Activity of ceftolozane/tazobactam against Gram-negative isolates among different infections in Hong Kong: SMART 2017-2019

Ceftolozane/tazobactam was approved by the Drug Office, Department of Health, Government of the Hong Kong Special Administrative Region in 2017. Currently the activity of ceftolozane/tazobactam against Gram-negative pathogens isolated from patients in Hong Kong is undocumented. It would be prudent to document the activity of ceftolozane/tazobactam against and Enterobacterales isolated from hospitalized patients in Hong Kong. To describe the susceptibility of recent clinical isolates of and the two most common Enterobacterales species ( , ) cultured from respiratory tract, intra-abdominal, urinary tract and bloodstream infection samples to ceftolozane/tazobactam and other commonly used antimicrobial agents. CLSI-defined broth microdilution MICs were determined and interpreted for Gram-negative isolates collected in Hong Kong from 2017 to 2019 by the SMART surveillance programme. For , 96.7 % of isolates ( =210) were susceptible to ceftolozane/tazobactam, while susceptibility rates were ≥14 % lower to meropenem (82.9 % susceptible), cefepime (82.4 %), ceftazidime (81.4 %), piperacillin/tazobactam (76.7 %) and levofloxacin (79.5 %). Ceftolozane/tazobactam inhibited 85.7 % of piperacillin/tazobactam-nonsusceptible isolates, 80.6-82.1 % of cefepime-, ceftazidime- or meropenem-nonsusceptible isolates, and 75.9 % of multidrug-resistant (MDR) isolates of . For , 96.1 % of isolates ( =308) were susceptible to ceftolozane/tazobactam compared with meropenem (99.0 % susceptible), piperacillin/tazobactam (93.8 %), cefepime (85.7 %) and ceftazidime (85.4 %). The majority (88.3 %) of ESBL (extended-spectrum β-lactamase) non-CRE (carbapenem-resistant Enterobacterales) phenotype isolates of were susceptible to ceftolozane/tazobactam, comparable to piperacillin/tazobactam (85.0 %) but lower than meropenem (100 %). For , 98.5 % of isolates ( =609) were susceptible to ceftolozane/tazobactam compared to meropenem (99.3 % susceptible), piperacillin/tazobactam (96.7 %), ceftazidime (82.3 %) and cefepime (76.5 %). The majority (96.7 %) of ESBL non-CRE phenotype isolates of were susceptible to ceftolozane/tazobactam, similar to both meropenem (100 %) and piperacillin/tazobactam (94.5 %). Overall, >96 % of clinical isolates of , and collected in Hong Kong in 2017-2019 were susceptible to ceftolozane/tazobactam, while the activity of several commonly prescribed β-lactams was reduced, especially for . Continued surveillance of ceftolozane/tazobactam and other agents is warranted.