The organisms are commensals of mucosal surfaces and sometimes give rise to
opportunistic infection. It is also one of the notable causes of
otitis media and
sinusitis. It causes similar symptoms to
Haemophilus influenzae, although it is much less
virulent. Unlike
Neisseria meningitidis, which is a morphological relative of
M. catarrhalis, it hardly ever causes
bacteremia or
meningitis. •
Moraxella lacunata is one of the causes of
blepharoconjunctivitis in human. •
Moraxella bovis is the cause of
infectious bovine keratoconjunctivitis, known colloquially in the United Kingdom as New Forest eye. As a strict aerobe,
M. bovis is confined to the cornea and conjunctiva, resulting in a progressive, nonself-limiting keratitis, ulceration, and – ultimately – rupture of the cornea. The disease is relatively common, infecting cattle only. Treatment is the use of either subconjunctival injection of a tetracycline, or topical application of cloxacillin, the former being more effective. The bacterium can be transmitted by flies, so fly control may be necessary on farms throughout the summer. Rupture of the eye is more serious, and requires immediate enucleation, though the procedure itself carries a good prognosis. ==References==