360. Bacteremic Pseudomonas aeruginosa pneumonia: Impact of adequate empirical antibiotic therapy and multidrug-resistance on the mortally using marginal structural model
Session: Poster Abstract Session: Community and Healthcare Acquired Pneumonia - Epidemiology
Friday, October 21, 2011
Room: Poster Hall B1
Background: Pseudomonas aeruginosa has become a center of increased attention in patients with pneumonia. We evaluated the effects of adequate empirical therapy and multidrug-resistance (MDR) in bacteremic P. aeruginosa pneumonia on the mortality.

Methods: A retrospective cohort study using marginal structural model was performed at the 2,700-bed tertiary care university hospital. We reviewed the medical records of all patients with bacteremic pneumonia caused by P. aeruginosa between January 1997 and February 2011. Pneumonia was defined when the patient met the entire requirement such as symptoms, radiographic and isolation of P. aeruginosa from cultures of appropriate sputum specimens. The empirical antibiotic therapy was considered adequate if the therapy given intravenously within 48 h of the onset of pneumonia included at least one antibiotic to which the isolate was susceptible. MDR was defined as resistance to more than three kinds of antibiotics such as anti-pseudomonal beta-lactams, carbapenems, fluoroquinolones and aminoglycosides.

Results: During the study period, there were 1,361 patients with P. aeruginosa bacteremia. 100 (7.3%) patients who had concomitant pneumonia were included in the final analysis. Hematologic malignancy (34%) was the most common underlying disease followed by solid cancer (23%). 65 patients (65%) were classified as adequate therapy group. Of 23 patients who isolated MDR pathogen, 8 (12%) received adequate therapy and 12 (34%) received inadequate therapy. 30-day mortality was significantly higher in inadequate therapy group (69% [24/35] vs. 42% [27/65], P = 0.01). However, mortality was not higher in MDR group (52% [12/23] vs. 51% [39/77]), P =0.9). In the mutivariable logistic regression analysis, risk factors for 30-day mortality were hematologic malignancy (P=0.004), inadequacy of empirical therapy (P=0.05), and Pitt bacteremia score (P=0.007). In marginal structural model, inadequate empirical therapy was significantly associated with 30-day mortality (OR, 3.02; 95% CI, 1.15-7.93; P=0.02).

Conclusion: Our study suggests that it may not be the existence of multi-drug resistance but the adequacy of empirical therapy be associated with increased mortality in bacteremic P. aeruginosa pneumonia.


Subject Category: C. Clinical studies of bacterial infections and antibacterials including sexually transmitted diseases and mycobacterial infections (surveys, epidemiology, and clinical trials)

So-Youn Park, MD1, Song Mi Moon, MD1, Hyun Jung Park, MD1, Yumi Lee, MD2, Sung-Han Kim, MD, PhD1, Sang-Oh Lee, MD1, Yang Soo Kim, MD, PhD1, Jun Hee Woo, MD, PhD1 and Sang-Ho Choi, MD, PhD1, (1)Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea, (2)Department of Infectious Diseases, Asan Medical Center, Seoul, South Korea

Disclosures:

S. Y. Park, None

S. M. Moon, None

H. J. Park, None

Y. Lee, None

S. H. Kim, None

S. O. Lee, None

Y. S. Kim, None

J. H. Woo, None

S. H. Choi, None

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