ABSTRACT
Chancroid is a superficial infection of the external genital tract caused by Hemophilus ducreyi. The bacteria are small Gram-negative rods measuring 0.5 µm by 1.5 to 2.0 µm, and are often seen in short chains or parallel arrays (‘school-of-fish’ or ‘fingerprint’ patterns). They may be cultivated with considerable difficulty, are nonmotile, and are not acid-fast. Bipolar staining is often demonstrable.
