Molecular Epidemiology of Penicillinase-Producing Neisseria gonorrhoeae Isolates and Their bla_TEM-135 Gene Variant in Bangkok, Thailand, 2015–2017

Abstract

Penicillinase-producing Neisseria gonorrhoeae (PPNG) possessing bla_TEM-135 is a serious public health threat. With only a single change in the amino acid sequence, bla_TEM-135 could evolve into a TEM-type extended-spectrum beta-lactamase (ESBL), which hydrolyzes extended-spectrum cephalosporins, including ceftriaxone and cefixime. We investigated the molecular epidemiological characteristics, types of plasmids in PPNG isolates, and prevalence of PPNG clinical isolates producing TEM-135 beta-lactamases. N. gonorrhoeae multi-antigen sequence typing (NG-MAST) was used to determine the molecular epidemiological characteristics of 99 PPNG isolates collected from 2015 to 2017. A mismatch amplification mutation assay was used to examine the bla_TEM-135 gene prevalence. Of the 89 identified NG-MAST sequence types, 65 (73.0%) were novel. Only 17.7% (43/243) of PPNG isolates belonged to 16 genogroups. The most frequent plasmid was African, followed by Rio/Toronto, and Asian. The bla_TEM-135 allele was found in Rio/Toronto plasmids. The bla_TEM-135 allele was present in 23.2% (23/99) of the PPNG isolates. PPNG isolates expressing TEM-135 beta-lactamase exhibited significantly higher penicillin MIC (minimum inhibitory concentration) values than TEM-1 PPNG isolates. The PPNG isolates showed high genetic diversity and a high proportion of bla_TEM-135 alleles. Mutation of the bla_TEM-135 allele is worrisome as only one mutation could cause TEM-1 to evolve into an ESBL variant that degrades ceftriaxone. Ongoing surveillance of bla_TEM-135 and new PPNG isolates is imperative.