STD UPDATE - Chancroid

BULLETIN FOR MEDICAL PRACTITIONERS

Dr Tan Hiok Hee, Consultant Dermatologist, National Skin Centre

Introduction
Chancroid is caused by Haemophilus ducreyi. It is a cause of genital ulceration and is a co-factor for HIV. Its incidence has declined over the years in Singapore, with only 27 cases being reported in 2000.[1]

Chancroid is a co-factor for HIV transmission. High rates of HIV infection among patients with chancroid occur in the USA and other countries. About 10% of persons who have chancroid acquired in the USA are co-infected with T. pallidum or HSV; this percentage is higher in persons acquiring chancroid outside the US.

Diagnosis
A definitive diagnosis requires identification of H. ducreyi on special culture media that is not widely available from commercial sources; even using these media, sensitivity is seldom higher than 80%.

A probable diagnosis, for both clinical and surveillance purposes, can be made if all the following criteria are met:

1. the patient has one or more painful genital ulcers;
2. the patient has no evidence of T pallidum infection by darkfield examination of ulcer exudate or by a serologic test for syphilis performed at least 7 days after the onset of ulcers;
3. the clinical presentation, appearance of gdnital ulcers, and if present, regional lymphadenopathy are typical for chancroid; and
4. a test for HSV performed on the ulcer exudate is negative.

The combination of a painful ulcer and tender inguinal adenopathy, symptoms occurring in one third of patients, suggests a diagnosis of chancroid; when accompanied by suppurative inguinal adenopathy, these signs are almost pathognomonic.

Treatment
Successful treatment for chancroid cures the infection, resolves the clinical symptoms, and prevents transmission to others. In advanced cases, scarring can result despite successful therapy. Recommended regimens [2] include:

Azithromycin 1 gram stat OR
Ceftriaxone 250 mg IM stat OR
Ciprofloxacin 500 mg BD x 3 days OR
Erythromycin 500 mg TID x 7 days OR
Cotrimoxazole 2 tabs BD x 7 days

Several isolates with resistance to cotrimoxazole, ciprofloxacin and erythromycin have been reported.

Other management considerations
Patients should be retested for syphilis and HIV 3 months after the initial diagnosis of chancroid if the first tests were negative.[3]

Patients should be examined 3-7 days after initiation of therapy. If treatment is successful, ulcers usually improve symptomatically within 3 days and objectively within 7 days after therapy. The time required for complete healing depends on the size of the ulcer. Large ulcers may require more than 2 weeks to heal completely. Clinical resolution of fluctuant lymphadenopathy is slower than that of ulcers and may require needle aspiration or incision and drainage.

References

1. Department of STD Control Annual Report 2000.
2. CDC. 2002 Guidelines for treatment of sexually transmitted diseases. MMWR 2002; 51 (RRO6): 16-8.
3. DSC STD treatment guidelines 1999.
    

DEDICATED TO EXCELLENCE IN DERMATOLOGY
By National Skin Centre (Singapore)
Copyright (C) 1995 - National Skin Centre (Singapore) 

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