title: Epidemiology of ventilator-acquired pneumonia based on protected bronchoscopic sampling.
abstract: We performed a prospective observational cohort study of the epidemiology and etiology of nosocomial pneumonia in 358 medical ICU patients in two university-affiliated hospitals. Protected bronchoscopic techniques (protected specimen brush and bronchoalveolar lavage) were used for diagnosis to minimize misclassification. Risk factors for ventilator-associated pneumonia were identified using multiple logistic regression analysis. Twenty-eight cases of pneumonia occurred in 358 patients for a cumulative incidence of 7.8% and incidence rates of 12.5 cases per 1, 000 patient days and 20.5 cases per 1,000 ventilator days. Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Hemophilus species made up 65% of isolates from the lower respiratory tract, whereas only 12.5% of isolates were enteric gram-negative bacilli. Daily surveillance cultures of the nares, oropharynx, trachea, and stomach demonstrated that tracheal colonization preceded ventilator-associated pneumonia in 93.5%, whereas gastric colonization preceded tracheal colonization for only four of 31 (13%) eventual pathogens. By multiple logistic regression, independent risk factors for ventilator- associated pneumonia were admission serum albumin <= 2.2 g/dl (odds ratio [OR] 5.9; 95% confidence interval [CI] 2.0-17.6; p = 0.0013), maximum positive end-expiratory pressure >= 7.5 cm H2O (OR, 4.6; 95% CI, 1.4 to 15.1; p = 0.012), absence of antibiotic therapy (OR, 6.7; 95% CI, 1.8 to 25.3; p = 0.0054), colonization of the upper respiratory tract by respiratory gram-negative bacilli (OR, 3.4; 95% CI, 1.1 to 10.1; p = 0.028), pack-years of smoking (OR, 2.3 for 50 pack-years; 95% CI, 1. 2 to 4.2; p = 0.012), and duration of mechanical ventilation (OR, 3. 4 for 14 d; 95% CI, 1.5 to 7.8; p = 0.0044). Several of these risk factors for ventilator-associated pneumonia appear amenable to intervention.
authors.affiliation: Divisions of Infectious Diseases and Pulmonary and Critical Care Medicine, University of Tennessee, Hospital Epidemiology Unit, Regional Medical Center, Memphis, TN, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: George
authors.forename: P S
authors.initials: PS
authors.lastname: Falk
authors.forename: R G
authors.initials: RG
authors.lastname: Wunderink
authors.forename: K V
authors.initials: KV
authors.lastname: Leeper
authors.forename: G U
authors.initials: GU
authors.lastname: Meduri
authors.forename: E L
authors.initials: EL
authors.lastname: Steere
authors.forename: C E
authors.initials: CE
authors.lastname: Corbett
authors.forename: C G
authors.initials: CG
authors.lastname: Mayhall
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D018893:Bronchoalveolar Lavage; D020680:Bronchoscopes; D001999:Bronchoscopy / Q000379:methods; D015331:Cohort Studies; D016001:Confidence Intervals; D003422:Critical Care; D003428:Cross Infection / Q000453:epidemiology*; D004755:Enterobacteriaceae; D004756:Enterobacteriaceae Infections / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D009666:Nose / Q000382:microbiology; D016017:Odds Ratio; D009960:Oropharynx / Q000382:microbiology; D018410:Pneumonia, Bacterial / Q000453:epidemiology*; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology; D011023:Pneumonia, Staphylococcal / Q000453:epidemiology; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000453:epidemiology; D011550:Pseudomonas aeruginosa; D012307:Risk Factors; D012709:Serum Albumin / Q000032:analysis; D012907:Smoking / Q000453:epidemiology; D013270:Stomach / Q000382:microbiology; D013714:Tennessee / Q000453:epidemiology; D013997:Time Factors; D014132:Trachea / Q000382:microbiology; D012122:Ventilators, Mechanical / Q000009:adverse effects* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D012709:Serum Albumin