Treponema pallidum causes
Treponema pallidum subspecies pallidum is a fastidious microaerophilic spirochete exhibiting distinctive corkscrew morphology with endoflagella located within periplasmic space between outer membrane and cytoplasmic cylinder, driving motility in viscous environments like mucosal secretions. Unable to be continuously cultured in vitro, it transmits via sexual contact causing syphilis characterized by primary chancre, secondary disseminated rash, and tertiary gummas, cardiovascular and neural damage. Taxonomic placement in family Spirochaetaceae reflects helical coiling, outer sheath lacking lip
Ref: CDC Syphilis Treponema pallidum spirochete; Jawetz Medical Microbiology 27th ed., Spirochaetes Treponema morphology dark-field
