Impact of microbiological samples in the hospital management of community-acquired, nursing home-acquired and hospital-acquired pneumonia in older patients.

We investigated the positivity rate, the detection rates for non-covered pathogens and the therapeutic impact of microbiological samples (MS) in community-acquired pneumonia (CAP), nursing home-acquired pneumonia (NHAP) and hospital-acquired pneumonia (HAP) in elderly hospitalised patients. Patients aged 75 years and over with pneumonia and hospitalised between 1/1/2013 and 30/6/2013 in the departments of medicine (5) and intensive care (1) of our university hospital were included. Microbiological findings, intra-hospital mortality and one-year mortality were recorded. Among the 217 patients included, there were 138 CAP, 56 NHAP and 23 HAP. MS were performed in 89.9, 91.1 and 95.6 % of CAP, NHAP and HAP, respectively. Microbiological diagnosis was made for 29, 11.8 and 27.3 % of patients for CAP, NHAP and HAP, respectively (p = 0.05). Non-covered pathogens were detected for 8 % of CAP, 2 % of NHAP and 13.6 % of HAP (p = 0.1). The antimicrobial spectrum was significantly more frequently reduced when the MS were positive (46.7 % vs. 10.8 % when MS were negative, p = 10(-7)). The MS positivity rate was significantly lower in NHAP than in CAP and HAP. MS revealed non-covered pathogens in only 2 % of NHAP. These results show the poor efficiency and weak clinical impact of MS in the management of pneumonia in hospitalised older patients and suggest that their use should be rationalised.