Dermatophilus congolensis

Dermatophilus congolensis
This micrograph demonstrates a clustering of Dermatophilus congolensis bacteria using a Giemsa stain.
Scientific classification
Kingdom:
Bacteria
Phylum:
Actinobacterias
Class:
Actinobacterias
Order:
Actinomycetales
Family:
Dermatophilaceae
Genus:
Dermatophilus
Species:
D. congolensis
Binomial name
Dermatophilus congolensis
van Saceghem, 1915

Dermatophilus congolensis is a Gram-positive bacterium and the cause of a disease called dermatophilosis (sometimes called mud fever) in animals and humans, a dermatologic condition that manifests as the formation of crusty scabs containing the microorganism. It has been erroneously called mycotic dermatitis.[1] Rainscald is another condition often seen in animals, which is also caused by D. congolensis.

Morphology

D. congolensis is facultative anaerobic actinomycete. It has two morphologic forms - filamentous hyphae and motile zoospores. The hyphae are characterized by branching filaments (1-5 µm in diameter) that ultimately fragment by both transverse and longitudinal separation into packets of coccoid cells. The coccoid cells mature into flagellated ovoid zoospores (0.6-1.0 µm in diameter).[1] With the microscope, one can observe the characteristic "tramcar line"-like D. congolensis colonies together with Gram-positive thin filaments and coccoid forms.[2]

Cultivation

D. congolensis is a carboxiphylic germ, so needs carbon dioxide to properly grow on laboratory media. The germ grows well on sheep blood-enriched agarose medium; the medium must then be incubated at 37°C and in a 5-10% CO
2 atmosphere. Colonies become visible in 24–48 hours. Initially, they are small, with about a 1.0-mm diameter and with a grey-yellow colour. After 3–4 days, the isolated bacterial colonies can reach a 3-mm diameter, and they have a rough surface and yellow-golden pigmentation. Beta hemolysis can be seen around the colonies.[2]

Pathogenesis

D. congolensis causes severe skin infections in animals and humans. More frequently, cattle, horses, sheep, and goats are affected. Humans can also get this skin disease if elementary hygiene measures are not observed after dealing with infected animals. This dermatologic condition is known by many names - cutaneous streptothrichosis (on cattle, goats, and horses), rain scald (on horses), lumpy wool (on sheep), and strawberry foot rot.[1]

The pathogenic factors are very diverse, but the most important ones are of an enzymatic nature (adenase and lecitinase).

References

  1. 1 2 3 Merck Veterinary Manual
  2. 1 2 Gheorghe Rapuntean, Sorin Rapuntean (editors) (2005). Bacteriologie Veterinara Speciala (I ed.). Editura AcademicPress, Cluj-Napoca, Romania. ISBN 973-7950-95-X. {{cite book}}: |author= has generic name (help)
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