Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), strains of MRSA that are able to infect otherwise healthy people outside of hospital settings, emerged in the late 1990s and have recently arisen in many countries around the globe. CA-MRSA strains are usually distinguished from their HA-MRSA counterparts by the following characteristics: Firstly, CA-MRSA strains are usually susceptible to non-lactam antibiotics. Secondly, CA-MRSA harbors type IV and V SCCmec elements, which are shorter than the traditional type I, II, and III SCCmec elements found in HA-MRSA strains. Thirdly, certain successful clones are associated with outbreaks of CA-MRSA infections reported in specific geographical locations. For example, ST1 and ST8 isolates are mostly reported in the USA and Canada, ST80 isolates are commonly found in Europe, and ST59 isolates are encountered in the Asia-Pacific region. Notably, all these characteristics have substantial limitations for discriminating CA-MRSA isolates due to their complex backgrounds. Although there were more and more studies of CA-MRSA in European countries and the US, few national epidemiological data were available about China. In this study, we investigated the epidemiological, clinical and molecular characteristics of CA-MRSA isolates recovered in Chinese hospitals, in order to understand the changing epidemiology of MRSA in China.

Eligibility criteria:

1. Inclusion criteria: Patients (Child, Adult) with infections caused by S. aureus from the sites as follows: blood stream, skin or soft tissue, cerebrospinal fluid, bone and joint, genitourinary tract, infection of indwelling intravascular device, surgical wound, respiratory tract (organism grown from sputum and infiltrate on chest X-ray), peritoneal fluid or other otherwise sterile body fluids.
2. Exclusion criteria: Patients with S. aureus from anterior nares or throat swabs cultures (colonization).

Outcome measures:

1. Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection rates in patients with S. aureus infections in Chinese hospitals.
2. Risk factors and clinical outcomes of CA-MRSA infection
3. Molecular characteristics of CA-MRSA isolates recovered in Chinese hospitals.

Definition:

A MRSA infection was considered to be HA-MRSA by the CDC epidemiologic definitions if, in the year prior to culture, the subject had surgery, hospitalization, hemodialysis or a stay in a long-term care facility, if an indwelling vascular catheter was in place at the time of culture, or if the subject was an inpatient hospitalized for 2 days at the time of culture. Otherwise, the subject was considered to have a CA-MRSA infection.

Inclusion Criteria:

• Patients (Child, Adult) with infections caused by S. aureus from the sites as follows: blood stream, skin or soft tissue, cerebrospinal fluid, bone and joint, genitourinary tract, infection of indwelling intravascular device, surgical wound, respiratory tract (organism grown from sputum and infiltrate on chest X-ray), peritoneal fluid or other otherwise sterile body fluids.

Exclusion Criteria:

• Patients with S. aureus from anterior nares or throat swabs cultures for colonization screening purpose.

All child and adult patients with Staphylococcus aureus visited any of the 60 particitant hospitals during the study period were included.