A pilot study of the epidemiology of Staphylococcus aureus in multiple site swine production

Abstract

Staphylococcus aureus (S. aureus) is a common colonizer of both humans and pigs (Lowy, 1998; Frana, 2012). The ability of S. aureus to acquire genes that confer resistance to multiple drugs has further elevated its importance to public health (Cuny and Witte, 2008a). In particular, clones of S. aureus that are resistant to methicillin and other beta-lactam antimicrobials (MRSA) are a major clinical problem, and the discovery of MRSA in livestock populations has raised concerns about the potential importance of livestock as reservoirs of MRSA (Voss et al., 2005).However, the importance of pigs in S. aureus transmission to humans and clinical disease is yet to be determined (Cuny and Witte, 2008b). Most recent studies of pigs have focused on MRSA, and there have been no comprehensive studies of the epidemiology of S. aureus (MSSA and MRSA) in pigs. Despite being considered ubiquitous in production animal facilities (Frana, 2012), S. aureus ecology in livestock production farms is poorly documented. Most recent research has used selective enrichment methods to study MRSA in swine populations, rather than generic S. aureus. S. aureus can be isolated from several anatomic sites of pigs, as well as from air, environmental samples and persons having contact with pigs. In fact, isolation of S. aureus in air samples from swine barns suggests this is likely an important route of exposure for people working in livestock facilities (Gibbs et al., 2006; Oppliger et al., 2012). Overall, the limited information on the ecology of S. aureus in the pork production chain limits the ability of the swine industry to understand and communicate the risks to public health in an informed manner.The core rationale for this thesis was that there has been no prior systematic effort to describe the occurrence of S. aureus in swine production systems. The vast majority of studies have focused on MRSA strains using selective culture methods, and/or focused on a limited number of matrices. The objective was therefore to obtain preliminary data on the occurrence of S. aureus in pigs, people, environmental and air samples on pig farms and some insight into the distribution of the organism in the swine farm milieu. Thus, a pilot study of the epidemiology of S. aureus in multiple site swine production was conducted.