title: Predictors of Pseudomonas and methicillin-resistant Staphylococcus aureus in hospitalized patients with healthcare-associated pneumonia.
abstract: OBJECTIVE
  Patients with healthcare-associated pneumonia (HCAP) are at high risk of infection with multidrug-resistant (MDR) pathogens. Factors discriminating infection with MDR Gram-negative (MDR-GN) organism from infection with methicillin-resistant Staphylococcus aureus (MRSA) are not well understood and patients are often treated for both organisms. This study was performed to determine risk factors predicting pneumonia due to Pseudomonas versus MRSA.
  
  
  METHODS
  Veterans age ≥65 hospitalized with HCAP between 2002 and 2012 were identified from the Veterans Affairs administrative databases. Patients were identified with Pseudomonas pneumonia, MRSA pneumonia or neither according to the International Classification of Diseases, 9th Revision, Clinical Modification codes. We assessed unadjusted and adjusted associations of patient characteristics and HCAP due to Pseudomonas or MRSA.
  
  
  RESULTS
  Of the 61,651 patients with HCAP, 1156 (1.9%) were diagnosed with Pseudomonas pneumonia, 641 (1.0%) with MRSA pneumonia and 59,854 (97.1%) with neither. MRSA pneumonia was positively associated with male gender, age >74, diabetes, chronic obstructive pulmonary disease (COPD), recent nursing home or hospital stay, recent exposure to fluoroquinolone or antibiotics treating Gram-positive organisms, and severe pneumonia. MRSA pneumonia was negatively associated with complicated diabetes. Pseudomonas pneumonia was positively associated with recent hospital stay, immunocompromise, COPD, hemiplegia, recent exposure to inhaled corticosteroids, β-lactam/cephalosporin/carbapenem antibiotics, antibiotics against Gram-positive organisms, 'other antibiotics' and severe pneumonia. Pseudomonas pneumonia was negatively associated with age >84, higher socioeconomic status, drug abuse and diabetes.
  
  
  CONCLUSIONS
  Patient characteristics may assist in identifying patients at risk for HCAP due to Pseudomonas or MRSA.
authors.affiliation: The Division of Pulmonary and Critical Care Medicine, University of Connecticut School of Medicine, Farmington, Connecticut, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Metersky
authors.affiliation: Pharmacotherapy Division, College of Pharmacy, The University of Texas at Austin, Austin, USA.|Pharmacotherapy Education and Research Center, School of Medicine, The University of Texas Health Science Center School of Medicine, San Antonio, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Frei
authors.affiliation: VA North Texas Health Care System and University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Mortensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003428:Cross Infection / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D011023:Pneumonia, Staphylococcal / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D011549:Pseudomonas / Q000187:drug effects / Q000302:isolation & purification; D011552:Pseudomonas Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D058014:Veterans Health / Q000706:statistics & numerical data
chemical_list: D000900:Anti-Bacterial Agents
keywords: Pseudomonas; aged; methicillin-resistant Staphylococcus aureus; patient care management; pneumonia