An automated image-based method for rapid analysis of Chlamydia infection as a tool for screening antichlamydial agents.

A major limitation in the identification of novel antichlamydial compounds is the paucity of effective methods for large-scale compound screening. The immunofluorescence assay is the preferred approach for accurate quantification of the intracellular growth of Chlamydia. In this study, an immunofluorescence image-based method (termed image-based automated chlamydial identification and enumeration [iBAChIE]) was customized for fully automated quantification of Chlamydia infection using the freely available open-source image analysis software program CellProfiler and the complementary data exploration software program CellProfiler Analyst. The method yielded enumeration of different species and strains of Chlamydia highly comparably to the conventional manual methods while drastically reducing the analysis time. The inhibitory capability of established antichlamydial activity was also evaluated. Overall, these data support that iBAChIE is a highly effective tool for automated quantification of Chlamydia infection and assessment of antichlamydial activities of molecules. Furthermore, iBAChIE is expected to be amenable to high-throughput screening studies for inhibitory compounds and fluorescently labeled molecules to study host-pathogen interactions.