Methicillin-resistant (preferrably called oxacillin-resistant) Staphylococcus aureus (MRSA, ORSA) is widespread around the world, posing ever increasing problems for control and treatment. Two distinct forms are present, differing in epidemiology and genetic content. The hospital-acquired form has been associated with a number of healthcare-related risk factors, while the community-acquired form may spread in persons without any of these risk factors.


Risk factors for hospital-acquired MRSA:

(1) prolonged hospitalization

(2) therapy with broad-spectrum antibiotics

(3) therapy with multiple antibiotics

(4) prolonged therapy with antibiotics

(5) admission to a burn or intensive care unit

(6) presence of a surgical wound

(7) contact or close proximity to a patient with hospital-acquired MRSA

(8) enteral feeding

(9) mechanical ventilation

(10) previous history of colonization with hospital-acquired MRSA

(11) insertion of an intravascular catheter


Risk factors for community-acquired MRSA:

(1) prison inmate

(2) participation in a contact sport (football, wrestling, rugby)

(3) other sports (fencers, divers)

(4) child, especially if attending a day care center

(5) homosexual male

(6) soldier

(7) homeless person

(8) intravenous drug user

(9) member of certain ethnic groups (Eskimos, Native Americans, Pacific Islanders)

(10) use of a contaminated sauna

(11) previous history of colonization with community-acquired MRSA


Factors affecting spread of community-acquired MRSA:

(1) poor hygiene

(2) recent or frequent exposure to antibiotics

(3) contact with someone with a skin or soft tissue infection

(4) crowded living conditions


The epidemiologic distinction between hospital-acquired and community-acquired MRSA is blurring as the prevalence of both forms is increasing. The genetic information in the community-acquired form is smaller and easier to pass, so may become the predominant form.


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