New study reveals how the household environment influences MRSA spread


New findings from the Washington University School of Medicine in St. Louis (MO, USA) and the University of Chicago (IL, USA) reveal how methicillin-resistant Staphylococcus aureus (MRSA) enters the household and what measures we should be taking to reduce spread amongst family members and pets.

The study, published in The Lancet Infectious Diseases, involved 150 children and most of their family members and pets, including 692 people and 154 cats and dogs. The children had a median age of 3 years old and had received medical treatment for Staphylococcus between 2012 and 2015.

Throughout 1 year, the researchers swabbed the family members (nostrils, armpits and groin) and pets (inside nose and on back) during each of their five visits. The team found that, at least once during the year, MRSA was present on nearly half of humans and one third of pets.

In addition, the team swabbed 21 household surfaces such as light switches, telephones and computer keyboards. Each of the 3819 samples were analyzed to determine the complex transmission dynamics of different Staphylococcus strains. The families also answered over 100 questions about their personal hygiene habits.

From the results, the team determined the top factors that cause MRSA to enter the household and spread from person to person. For example, people who wash their hands frequently are less likely to introduce bacteria into their homes, whereas children who attend day-care are more likely to introduce the bacteria into their homes.

Moreover, the bacterium is more likely to spread if there is a notable level of MRSA found on household surfaces. Spread of the bacteria is also more likely when people share hygiene items, beds and towels, or live in crowded or unclean homes.

“The household environment plays a key role in the transmission of MRSA in the community setting,” explained Stephanie A. Fritz, a senior author of the study. “This suggests that aggressive attempts to rid MRSA from household surfaces may significantly lower the number of MRSA infections we’re seeing now.”

Importantly, the study has revealed key transmission-reducing tactics to implement in the household. These include simple hygiene habits such as using antibacterial hand soap, showering instead of taking a bath and brushing teeth twice a day.

With thousands of MRSA infections and 20,000 deaths each year in the US alone, this study and more like it, are vital for helping to prevent MRSA infections.

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Sources: Mork RL, Hogan PG, Muenks CE et al. Longitudinal, strain-specific Staphylococcus aureus introduction and transmission events in households of children with community-associated meticillin-resistant S. aureus skin and soft tissue infection: a prospective cohort study. Lancet Infect. Dis. doi:10.1016/S1473-3099(19)30570-5 (2019);


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