A diagnostic key employing biological reactions for differentiating pathogenic Corynebacterium genitalium (NSU corynebacteria) from commensals of the urogenital tract.

More than 100 strains of Corynebacterium genitalium, probably responsible for coryneform urethritis and other infections, and 600 commensals of the male and female urogenital tracts have been studied and grouped into five pathogenic types numbered I to V and six saprophytic types designated C-1 to C-6 on the basis of eight biological reactions. This preliminary classification has been based on differences in requirements for oxygen, on the fermentation of fructose, dextrose, sucrose, and starch together with the production of the enzymes gelatinase, lipase, and urease. One criterion differentiated the pathogens from the commensals: All pathogens were nonfructose fermenters whereas every commensal fermented this sugar.