2777. Species Distribution and Antimicrobial Susceptibility of Enterobacter in Bacteremia of Korean Children, 2011-2022

BACKGROUND: Enterobacter is an increasingly important nosocomial pathogen due to the resistance to penicillin and cephalosporin mediated by a chromosomal (ampC) beta-lactamase. We aimed to identify the species distribution and antimicrobial susceptibility isolated from the blood of Korean children. METHODS: Demographic, clinical, and laboratory data were retrospectively reviewed from patients under 21 hospitalized for bacteremia at Seoul National University Children's Hospital during 2011-2022. A VITEK II automated was used for species identification and antimicrobial susceptibility testing, and the susceptibility was determined according to the Clinical and Laboratory Standards Institute guidelines. RESULTS: Bacteremia due to Enterobacter species was identified in 106 cases in a total of 102 patients. The proportion of patient’s age group was 33.0% in infants (< 1 year old), 17.9% in toddlers (1-4 years old), 22.6% in children (5-11 years old), and 26.4% in adolescents (12-20 years old). Species were 70.8% of Enterobacter cloacae, 23.6% of K. aerogenes, 3.8% of Enterobacter asburiae, and each one (0.9%) of Enterobacter amnigenus and Enterobacter intermedius. Overall, non-susceptibility to piperacillin-tazobactam (PIP-TAZ), cefotaxime (CTX), cefepime, and carbapenem were 27.4%, 36.8%, 7.5%, and 4.7%, respectively. The most susceptible antibiotic was amikacin (99.1%). Multidrug resistance (MDR) was identified in 16.0% of isolates. Although statistically non-significant, the non-susceptibilities to PIP-TAZ and CTX increased from 16.7% and 8.3% in 2013 to 60.0% and 40.0%, respectively, in 2022. In addition, the proportion of E. cloacae has significantly increased (p for trend=0.034) from 66.7% in 2014 to 91.7% in 2020. K. aerogenes is significantly (p=0.002) more common in infants than E. cloacae, and E. cloacae (17.3%) showed more than twice as many MDR feature as K. aerogenes (8.0%), although not statistically significant. CONCLUSION: Although Enterobacter species has been steadily detected as a cause of pediatric bacteremia, the rate of E. cloacae has been increasing recently. Considering antibiotic susceptibility data, cefepime alone or combination with a third-generation cephalosporin and amikacin might be reasonable empirical antibiotic therapy regimen. DISCLOSURES: All Authors: No reported disclosures