FilmArray Respiratory Panel Assay: Comparison of Nasopharyngeal Swabs and Bronchoalveolar Lavage Samples

The FilmArray respiratory panel (FARP) reliably and rapidly identifies 17 viruses and 3 bacterial pathogens. A nasopharyngeal swab FARP (NP FARP) is performed for many patients with respiratory symptoms. For patients who are acutely ill or immunocompromised or fail to improve, a bronchoalveolar lavage sample FARP (BAL FARP) is performed in addition to the NP FARP. To date, no studies have compared the yield of a BAL FARP with that of an NP FARP. We retrospectively studied all patients who had a BAL FARP within 7 days after an NP FARP between June 2013 and May 2014. Demographic information, comorbidities, FARP results, and all microbiologic data from BAL fluid were collected. Eighty-six patients had a BAL FARP performed within 7 days (mean, 1.6; median, 1) after an NP FARP. Of these, 66 (77%) had concordant BAL and NP FARP results: 15 (23%) had the same pathogen identified from the NP and BAL FARPs, and 51 (77%) had concordant negative FARP results. In 18 of the 86 patients (21%), a pathogen was detected from the NP FARP; of these, 15 (83%) had a concordant match on a subsequent BAL FARP, and the remaining 3 had negative BAL FARPs. In 17 of the 86 patients (20%), pathogens were identified from the BAL FARPs that were not detected by the NP FARPs; of these, 16 (94%) had initial negative NP FARPs. The data suggest that once a pathogen is identified by an NP FARP, a subsequent BAL FARP is unlikely to add new microbiologic information. However, a BAL FARP may provide new, useful microbiologic information when performed within 7 days after a negative NP FARP.