1698. Activity of ceftolozane/tazobactam in vitro against Gram-negative isolates from pediatric patients: SMART 2017-2021

BACKGROUND: The study aims to evaluate the in vitro activity of ceftolozane/tazobactam (C/T) and other common-used antibiotics against clinical Gram-negative bacterial (GNB) isolates obtained from Chinese pediatric patients using data from The Study for Monitoring Antimicrobial Resistance Trends (SMART). METHODS: From 2017-2021, 554 Gram-negative isolates were collected from 16 pediatric departments across China. GNB isolates from pediatric departments were mainly derived from bloodstream (n = 135), intraperitoneal (n = 129), lower respiratory tract (n = 198) and urinary tract (n = 92) infections (Figure 1). The minimum inhibitory concentrations (MICs) were tested using a Trek Diagnostic System (Thermo Fisher Scientific). Susceptibility was determined by CLSI broth microdilution and interpreted with CLSI M100 (2021) breakpoints. [Figure: see text] RESULTS: E. coli (34.30%) and K. pneumoniae (27.62%) were the most common pathogens, followed by P. aeruginosa (15.34%). Susceptibility of species with more than 20 isolates were showed in Table 1. The susceptibility of P. aeruginosa to C/T was 89.41%, which was the highest among beta-lactams and was second only to amikacin. The susceptibilities of E. coli and K. pneumoniae isolates to C/T were 92.63% and 58.17%, respectively. When exclude carbapenem-resistant E. coli and K. pneumoniae, the susceptibility to C/T increased to 96.17% and 86.14%. C/T showed similar activities to E. coli and K. pneumoniae isolated from pediatric patients < 1 year (Table 2). Thirteen P. aeruginosa isolates were collected from patients < 1 year and 13/13 were susceptible to C/T (Table 3). [Figure: see text] [Figure: see text] [Figure: see text] CONCLUSION: P. aeruginosa and E. coli obtained from pediatric patients in China showed a high susceptibility to C/T. When excluding carbapenem resistant isolates, C/T also showed good activities against K. pneumoniae. DISCLOSURES: Pengcheng Li, M.D., MSD China: Employee of MSD China