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Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Rhodococcus hoagii
Etymology: Genus name: red coccus (grain or berry)
Species epithet: named after the bacteriologist Louis Hoag, who first isolated this bacterium.
Significance:  [Very important]   
Alternative Species Name(s):Prescottella equi, Corynebacterium equi, Rhodococcus equi,
Type Strain: ATCC 25729 och 6939 = CCUG 892 = NCTC 1621
Macromorphology (smell):
Large glistening colonies, which often flow together on the agar plate due to strong mucus production (capsule). On purple lactose agar and Sabouraud agar, the colonies turn salmon-pink due to production of a γ-carotene like pigment. Typical odor (underground cellars, old stumps or rotten pear).
Micromorphology: Can undergo different morphological stages during culture from rods (exponential phase) to cocci (stationary phase).
Gram +/Gram -:
Metabolism: Strictly aerobic
Other Enzymes: Esculinase -, hippuricase (-), tryptophanase -, urease (+)
Biochemical Tests: Hydrogensulphide (H2S) v.
Fermentation of carbohydrates: R. hoagii does not ferment carbohydrates.
Microbiological tests:
Rhodococcus hoagii  
R. hoagii does not produce hemolysis on blood agar, but it gives synergistic hemolysis with Staphylococcus aureus subsp. aureus or Corynebacterium pseudotuberculosis. Synergistic hemolysis can be demonstrated by the so-called CAMP-test.
Spec. Char.:
Reservoir: Soil
HostsDiseaseClinical picture
Horses (only foal)Pyogranulomatous bronchopneumonia Pneumonia, usually purulent inflammation with abscesses, decreased AT, fever, high mortality
PigsGranulomatous lymphadenitisPneumonia and oral abscesses
Virulence Factors: VapA (Virulence Associated Protein A) is a protein required to neutralize or destroy the phagosomes and lysosomes of the host cell. R. hoagii is facultatively intracellular and VapA prevents the bacterium from being taken up and broken down by phagosomes/lysosomes.
Genome Sequence:
Acc-noStrainSize (bp)Genome
FN563149 103S 5 043 170 1c + 1c 
Two strains have been sequenced and they have 0-1 plasmid.

16S rRNA Seq.:
Acc-noStrainNumber of NTOperonSequence similarity
X80614 DSM 20307T 1 478 99.9-100% 

About 50 species have been described within genus Rhodococcus, which is closely related to the following genera: Crossiella och Nocardia.
Reference(s): No. 14, 122, 149


New names of taxa within the classification category phylum

During October 2021, an article was published by A. Oren och G.M. Garrity, in which new names are proposed for a number of taxa within the classification category phylum. This has resulted in many discussions in social media about whether it was really necessary to make these changes, which have created confusion among microbiologists and other professionals who come into contact with bacteriology.

Published 2022-09-28. Read more...

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