''Dermatophilus congolensis'' is a

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

bacterium and the cause of a disease called

dermatophilosis Rain scald (also known as dermatophilosis, tufailosis, rain rot or streptothricosis) is a Dermatology, dermatological disease affecting cattle and horses. Once in the skin, the bacterium ''Dermatophilus congolensis'' causes inflammation of the skin ...

(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.Merck Veterinary Manual
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Rainscald Rain scald (also known as dermatophilosis, tufailosis, rain rot or streptothricosis) is a dermatological disease affecting cattle and horses. Once in the skin, the bacterium ''Dermatophilus congolensis'' causes inflammation of the skin as well as ...

is another condition often seen in animals, which is also caused by ''D. congolensis''.

Morphology

''D. congolensis'' is

facultative anaerobic A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are '' Staphylococc ...

actinomycete The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycete ...

. It has two morphologic forms - filamentous

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e and motile

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or mo ...

s. 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). With the microscope, one can observe the characteristic "tramcar line"-like ''D. congolensis'' colonies together with Gram-positive thin filaments and coccoid forms.

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 Agarose is a heteropolysaccharide, generally extracted from certain red seaweed. It is a linear polymer made up of the repeating unit of agarobiose, which is a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose. Agarose is o ...

medium; the medium must then be incubated at 37°C and in a 5-10% 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.

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

Etymology and Discovery

From the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''derma'' (skin) + ''philos'' (loving), ''Dermatophilus congolensis'' is a

, aerobic actinomycete, and facultatively anaerobic bacteria. D. congolensis infects the epidermis and produces exudative dermatitis termed dermatophilosis that was previously known as rain rot, rain scald, streptotrichosis, and mycotic dermatitis. In 1915, René Van Saceghem, a

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...

military veterinarian stationed at a veterinary laboratory in the former

Belgian Congo The Belgian Congo (french: Congo belge, ; nl, Belgisch-Congo) was a Belgian colony in Central Africa from 1908 until independence in 1960. The former colony adopted its present name, the Democratic Republic of the Congo (DRC), in 1964. Colo ...

(thus, the species name ''congolensis''), reported D. congolensis from exudative dermatitis in cattle. Local breeders and veterinarians had observed the disease since 1910, but the causal agent was not identified.

References

External links

Type strain of ''Dermatophilus congolensis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
* http://awp.eduwikis.co.za/index.php/Dermatophilus {{Taxonbar, from=Q5262706 Micrococcales Pathogenic bacteria Bacteria described in 1915