The results of the study indicate that aerosolized MRSA in the respirable size range can be detected inside a swine building and 215 m downwind of the swine building. Aim 2 results indicated that the N95 respirator was efficient at potentially protecting workers exposed to MRSA particles greater than 5 µm but not as effective with MRSA particles less than 5 µm. The viii TABLE OF CONTENTS LIST OF TABLES .