(P11) Chlamydia trachomatis genovar distribution in heterosexual men with acute nongonococcal urethritis compared to historical genovar data in women

Background:

Eighteen genovars of Chlamydia trachomatis (CT) based on the Major Outer Membrane Protein (MOMP) have been characterized and are grouped into trachoma (A-C), urogenital (D-K), and lymphogranuloma venereum (LGV, L1-L3) genovars. Genovar identification is rarely performed on clinical urogenital CT infections as the results rarely impact treatment decisions. As a result, little is known about how the CT genovar distribution changes over time. As CT-specific immunity is often genovar-specific, understanding the genovar distribution has important implications for vaccine development and immunological studies that challenge with MOMP antigens or live CT organisms. However, no recent data on the prevalence and genotype distribution of CT infections exists. Whether the CT genovar distribution (1) differs in heterosexual men compared to women or (2) significantly changes over time remains unclear.



Methods:

Within the Idiopathic Urethritis Men’s Project (IUMP), we identified heterosexual men who presented to the Bell Flower sexually transmitted infection clinic in Indianapolis, Indiana, with CT-associated acute nongonococcal urethritis (CT-NGU) between 2016-2020. CT serovar identification was performed by ompA-based sequencing and genotyping. IUMP genovar data was compared to a prior study of CT genovar distribution in adolescent heterosexual women from Indianapolis between 1999-2005. Significance was evaluated by Mann-Whitney.



Results: Genovars from 103 heterosexual men with CT-NGU are included in this analysis and are compared to 262 CT-infected women from the Young Women’s Project (Batteiger et al, Sex Transm Dis, 2010). In both groups, the two most common genovars were E (28-32%) and D (20-26%). Genovars F (10-13%), J/Ja (8-15%), and I/Ia (11-15%) were the next most common. Genovars B, G, H, and K were infrequent; one L genovar was detected. No statistically significant difference was found when comparing the genovar distribution by cohort.



Conclusions: The distribution of CT genovars appears to be remarkably stable within heterosexual sexual networks across time. When considering multivalent MOMP antigens for vaccine inclusion or when eliciting CT-specific responses in immunological studies, challenge studies using MOMP antigens or CT organisms should prioritize serovars D and E, and perhaps I/Ia, F, and J/Ja.