| Histophilus somni |
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Pseudomonadota (Proteobacteria), Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus
Histophilus, Histophilus somni Angen et al. 2003, type species of the genus.
Haemophilus agni and H. somnus may be synonyms of Histophilus somnis (formerly Histophilus ovis). De Ley et al., (1990)
suggested that H. agni and H. somnus to be transferred to genus Histophilus, Histophilus ovis being a senior synonym for H. agni.
However, none of these names are valid, and no types have been designated.
Histophilus, Histophilus somni Angen et al. 2003, type species of the genus.
Haemophilus agni and H. somnus may be synonyms of Histophilus somnis (formerly Histophilus ovis). De Ley et al., (1990)
suggested that H. agni and H. somnus to be transferred to genus Histophilus, Histophilus ovis being a senior synonym for H. agni.
However, none of these names are valid, and no types have been designated.
Gram-negative rods or coccobacilli. Non-motile. Non-spore-forming.
Colonies are pinpoint after 24 h and up to 1-1.5 mm in diameter after 48 h.
Haemolysis may vary; can be non-haemolytic, alpha-haemolytic or beta-haemolytic on
calf blood agar. Most isolates a yellow pigment. Growth is not dependent on V factor
or X factor. Thiamin monophosphate is required for growth. Growth of most strains
requires addition of 5-10% CO2.
Haemolysis may vary; can be non-haemolytic, alpha-haemolytic or beta-haemolytic on
calf blood agar. Most isolates a yellow pigment. Growth is not dependent on V factor
or X factor. Thiamin monophosphate is required for growth. Growth of most strains
requires addition of 5-10% CO2.
The type strain was isolated in the USA from a bovine brain with thromboembolic meningoencephalitis (TME) lesions.
‘Histophilus ovis’ was isolated from mastitis in sheep and has since been isolated from ovine septicaemia, synovitis and
epididymitis and from ovine vaginas.
‘Histophilus ovis’ was isolated from mastitis in sheep and has since been isolated from ovine septicaemia, synovitis and
epididymitis and from ovine vaginas.
Opportunistic pathogen to cattle and sheep (TME, pneumonia, septicaemia, mastitis, arthritis, myocarditis and reproductive disease).
It is also found as a commensal in the prepuces and semen and in the female genital tract and may also be part of the resident
microbial flora of the upper respiratory tract
It is also found as a commensal in the prepuces and semen and in the female genital tract and may also be part of the resident
microbial flora of the upper respiratory tract
- Angen O, Ahrens P, Kuhnert P, Christensen H, Mutters R. Proposal of Histophilus somni gen. nov., sp. nov. for the three species
incertae sedis 'Haemophilus somnus', 'Haemophilus agni' and 'Histophilus ovis'. Int J Syst Evol Microbiol 2003; 53:1449-1456. - Claxton PD, Everett RE. Recovery of an organism resembling Histophilus ovis from a ram. Aust Vet J 1966; 42:457-458.
Positive results for alkaline phosphatase, indole production (most strains), nitrate reduction, ONPG, oxidase, and acid production from
D-glucose (without gas).
Negative results for arginine dihydrolase, catalase, Simmons’ citrate, gelatinase, lysine decarboxylase, ornithine decarboxylase,
urease, Voges-Proskauer test, acid production from: adonitol, L-arabinose, dulcitol, aesculin, D-fructose, D-galactose, meso-inositol, D-
lactose, maltose, mannitol, raffinose, L-rhamnose, L-sorbose, salicin, sorbitol, sucrose, trehalose and D-xylose.
Variable fermentation for D-mannose.
D-glucose (without gas).
Negative results for arginine dihydrolase, catalase, Simmons’ citrate, gelatinase, lysine decarboxylase, ornithine decarboxylase,
urease, Voges-Proskauer test, acid production from: adonitol, L-arabinose, dulcitol, aesculin, D-fructose, D-galactose, meso-inositol, D-
lactose, maltose, mannitol, raffinose, L-rhamnose, L-sorbose, salicin, sorbitol, sucrose, trehalose and D-xylose.
Variable fermentation for D-mannose.
(c) Costin Stoica
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