Quality of Non-Bronchoscopic Bronchoalveolar Lavage Specimens and the Diagnosis of Ventilator-Associated Pneumonia

Abstract Background Ventilator-associated pneumonia (VAP) is a significant cause of hospital-acquired infection. Many institutions use National Healthcare Safety Network (NHSN) definitions for VAP surveillance. One criterion of the NHSN definition for possible VAP (PVAP) is a positive culture obtained via non-bronchoscopic bronchoalveolar lavage (NB-BAL). NB-BAL specimens are not routinely assessed for oropharyngeal contamination prior to quantitative culture. Thus, we hypothesized that NB-BALs can yield poor quality specimens that may contribute to the misdiagnosis of PVAP. Methods From May 2016 to January 2017, we performed background quality assessments for NB-BAL specimens collected from patients on mechanical ventilation for >3 days. Thereafter, we retrospectively reviewed NB-BAL quality, culture results, and contribution to NHSN-defined PVAPs. Quality assessments included number of white blood cells (WBC) or squamous epithelial cells (SEC) per low-power field (lpf). Specimens were deemed acceptable if they had ≤10 SEC/lpf by “standard” criteria and zero SEC/lpf by “strict” criteria. All specimens were cultured regardless of quality assessment results, which were not revealed to ordering clinicians. Results Of 117 NB-BAL specimens, 8 (7%) did not pass standard quality assessment and an additional 47 (40%) did not pass strict quality assessment. Most samples (82%) were purulent (>25 WBC/lpf). Overall, 56 (48%) of samples resulted in significant growth of at least one species of bacteria (>104 CFU/mL). Of the 8 samples that did not pass standard assessment, 7 (87%) resulted in significant bacterial growth. Four PVAPs were diagnosed on the basis of NB-BAL specimens. Of these, all were acceptable by standard criteria, but one failed by strict criteria. Conclusion Approximately 50% of our NB-BAL specimens had evidence of oropharyngeal contamination on quality assessment, including one specimen that contributed to a NHSN-reported PVAP. While limited by small sample size and short study duration, our data suggest that the quality of NB-BAL specimens may affect the diagnosis and surveillance of VAP. Disclosures All authors: No reported disclosures.