Ann Lab Med 2018; 38(4): 324-330  
Recent Increase in the Incidence of TEM-135 β-Lactamase-harboring Neisseria gonorrhoeae in Korea
John Hoon Rim, M.D.1,2,3, Hyunsoo Kim, M.D.4, Hyukmin Lee, M.D.1, Dongeun Yong, M.D.1, Seok Hoon Jeong, M.D.1, and Kyungwon Lee, M.D.1
Department of Laboratory Medicine and Research Institute of Bacterial Resistance1, and Department of Pharmacology2, Yonsei University College of Medicine, Seoul; Department of Medicine3, Physician-Scientist Program, Yonsei University Graduate School of Medicine, Seoul; Department of Laboratory Medicine4, The National Police Hospital, Seoul, Korea
Corresponding author: Hyukmin Lee
Department of Laboratory Medicine, Yonsei University College of Medicine, 211 Eonjuro, Gangnam-gu, Seoul 06273, Korea
Tel: +82-2-2019-3777
Fax: +82-2-2057-8926
Received: July 25, 2017; Revised: September 30, 2017; Accepted: February 27, 2018; Published online: July 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

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Background: We investigated the molecular epidemiological characteristics and antimicrobial susceptibility pattern of penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates to monitor the change in distribution of blaTEM in Korea.
Methods: We collected 804 PPNG isolates from diverse hospitals and clinics mainly located in Seoul, Korea, over a period of 11 years (2005–2015). Isolate susceptibility to seven antimicrobials was determined using the agar dilution test. The molecular epidemiological characteristics of the isolates were determined by Sanger sequencing of blaTEM, N. gonorrhoeae multiantigen sequence typing (NG-MAST) and plasmid typing.
Results: Among 72 fully sequenced PPNG isolates, sixteen (22.2%) possessed TEM-135. All TEM-135 isolates had a common silent mutation (c.18C>T), which was previously unreported. We observed a pattern of continuous increase in the number of TEM-135 isolates since 2012. The median and 90% minimum inhibitory concentration of azithromycin were substantially lower in the TEM-135 group than in the non-PPNG and TEM-1 groups. All TEM-135 isolates showed different NG-MAST types and predominantly harbored Toronto/ Rio (75%) plasmids. A comprehensive comparative analysis of PPNG with TEM-135 according to NG-MAST, plasmid type, and year of isolation revealed a wide distribution.
Conclusions: The proportion of TEM-135 PPNG has continuously increased since 2012, in association with clonal spread. The difference at position 18 of the TEM-135 sequence can be interpreted as the existence of multiple clonal complexes. The possibility that TEM-135 was acquired via foreign plasmids requires careful follow-up and continuous monitoring of TEM-135 to ascertain whether it constitutes a step towards evolutionary change.
Keywords: Penicillinase-producing Neisseria gonorrhoeae, blaTEM, TEM-135 β-lactamase, NG-MAST, Plasmid typing, Antibiotic resistance, Korea

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