Transmission of Methicillin-Resistant Staphylococcus aureus to Household Contacts

Methicillin-resistant Staphylococcus aureus (MRSA) is currently the most prevalent antibiotic-resistant pathogen in hospitals in many parts of the world, and there are a growing number of reports describing its increasing prevalence in various community populations (10-12). MRSA is an important cause of infections, and MRSA infections are increasing in both health care centers and the community. Compared to methicillin-sensitive Staphylococcus aureus (MSSA), infections with MRSA are more difficult to treat and tend to have a poorer outcome (2, 8). Carriage of MRSA is a prerequisite for most MRSA infections and plays an important role in the dissemination of this organism within health care facilities and into the community (3, 6, 7, 9). In the Netherlands, due to the “search-and-destroy” infection control policy and a strict antibiotic policy, the number of patients colonized with MRSA is still very limited (13, 31, 34). The “Destroy” part of this policy is important, as it eliminates two out of the three known reservoirs, carriage in patients and carriage in health care workers (HCWs), whereas the third reservoir is the environment. But even in low-prevalence countries like the Netherlands, the emergence of community-acquired MRSA has caused a change in MRSA epidemiology and an increasing number of MRSA cases (13). In the past, it has been shown that carriers of Staphylococcus aureus and MRSA can be a source of transmission of these pathogens to their household contacts (5, 17, 18, 21, 26). The exact risk factors for transmission of MRSA to household contacts have not been studied properly, but close contact, the environment, or being an HCW are thought to be plausible risk factors for transmission (28, 29, 32). The contribution of transmission in households to the MRSA burden has not yet been studied, and because of lack of data and well-calculated scenarios, no evidence-based policy for this reservoir has been developed. For this reason, being a household contact of a MRSA carrier has not yet been established as a risk group for MRSA under the Dutch “search-and-destroy” policy. The aims of this study are to gain insight in the frequency of and risk factors for transmission of MRSA to household contacts and therefore into the community. (The work was presented in part at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy—Infectious Diseases Society of America [ICAAC/IDSA], 24 to 28 October 2008, Washington, DC [24a].)