Phylum Proteobacteria, Class Gammaproteobacteria, Order Pseudomonadales, Family Moraxellaceae, Genus Moraxella, Moraxella
osloensis Bøvre and Henriksen 1967.
Gram-negative plump rods, 1-2 μm, with obtuse, often nearly square ends, often very
short diplobacilli, occasionally occurring in short chains. Diplococcus-like forms are
frequent. Some strains show a more fusiform or lanceolate shape, others show a
preponderance of diplococcal cells. May show variations in size and shape, often with
giant forms and filamentous forms, especially in old cultures. Nonmotile. Endospores
are not produced. May be encapsulated.
On blood agar 1 mm in diameter after 24 h., circular periphery and even, glistening
surface. Soft or coherent consistency. Unpigmented, soft or friable consistency. No
haemolysis. Some strains are strongly mucoid with large, domed, shiny and viscous
Strict aerobe. Slight growth at room temperature, optimal growth at 33 ºC - 37 ºC.
Sometimes the mucoid strains fail or are inhibited by a dry atmosphere. Grows on
Hugh and Leifson's medium, in Koser's and Simmons' citrate media (without
alkalizing the latter ) and in Audureau's medium with ethanol as source of carbon.
Growth on MacConkey agar is variable.
Isolated from genito-urinary tract, blood, spinal fluid, chest fluid, and nose, but seems to be rare in respiratory tract. Habitat is uncertain.
- Kjell Bovre and S. D. Henriksen. A new Moraxella species, Moraxella osloensis, and a revised description of Moraxella
nonliquefaciens. Int J Syst Bacteriol April 1967 17:127-135.
- 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.
Nitrates may or may not be reduced to nitrites. No urease activity, except for irregular reactions which may be observed in fresh
isolates. Positive results for catalase, esterase & oxidase.
Negative results for alkaline & acid phosphatase, DN-ase, gelatin liquefaction, H2S production, indole production, phenylalanine
deaminase, Tween 80 hydrolysis. No acid production from glucose and other sugars.
(c) Costin Stoica