Pathophysiology
Clinical meaning
Cervicitis is inflammation of the uterine cervix, most commonly caused by sexually transmitted pathogens. The cervical transformation zone - where columnar epithelium meets squamous epithelium - is particularly vulnerable to infection due to its single-layer columnar cells and high density of immune cells. Chlamydia trachomatis has a unique biphasic developmental cycle. The elementary body (EB) is the infectious extracellular form - metabolically inert, resistant to environmental stress, with a rigid disulfide-cross-linked outer membrane. EBs attach to host columnar epithelial cells via heparan sulfate proteoglycans and MOMP (Major Outer Membrane Protein) interaction with host cell receptors. Following receptor-mediated endocytosis, EBs reside within membrane-bound inclusions that evade lysosomal fusion through type III secretion system (T3SS) effector proteins (Inc proteins - IncA, IncD, IncG) that modify the inclusion membrane. Within 6-8 hours, EBs differentiate into reticulate bodies (RBs) - the metabolically active, non-infectious intracellular form that replicates by binary fission. After 48-72 hours, RBs condense back into EBs, and the inclusion ruptures (or is extruded), releasing 200-1000 infectious EBs to infect adjacent cells. Chlamydia induces a chronic inflammatory response dominated by Th1 cytokines...