To the Editor.—
A 26-year-old man came to Harbor General Hospital with fever, chills, and a sore throat. His temperature was 40 C (104 F) and there was marked pharyngeal and tonsillar inflammation, with a peritonsillar exudate. Pharyngeal culture grew Neisseria lactamicus in pure culture. This organism appears identical to N meningitidis on culture media, and distinction between the two can only be made on serologic or biochemical grounds.1,2Neisseria lactamicus differs from N meningitidis in that it ferments lactose and produces a β-galactosidase. The carrier rate of N lactamicus in adults is 0% to 2%.2 The importance of distinguishing the different Neisseria species lactamicus, meningitidis, and gonorrhoeae) has obvious epidemiologic and therapeutic importance.