HYPERKERATOSIS-ASSOCIATED CORYNEFORM INFECTION IN SEVERE COMBINED IMMUNODEFICIENT MICE

Hyperkeratosis-associated coryneform (HAC) is a coryneform bacterium, with a biochemical profile similar to Corynebacterium bovis, that caus es hyperkeratotic dermatitis in athymic nude mice. In the present stud y 28 severe combined immunodeficient (SCID) mice coming from six diffe rent animal facilities were submitted for bacteriological and patholog ical examination. HAC was isolated from 10 SCID mice belonging to two of these facilities. Two of the MAC-infected mice showed macroscopical lesions consisting in large alopecic areas, with small white flakes, involving the dorsum, flanks, neck and cheeks. Histologically, the ski n of these animals was characterized by diffuse acanthosis and hyperke ratosis. In the other eight MAC-infected SCID mice no macroscopical le sions were observed but focal areas of minimal to mild acanthosis were histologically detected in five cases. These results suggest that HAC can infect SCID mice inducing skin lesions similar, although generall y less severe, to those observed in nude mice with hyperkeratotic derm atitis. Our results pointed out that SCID mice may play an important r ole in the epidemiology of hyperkeratotic dermatitis of athymic nude m ice.