Chlamydia trachomatis infections are the most prevalent sexually transmitted bacterial infections in the world. There is scarce data available referring to the distribution of C. trachomatis genotypes in Argentina. The aim of this study was to identify the genotypes of C. trachomatis circulating in the metropolitan area of Buenos Aires (Argentina) associated with ophthalmia neonatorum and genital infections.

Chlamydia trachomatis is one of the most common sexually transmitted infections worldwide. Based on sequence variation in the ompA gene encoding the major outer membrane protein, the genotyping scheme distinguishes 17 recognized genotypes, i.e. A, B, Ba, C, D, Da, E, F, G, H, I, Ia, J, K, L1, L2, and L3. Genotyping is an important tool for epidemiological tracking of C. trachomatis infections, including the revelation of transmission pathways and association with tissue tropism and pathogenicity. Moreover, genotyping can be useful for clinicians to establish the correct treatment when LGV strains are detected. Recently a microarray assay was described that offers several advantages, such as rapidity, ease of standardization and detection of mixed infections. The aim of this study was to evaluate the performance of the DNA microarray-based assay for C. trachomatis genotyping of clinical samples already typed by PCR-RFLP from South America. The agreement between both typing techniques was 90.05% and the overall genotype distribution obtained with both techniques was similar. Detection of mixed-genotype infections was significantly higher using the microarray assay (8.4% of cases) compared to PCR-RFLP (0.5%). Among 178 samples, the microarray assay identified 10 ompA genotypes, i.e. D, Da, E, F, G, H, I, J, K and L2. The most predominant type was genotype E, followed by D and F.

Graphical Using target enrichment, RNA baits designed around a panel of bacterial sexually transmitted infections were used to fish target DNA from the clinical sample, leading to complete bacterial genome sequences.

Since the Lymphogranuloma venereum (LGV) outbreak was first described in Buenos Aires in 2017, the detected strains presented peculiar characteristics. Our goal was to increase the understanding of the strains involved in the LGV outbreak in Argentina. We characterized the ompA gene sequences, using Sanger sequencing, of 88 LGV strains from 239 symptomatic patients in Buenos Aires enrolled between 2017 and 2019, and selected 20 C. trachomatis strains for further characterization using Multilocus Sequence Typing (MLST). Following the ompA gene analysis of the 88 LGV strains, we detected 43% L2b, 31% L1-like, and 26% L2. Among the 38 L2b samples analyzed, there were 7 distinct sequences, 3 of them not previously reported (L2bv12, L2bv13, and L2bv14). Additionally, we detected a strain with a new mutation (AM884176.1:g.59122A>T) found in the position defining L2 or L2b, proposed as L2i. Using MLST, five different sequence types (STs) were detected, including the ST2 (corresponding to the L1-like strains) and a new one (ST60). ST58 was associated with the concomitant presence of another STI and HIV. A high genetic diversity in C. trachomatis LGV strains in Argentina was observed in a short period of time, with a relatively low number of samples from a limited geographical area.

Graphical We describe a new lineage of Chlamydia trachomatis lymphogranuloma venereum identified in Argentina, carrying ompA-genotype L4. We also present further diversification of the globally circulating L2b lineage.