Households can serve as a reservoir for transmitting meticillin-resistant Staphylococcus aureus (MRSA) and once the organism enters a home it can linger for years, spreading from person to person and evolving genetically to become unique to that household. MRSA are strains of the bacterium Staphylococcus aureus that are resistant to almost all beta-lactam antibiotics and since the 1990s community-associated MRSA infections (mostly skin infections) have been on the rise in healthy people.
This latest study used advanced gene-fingerprinting techniques to show that MRSA isolated within households clustered into closely related groups, suggesting a single common ancestral strain was introduced to and transmitted within each household. Researchers also determined from a technique called Bayesian evolutionary reconstruction that USA300 MRSA persisted within households from 2.3 to 8.3 years before the samples were collected, were able to estimate the speed of evolution in these strains and also showed they continued to continued to exchange genetic material (DNA) with other organisms – a principal way resistance is spread.
They found that MRSA strains within households were more similar to each other than those from different households and when MRSA gets into a household it can stay there for years moving from person to person.