PATHOGENS

• Treponema pallidum subsp. pallidum are obligate microaerophilic, Gram-negative spirochetes that cause syphilis, a chronic bacterial infection.[5]
  • Upon infection, T. pallidum disseminates widely and invades the central nervous system.
    • In the early 20th century, syphilis was a leading cause of neurological and cardiovascular disease.[25]
  • Its genome lacks transposable elements and remains conserved, which helps explains why T. pallidum remains exquisitely sensitive to penicillin.[30]
  • T. pallidum causes congential infection via vertical transmission from mother to infant.[18]
• Endemic (i.e., nonvenereal) treponematoses include T. pallidum subsp. pertenue → yaws; T. carateum → pinta; T. pallidum subsp. endemicum → bejel.
  • Acquisition tends to occur at a young age, and the primary lesion occurs on an extremity.