title: Analysis of pathogen and host factors related to clinical outcomes in patients with hospital-acquired pneumonia due to methicillin-resistant Staphylococcus aureus.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial pneumonia. To characterize pathogen-derived and host-related factors in intensive care unit (ICU) patients with MRSA pneumonia, we evaluated the Improving Medicine through Pathway Assessment of Critical Therapy in Hospital-Acquired Pneumonia (IMPACT-HAP) database. We performed multivariate regression analyses of 28-day mortality and clinical response using univariate analysis variables at a P level of <0.25. In isolates from 251 patients, the most common molecular characteristics were USA100 (55.0%) and USA300 (23.9%), SCCmec types II (64.1%) and IV (33.1%), and agr I (36.7%) and II (61.8%). Panton-Valentine leukocidin (PVL) was present in 21.9%, and vancomycin heteroresistance was present in 15.9%. Mortality occurred in 37.1% of patients; factors in the univariate analysis were age, APACHE II score, AIDS, cardiac disease, vascular disease, diabetes, SCCmec type II, PVL negativity, and higher vancomycin MIC (all P values were <0.05). In multivariate analysis, independent predictors were APACHE II score (odds ratio [OR], 1.090; 95% confidence interval [CI], 1.041 to 1.141; P < 0.001) and age (OR, 1.024; 95% CI, 1.003 to 1.046; P = 0.02). Clinical failure occurred in 36.8% of 201 evaluable patients; the only independent predictor was APACHE II score (OR, 1.082; 95% CI, 1.031 to 1.136; P = 0.002). In summary, APACHE II score (mortality, clinical failure) and age (mortality) were the only independent predictors, which is consistent with severity of illness in ICU patients with MRSA pneumonia. Interestingly, our univariate findings suggest that both pathogen and host factors influence outcomes. As the epidemiology of MRSA pneumonia continues to evolve, both pathogen- and host-related factors should be considered when describing epidemiological trends and outcomes of therapeutic interventions.
authors.affiliation: Division of Infectious Diseases, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Nadia Z
authors.initials: NZ
authors.lastname: Haque
authors.forename: Samia
authors.initials: S
authors.lastname: Arshad
authors.forename: Paula
authors.initials: P
authors.lastname: Peyrani
authors.forename: Kimbal D
authors.initials: KD
authors.lastname: Ford
authors.forename: Mary B
authors.initials: MB
authors.lastname: Perri
authors.forename: Gordon
authors.initials: G
authors.lastname: Jacobsen
authors.forename: Katherine
authors.initials: K
authors.lastname: Reyes
authors.forename: Ernesto G
authors.initials: EG
authors.lastname: Scerpella
authors.forename: Julio A
authors.initials: JA
authors.lastname: Ramirez
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Zervos
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001427:Bacterial Toxins; D003428:Cross Infection / Q000382:microbiology* / Q000401:mortality*; D005098:Exotoxins; D005260:Female; D005838:Genotype; D006801:Humans; D007956:Leukocidins; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000472:pathogenicity*; D008875:Middle Aged; D058889:Molecular Typing; D011023:Pneumonia, Staphylococcal / Q000382:microbiology* / Q000401:mortality*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome; D020713:Vancomycin Resistance; D037521:Virulence Factors / Q000235:genetics; D055815:Young Adult
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors