Chancroid vs. Donovanosis
These are less common ulcerative STIs that must be distinguished from syphilis and herpes.
| Feature | Chancroid | Donovanosis (Granuloma Inguinale) |
|---|---|---|
| Pathogen | Haemophilus ducreyi | Klebsiella granulomatis |
| Ulcer Appearance | Painful, deep ulcer with ragged borders and gray/yellow purulent base. | Painless, beefy-red granular base; slowly progressive. |
| Lymphadenopathy | Common, painful, suppurative “buboes.” | Rare (often presents as pseudobuboes). |
Diagnostic Hallmarks
- Chancroid: Diagnosis is usually clinical; PCR is available. Culture is difficult due to the fastidious nature of H. ducreyi.
- Donovanosis: Diagnosis confirmed by identifying Donovan bodies (intracellular bipolar-staining rods in macrophages) on Giemsa or Wright stain.
High-Yield Exam Pearl:
- Pain vs. Painless: Remember the mnemonic: Chancroid is painful (the “C” for painful “C”hancroid); Donovanosis is classically painless, beefy-red, and friable.
- Donovan Bodies: Always look for the mention of “bipolar staining” or “safety pin” appearance on board exams regarding Donovanosis.