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Human and Animal Exposure to Airborne Methicillin-resistant Staphylococcus aureus (MRSA): Laboratory Evaluations and Veterinary Hospital Pilot Study

Lutz, Eric Anthony
http://rave.ohiolink.edu/etdc/view?acc_num=osu1276101615

Abstract Details

2010, Doctor of Philosophy, Ohio State University, Public Health.
Methicillin-resistant Staphylococcus aureus (MRSA) is a significant infectious disease concern in human and veterinary healthcare settings where airborne transmission is suspected. A better understanding of sampling methods used for airborne MRSA surveillance is fundamental for accurately evaluating and successfully controlling the threat. Accordingly, we conducted laboratory and field studies to evaluate methods and risk associated with airborne MRSA. In the laboratory, Methicillin-susceptible Staphylococcus aureus (MSSA) was used as a surrogate for MRSA. Using a laboratory environmental chamber, we systematically evaluated: 1) MSSA particle size distribution, 2) efficiency of two aerosol generating methods (6-jet Collison nebulizer and Bubbler), and 3) recovery and collection of MSSA using three air sampling methods (Gelatine Filter, single-stage Impactor, and Impinger). Generation efficiencies of MSSA were evaluated using the ratio of the number concentration of airborne culturable particles to total particles. Total particle concentrations were evaluated with an aerodynamic particle sizer (TSI, Inc.) and culturable particles were evaluated using standard methods. Differences in generation efficiency were evaluated using a two sample t-test. Sampler performance was evaluated by examining: 1) loss of MSSA spiked onto the sampler over time, and 2) side-by-side measured concentration differences of airborne MSSA collection across a 4-log range aerosolized from the generator reservoir. Sampler recovery and collection comparisons were made using paired t-tests. From these laboratory studies, a pilot-scale field investigation of airborne and surface Staphylococcus spp., was performed within a veterinary hospital during periods of no known clinical Staphylococcal infections. Based on the laboratory studies we observed the aerodynamic particle size of airborne S. aureus at 0.723-0.777 micrometers. The Bubbler (1.16 x 10-4 CFU/particle) was observed to be marginally more efficient (2.6%, p=0.034) than the Collison (1.13 x 10-4 CFU/particle) in producing culturable particles. For sampler recovery, we found mean recoveries of MSSA spiked onto the Filter, Impactor, and Impinger to quickly decrease from the 84%, 52%, and 35%, respectively after 5-minutes, to 7%,4%, and 5%, respectively after 60 minutes with no difference between samplers at any of the five time points (p=0.663). The sampler collection experiments resulted in no difference (p>0.05) observed for average MSSA airborne concentrations collected by the three samplers during side-by-side sampling across a 4-log range in generator reservoir concentrations. The Veterinary Hospital environmental surveillance study detected airborne Staphylococcus spp., in 26% (25/96) of samples and airborne Methicillin-resistant Staphylococcus spp., in 6% (6/96) of samples. Among daytime air samples, detected Staphylococcus spp., were observed to vary by functional area (p=0.000) and airborne Methicillin-resistant Staphylococcus spp., to vary by human (but not animal, p=0.770) activity level (p=0.011). Although our sample size was small (n=20), we found no indication that Staphylococcus spp., detected on surfaces was predictive of detection in air (p=1.000), suggesting that surface sampling is not an effective strategy for characterizing inhalation risk. Taken together, these studies provide means and justification for focused attention on airborne MRSA for stemming this public health threat. Applying these findings to field airborne MRSA surveillance, improvements can be made in the accuracy and precision of exposure classification and determination of risk.
Timothy Buckley, PhD (Advisor)
Armando Hoet, PhD (Committee Member)
Michael Pennell, PhD (Committee Member)
Kurt Stevenson, MD (Committee Member)
186 p.
Occupational Safety; Public Health; Veterinary Services
airborne MRSA; Staphylococcus spp.; environmental surveillance; aerodynamic diameter; particle size distribution; air sampling

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Citations

  • Lutz, E. A. (2010). Human and Animal Exposure to Airborne Methicillin-resistant Staphylococcus aureus (MRSA): Laboratory Evaluations and Veterinary Hospital Pilot Study [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276101615

    APA Style (7th edition)

  • Lutz, Eric. Human and Animal Exposure to Airborne Methicillin-resistant Staphylococcus aureus (MRSA): Laboratory Evaluations and Veterinary Hospital Pilot Study. 2010. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1276101615.

    MLA Style (8th edition)

  • Lutz, Eric. "Human and Animal Exposure to Airborne Methicillin-resistant Staphylococcus aureus (MRSA): Laboratory Evaluations and Veterinary Hospital Pilot Study." Doctoral dissertation, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276101615

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.