Pustular Dermatitis Caused by Dermatophilus congolensis

Abstract

We describe a case of pustular dermatitis in a 15-year-old girl who had just returned from horseback riding camp. Based on gram staining, colony characteristics, biochemical reactions, and whole-cell fatty acid analysis, the causative agent was identified as Dermatophilus congolensis. The literature contains few reports of human infection with this organism. CASE REPORTA 15-year-old Caucasian girl with a history of recalcitrant verruca on both hands presented to the dermatology clinic with an eruption on her left inner thigh. The eruption began after the patient returned home from a 2-week session at a horseback riding camp in rural Michigan. The weather had been hot and humid, and the campers often rode bareback, wore shorts, and did not shower regularly. The eruption was slightly tender to touch but not painful or pruritic, and there was no burning or tingling in the area prior to the lesion's appearance. Examination of the skin revealed multiple erythematous papules and pustules over a large portion of the left medial thigh. A few other campers had similar lesions, but they were not as severe. Samples from the pustules were taken for bacterial and fungal cultures by swabbing the purulent discharge. Gram staining was not performed. The patient was placed on cephalexin at 500 mg four times a day for 10 days and was encouraged to wash with an antibacterial soap.An organism was isolated in pure culture. The organism grew readily on blood and chocolate agars (Remel, Lenexa, KS) after overnight incubation at 35°C in 5% CO 2 . Colonies were slightly beta-hemolytic, yellowish, irregular, hard, and adherent to the agar surface and produced pits in the agar medium. Gram staining of the colonies showed gram-positive coccoid forms and large, long, irregular, tapering filaments, many with transverse septa (Fig. 1). The organism was catalase positive and urease positive. Based on these characteristics, the organism was presumptively identified as Dermatophilus congolensis. Definitive identification was performed by the Michigan Department of Community Health based on a variety of biochemical reactions and whole-cell fatty acid analysis with the Sherlock Microbial Identification System (MIDI, Inc., Newark, DE). The organism hydrolyzed casein and starch but not xanthine or tyrosine (Becton Dickinson, Sparks, MD). Nitrates were reduced, urease was produced, and gelatin was liquefied slowly (Remel, Lenexa, KS). The organism produced an alkaline reaction with peptonization in litmus milk (Becton Dickinson, Sparks, MD; prepared at the Michigan Department of Community Health [MDCH]) and grew in standard nutrient broth (Becton Dickinson, Sparks, MD; prepared at MDCH) but not in the presence of 6% sodium chloride. With Purple Broth Base containing 1% carbohydrates (Becton Dickinson, Sparks, MD; prepared at MDCH), dextrose was weakly fermented but xylose, mannitol, lactose, sucrose, maltose, salicin, inositol, sorbitol, arabinose, raffinose, rhamnose, galactose, and glycerol were not fermented. The organism was not acid fast and gre...

Successful therapy in unusual generalized Dermatophilus congolensis infection in a calf based on modified in vitro disk diffusion test

“…These microorganisms are facultative anaerobic, capnophilic or aerobic tolerant bacteria that belong to the Actinomycetales order (QUINN et al, 2011). The pathogen causes exudative dermatitis affecting mainly livestock, occasionally companion animals (GREENE, 2007;NATH et al, 2010;DALIS et al, 2014) and wildlife, and rarely humans (ZARIA, 1993;BURD et al, 2007). It is an atypical bacterium, because it produces infective motile zoospores and aerial mycelia (SONGER; POST, 2005;GIUFFRIDA, 2016).…”

“…A wide variety of topical and parenteral antimicrobials (monotherapy or combined use) has been recommended for treatment, although topical procedure is recognized as largely ineffective and some conventional drugs do not reach epidermal therapeutic concentrations (BURD et al, 2007). In addition, treatment outcome is influenced by severity and extent of lesions (QUINN et al, 2011), since disseminated lesions are generally refractory to therapy.…”

Outbreak of Dermatophilus congolensis in Grazing Beef Cattle in Northeastern Mexico: First Report

“…In bovines, D. congolensis causes an acute or chronic disease of the epidermis, characterized by inflammatory lesions that leave exudative and bleeding scabs, affecting mostly ruminants [2]. Animals are infected by mobile zoospores and the main routes of transmission are tick bites and contact with contaminated fomites and exudates or scabs from infected animals.…”

“…The first case was reported in Congo in 1915 and it has been isolated since then in animal infections chiefly in Africa: Kenya, Ethiopia, Tanzania, Nigeria, South Africa, Asia: Turkey, India, China, and Central and South America: Argentina, Uruguay, and Brazil, but also in Australia, the United States: New York, Kentucky, Florida, Texas, Canada, and Europe: France, Spain, Germany, as a chronic endemic disease and, more rarely, as an acute and epidemic infection. It is most commonly associated with goats, sheep, cows and horses but also affects a worldwide variety of domestic and wild animals, such as marine mammals, cats, antelope, buffalo and deer [2][3][4][5][6][7][8][9][10].…”

An outbreak of dermatophilosis and caseous lymphadenitis mixed infection in camels (Camelus dromedaries) in Jordan

“…The condition has been described in a wide range of animal hosts and humans [3,4]. The most affected domestic animals are cattle [5], camels [6,7], horses [8], sheep [9], goats [10], occasionally cats [11], and other species [4].…”