Risk factors for acquiring potentially drug-resistant pathogens in immunocompetent patients with pneumonia developed out of hospital.

BACKGROUND The concept of healthcare-associated pneumonia (HCAP) exists to identify patients infected with highly resistant pathogens who are exposed to the healthcare environment. However, many studies have included immunosuppressed patients who were excluded from the original concept. OBJECTIVES The risk factors of potentially drug-resistant (PDR) pathogens in patients with pneumonia developed outside the hospital were reevaluated after excluding the patients who had immunosuppression. METHODS This was a retrospective study of prospectively collected data from all consecutive patients with pneumonia who were admitted to hospital via the emergency department between January 2008 and December 2011. RESULTS Pathogens were isolated in a total of 315 patients with pneumonia from our cohort; 33% with PDR pathogens did not meet the criteria for HCAP, but 44% without PDR pathogens did meet the criteria. Variables independently associated with PDR included nursing home residency, hospitalization in the preceding 90 days, antibiotics in the 30 days prior to pneumonia, poor function status and chronic lung disease. The new predictive scoring system based on the logistic regression model had a higher predictive power for the risk of PDR pathogens than the presence of the risk factors or the HCAP criteria. CONCLUSIONS Functional status, pulmonary comorbidity and previous exposure to the healthcare environment were significantly associated with acquiring PDR pathogens in immunocompetent patients with pneumonia that developed out of hospital. However, a risk stratification model was more accurate than the presence of the risk factors or the HCAP criteria for assessing the probability of PDR pathogens.