Meningitis Caused by Atypical Gram-negative Cocci.

Gram-negative cocci found in samples of purulent spinal fluid during routine laboratory examinations are apt to be reported as meningococci without further confirmation. While the meningococcus no doubt is the most common gram-negative coccus associated with acute meningitis, there are many others which play a r6le, particularly in sporadic cases. Error in diagnosis is also apt to occur in certain cases of meningitis caused by metachromatic cocci or by gram-positive cocci if the Gram stain is improperly applied, and also as a result of the fact that cocci, ordinarily gram-positive, may be decolorized when they are dead or phagocyted. Recognition of these problems and greater care in laboratory diagnosis will prevent wasting antimeningococcus serum in disease not caused by typical meningococci and may help to explain the failure of specific antimeningococcus serum in certain instances. Branham, Mitchell and Brainin, (1938) recently pointed out the difficulties attending the differentiation of even such wellknown bacteria as gonococci from the meningococcus in cases of meningitis. Many of the strains of gonococci which they studied were agglutinated by polyvalent antimeningococcus serum. Sugar fermentation reactions were somewhat more reliable in differentiation but the most fundamental differences appeared in cultural studies pertaining to colony morphology and growth requirements. Even more confusion in diagnosis is apt to arise in dealing with other gram-negative cocci such as Micrococcus catarrhalis, Micrococcus florens, Micrococcus crassus,