title: Incidence of and risk factors for clinically significant methicillin-resistant Staphylococcus aureus infection in a cohort of HIV-infected adults.
abstract: OBJECTIVE
  Outbreaks of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) have been noted in multiple sites in the United States. This study's purpose was to estimate trends in the incidence of and risk factors for clinically significant MRSA (CS-MRSA) infection in a cohort of HIV-infected adults.
  
  
  METHODS
  A retrospective clinic-based cohort (January 1, 2000-December 31, 2003) study.
  
  
  METHODS
  We ascertained all initial episodes of CS-MRSA and categorized them by primary site. Incidence rates were estimated by half year. Risk factors for CA-MRSA infection were identified using Cox modeling.
  
  
  RESULTS
  Of 126 potential events, 94 were CS. Their primary sources were 83% skin or soft tissue, 10% blood, 6% respiratory, and 1.0% other sites. Among these, 60% were CA and 40% were nosocomial. Of antibiotics tested, only cotrimoxazole resistance was associated with nosocomial acquisition. The 3455 patients contributed 7003 person-years at risk. The incidence of CS-MRSA infection increased 6.2-fold from the first to the last half year. In multivariate analysis, independent predictors of CA-MRSA infection included HIV transmission by men who have sex with men or by injection drug use, CD4 count <50 cells/muL, log10 HIV plasma viral load, and absence of cotrimoxazole prophylaxis.
  
  
  CONCLUSIONS
  The incidence of initial CS-MRSA events increased more than 6-fold in a 4-year period. The associations between CA-MRSA infection and HIV severity indicators merit examination in other cohorts.
authors.affiliation: Department of Medicine, University of California, San Diego, Owen Clinic, UCSD Medical Center, San Diego, CA 92103, USA. cmathews@ucsd.edu
authors.forename: Wm Christopher
authors.initials: WC
authors.lastname: Mathews
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Caperna
authors.forename: R Edward
authors.initials: RE
authors.lastname: Barber
authors.forename: Francesca J
authors.initials: FJ
authors.lastname: Torriani
authors.forename: Loren G
authors.initials: LG
authors.lastname: Miller
authors.forename: Susanne
authors.initials: S
authors.lastname: May
authors.forename: J Allen
authors.initials: JA
authors.lastname: McCutchan
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D015994:Incidence; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000150:complications / Q000453:epidemiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*