Three isolates of a previously undescribed Dermatophilus sp. obtained from chelonids (two strains obtained from turtles and one strain obtained from a tortoise) were compared with 30 Dermatophilus congolensis isolates obtained from Australian mammals. The microscopic appearance, the colony morphology, and most biochemical test results for the chelonid isolates were characteristic of the genus Dermatophilus. Our isolates differed from the mammalian D. congolensis isolates in a number of cultural characteristics, including faster growth at 27°C than at 37"C, formation of two hemolysis zones around colonies on blood agar at 37°C in the presence of 10% CO,, poor motility, and production of a distinctive odor. The DNA restriction enzyme digestion and protein electrophoresis patterns of our strains were distinct. The electrophoretic mobilities of 11 enzymes differed from the mobilities observed with D. congolensis strains. A monoclonal antibody to a surface antigen of an ovine isolate did not react with zoospores or filaments of the chelonid isolates. Biochemical differences between our isolates and D. congolensis included the ability of the chelonid isolates to reduce nitrate to nitrite and the fact that the chelonid isolates exhibit collagenase activity in vitro. We propose that the chelonid isolates should be placed in a new species, Dermatophilus chelonae. Strain W16, which was isolated from a nose scab on a snapping turtle, is the type strain; a culture of this strain has been deposited in the American Type Culture Collection as strain ATCC 51576.A skin disease caused by the actinomycete Dermatophilus congolensis affects a wide variety of animal species and occurs throughout the world. This disease is economically important in cattle in tropical regions and in sheep in high-rainfall areas. Dermatophilosis lesions have also been found in goats, horses, deer, gazelles, giraffes, foxes, chamois, Columbian ground squirrels, cottontail rabbits, owl monkeys, polar bears, seals, pigs, and humans (13). To date, there apparently have been no reports of isolations of D. congolensis from chelonids, although the organism has been isolated from lizards (2,23,30). It has been reported that there is considerable variation in the colony morphology and cultural characteristics of D. congolensis (12). Significant variations in serological, biochemical, and virulence characteristics within the species have also been documented (1,8,10,12,16,18,19,21,33). A study of the variations in the cultural, biochemical, and morphological properties of Australian mammalian isolates of D. congolensis was recently undertaken (9). In our study we compared the properties of three isolates obtained from chelonids with the properties of these mammalian D. congolensis isolates.
MATERIALS AND METHODSBacterial isolates. Dermatophilus sp. isolates were obtained from an abscess in a tortoise in 1980 (isolate WS), from skin lesions on a turtle in 1982 (isolate Wll), and from a nose scab on a snapping turtle in 1987 (isolate W16= [T = type strain]); all of...
