Having a first-degree relative, especially a sibling, with a history of staph infection significantly increases a person's risk for the disease, regardless of sex of the family member, comorbid conditions, or direct contamination. The results of a large national study are published in Annals of Internal Medicine.

The incidence of Staphylococcus aureus bacteremia, or staph infection, has increased over the past few decades, with antibiotic resistance adding to the problem. Animal studies have shown a link between host genetics and staph infection, but whether human host genetics in general are associated with the risk for acquiring staph infection is unclear. This knowledge could have important implications for influencing future therapeutic interventions and strategies.

Researchers reviewed a national registry in Denmark to determine whether a history of S. aureus bacteremia in first-degree relatives is associated with an increased risk for microbiologically confirmed S. aureus bacteremia. They found that having a first-degree relative hospitalized with confirmed staph infection significantly increased a person's risk for the disease. The risk was significantly higher if the infected patient was a sibling than a parent. According to the researchers, the results are unlikely to be explained by direct transmission of the pathogen because more than 80 percent of exposed individuals acquiring staph were infected with a strain genetically different from the infected relative.