Moraxella, down but not out—the eye bug that won’t go away

Ocular infections caused by Moraxella sp have an interesting social history, often with somewhat unsavoury associations. To begin with, Moraxella is a true ophthalmic pathogen, an “eye bug” par excellence that can occasionally be found colonising the nasopharynx and on other mucous membranes,1 although rarely causing infections in other parts of the body. Originally isolated by Morax2 and Axenfeld3 in 1896 and 1897, respectively, from patients with angular blepharitis, the organism was at first called the diplobacillus of Morax–Axenfeld, and later came to be known as M lacunata. In 1899, Petit4 isolated a similar organism from a central corneal ulcer that he called, not surprisingly, the diplobacillus of Petit. This organism was later renamed M liquefaciens. A third species was also isolated, M nonliquefaciens, which was felt to be more benign, rarely causing keratitis or severe ocular infections. These rather arbitrary divisions into different species were based on the degree of liquefaction produced by the organisms when they were inoculated on to coagulated human serum, known as Loeffeler’s medium.

In 1900, Moraxella sp was reported by several authors to be the most common cause of conjunctivitis in Europe.5 But by the middle of the century, Thygeson and Kimura,6 Jones et al7 and others reported that the organism could be cultured in ≤1% of all cases of conjunctivitis, an apparent dramatic decline in the prevalence of Moraxella ocular infections in the population. The organism was down but still not out. A common view at the time was that different species of the organism selectively grew only in specific areas of the external eye. Angular blepharitis was thought to …