A Comparison of Fluorescent Microscopy Methods for the Detection of Chlamydia trachomatis

Chlamydia trachomatis (C. trachomatis) is the most common bacterial sexually transmitted pathogen worldwide, especially in low- and middle-income countries, including South Africa. Although frequently asymptomatic, C. trachomatis infections in women cause pronounced genital inflammation. Given that genital inflammation increases women's risk for human immunodeficiency virus (HIV) infection, treating and preventing chlamydia is vital. Thus, there is an urgent need for effective interventions to curb chlamydia infection. Although vaccines are currently in development, none are yet approved for use. New drugs should also be developed and tested given the general rise of antimicrobial resistance. To advance such interventions, expertise in the basic microbiology of C. trachomatis is required. Techniques have indeed advanced over time; however, the standard methods of culture and quantification of C. trachomatis in vitro remain challenging. In South Africa, expertise in C. trachomatis culture and in vitro manipulation is particularly limited. Therefore, I aimed to establish a method to quantify laboratory-adapted stocks of C. trachomatis in in vitro cell culture, to develop research capacity and set the stage for the important future research needed to combat this pathogen. In this study, C. trachomatis was cultured from existing laboratory stocks and used to optimise and compare microscopy-based quantification methods. First, representative C. trachomatis urogenital serovars (E, H) and lymphogranuloma venereum (LGV) serovars (L1 and L2) were propagated in McCoy cells, using an established centrifugation protocol. These stocks were used for all assays comparing three commercially available reagents: (1) Pathfinder's C. trachomatis monoclonal antibody, (2) Invitrogen's C. trachomatis major outer membrane protein (MOMP) antibodies, and (3) Trinity Biotech MicroTrak C. trachomatis culture confirmation kit. In the research setting, fluorescent microscopy techniques are widely used for quantification of C. trachomatis due ...