417 - Impact of Multiplex PCR on Antimicrobial Stewardship in Pediatric Enterobacterales Bacteremia

Publication Number: 2405.417

Makiko Kawasaki, Department of General Pediatrics, Tokyo Metropolitan Children's Medical Center, Kunitachi-city, Tokyo, Japan; Aki Miyashita, Tokyo metropolitan children’s medical center, Fuchu, Tokyo, Japan; Hanako Funakoshi, Tokyo Metropolitan Children's Medical Center, Mitaka-shi, Tokyo, Japan; Yusuke Isobe, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan; Hiroshi Sakakibara, Tokyo Metropolitan Children's Medical Center, Fuchu-shi, Tokyo, Japan; Yuho Horikoshi, Tokyo metropolitan children's medical center, Fuchu, Tokyo, Japan

Background: The emergence of multidrug resistance among Enterobacterales is of particular concern in the treatment of pediatric invasive infections. Recent molecular advances in rapid pathogen and resistance gene identification from positive blood cultures have enabled earlier optimization of antimicrobial therapy.

Objective: To evaluate the impact of multiplex PCR on the management of Enterobacterales bacteremia, focusing on carbapenem use in children.

Design/Methods: We conducted a retrospective study of patients with Enterobacterales bacteremia at Tokyo Metropolitan Children's Medical Center between July 2016 and March 2025. Patients aged < 18 years with a positive blood culture for Enterobacterales were included. Cases with repeated positive cultures during the same admission or incomplete treatment due to transfer were excluded. Multiplex PCR was performed using FilmArray Blood Culture Identification Panels 1 and 2 (BioFire, Salt Lake City). Panel 1 detected only KPC, while Panel 2 detected five carbapenemases and CTX-M. The turnaround time was 1–1.5 hours after blood culture positivity, followed by mandatory consultation with the infectious diseases service. The study period was divided into three groups: pre-PCR (July 26, 2016–July 25, 2019), Panel 1 (July 26, 2019–July 25, 2021), and Panel 2 (April 1, 2023-March 31, 2025). The transition period between panels was excluded from the study period. The primary outcome was the use of carbapenem antibiotics; the secondary outcome was the duration of carbapenem use until therapy optimization.

Results: A total of 169 cases were identified: 66 in the pre-PCR group, 46 in the Panel 1 group, and 57 in the Panel 2 group. The median age was 12 months (IQR, 3–106 months), and 52% were boys. Escherichia coli (50%), Klebsiella pneumoniae (18%), and K aerogenes (8%) were the predominant pathogens. Carbapenem use was observed in 49 (74%) pre-PCR, 38 (83%) Panel 1, and 37 (65%) Panel 2 cases (p=0.127). Median duration of carbapenem use until optimization was 39 hours, 41 hours, and 64 hours, respectively (p=0.237). In the Panel 2 group, four CTX-M and one IMP genes were detected, leading to prompt antibiotic optimization in those cases.

Conclusion(s): Implementation of multiplex PCR did not significantly reduce carbapenem use in pediatric Enterobacterales bacteremia; however, resistance gene detection enabled timely antibiotic optimization in 9% of cases.