Trends in Microbiology
ReviewStaphylococcus aureus infections: transmission within households and the community
Section snippets
Staphylococcus aureus as a community pathogen
In 1960, Roodyn remarked that ‘even in the comparative simplicity of a single household, the epidemiology of staphylococcal infections appears baffling’ [1]. It has been 54 years since Roodyn's publication on staphylococcal infections in the home, yet many might say that the dynamics of staphylococcal disease in the household, as well as in the community, continue to ‘baffle’ us. Understanding the basis for these community-based infections is critical because they have contributed to the
The intersection of community reservoirs with the household
There is a dynamic interaction between community-based sources of CA-MRSA and the introduction of these clones into the household. This dynamic is perhaps best illustrated by the numerous reported outbreaks of CA-MRSA infections that have occurred in a variety of community-based reservoirs, including sports clubs, daycare facilities, jails, schools, and places of work 15, 16, 17, 18. Humans at these sites may then transport newly acquired strains of CA-MRSA into their homes 7, 17, 27, 28.
The application of WGS to address CA-MRSA transmission in communities
Recent studies have highlighted the limitations of traditional molecular typing tools in understanding the spread of pathogens in both the healthcare and community setting 36, 37. The advent of WGS, with its enhanced ability to discriminate among clones, has provided a greater understanding of how these spread within different settings. In particular, it has allowed for a more accurate determination of whether specific clones are unique or are involved in a transmission event 38, 39.
To date,
Staphylococcus aureus transmission and disease within the household
Several studies have highlighted the role of the household as the primary reservoir for S. aureus in the community 24, 25, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58. The events that follow a CA-MRSA infection in a household include an increase in: (i) the risk of infections among other household members 26, 44, 45, 48, 49, 50, 51; (ii) MRSA colonization among other household members 46, 47, 52, 53, 54, 55, 56, 57, 59; and (iii) contamination of environmental surfaces 24
Limitations of research on the transmission of CA-MRSA within the household
To date, most research identifying risk factors for infection has been primarily restricted to retrospective case-control studies. As a result, studies of CA-MRSA household transmission are often limited to analyses of cross-sectional data collected after a household index infection has occurred. Therefore, neither the directionality nor the source of transmission may be ascertained and shared strains, the standard proxy measure for transmission, potentially indicate a shared exposure. Analyses
Interventions to reduce the incidence of S. aureus infections in the home
As noted above, households with a previously infected individual are at increased risk of recurrent infection 26, 44, 45, 48, 49, 50, 51. In addition to the household risks, patients recently discharged from healthcare facilities with a history of staphylococcal infections or with evidence of S. aureus colonization are also at increased risk of recurrent infection 98, 99. Several studies have investigated the efficacy of intervention strategies to reduce the incidence of recurrent infections in
Concluding remarks and future directions
A combination of epidemiological, genomic, and modeling studies has provided considerable insight into the factors that contribute to the spread of CA-MRSA within the community and the household; however, numerous questions remain. For example, while there has been a major focus on defining the epidemiology of CA-MRSA, methicillin sensitive S. aureus has been relatively understudied and the likely interaction among MRSA and methicillin sensitive S. aureus strain types remains largely undefined.
Acknowledgments
This work was supported by the National Institutes of Health (NIH/NIAID) to F.D.L. (R01 AI077690, R01 AI077690-S1 and R21 AI103562) and to A-C.U. (K08 AI090013) and the Paul A. Marks Scholarship. We appreciate the assistance of Skye Peebles in the preparation of Figure 1.
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