Donovanosis laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Kalsang Dolma, M.B.B.S.[2]; Nate Michalak, B.A.
Overview
The standard method for identifying K. granulomatis and suggesting donovanosis as the diagnosis is a smear and stain of ulcer material. Microscopy of the stain reveals Donovan bodies within monocytes that may or may not be capsulated. If swabs are taken for other diagnostic tests, the smear for Donovan bodies should be taken first to ensure there is adequate material to detect the Donovan bodies. K. granulomatis has been isolated via culture methods but is difficult and not practical as a tool for diagnosis.
Laboratory Findings
Microscopy
- Identification of Donovan bodies in tissue smears indicates donovanosis as a strong diagnosis. Donovan bodies are sufficiently unique from other etiologic agents that parasitize macrophages.[1]
- Slides can be created using two methods:[2]
- Tissue smear: after cleaning ulcer surface with saline, a cotton swab is rolled over the ulcer and then rolled over a slide.
- Tissue biopsy: tissue can be obtained from lesion with punch biopsy, forceps, or scalpel and then crushed between two slides. The lesion is often friable but local anesthetic may be necessary.
- Slides are then stained with Giemsa, Leishman's, or Wright's stain to reveal intracellular Donovan bodies within monocytes that may or may not be capsulated.[2]
- Haematoloxylin and eosin are poor stains.
- If swabs are taken for other diagnostic tests, the smear for Donovan bodies should be taken first to ensure there is adequate material to detect the Donovan bodies.
Culture
- K. granulomatis has been successfully cultured in human epithelial (HEp-2) cells with a technique adapted from Chlamydia culture.[3]
- Culturing K. granulomatis is difficult and not a practical means for diagnosis.
Polymerase Chain Reaction
- A PCR targeting the PhoE gene has been developed but is currently only available as a research tool.[2]
Serology
- An indirect immunofluorescence test has been developed but has a low sensitivity and is not practical for diagnosis.[2]
References
- ↑ Richens J (1991). "The diagnosis and treatment of donovanosis (granuloma inguinale)". Genitourin Med. 67 (6): 441–52. PMC 1194766. PMID 1774048.
- ↑ 2.0 2.1 2.2 2.3 O'Farrell N (2002). "Donovanosis". Sex Transm Infect. 78 (6): 452–7. PMC 1758360. PMID 12473810.
- ↑ Carter J, Hutton S, Sriprakash KS, Kemp DJ, Lum G, Savage J; et al. (1997). "Culture of the causative organism of donovanosis (Calymmatobacterium granulomatis) in HEp-2 cells". J Clin Microbiol. 35 (11): 2915–7. PMC 230086. PMID 9350758.