Genomics of Ocular Chlamydia trachomatis after 5 years of SAFE interventions for trachoma in Amhara, Ethiopia.

Genomics of Ocular Chlamydia trachomatis after 5 years of SAFE interventions for trachoma in Amhara, Ethiopia.

Pickering H, Chernet A, Sata E, Zerihun M, Williams CA, Breuer J, Nute AW, Haile M, Zeru T, Tadesse Z, Bailey RL, Callahan EK, Holland MJ, Nash SD

To eliminate trachoma as a public health problem, the WHO recommends the SAFE (Surgery, Antibiotics, Facial cleanliness, and Environmental improvement) strategy. As part of the SAFE strategy in the Amhara Region, Ethiopia, the Trachoma Control Program distributed over 124 million doses of antibiotic between 2007 and 2015. Despite this, trachoma remained hyperendemic in many districts and a considerable level of Chlamydia trachomatis (Ct) infection was evident. We utilised residual material from Abbott m2000 Ct diagnostic tests to sequence 99 ocular Ct samples from Amhara and investigated the role of Ct genomic variation in continued transmission of Ct. Sequences were typical of ocular Ct, at the whole-genome level and in tissue tropism-associated genes. There was no evidence of macrolide-resistance in this population. Polymorphism around ompA gene was associated with village-level trachomatous inflammation-follicular prevalence. Greater ompA diversity at the district-level was associated with increased Ct infection prevalence. We found no evidence for Ct genomic variation contributing to continued transmission of Ct after treatment, adding to evidence that azithromycin does not drive acquisition of macrolide resistance in Ct. Increased Ct infection in areas with more ompA variants requires longitudinal investigation to understand what impact this may have on treatment success and host immunity.