425 - Plasma cell free DNA (cfDNA) Test (Karius Test®) for Diagnosis of Infectious Diseases in Children: A Tertiary Care Children’s Hospital Experience

Plasma cell free DNA (cfDNA) test (Karius Test®, KT) has emerged as an attractive diagnostic modality allowing noninvasive broad-range pathogen detection, and fast diagnosis. There are however few studies examining the impact of the KT in the diagnosis and management of infections in children.

Objective:

Our study aimed at evaluating the clinical impact of plasma cfDNA test since it was used at our institution.

Design/Methods:

Our retrospective study included children between 0 to 21 years of age who were admitted to Driscoll Children’s Hospital, Corpus Christi, Texas between January 2019 and January 2022. Demographic and clinical course data were collected. KT and conventional tests (CT) results were analyzed to determine their agreement and clinical relevance of organisms. Clinical impact in diagnosis was assessed separately according to revised objective grading criteria.

Results:

Among 182 patients identified, the median (SD) age was 9 (6.1) years, with 99 (54.4%) males and 150 (82.4%) Hispanic, 53 (29.1%) patients are immunocompromised, the median (SD) hospital length of stay was 17.2 (37.7) days. Among 186 Karius Test® ordered (Table 1), 97 (52.2%) tests were sent from general wards. 102 (54.8%) were positive for one or more organisms. Median (range) turn-around time for KT 2.8 (1.7-11.6) days. 59 (31.7%) KT results had positive clinical impact in diagnosis (Table 2 and 3), higher positive impact were found in the diagnosis of pneumonia (44.4%), bacteremia (42.9%), and musculoskeletal infection (41.2%). KT was the only diagnostic modality that provided the diagnosis in 41 (22%) cases (Table 3), including Streptococcus pneumoniae, Pneumocystis jirovecii, Rickettsia typhi, and Bartonella henselae. Among 41 cases, KT had shorter turnaround time than conventional tests in 31 (75.6%) cases.

Conclusion(s):

In this retrospective cohort, we show that the plasma cell free DNA (cfDNA) test (Karius Test®) provided the only method of etiological diagnosis in 41 children. It was particularly useful in the diagnosis of pneumonia, musculoskeletal infection, bacteremia, Pneumocystis jirovecii and murine typhus with a relatively short turnaround time.