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. 2014 May;122(5):471-7.
doi: 10.1289/ehp.1306741. Epub 2014 Feb 7.

Multidrug-resistant and methicillin-resistant Staphylococcus aureus (MRSA) in hog slaughter and processing plant workers and their community in North Carolina (USA)

Ricardo Castillo Neyra  1 , Jose Augusto Frisancho, Jessica L Rinsky, Carol Resnick, Karen Colleen Carroll, Ana Maria Rule, Tracy Ross, Yaqi You, Lance B Price, Ellen Kovner Silbergeld
Affiliations

Multidrug-resistant and methicillin-resistant Staphylococcus aureus (MRSA) in hog slaughter and processing plant workers and their community in North Carolina (USA)

Ricardo Castillo Neyra et al. Environ Health Perspect. 2014 May.

Abstract

Background: Use of antimicrobials in industrial food-animal production is associated with the presence of antimicrobial-resistant Staphylococcus aureus (S. aureus) among animals and humans. Hog slaughter/processing plants process large numbers of animals from industrial animal operations and are environments conducive to the exchange of bacteria between animals and workers.

Objectives: We compared the prevalence of multidrug-resistant S. aureus (MDRSA) and methicillin-resistant S. aureus (MRSA) carriage among processing plant workers, their household members, and community residents.

Methods: We conducted a cross-sectional study of hog slaughter/processing plant workers, their household members, and community residents in North Carolina. Participants responded to a questionnaire and provided a nasal swab. Swabs were tested for S. aureus, and isolates were tested for antimicrobial susceptibility and subjected to multilocus sequence typing.

Results: The prevalence of S. aureus was 21.6%, 30.2%, and 22.5% among 162 workers, 63 household members, and 111 community residents, respectively. The overall prevalence of MDRSA and MRSA tested by disk diffusion was 6.9% and 4.8%, respectively. The adjusted prevalence of MDRSA among workers was 1.96 times (95% CI: 0.71, 5.45) the prevalence in community residents. The adjusted average number of antimicrobial classes to which S. aureus isolates from workers were resistant was 2.54 times (95% CI: 1.16, 5.56) the number among isolates from community residents. We identified two MDRSA isolates and one MRSA isolate from workers as sequence type 398, a type associated with exposure to livestock.

Conclusions: Although the prevalence of S. aureus and MRSA was similar in hog slaughter/processing plant workers and their household and community members, S. aureus isolates from workers were resistant to a greater number of antimicrobial classes. These findings may be related to the nontherapeutic use of antimicrobials in food-animal production.

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Conflict of interest statement

No commercial party with a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. The authors declare they have no actual or potential competing financial interests.

Figures

Figure 1
Figure 1
Heat map showing the pattern of anti­microbial resistance of the 78 isolates of S. aureus. Each row represents one isolate tested for susceptibility from a S. aureus–positive participant. Antimicrobial resistance was assessed by disk diffusion and cutoffs defined by CLSI (2008) guidelines; resistance to cefoxitin was classified as either susceptible or resistant, based on CLSI (2008) guidelines.
Figure 2
Figure 2
S. aureus sequence type diversity and distribution. Sequence types were based on seven housekeeping genes that were derived from whole genome sequences of each isolates.
See this image and copyright information in PMC

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