title: Role of previous hospitalization in clinically-significant MRSA infection among HIV-infected inpatients: results of a case-control study.
abstract: BACKGROUND
  HIV-infected subjects have high incidence rates of Staphylococcus aureus infections, with both methicillin-susceptible and methicillin-resistant (MRSA) strains. Possible explanations could include the high burden of colonization, the behavioral risk factors, and the frequent exposures to health care facilities of HIV-infected patients. The purpose of the study was to assess the risk factors for clinically- significant methicillin-resistant Staphylococcus aureus (CS-MRSA) infections in HIV-infected patients admitted to Infectious Diseases Units.
  
  
  METHODS
  From January 1, 2002 to December 31, 2005, we conducted a retrospective case-control (1:2) study. We identified all the cases of CS-MRSA infections in HIV-infected patients admitted to the National Institute for Infectious Diseases (INMI) "Lazzaro Spallanzani" in the 4-year study period. A conditional logistic regression model was used to identify risk factors for CS-MRSA infection.
  
  
  RESULTS
  We found 27 CS-MRSA infections, i.e. 0.9 CS-MRSA infections per 100 HIV-infected individuals cared for in our Institute. At multivariate analysis, independent predictors of CS-MRSA infection were cumulative hospital stay, invasive procedures in the previous year, and low CD4 cell count. Particularly, the risk for CS-MRSA increased by 14% per an increase of 5 days hospitalization in the previous year. Finally, we identified a low frequency of community-acquired MRSA infections (only 1 of 27; 3.7%) among HIV-infected patients.
  
  
  CONCLUSIONS
  Clinicians should be aware of the risk for CS-MRSA infection in the clinical management of HIV-infected patients, especially in those patients with a low CD4 cell count, longer previous hospital stay, and previous invasive procedures.
authors.affiliation: 2nd Infectious Diseases Division, National Institute for Infectious Diseases L. Spallanzani, Rome, Italy. c.drapeau@yahoo.it <c.drapeau@yahoo.it>
authors.forename: Cecilia M J
authors.initials: CM
authors.lastname: Drapeau
authors.forename: Claudio
authors.initials: C
authors.lastname: Angeletti
authors.forename: Anna
authors.initials: A
authors.lastname: Festa
authors.forename: Nicola
authors.initials: N
authors.lastname: Petrosillo
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count; D016022:Case-Control Studies; D003428:Cross Infection / Q000382:microbiology*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006760:Hospitalization; D006801:Humans; D007902:Length of Stay; D008297:Male; D016106:Methicillin Resistance; D015999:Multivariate Analysis; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000150:complications*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity