eChapter Name: Moraxella
9789389571707
eBook Name: VETERINARY BACTERIOLOGY
by Indranil Samanta
The genus was named after Morax who first isolated the organisms from human conjunctivitis in 1896.
Properties of genus
1. Morphology : Moraxella are gram negative, small rods occurring in pair (diplobacilli). The aged cultures exhibit pleomorphism, occurring in pairs or chains as short, plump rods with rounded ends. Some strains may appear as cocci. The capsule is present in fresh isolates of some species (except Moraxella catarrhalis). They are non-motile and non-sporing. Moraxella bovis contains numerous type IV fimbriae on its surface.
2. Moraxella is aerobic, fastidious and non-fermenting in nature. However, some strains prefer anaerobic condition for their growth.
3. Classification : The genus Moraxella belongs to the Moraxellaceae family. Previously it was known as Branhamella. Most of the species are commensal except a few, which have disease producing capabilities. Important species are M. bovis, M. ovis, M. catarrhalis, M. boevrei, M. canis, M. caprae, M. caviae, M. cuniculi, M. phenylpyruvica.
4. Resistance : Resistance to physical and chemical agents is not remarkable. They are susceptible to desiccation and do not survive long outside the host. The beta- lactam antibiotic resistance is observed among M. catarrhalis isolates from clinical cases. This resistance is associated with the production of beta-lactamase enzyme.