Chancroid laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.; Nate Michalak, B.A.; Serge Korjian M.D.
Overview
Lack of rapid and reliable laboratory tests make diagnosis and treatment decisions based on microbiologic findings difficult. Available laboratory tests involve acquiring a sample of ulcer exudate and include: gram stain, culture, and multiplex PCR (M-PCR).
Laboratory Findings
Gram Stain
- Ulcer exudate can stained to typically reveal gram negative coccobacilli organized in a chain, so-called a "school of fish."[1]
- Sensitivity of gram stain is poor and cannot be used for definitive diagnosis.
Culture
- Definitive diagnosis of chancroid requires culturing Haemophilus ducreyi from ulcer exudate.
- H. ducreyi is a fastidious bacterium and is therefore difficult to culture. Most facilities do no have the required media or experience to culture the bacterium.[2]
Polymerase Chain Reaction (PCR)
- A multiplex PCR (M-PCR) technique has been developed to amplify DNA from ulcer exudate and identify H. ducreyi.[3]
- PCR tests have not yet been approved by the FDA.
- PCR may not be practical due to the high cost of testing and slow availability of results.
Gallery
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Direct smear microscopic exam revealed the presence of Haemophilus ducreyi indicative of a chancroid infection. From Public Health Image Library (PHIL). [4]
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Photomicrograph of a rabbit blood culture showing Haemophilus ducreyi bacteria using Gram-stain technique. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria, which had been extracted from a culture. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria, which had been extracted from a culture. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria (1200x mag). From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria arranged in parallel rows. From Public Health Image Library (PHIL). [4]
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Gram-negative Haemophilus ducreyi bacteria arranged in parallel rows. From Public Health Image Library (PHIL). [4]
References
- ↑ A. K. Joseph & T. Rosen (1994). "Laboratory techniques used in the diagnosis of chancroid, granuloma inguinale, and lymphogranuloma venereum". Dermatologic clinics. 12 (1): 1–8. PMID 8143374. Unknown parameter
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ignored (help) - ↑ Lewis, D A (2003). "Chancroid: clinical manifestations, diagnosis, and management". Sexually Transmitted Infections. 79 (1): 68–71. doi:10.1136/sti.79.1.68. ISSN 1368-4973.
- ↑ Orle KA, Gates CA, Martin DH, Body BA, Weiss JB (1996). "Simultaneous PCR detection of Haemophilus ducreyi, Treponema pallidum, and herpes simplex virus types 1 and 2 from genital ulcers". J Clin Microbiol. 34 (1): 49–54. PMC 228728. PMID 8748271.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 "Public Health Image Library (PHIL)".