Multicenter surveillance of antimicrobial susceptibilities and resistance mechanisms among Enterobacterales species and non-fermenting Gram-negative bacteria from different infection sources in Taiwan from 2016 to 2018

Abstract

To explore the invitro antimicrobial susceptibility among clinically important Gram-negative bacteria (GNB) in Taiwan. From 2016 through 2018, a total of 5458 GNB isolates, including Escherichia coli (n=1545), Klebsiella pneumoniae (n=1255), Enterobacter species (n=259), Pseudomonas aeruginosa (n=1127), Acinetobacter baumannii complex (n=368), and Stenotrophomonas maltophilia (n=179), were collected. The susceptibility results were summarized by the breakpoints of minimum inhibitory concentration (MIC) of CLSI 2020, EUCAST 2020 (for colistin), or published articles (for ceftolozane/tazobactam). The resistance genes among multidrug-resistant (MDR) or extensively drug-resistant (XDR)-GNB were investigated by multiplex PCR. Significantly higher rates of non-susceptibility (NS) to ertapenem and carbapenemase production, predominantly KPC and OXA-48-like beta-lactamase, were observed in Enterobacterales isolates causing respiratory tract infection than those causing complicated urinary tract or intra-abdominal infection (12.7%/3.44% vs. 5.7%/0.76% or 7.7%/0.97%, respectively). Isolates of Enterobacter species showed higher rates of phenotypic extended-spectrum β-lactamase and NS to ertapenem than E. coli or K. pneumoniae isolates. Although moderate activity (54-83%) was observed against most potential AmpC-producing Enterobacterales isolates, ceftolozane/tazobactam exhibited poor invitro (44.7-47.4%) activity against phenotypic AmpC Enterobacter cloacae isolates. Additionally, 251 (22.3%) P. aeruginosa isolates exhibited the carbapenem-NS phenotype, and their MDR and XDR rate was 63.3% and 33.5%, respectively. Fifteen (75%) of twenty Burkholderia cenocepacia complex isolates were inhibited by ceftolozane/tazobactam at MICs of ≤4μg/mL. With the increase in antibiotic resistance in Taiwan, it is imperative to periodically monitor the susceptibility profiles of clinically important GNB.