<P> As many as 22 percent of people infected with MRSA do not have any discernable risk factors . </P> <P> People who are hospitalized, including the elderly, are often immunocompromised and susceptible to infection of all kinds, including MRSA; when the infection is by MRSA this is called healthcare - associated or hospital - acquired methicillin - resistant S. aureus (HA - MRSA). Generally, those infected by MRSA will stay infected for just under 10 days, if treated by a doctor, although effects may vary from person to person . </P> <P> Surgical as well as nonsurgical wounds can be infected with HA - MRSA . Surgical site infections (SSI) occur on the skin surface but can spread to internal organs and blood to cause sepsis . Transmission occurs between healthcare providers and patients . This is because some providers may inconsistently neglect to perform hand - washing between examinations . </P> <P> People in nursing homes are at risk for all the reasons above, further complicated by the generally weaker immune systems of the elderly or other residents in need of such care . </P>

Where are the resistance genes found in mrsa