A Nationwide Investigation on the Distribution and Antimicrobial Susceptibility Profiling of Chlamydia trachomatis Collected from Patients in Korea.

BACKGROUND

In Korea, data on circulating Chlamydia trachomatis strains and their antimicrobial susceptibility profiles remain limited despite its significance in terms of public health. To date, their antimicrobial susceptibility or related genes are not fully characterized yet. This study aimed to determine the distribution of C. trachomatis genotypes and antimicrobial susceptibility profiles, and the presence of antimicrobial susceptibility related genes in Korea from 2016 to 2019.

MATERIALS AND

METHODS

A total number of 118 clinical C. trachomatis isolates were obtained from 1,011 samples for analysis. We characterized patient demographics and performed ompA genotyping and multilocus sequence typing (MLST) on the isolates, determined their in vitro susceptibilities to tetracycline, levofloxacin, azithromycin, and rifampicin, and screened for susceptibility-associated genes in both isolates and clinical samples.

RESULTS

The genotype D/Ep6, which is rarely reported globally, was the predominant strain (82, 69.5%), followed by genotypes F (14, 11.9%), Ja (12, 10.2%), E (9, 7.6%), and J (1, 0.9%) out of 118 C. trachomatis isolates. The MLST revealed eight sequence types (STs), including two novel STs. Of clinically isolated C. trachomatis (n=118), many isolates were susceptible to tetracycline at 125 ng/mL (52, 44.1%), levofloxacin at 250 ng/mL (81, 68.6%), azithromycin at 62.5 ng/mL (50, 42.4%), and rifampicin at 7.81 ng/mL (50, 42.4%). In antimicrobial susceptibility profiling. One isolate was susceptible to both azithromycin at 256 µg/mL and rifampicin at 8 µg/mL. Also, several single nucleotide polymorphisms (SNPs) on rpoB genes and tet(C) gene of C. trachomatis L2/tet9 were detected.

CONCLUSION

A rarely reported genotype, D/Ep6, was the dominant C. trachomatis variant in Korea during 2016 to 2019. The detection of SNPs and novel rpoB mutations may suggest unique C. trachomatis landscape in Korea. Our findings provide meaningful distribution landscape and antimicrobial susceptibility profiling of C. trachomatis in Korea.