547 - Diagnostic accuracy of multiplex RT-PCR compared to standard bacterial culture for tracheal aspirates in children with suspected pneumonia.

Poster Number: 547
Publication Number: 547.328

Christina M. Osborne, University of Colorado School of Medicine, Aurora, CO, United States; Kayla Williamson, University of Colorado Anschutz Department of Biostatistics and Informatics, Mount Pleasant, SC, United States; Lilliam Ambroggio, Children's Hospital Colorado, Aurora, CO, United States; Charles Langelier, University of California San Francisco, San Francisco, CA, United States; Robert A. Levy, University of Washington School of Medicine, Seattle, WA, United States; Eric A. Simões, University of Colorado School of Medicine, Aurora, CO, United States; Todd Carpenter, University of Colorado School of Medicine, Aurora, CO, United States; Aline B. Maddux, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, CO, United States; Matthew Leroue, University of Colorado School of Medicine, Aurora, CO, United States; Alexandra Tsitsiklis, University of California, San Francisco, School of Medicine, San Francisco, CA, United States; Eran Mick, UCSF, San Francisco, CA, United States; Peter M. Mourani, University of Arkansas for Medical Sciences, Little Rock, AR, United States; Samuel R. Dominguez, Children's Hospital Colorado University of Colorado, Aurora, CO, United States

Background: Bacterial lower respiratory tract infection (LRTI) is a significant cause of morbidity and mortality in children who require mechanical ventilation (MV). Diagnosis is made with bacterial cultures of lower respiratory tract specimens; however, these are resource intensive and may not be sensitive or specific. Multiplex real-time polymerase chain reaction (RT-PCR) assays for detection of bacteria are available with the potential to provide rapid results and lead to more targeted antibiotic management.

Objective: Compare results of RT-PCR testing to bacterial culture of tracheal aspirate samples in children requiring MV with suspected LRTI.

Design/Methods: Critically ill children (30 days to 17 years) requiring MV via an endotracheal tube for ≥72 hours were enrolled prospectively from a tertiary care pediatric hospital. Tracheal aspirates (TA) were collected within 48 hours of intubation and analyzed by RT-PCR using the Biofire FilmArray Pneumonia Panel which targets 15 typical bacterial pathogens. Concurrent (within 24 hours) clinical culture results from TA samples were compared with RT-PCR results. Cohen’s Kappa was used to assess concordance.

Results: We compared 54 paired TA culture and RT-PCR samples. Median age was 2.5 years (IQR 0.7-10.3). Thirty (55.5%) had positive culture with 15 organisms detected. Ten (33%) had positive cultures for organisms not on the PCR panel, and 20 had positive culture results with organisms detectable by RT-PCR, all of which had positive PCR results. Forty of 54 (74.1%) were positive by RT-PCR with 10 organisms detected. RT-PCR more frequently detected only one organism compared with culture (21 [39%] versus 14 [26%], p=0.01). The most common bacteria detected were Staphylococcus aureus (culture: 8 [14.5%]; RT-PCR 20 [36.3%]). Of 54 subjects, 26 (48.1%) had complete concordance with all bacteria the same, 18 (33.3%) had at least one of the same bacteria detected by both methods for an overall concordance of 81.4% for at least one pathogen. Concordance of bacteria are shown in Table 1 with increased detection of organisms via RT-PCR. One case had bacterial culture identify a potential pathogen when the RT-PCR did not, while 39 potential pathogens were identified by RT-PCR that were not found on culture.Conclusion(s): Multiplex RT-PCR assays demonstrated variable agreement with standard bacterial culture for TA cultures in children with suspected LRTI who require MV. RT-PCR detected bacteria more frequently than TA culture and could represent a potential diagnostic tool for effective therapy but additionally may increasingly detect colonization and not true infection.
christina_osborne_CV2021.pdf