Abstract
ObjectivesAdministration of antibiotics to food animals may select for drug-resistant pathogens of clinical significance, such as methicillin-resistant Staphylococcus aureus (MRSA). In the United States, studies have examined prevalence of MRSA carriage among individuals exposed to livestock, but prevalence of multidrug-resistant S. aureus (MDRSA) carriage and the association with livestock raised with versus without antibiotic selective pressure remains unclear. We aimed to examine prevalence, antibiotic susceptibility, and molecular characteristics of S. aureus among industrial livestock operation (ILO) and antibiotic-free livestock operation (AFLO) workers and household members in North Carolina.MethodsParticipants in this cross-sectional study were interviewed and provided a nasal swab for S. aureus analysis. Resulting S. aureus isolates were assessed for antibiotic susceptibility, multi-locus sequence type, and absence of the scn gene (a marker of livestock association).ResultsAmong 99 ILO and 105 AFLO participants, S. aureus nasal carriage prevalence was 41% and 40%, respectively. Among ILO and AFLO S. aureus carriers, MRSA was detected in 7% (3/41) and 7% (3/42), respectively. Thirty seven percent of 41 ILO versus 19% of 42 AFLO S. aureus-positive participants carried MDRSA. S. aureus clonal complex (CC) 398 was observed only among workers and predominated among ILO (13/34) compared with AFLO (1/35) S. aureus-positive workers. Only ILO workers carried scn-negative MRSA CC398 (2/34) and scn-negative MDRSA CC398 (6/34), and all of these isolates were tetracycline resistant.ConclusionsDespite similar S. aureus and MRSA prevalence among ILO and AFLO-exposed individuals, livestock-associated MRSA and MDRSA (tetracycline-resistant, CC398, scn-negative) were only present among ILO-exposed individuals. These findings support growing concern about antibiotics use and confinement in livestock production, raising questions about the potential for occupational exposure to an opportunistic and drug-resistant pathogen, which in other settings including hospitals and the community is of broad public health importance.
Highlights
Staphylococcus aureus is an opportunistic pathogen carried by animals and approximately one third of humans, primarily in the nares [1]
Despite similar S. aureus and methicillin-resistant Staphylococcus aureus (MRSA) prevalence among industrial livestock operation (ILO) and antibiotic-free livestock operation (AFLO)-exposed individuals, livestock-associated MRSA and multidrugresistant strains of S. aureus (MDRSA) were only present among ILO-exposed individuals. These findings support growing concern about antibiotics use and confinement in livestock production, raising questions about the potential for occupational exposure to an opportunistic and drug-resistant pathogen, which in other settings including hospitals and the community is of broad public health importance
Recognition of the prominence of community-acquired compared with hospital-acquired infections [6], the importance of MDRSA as causes of infection [7], and the role of nasal carriage, which has been shown to increase the risk of subsequent S. aureus infection in clinical settings [8], is increasing
Summary
Staphylococcus aureus is an opportunistic pathogen carried by animals and approximately one third of humans, primarily in the nares [1]. S. aureus causes a range of human infections, from superficial to systemic [2] and strains resistant to methicillin (MRSA) have become leading causes of morbidity and mortality in the United States [3,4]. Recognition of the prominence of community-acquired compared with hospital-acquired infections [6], the importance of MDRSA (that are not necessarily resistant to methicillin) as causes of infection [7], and the role of nasal carriage, which has been shown to increase the risk of subsequent S. aureus infection in clinical settings [8], is increasing. The origins and routes of transmission of community-acquired S. aureus infection as well as reservoirs of selective pressure that drive emergent strains and drug resistance remain poorly characterized in the United States [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
