707Rapid Identification of Pathogens Causing Septic Arthritis using FilmArray®

Background. Septic arthritis (SA) is a common and serious infection in children and can cause significant orthopedic morbidity. Bacteria are most often implicated, but routine cultures are frequently negative, because of prior antibiotics or delayed evaluation of joint fluid (JF). As such, children are treated with broad-spectrum antibiotics. A rapid molecular test that can identify the common bacteria causing joint infection could improve patient care. Methods. The FilmArray1 (FA) Blood Culture ID (BCID) System (BioFire Diagnostics, Inc., Salt Lake City, UT) performs nucleic acid purification and multiplex PCR to identify 22 bacterial pathogens in approx. 1 hour. The BCID system is approved only for use with positive blood cultures. Testing was performed on archived JF samples collected from children <18 years old with clinical signs and symptoms of SA at Primary Children’s Hospital (UT) fromOctober 2012 to April 2014. FA identification was compared to conventional culture. Results. JF from 28 children with SA were evaluated. A bacteria was identified by culture (blood and/or JF) in 14 (50%) children, (JF-11 (39%), Blood-8 (29%)). By FA testing, a bacteria was identified in 14 (50%) JF. Of the 14 culture-identified pathogens, 13 (93%) were contained on the FA BCID panel, of which 11 (85%) were identified by FA testing of JF. 8 children had S. aureus identified by culture and 6 were identified by PCR of JF. Those not identified by the FA were identified by blood culture only. In addition, FA identified 3 additional pathogens in culture-negative JF; Haemophilus influenzae type a2 and H. influenzae type b1 (Table).