In a recent communication on diplobacillary keratitis, we1 commented upon the variable morphology of the Morax-Axenfeld Gram-negative diplobacillus (Moraxella lacunata). We have had an unique opportunity to demonstrate this remarkable, and hitherto unstressed, variability, and we hope that our findings will help to explain some of the discrepancies found in the literature. Through the courtesy of Dr. Y. Mitsui, of Kumamoto, and Dr. Seymour Halpert, of New York, we were able to obtain a culture of the Gram-positive micrococci described by Mitsui and his colleagues2 as etiologic agents in angular conjunctivitis.
In our laboratory, we noticed accidentally that when a culture of the Morax-Axenfeld bacillus was left out for five days the microscopic appearance of the organisms changed. The bacteria became much shorter and tended to lose their Gram-negative staining characteristic. Moreover, they tended to retain these new characteristics on subsequent blood-agar transfers. An interesting example of this
HORWICH H, FEDUKOWICZ H. Variations in Morax-Axenfeld Diplobacillus. AMA Arch Ophthalmol. 1955;54(4):580–585. doi:10.1001/archopht.1955.00930020586011