684 



THE PARASITES OF RINGWORM 



circular yellow growth with raised powdery centre. On potato numerous 

 small yellowish and powdery star-shaped growths appear. 



In cultures on media containing maltose, Tricophyton tonsurans gives origin to a 

 mycelium with spore-bearing hyphse arranged in racemes. In ordinary peptone 

 media the growth is less luxuriant and the morphology is the same as in human 

 lesions. 



FIG. 324. Tricophyton from a case of "conglomerate folliculitis." (T. 

 megalosporum ectothrix.) The hair shaft is filled with spores in chains. (From 

 a photograph kindly lent by Dr. H. G. Adamson.) 







3. Experimental inoculation. It is difficult to infect man because the 

 cutaneous secretions are acid in reaction and the parasite will not grow in 

 an acid medium (Verujsky). To ensure infection the patient should be given 

 15-20 grams of sodium bicarbonate to render the perspiration alkaline. 

 Another means of producing infection is to cauterize the skin with the 

 red-hot end of a match which has been extinguished ; this forms a small 

 vesicle containing a drop of serum which is neutral in reaction, and on the 

 following day the parasite can be inoculated into the vesicle. 



The infection of animals (guinea-pigs, rabbits and cats) is also somewhat 

 difficult. After pulling out the hairs from a small area of the skin on the 

 back scarify the latter and rub in the culture. The lesion heals spontaneously 

 in 5-6 weeks. 



2. Tricophyton sabouraudi. 

 [Syn. Tricophyton acuminatum Bodin.] 



T. sabouraudi (Blanchard) corresponds to the T. endothrix with " fragile 

 mycelium " of Sabouraud. It occurs only in the hair. 



Tricophyton sabouraudi is the cause of the alopecia-like ringworm of children 

 TColcott Fox found T. sabouraudi in 26 per cent, of cases of scalp tricophytosis 

 in children]. The affected hair breaks off level with the skin and is very 

 difficult to epilate. Microscopically the hair is crammed with rounded pseudo- 

 spores which escape from the broken surface of the hair " like billiard balls 

 out of a bag " (Sabouraud). The mycelium is composed of moniliform cells, 

 and is easily dissociated in potash (fragile mycelium). 



