Rapid Automated Microscopy for Microbiologic Surveillance of Ventilator-associated Pneumonia.

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Rapid Automated Microscopy for Microbiologic Surveillance of Ventilator-associated Pneumonia.

Am J Respir Crit Care Med. 2015 Jan 13;

Authors: Douglas IS, Price CS, Overdier KH, Wolken RF, Metzger SW, Hance KR, Howson DC

Abstract
Rationale: Diagnosis of ventilator-associated pneumonia (VAP) is imprecise. Objectives: To 1) determine if alternate-day surveillance mini-bronchoalveolar lavage (mini-BAL) in ventilated adults could reduce time to initiation of targeted treatment and 2) evaluate the potential for automated microscopy to reduce analysis time. Methods: Adult ICU patients were included who were anticipated to require ventilation for at least a further 48 h. Mini-BALs were processed for identification, quantitation and antibiotic susceptibility using a) clinical culture (50 ± 7 h) and b) automated microscopy (~5 h plus offline analysis). Measurements and Main Results: 77 mini-BALs were performed in 33 patients. 1 patient (3%) was clinically diagnosed with VAP. Of 73 paired samples, culture identified 7 containing pneumonia panel bacteria >104 CFU/ml from 5 patients (15%) (4 Staphylococcus aureus (3 MRSA), 2 Stenotrophomonas maltophilia, 1 Klebsiella pneumoniae) and resulted in antimicrobial changes/additions to 2/5 (40%) of those patients. Microscopy identified 7/7 microbiologically-positive organisms and 64/66 negative samples compared to culture. Antimicrobial responses were concordant in 4/5 comparisons. Antimicrobial changes/additions would have occurred in 3 of 7 microscopy-positive patients (43%) had those results been clinically available in 5 h, including one patient diagnosed later with VAP despite negative mini-BAL cultures. Conclusions: Microbiological surveillance detected infection in patients at risk for VAP independent of clinical signs, resulting in changes to antimicrobial therapy. Automated microscopy was 100% sensitive and 97% specific for high-risk pneumonia organisms compared to clinical culturing. Rapid microscopy-based surveillance may be informative for treatment and antimicrobial stewardship in patients at risk for VAP. Clinical trial registration available at www.clinicaltrials.gov, ID NCT00938002.

PMID: 25585163 [PubMed - as supplied by publisher]