Ceftolozane/tazobactam: Literature review of its activity on Taiwanese isolates before its launch in Taiwan (2012–2021)

Ceftolozane, a novel cephalosporin, combined with tazobactam, a known β-lactamase inhibitor, shows robust antipseudomonal activity, although it doesn't cover carbapenemases. Our review of data from 2012 to 2021 in Taiwan highlights TOL/TAZ's in-vitro performance. TOL/TAZ is most effective against Pseudomonas aeruginosa (91.3–94.4 % susceptible, with an MIC <4 μg/mL). It also demonstrates good activity against Enterobacterales, including Escherichia coli (88–94.3 % susceptible), Klebsiella pneumoniae (72.6–84.1 % susceptible), Citrobacter koseri (93.3 % susceptible), Klebsiella oxytoca (98.1–100 % susceptible), and Proteus mirabilis (100 % susceptible). However, its efficacy varies among species typically associated with chromosomally-mediated AmpC production, such as Morganella morganii (100 % susceptible), Serratia marcescens (81.3–90.0 % susceptible), Enterobacter cloacae species complex (76.6–76.7 % susceptible), Klebsiella aerogenes (66.7–89.6% susceptible), and Citrobacter freundii (60.0 % susceptible). For carbapenem-nonsusceptible isolates, TOL/TAZ is less effective against K. pneumoniae and E. coli (susceptibility <10 %) but remains useful for P. aeruginosa (susceptibility 81.3–91.8 %). In conclusion, TOL/TAZ shows potent activity against P. aeruginosa and carbapenem-susceptible Enterobacterales in Taiwan.