Community-acquired pneumonia with risk for drug-resistant pathogens

Pneumonia is a leading infectious cause of morbidity and mortality in the United States. The Infectious Disease Society of America (IDSA) and American Thoracic Society (ATS) have published treatment guidelines for community-acquired pneumonia (CAP) based upon the site of acquisition and specific pathogen risk. The literature demonstrates improved outcomes with guideline-concordant empiric therapy. A subset of patients with CAP has risk factors for drug-resistant pathogens (DRPs). IDSA/ATS treatment guidelines do not provide clear recommendations for empiric treatment, and clinical studies have not provided descriptive data for this group.

A retrospective chart review of all admissions between January 1, 2008 and April 19, 2009 with an International Classification of Diseases-9 code and physician-documented diagnosis of pneumonia at two community hospitals were performed. IDSA pneumonia type and presence of risk factors for DRP were recorded for each patient, and the empiric antibiotic therapy received was evaluated. Admissions were excluded if immunosuppression or pregnancy was present.

Of the 400 admissions reviewed, 343 patients were included. A total of 228 patients (71%) had CAP. Forty-three percent of patients with CAP had risk factors for DRP. Only 2% of this group received an antibiotic regimen with coverage of the specific DRP risk factor present. The most common DRPs not receiving coverage in this group were Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. P. aeruginosa and methicillin-resistant S. aureus occurred more commonly in culture-positive patients with CAP with DRP risk factors but did not achieve statistical significance. A larger sample size would be needed to determine whether this difference is significant.

Risk factors for DRP occurred commonly in our CAP population. Patients with CAP with risk for DRP may be a distinct group who are without clear guidance on treatment. Future studies are needed to define the risk of DRP and the impact upon empiric therapy for patients with CAP.