P-1148. Invasive Infections by Carbapenemase-producing Enterobacterales and <i>Pseudomonas aeruginosa</i> in Children

Abstract Background Enterobacterales and Pseudomonas aeruginosa cause invasive infections and their spread of antimicrobial resistance is of great concern in the worldwide scientific community. Carbapenemases represent the main mechanism of resistance in Enterobacterales and can spread horizontally through mobile genetic elements. Clinical evidence suggests that mortality would be related to inadequate initial empirical treatment. Methods A prospective observational study was carried out in three tertiary care pediatric hospitals in Argentina, since 12/1/2021 to 11/30/2022, including children between 0 to 18 years of age with a positive culture for carbapenemase-producing Enterobacterales or P. aeruginosa isolated from a sterile site and/or tracheal aspirate with pulmonary radiological confirmation. Results We enrolled 29 patients, 62% male. Median age: 25 months (IQR 5-127). Median length of hospitalization: 44 days (IQR 17-91). Comorbidities: 93%, oncohematological disease: 40%; 62% (18/29) were admitted to Intensive Care Unit. The most frequent isolation was Klebsiella pneumoniae: 62% (18/29), Escherichia coli 17% (5/29), Enterobacter cloacae 10% (3/29), Serratia marcescens 7% (2/29), P. aeruginosa 7% (2/29). Bacteremia: 55% (16/29). Most frequent site of infection: urinary tract 44.8%. Metallobetalactamase (MBL) was detected in 48% (14/29), KPC: 34% (10/29), OXA: 14% (4/29). Initial empirical treatment: meropenem 53% (16/29). Adjustment of initial empirical treatment at 48 hours: 79% (23/29) according to cultures and antibiogram. Ceftazidime/avibactam: 48.2%; aztreonam combined in MBL strains. Extended infusion meropenem: 24% (7/29) if MIC ≤ 8 ug/ml. Overall mortality: 20.6%, in 6.8% it was related to infection. Conclusion In recent years we have seen an increase in antimicrobial resistance. Metallobetalactamases were the most frequently detected in patients hospitalized in critical areas. Resistance data in Argentina showed K. pneumoniae as one of the most prevalent bacteria in multidrug-resistant infections. Carbapenemes in high doses and extended infusions plus other antibiotics were useful to treat strains with low MIC values. Ceftazidime/avibactam was a good option for KPC and some OXA infections. Aztreonam in combined use was indicated for MBL strains. Disclosures All Authors: No reported disclosures