Moraxella lacunata is a rod-shaped, Gram-negative, nonmotile bacterium, generally present as diploid pairs. It is typically regarded as a commensal organism of the upper respiratory tract. M. lacunata is associated with chronic conjunctivitis.
Moraxella lacunata was first described independently by Victor Morax (1896) and Theodor Axenfeld (1897), hence the alternate name "Morax-Axenfeld diplobacilli" and the name of eye infection in humans is sometimes called Morax-Axenfeld conjunctivitis.
It has the ability to change its morphology in laboratory. M. lacunata became shorter and tended to lose its Gram-negative staining characteristic when left out for 5 days. It also tended to retain these new characteristics on subsequent blood-agar transfers.
Infection occurs mainly in adults, but can occur at any age. It is characterized by: