title: Patients presenting to the hospital with MRSA pneumonia: differentiating characteristics and outcomes with empiric treatment.
abstract: BACKGROUND
  Concern for MRSA in patients presented to the hospital with pneumonia may be overestimated leading to excessive prescribing of empiric anti-MRSA therapy. This study aims to identify at-risk patients and treatment outcomes.
  
  
  METHODS
  Adults hospitalized during 2005-2011 with pneumonia diagnosed within 48 h of admission were included. Medical charts were retrospectively reviewed for relevant data. Patients with MRSA were matched 1:1 to those with non-MRSA pathogen or negative culture. A published risk scoring system for MRSA pneumonia was applied.
  
  
  RESULTS
  268 elderly patients were included, 134 patients in each group. Compared to non-MRSA group, MRSA patients presented more acutely ill (p < 0.0001) (pneumonia severity index score, 150 vs 93; vasopressor therapy, 34% vs 6%; ICU admission, 47% vs 13%; and mechanical ventilation, 35% vs 10%) and had worse outcomes (p < 0.0001) (time to reach clinical stability, 6 vs 2.5d; length of stay, 10 vs 5d; clinical failure, 28% vs 4%; 28-day mortality, 22% vs 3%). When applied to our patients, a published risk scoring scheme had 93% sensitivity but lacked specificity at 55%; 40% of medium-risk patients did not have MRSA. A history of MRSA infection or pneumonia differentiated the latter group. Most MRSA patients (66%, 88/134) were treated empirically (primarily vancomycin) but outcome was not improved by receipt of empiric therapy.
  
  
  CONCLUSIONS
  Use of a published risk scoring scheme with additional variables from this study can potentially reduce overprescribing of anti-MRSA empiric therapy in patients presented to the hospital with pneumonia. Prospective studies evaluating the treatment benefit of non-vancomycin alternatives as empiric therapy are needed.
authors.forename: Emi
authors.initials: E
authors.lastname: Minejima
authors.forename: Mimi
authors.initials: M
authors.lastname: Lou
authors.forename: Paul
authors.initials: P
authors.lastname: Nieberg
authors.affiliation: University of Southern California, School of Pharmacy, 1985 Zonal Ave, Los Angeles, CA 90033, USA. anniew@usc.edu.
authors.forename: Annie
authors.initials: A
authors.lastname: Wong-Beringer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002140:California / Q000453:epidemiology; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D011014:Pneumonia / Q000188:drug therapy / Q000382:microbiology* / Q000401:mortality; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D016896:Treatment Outcome; D014640:Vancomycin / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin