Typical differences between HA-MRSA and CA-MRSA
| Parameter | HA-MRSA | CA-MRSA |
| Typical patient | Elderly, debilitated and/or critically or chronically ill | Young healthy people, students, professional athletes and military personnel |
| Infection site | Often bacteraemia with no obvious source of infectionAlso surgical wounds, open ulcers, i.v. lines and catheter urinesMay cause ventilator-associated pneumonia | Predilection for skin and soft tissue producing cellulitis and abscessesMay cause necrotising community-acquired pneumonia, septic shock or bone and joint infections |
| Transmission | Within healthcare settings; little spread among household contacts | Community acquired; may spread in families and sports teams |
| Clinical setting of diagnosis | In an in-patient setting, but increasingly HA-MRSA infections in soft tissue and urine are occurring in primary care | In an outpatient or community setting |
| Medical history | History of MRSA colonisation, infection or recent surgery; admission to a hospital or nursing home; antibiotic use; dialysis, permanent indwelling catheter | No significant medical history or healthcare contact |
| Virulence of infecting strain | Community spread is limited PVL genes usually absent | Community spread occurs easily PVL genes often present, predisposing to necrotising soft tissue or lung infection |
| Antibiotic susceptibility | Often multiresistant with the result that the choice of agents is often very limited | Generally susceptible to more antibiotics than HA-MRSA |
HA-MRSA: hospital-associated methicillin-resistant Staphylococcus aureus; CA-MRSA: community-acquired methicillin-resistant Staphylococcus aureus. PVL: Panton–Valentine leukocidin. Reproduced from 17 with permission from the publisher.