I can never remember the difference between chancre and chancroid. They are both sexually transmitted infections (STIs) but I always get them confused. Maybe typing this up will help me remember.

A chancre is the initial lesion of syphilis (primary), which is caused by the spirochete Treponema pallidum. The typical ulcer is painless, red, round, firm, with indurated borders. It arises three weeks after inoculation and disappears after two to six weeks without therapy. T. pallidum can be identified by serum antibody tests (MHA-TP, FTA-ABS), and material expressed from a chancre reveals motile spirochetes under dark-field microscopy. Treat with intramuscular benzathine penicillin G (alternative treatments are tetracycline and doxycycline).

Chancroid is also sexually transmitted, manifesting as a tender ulcer. It is more common in males, is usually painful, has ragged edges and a necrotic base. Tender inguinal lymphadenopathy is also common. It is caused by Haemophilus ducreyi, a small gram-negative rod and usually diagnosed clinically but can be confirmed with biopsy and/or culture (difficult). Treat with oral azithromycin or intramuscular ceftriaxone.

So, how will I try to remember the difference? A friend of mine suggested that "chancroid" could remind me of the word "android" (more common in males). A "lad" is male (common abbreviation for lymphadenopathy, which is painful). I could name the android "Duke," which might help remind me about H. ducreyi. Silly, I know, but sometimes this stuff really works!