Utility of Blood Cultures in Pneumonia.
Am J Med. 2019 Apr 12;:
Authors: Zhang D, Yang D, Makam AN
INTRODUCTION: Blood cultures are of limited utility in non-severe community-acquired pneumonia, though routinely recommended for severe community-acquired pneumonia or healthcare-associated pneumonia, due to perceived greater bacteremia risk, particularly with multidrug resistant organisms. The utility of this practice is unknown.
METHODS: In this observational cohort study, we abstracted data from medical records for consecutive hospitalizations for pneumonia by adults to an academic medical center from 2014 to 2015. The primary outcomes included bacteremia, multidrug resistant organism bacteremia, and appropriate management changes attributed to culture results, stratified by pneumonia classification (non-severe community-acquired pneumonia, severe community-acquired pneumonia, or healthcare-associated pneumonia) and likelihood the bacteremia was due to pneumonia versus another infection. We assessed the diagnostic test performance of ≥1 guideline-defined risk factors for bacteremia in non-severe community-acquired pneumonia, for whom cultures are routinely recommended.
RESULTS: Of 456 pneumonia hospitalizations, 30 (6.6%) had bacteremia, with a greater incidence in severe community-acquired pneumonia (14.7%) than non-severe community-acquired pneumonia (7.8%) and healthcare-associated pneumonia (6.6%; p=0.12). Seventeen bacteremia cases were likely due to pneumonia (3.7%). Only 2 (0.4%) had multidrug resistant organisms (both healthcare-associated pneumonia), 1 of whom was due to pneumonia. Appropriate management changes occurred in 8 cases (1.8%; 7 de-escalation and 1 escalation of antibiotics); only 1 with bacteremia likely due to pneumonia (de-escalation). The one case of appropriate antibiotic escalation occurred in a patient with vancomycin-resistant enterococcus unrelated to pneumonia. Having ≥1 guideline-defined risk factors did not identify bacteremia in non-severe community-acquired pneumonia (positive likelihood ratio, 1.10, 95% CI, 0.61-1.99).
CONCLUSION: Routine blood cultures in pneumonia have extremely low yield and utility irrespective of severity and risk.
PMID: 30986394 [PubMed - as supplied by publisher]