Molecular epidemiology of carbapenem-resistant Enterobacterales in Thailand, 2016-2018

Carbapenem-resistant Enterobacterales (CRE) is a global threat. Enterobacterales develops carbapenem resistance through several mechanisms, including the production of carbapenemases. We aim to describe the prevalence of Carbapenem-resistant Enterobacterales (CRE) with and without carbapenemase production and distribution of carbapenemase-producing (CP) genes in Thailand using 2016-2018 data from a national antimicrobial resistance surveillance system developed by the Thailand National Institute of Health (NIH).

CRE was defined as any Enterobacterales resistant to ertapenem, imipenem, or meropenem. Starting in 2016, 25 tertiary care hospitals from the five regions of Thailand submitted the first CRE isolate from each specimen type and patient admission to Thailand NIH, accompanied by a case report form with patient information. NIH performed confirmatory identification and antimicrobial susceptibility testing and performed multiplex polymerase chain reaction testing to detect CP-genes. Using 2016-2018 data, we calculated proportions of CP-CRE, stratified by specimen type, organism, and CP-gene using SAS 9.4.

Overall, 4,296 presumed CRE isolates were submitted to Thailand NIH; 3,946 (93%) were confirmed CRE. Urine (n = 1622, 41%) and sputum (n = 1380, 35%) were the most common specimen types, while blood only accounted for 323 (8%) CRE isolates. The most common organism was Klebsiella pneumoniae (n = 2660, 72%), followed by Escherichia coli (n = 799, 22%). The proportion of CP-CRE was high for all organism types (range: 85-98%). Of all CRE isolates, 2909 (80%) had one CP-gene and 629 (17%) had > 1 CP-gene. New Delhi metallo-beta-lactamase (NDM) was the most common CP-gene, present in 2392 (65%) CRE isolates. K. pneumoniae carbapenemase (KPC) and Verona integron-encoded metallo-β-lactamase (VIM) genes were not detected among any isolates.

CP genes were found in a high proportion (97%) of CRE isolates from hospitals across Thailand. The prevalence of NDM and OXA-48-like genes in Thailand is consistent with pattern seen in Southeast Asia, but different from that in the United States and other regions. As carbapenemase testing is not routinely performed in Thailand, hospital staff should consider treating all patients with CRE with enhanced infection control measures; in line with CDC recommendation for enhanced infection control measures for CP-CRE because of their high propensity to spread.