title: Clinical and laboratory features of invasive community-onset methicillin-resistant Staphylococcus aureus infection: a prospective case-control study.
abstract: Differences between the features of invasive community-onset methicillin-resistant Staphylococcus aureus (cMRSA) and methicillin-susceptible S. aureus (cMSSA) infections are incompletely understood. Fifty-seven patients with invasive cMRSA infection were prospectively identified at two teaching hospitals; for each cMRSA case, two cases of invasive cMSSA infection acted as controls. The primary outcome was 30-day all-cause mortality. Patients with invasive cMRSA infection were more likely to be Aboriginal (25% vs. 14%, age-adjusted odds ratio [OR] 2.5, p = 0.037), reside in a long-term care facility and/or have been hospitalised in the previous year (51% vs. 34%, p = 0.04) and less likely to have endocarditis (2% vs. 12%, p = 0.02) or require admission to an intensive care unit or high-dependency area (7% vs. 21%, p = 0.02). All-cause mortality at 30 days was similar in the cMRSA and cMSSA groups (9% vs. 7%, p = 0.68). Panton-Valentine leukocidin (PVL) genes were detected in a similar proportion of cMRSA and cMSSA isolates (32% vs. 27%, p = 0.49) and the presence of PVL genes was associated with younger age (35 years vs. 55 years, p < 0.001), Aboriginal ethnicity (38% vs. 10%, p < 0.001), skin and soft-tissue infection (54% vs. 19%, p < 0.001), lower illness severity at presentation (SAPS II score 9 vs. 21, p = 0.001) and shorter hospitalisation (9 days vs. 24 days, p < 0.001). Patients with "PVL-positive" and "PVL-negative" S. aureus infection had similar 30-day all-cause mortality (4% vs. 9%, p = 0.28). Few clinical features differentiated patients with invasive cMRSA infection from those with infection caused by cMSSA. Invasive "PVL-positive" S. aureus infection was associated with less morbidity but similar mortality to "PVL-negative" infection.
authors.affiliation: Department of Microbiology and Infectious Diseases, Royal Perth Hospital and PathWest Laboratory Medicine, Western Australia, Perth, Australia. michael.wehrhahn@sswahs.nsw.gov.au
authors.forename: M C
authors.initials: MC
authors.lastname: Wehrhahn
authors.forename: J O
authors.initials: JO
authors.lastname: Robinson
authors.forename: J C
authors.initials: JC
authors.lastname: Pearson
authors.forename: F G
authors.initials: FG
authors.lastname: O'Brien
authors.forename: H L
authors.initials: HL
authors.lastname: Tan
authors.forename: G W
authors.initials: GW
authors.lastname: Coombs
authors.forename: E M
authors.initials: EM
authors.lastname: Pascoe
authors.forename: R
authors.initials: R
authors.lastname: Lee
authors.forename: P
authors.initials: P
authors.lastname: Salvaris
authors.forename: R
authors.initials: R
authors.lastname: Salvaris
authors.forename: D
authors.initials: D
authors.lastname: New
authors.forename: R J
authors.initials: RJ
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001427:Bacterial Toxins / Q000235:genetics; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000382:microbiology* / Q000401:mortality / Q000473:pathology*; D005006:Ethnicity; D005098:Exotoxins / Q000235:genetics; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006784:Hospitals, Teaching; D006801:Humans; D007956:Leukocidins / Q000235:genetics; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000401:mortality / Q000473:pathology*; D037521:Virulence Factors / Q000235:genetics; D055815:Young Adult
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors