Phylum Proteobacteria, Class Gammaproteobacteria, Order Pseudomonadales, Family Moraxellaceae, Genus Moraxella, Moraxella
equi Hughes and Pugh 1970.
Gram-negative diplococci. Nonmotile.
Colonies on blood agar are 0.5-1.0 mm in diameter, resembling M. bovis, but are non-
hemolytic and butyrous. Produces an alkaline reaction in several carbohydrate
fermentation media, grows well on Herellea agar, unlike M. bovis which reportedly
fails to grow on Herellea agar.
Aerobic. Optimum growth temperature 37 ºC. Can grow at 42 ºC. No growth on
MacConkey agar, Simmons citrate medium and KCN medium.
Precipitin lines indistinguishable from those with control homologous antiserum
were produced when M. equi cells were tested against three M. bovis antisera
Isolated from the eyes of two groups of horses and ponies that had signs of conjunctivitis and erosion of the epithelium of their eyelid
Cause conjunctivitis and erosion of the epithelium of eyelid margins in horses. Becomes established when introduced into equine
eyes but not into bovine eyes, in contrast to M. bovis, which does not survive in equine eyes.
- Elliot Juni and Kjell Bovre. Order IX Pseudomonadales Orla-Jensen 1921, Family II Moraxellaceae Rossau, Van Landschoot,
Gillis and De Ley 1991 In: Bergey’s Manual of Systematic Bacteriology, Second edition,Vol two, part B, George M. Garrity (Editor-in-
Chief), pp. 411-442.
Biochemically indistinguishable from M. bovis.
Positive results for catalase, gelatin liquefaction & oxidase.
Negative results for H2S production, indole production, nitrate reduction, ornithine decarboxylase, lysine decarboxylase & urease.
(c) Costin Stoica