194 - Antibiotic-resistant bloodstream infections in pediatric oncology patients on levofloxacin prophylaxis

Background: Levofloxacin prophylaxis in pediatric oncology patients with chemotherapy-induced severe prolonged neutropenia has been shown to reduce risk for febrile neutropenia and systemic infections.  With increased use of prophylaxis there is concern for development of antibiotic-resistant infections. We analyzed bloodstream infections (BSI) in pediatric oncology patients exposed to levofloxacin prophylaxis during prolonged severe neutropenic episodes to determine the rate of antibiotic resistance

Methods: We performed a retrospective chart review of pediatric oncology patients who received levofloxacin prophylaxis between January 2015 – December 2019. Patients were placed on levofloxacin prophylaxis based on institutional guidelines for patients at risk for severe prolonged neutropenia (i.e., absolute neutrophil count [ANC] < 500 cells/µL for >7 days). Demographic information, start and end dates for levofloxacin prophylaxis, and all BSI episodes within 2 months after exposure to the fluoroquinolone were collected

Results: Thirty-five patients were identified who received levofloxacin prophylaxis.  There were 32 BSI in 12 patients. Twenty-five BSI involved gram-positive organisms (GP), including nine (36%) due to coagulase negative Staphylococcus and seven (28%) due to viridans Streptococcus.  Seven BSI episodes involved gram-negative (GN) organisms with 4 (57%) from E.coli. Resistance   to fluroquinolones was noted in 42% and 48% of BSI from GN and GP organisms respectively. The vast majority (85%) of viridans Streptococcus isolates were resistant to levofloxacin.  In contrast, 8% of viridans Streptococcus isolates were resistant to fluoroquinolones from the same time frame per our hospital antibiogram.

Conclusion: In this recent cohort of pediatric oncology patients with BSI after exposure to levofloxacin prophylaxis, there was a high percentage infected with fluoroquinolone-resistant organisms.This contrasts with some of the earlier published data from adults which reported low rate of fluoroquinolone resistance. This case series highlights the need for close monitoring for development of antibiotic resistance as utilization of prophylactic levofloxacin increases in pediatric oncology patients.