VetBact logo


Swedish University of Agricultural Sciences

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:

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


The taxonomy of chlamydias

Species within the family Chlamydiaceae were previously divided into two genera Chlamydia and Chlamydophila. However, the differences between these two genera were not that great and many research groups have not accepted this division. Therefore, the genus Chlamydophila has been returned to the genus Chlamydia and this change has now been incorporated in VetBact

Published 2023-03-15. Read more...
New names of bacterial phyla

The taxonomic category phylum was previously not regulated by the International Code of Nomenclature of Prokaryotes (ICNP), but now this has changed and it was decided to revise the names of bacterial phyla. All phyla must be written in italics (which has been done on VetBact also before) and have the ending -ota.

Published 2023-03-01. Read more...

Recently Updated

Recent blog posts

Most recent comment

Swedish University of Agricultural Sciences