Phylum Proteobacteria, Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus Haemophilus,
Haemophilus agni Kennedy, Frazier, Theilen and Biberstein 1958. H. agni has been described as a member of the genus
Haemophilus. By current standards it does not qualify for inclusion in the genus.
De Ley et al., (1990) suggested that H. agni & H. somnus 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, pleomorphic rods or coccobacilli, long forms containing spherical
and thickened fusiform bodies, nonmotile. Presence of capsules is probable.
Colonies are convex, translucent, 0.5-1.5 mm in diameter and become flattened
peripherally and more sharply contoured edges in 5-10% CO2. Growth occurs on
hemoglobin cystein agar, chocolate agar and blood agar. Growth is very slight in air.
Hemolysis is negative.
X-factor and V-factor are not required. 5-10% CO2 atmosphere is required for growth.
Growth on MacConkey agar is negative.
The reservoir of Haemophilus agni has not been determined.
Associated with septicemia, meningitis, polyarthritis, myositis, pneumonia, and mastitis of sheep. Experimentally, only suckling mice
- Mogens Kilian, 2004. Genus III. Haemophilus. In: Bergey’s Manual of Systematic Bacteriology, Second edition, Vol two, part B,
George M. Garrity (Editor-in-Chief), pp. 883-904.
- J. G. Holt et al., 1994. Facultatively Anaerobic Gram-Negative Rods. Subgroup 3. Family Pasteurellaceae. In: Begey’s Manual of
Determinative Bacteriology, 9th-edition, Williams & Wilkins, pp 194-196.
Positive results for nitrates reduction, oxidase, ornithine decarboxylase, acid production
from: D(+) glucose, D(-) fructose, D(+) galactose (weak), maltose (weak), L(+)
arabinose (weak), D(+) xylose (weak) & mannitol (weak).
Negative results for alkaline phosphatase, catalase, arginine dehydrolase, lysine decarboxylase, indole production, acid production
from: dulcitol, meso-inositol, D(-) sorbitol, D(+) mannose, L(+) rhamnose, L(-) sorbose, cellobiose, lactose, sucrose (saccharose),
trehalose, raffinose, esculin, salicin & gas production from D(+) glucose are negative.
Urease activity is variable.
(c) Costin Stoica