Community-acquired pneumonia due to gram-negative bacteria and pseudomonas aeruginosa: incidence, risk, and prognosis

Arch Intern Med. 2002 Sep 9;162(16):1849-58. doi: 10.1001/archinte.162.16.1849.

Abstract

Background: Initial empirical antimicrobial treatment of patients with community-acquired pneumonia (CAP) is based on expected microbial patterns. We determined the incidence of, prognosis of, and risk factors for CAP due to gram-negative bacteria (GNB), including Pseudomonas aeruginosa.

Methods: Consecutive patients with CAP hospitalized in our 1000-bed tertiary care university teaching hospital were studied prospectively. Independent risk factors for CAP due to GNB and for death were identified by means of stepwise logistic regression analysis.

Results: From January 1, 1997, until December 31, 1998, 559 hospitalized patients with CAP were included. Sixty patients (11%) had CAP due to GNB, including P aeruginosa in 39 (65%). Probable aspiration (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.02-5.2; P =.04), previous hospital admission (OR, 3.5; 95% CI, 1.7-7.1; P<.001), previous antimicrobial treatment (OR, 1.9; 95% CI, 1.01-3.7; P =.049), and the presence of pulmonary comorbidity (OR, 2.8; 95% CI, 1.5-5.5; P =.02) were independent predictors of GNB. In a subgroup analysis of P aeruginosa pneumonia, pulmonary comorbidity (OR, 5.8; 95% CI, 2.2-15.3; P<.001) and previous hospital admission (OR, 3.8; 95% CI, 1.8-8.3; P =.02) were predictive. Infection with GNB was independently associated with death (relative risk, 3.4; 95% CI, 1.6-7.4; P =.002).

Conclusions: In our setting, in every tenth patient with CAP, an etiology due to GNB has to be considered. Patients with probable aspiration, previous hospitalization or antimicrobial treatment, and pulmonary comorbidity are especially prone to GNB. These pathogens are also an independent risk factor for death in patients with CAP.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use
  • Chile / epidemiology
  • Community-Acquired Infections / diagnosis
  • Community-Acquired Infections / drug therapy
  • Community-Acquired Infections / epidemiology
  • Community-Acquired Infections / microbiology
  • Comorbidity
  • Confidence Intervals
  • Female
  • Gram-Negative Bacterial Infections* / diagnosis
  • Gram-Negative Bacterial Infections* / drug therapy
  • Gram-Negative Bacterial Infections* / epidemiology
  • Gram-Negative Bacterial Infections* / microbiology
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Odds Ratio
  • Patient Readmission
  • Pneumonia, Bacterial* / diagnosis
  • Pneumonia, Bacterial* / drug therapy
  • Pneumonia, Bacterial* / microbiology
  • Prospective Studies
  • Pseudomonas Infections / diagnosis
  • Pseudomonas Infections / drug therapy
  • Pseudomonas Infections / epidemiology
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / isolation & purification*
  • Risk Factors
  • Time Factors

Substances

  • Anti-Bacterial Agents