A clinical diagnosis of donovanosis made by an experienced practitioner on the basis of the lesion’s appearance usually has a high positive predictive value. The diagnosis is confirmed by microscopic identification of Donovan bodies (Fig. 70-2) in tissue smears. Preparation of a good-quality smear is important. If donovanosis is suspected on clinical grounds, the smear for Donovan bodies should be taken before swab samples are collected to be tested for other causes of genital ulceration so that enough material can be collected from the ulcer. A swab should be rolled firmly over an ulcer previously cleaned with a dry swab to remove debris. Smears can be examined in a clinical setting by direct microscopy with a rapid Giemsa or Wright’s stain. Alternatively, a piece of granulation tissue crushed and spread between two slides can be used. Donovan bodies can be seen in large, mononuclear (Pund) cells as gram-negative intracytoplasmic cysts filled with deeply staining bodies that may have a safety-pin appearance. These cysts eventually rupture and release the infective organisms. Histologic changes include chronic inflammation with infiltration of plasma cells and neutrophils. Epithelial changes include ulceration, microabscesses, and elongation of rete ridges.
Pund cell stained by rapid Giemsa (RapiDiff) technique. Numerous Donovan bodies are visible.
A diagnostic polymerase chain reaction (PCR) test was based on the observation that two unique base changes in the phoE gene eliminate Hae111 restriction sites, enabling differentiation of K. granulomatis comb nov from related Klebsiella species. PCR analysis with a colorimetric detection system can now be used in routine diagnostic laboratories. A genital ulcer multiplex PCR that includes K. granulomatis has been developed. Serologic tests are only poorly specific and are not currently used.
The differential diagnosis of donovanosis includes primary syphilitic chancres, secondary syphilis (condylomata lata), chancroid, lymphogranuloma venereum, genital herpes, neoplasm, and amebiasis. Mixed infections are common. Histologic appearances should be distinguished from those of rhinoscleroma, leishmaniasis, and histoplasmosis.
Many patients with donovanosis present quite late with extensive ulceration. They may be embarrassed and have low self-esteem related to their disease. Reassurance that they have a treatable condition is important, as is the need to administer antibiotics and monitor patients for an adequate interval (see below). Epidemiologic treatment of sexual partners and advice about how to improve genital hygiene are recommended.
The recommended drug regimens for donovanosis are shown in Table 70-1. Gentamicin can be added if the response is slow. Ceftriaxone, chloramphenicol, and norfloxacin are also effective. Patients treated for 14 days should be monitored until lesions have healed completely. Those treated with azithromycin probably do not need such rigorous follow-up.
Surgery may be indicated for very advanced lesions.
TABLE 70-1EFFECTIVE ANTIBIOTICS FOR THE TREATMENT OF DONOVANOSIS ||Download (.pdf) TABLE 70-1 EFFECTIVE ANTIBIOTICS FOR THE TREATMENT OF DONOVANOSIS
|ANTIBIOTIC ||ORAL DOSE |
|Azithromycin ||1 g on day 1, then 500 mg daily for 7 days or 1 g weekly for 4 weeks |
|Trimethoprim-sulfamethoxazole ||960 mg bid for 14 days |
|Doxycycline ||100 mg bid for 14 days |
|Erythromycin ||500 mg qid for 14 days (in pregnant women) |
|Tetracycline ||500 mg qid for 14 days |