Dermatology - Chancroid

Dermatology - Chancroid 
Haemophilus ducreyi, a gram-negative streptobacillus that is endemic in tropical and subtropical underdeveloped countries but rare in industrialized ones, is the cause of chancroid.

Four to seven days after exposure, a primary infection (break in epithelium) occurs at the site of inoculation, followed by lymphadenitis. Prepuce edema is frequent. Fifty percent of patients experience a painful, typically unilateral, gingual lymphadenitis 7–21 days following the original lesion.

A painful and irritable papule with an erythematous halo develops into an erosion, pustule, and ulcer. The base of the ulcer is friable with granulation tissue and covered in gray to yellow exudate. The ulcer's edges are sharp, undermined, and not indurated.
One or more ulcers may combine to become massive, serpiginous ulcers that are larger than two centimeters. An ulcer could heal before a buboe appears. Buboes can drain on their own and have erythema overlaying them.

One-third of patients had tender lymphadenopathy along with a painful ulcer, which suggests chancroid. The identification of H. ducreyi on specialized culture media is necessary for a conclusive diagnosis. Eliminate co-infections with T. pallidum, herpes simplex virus, and HIV. The differential include lymphogranuloma venereum, genital herpes, syphilis, trauma, inguinal hernia, plague, and tularemia.

Options for treatment include intramuscular ceftriaxone in a single dosage, ciprofloxacin 500 mg twice daily for three days (not recommended in pregnancy), erythromycin base 500 mg three times daily for seven days, and azithromycin 1 g in a single dose. There have been reports of erythromycin and ciprofloxacin resistance.