Distribution of b-lactamases and emergence of carbapenemases co-occurring Enterobacterales isolates with high-level antibiotic resistance identified from patients with intra-abdominal infection in the Asia-Pacific region, 2015-2018

Purpose: In this study, we aimed to assess the geographic distribution and molec-ular characteristics of B-lactamases among Enterobacterales isolates causing intra-abdominal infections (IAIs) from 2015 to 2018 in the Asia-Pacific region.Method: Isolates were investigated for extended-spectrum B-lactamases (ESBLs), AmpC B-lac-tamases, and carbapenemases using multiplex PCR assays and full-gene DNA sequencing.Result: A total of 832 Enterobacterales isolates from 8 different countries with B-lactamase genes were analysed. Plasmid-mediated ESBLs and AmpC B-lactamases were encoded in 598 (71.9 %) and 314 (37.7 %) isolates, respectively. In 710 (85.3 %) carbapenemase-negative iso-lates, positivity for both AmpC B-lactamases and ESBLs was identified in 51 (8.5 %) Escherichia coli and 24 (3.4 %) Klebsiella pneumoniae isolates. The most prevalent countries were Taiwan and Vietnam, and the co-occurrence of CMY/CTX-M in E. coli and DHA-1/ESBLs in K. pneumo-niae was predominant. All isolates showed high susceptibility to colistin, but susceptibility to carbapenems varied among different resistance mechanism combinations. Among 122 (14.7 %) isolates encoding carbapenemase, NDM (n = 67, including 64.2 % NDM-1) was the most com-mon, followed by the OXA-48-type (n = 49), KPC (n = 24) and IMP (n = 4). The most prevalent country was Thailand (n = 44), followed by Vietnam (n = 35) and the Philippines (n = 21). Twenty-two isolates were found to encode multiple carbapenemases, 16 of which were collected from Thailand and harbored NDM-1, OXA-232 and CTX-M-15. Despite high susceptibil-ity to amikacin, susceptibility to colistin was only 56 %.Conclusion: The emergence of carbapenem-non-susceptible AmpC/ESBL co-occurring Entero-bacterales and colistin non-susceptible carbapenemases co-occurring K. pneumoniae high-lights potential therapeutic challenges in the Asia-Pacific region.Copyright (c) 2021, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).