JOURNAL OF BACTERIOLOGY AND VIROLOGY ISSN:1598-2467(Print) 2093-0429(Online)

Chlamydia trachomatis infections are increasing worldwide and constitute a significant threat to global public health. The number of chlamydial infection cases was estimated as 129 million in 2020. In addition, several countries have reported antimicrobial resistance in C. trachomatis, particularly against azithromycin, which is used for the first-line treatment of C. trachomatis infections. Despite such clinical significance, the molecular mechanisms of antimicrobial resistance acquisition are not comprehensively understood. In this study, antimicrobial resistance was induced in clinically isolated C. trachomatis via an in vitro model. We also attempted to detect single nucleotide polymorphism (SNP) in antimicrobial resistance-associated genes, such as 23S rRNA and rplD (L4). Resistance against azithromycin was induced in clinical C. trachomatis isolates. More importantly, an SNP causing an amino acid change on 23S rRNA was observed in azithromycin resistance-induced clinical isolates. This SNP (2058A<C, E686D) was previously reported to be associated with antimicrobial resistance. Our finding empirically proved that the abusive use of antimicrobials during C. trachomatis treatment may lead to the emergence of antimicrobial resistance. At the same time, the identified SNP on 23S rRNA can be used as a target to detect azithromycin resistance upon treatment failure in case of C. trachomatis infections. Continuous surveillance and investigations should be conducted to better comprehend the nature of C. trachomatis infections.