Infection with methicillin-resistant Staphyloccocus aureus, better known as MRSA, is usually associated with places like hospitals and nursing homes. But a new study in the journal Proceedings of the National Academy of Sciences shows households can also be a reservoir for MRSA, particularly a strain called USA300.
The study, conducted by researchers from Columbia University Medical Center, the Wellcome Trust Sanger Institute and the University of Cambridge, involved genome sequencing of 387 isolates of the USA300 strain of MRSA that were taken from 161 MRSA infections that occurred in New York City between 2009 and 2011.
The researchers found that the strain likely emerged in 1993 when it diverged from its ancestor. In addition, researchers "observed that most USA300 isolates had become endemic in households, indicating their critical role as reservoirs for transmission and diversification," they wrote in the study.
Specifically, swabs taken from the homes of the MRSA patients showed that the MRSA was genetically similar to the MRSA that infected the patients from those households. Meanwhile, MRSA samples between households were more genetically different from each other, HealthDay reported.
Researchers also found that genetic mutations in the mid-1990s likely were responsible for the bacteria's resistance to the fluoroquinolone antibiotics.
MRSA are resistant to many different kinds of antibiotics that are typically used to treat staph infections. MRSA that's spread in a community setting, versus a health-care setting, is spread through skin-to-skin contact, and often appears first as a skin boil, according to the Mayo Clinic.
While staph bacteria is commonly carried in people's noses -- one in three people -- MRSA in particular is carried in two out of 100 people, according to the Centers for Disease Control and Prevention.