Significance of Prior Digestive Colonization With Extended-Spectrum ß-Lactamase-Producing Enterobacteriaceae in Patients With Ventilator-Associated Pneumonia.

ABSTRACT

OBJECTIVES: Ventilator-associated pneumonia is frequent in ICUs. Extended-spectrum ß-lactamase-producing Enterobacteriaceae are difficult-to-treat pathogens likely to cause ventilator-associated pneumonia. We sought to assess the interest of screening for extended-spectrum ß-lactamase-producing Enterobacteriaceae rectal carriage as a way to predict their involvement in ventilator-associated pneumonia. DESIGN: A retrospective cohort study of patients with suspected ventilator-associated pneumonia in a medical ICU was conducted. PATIENTS Every patient admitted between January 2006 and August 2013 was eligible if subjected to mechanical ventilation for more than 48 hours. Each patient with suspected ventilator-associated pneumonia was included in the cohort. Active surveillance culture for extended-spectrum ß-lactamase-producing Enterobacteriaceae detection was routinely performed in all patients at admission and then weekly throughout the study period. Extended-spectrum ß-lactamase colonization was defined by the isolation of at least one extended-spectrum ß-lactamase-producing Enterobacteriaceae from rectal swab culture. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among 587 patients with suspected ventilator-associated pneumonia, 40 (6.8%) were colonized with extended-spectrum ß-lactamase-producing Enterobacteriaceae prior to the development of pneumonia. Over the study period, 20 patients (3.4%) had ventilator-associated pneumonia caused by extended-spectrum ß-lactamase-producing Enterobacteriaceae; of whom, 17 were previously detected as being colonized with extended-spectrum ß-lactamase-producing Enterobacteriaceae. Sensitivity and specificity of prior extended-spectrum ß-lactamase-producing Enterobacteriaceae colonization as a predictor of extended-spectrum ß-lactamase-producing Enterobacteriaceae involvement in ventilator-associated pneumonia were 85.0% and 95.7%, respectively. The positive and negative predictive values were 41.5% and 99.4%, respectively. The positive likelihood ratio was 19.8. CONCLUSIONS: Screening for extended-spectrum ß-lactamase-producing Enterobacteriaceae digestive colonization by weekly active surveillance cultures could reliably exclude the risk of the involvement of such pathogens in patients with ventilator-associated pneumonia in low-prevalence area.