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 AsiaePacific region, 2015e2018

Abstract

Abstract Purpose: In this study, we aimed to assess the geographic distribution and molecular characteristics of b-lactamases among Enterobacterales isolates causing intraabdominal infections (IAIs) from 2015 to 2018 in the AsiaePacific region. Method: Isolates were investigated for extended-spectrum b-lactamases (ESBLs), AmpC b-lactamases, 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 isolates, 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. pneumoniae was predominant. All isolates showed high susceptibility to colistin, but susceptibility tocarbapenems varied among different resistance mechanism combinations. Among 122 (14.7 %) isolates encoding carbapenemase, NDM (n Z 67, including 64.2 % NDM-1) was the most common, followed by the OXA-48-type (n Z 49), KPC (n Z 24) and IMP (n Z 4). The most prevalent country was Thailand (n Z 44), followed by Vietnam (n Z 35) and the Philippines (n Z 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 susceptibility to amikacin, susceptibility to colistin was only 56 %. Conclusion: The emergence of carbapenem-non-susceptible AmpC/ESBL co-occurring Enterobacterales and colistin non-susceptible carbapenemases co-occurring K. pneumoniae highlights potential therapeutic challenges in the AsiaePacific region.