PURPOSE:Pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA) cause pneumonia in patients presenting to the hospital. The healthcare associated pneumonia (HCAP) concept attempts to capture this. We sought 1) to determine the predictive significance the HCAP syndrome at identifying persons with pneumonia due to resistant organisms and 2) to develop a risk score for resistance in pneumonia.
METHODS:We examined patients admitted over a three year period with pneumonia. The diagnosis of pneumonia required signs and symptoms of infection along with radiographic evidence of an infiltrate. Infection with a resistant pathogen (e.g., MRSA, PA, extended-spectrum beta-lactamase producing organisms) served as the endpoint. HCAP was present if a patient met one of the following: recent hospitalization (RH), nursing home residence (NHR), chronic hemodialysis (HD), or immunosuppression. We compared rates of resistant infection among patients meeting any criteria for HCAP to those without HCAP. We created a scoring system based on the independent factors associated with resistant infection from logistic regression.
RESULTS:Among the cohort (n=639) resistant pathogens were recovered in 289 (45.2%). Although each component of HCAP occurred more frequently in persons with resistant infections, the broad definition had low specificity (48.6%) and misclassified 1/3rd of subjects. Four variables were independently associated with resistant pneumonia: RH, NHR, HD, and ICU admission. A scoring system assigning points as follows –RH (4), NHR (3), HD (2), and ICU (1) –had moderate predictive power at identifying those with resistant bacteria. Among patients with fewer than 3 points, the prevalence of resistant pathogens was < 20% compared to 55% and > 75% in persons with scores of between 3–5 and scores of > 5 points, respectively (p<0.001).
CONCLUSION:While resistance is common in HCAP, not all component criteria for HCAP convey similar risk.
CLINICAL IMPLICATIONS:Resistant pathogens are a common cause of pneumonia presenting to the hospital. A simple risk score may help clinicians identify persons requiring initially broad spectrum antimicrobial therapy.
DISCLOSURE:Andrew Shorr, Grant monies (from industry related sources) Ortho-MacNeil-Jansen; No Product/Research Disclosure Information