Methicillin resistance in S. aureus is defined as an Oxacillin (MIC) > 4microgram/mL. Isolates resistant to oxacillin or methicillin are alsoresistant to all beta - lactam agents including cephalosporins.

The mecA gene responsible for methicillin resistance

Staphylococcal cassette chromosome (SCCmec).

There are five SCCmec types (I-V) that vary in geneticmakeup and size.

Hospital AssociatedMRSA

Community Associated MRSA

HA - MRSA CA - MRSA

type I, II, or III SCCmec type IV SCCmec

Multiple antibiotic resistance

does not carry the multiple antibiotic resistance

Sensitive to Bactrim, Clindamycin & 50% fluoroquinolones.

Panton-Valentine leukocidin•SCCmec type IV CA-MRSA •skin •soft tissue•necrotizing pneumonia •MRSA USA300Prolonged hospitalization

12-29%

Prior skin infection

Previous antibiotic use

Illicit drug use

Tattoo recipients

Prison residence

Military personnel

A higher body mass index

Cosmetic body shaving

Physical contact with a person who has a draining lesion or is a carrier of MRSA

Sharing equipment that is not cleaned or laundered between users

Antibiotic use within three months before admission.

Hospitalization during the past 12 months.

Diagnosis of skin or soft-tissue infection at admission

HIV infection

Skin or soft tissue infections.

Necrotizing pneumonia.

Necrotizing fasciitis

Rapidly fatal septicemia

Endocarditis

Osteomyelitis