The Types Mitis, Intermedius and Gravis of Corynebacterium Diphtheriae

Corynebacterium diphtheriae and Its Relatives1

“…Better-known examples of such colonial forms of bacteria are the smooth and rough pneumococci, smooth and rough Escherichia coli, smooth and rough Shigella, etc. Although smooth and rough C. diphtheriae had been recognized from about the turn of the century, it took the systematic work of the Leeds group under J. W. McLeod to obtain general recognition of the so-called colonial "types" gravis, mitis, and intermedius (196). By using the manifestation of toxaemic diphtheria as a means of selection, these workers established a correlation between the colonial appearance of the strain of C. diphtheriae re-W.…”

“…There are other peculiarities of these genotypes that need investigating (106,107,188).] It was, of course, a step forward for the diphtheriologist to have reemphasized the fact that C. diphtheriae is an epithet applied to an assemblage of corynebacteria, differing one from the other according to certain stable and easily recognizable properties; Dr. McLeod is certainly correct when he says that "the existence of these types has been so widely recognized and accepted that it cannot be considered to be any longer in doubt" (196). Unfortunately, this kind of analysis is today far too superficial.…”

Description ofCorynebacterium rouxiisp. nov., a novel member of thediphtheriaespecies complex

“…The most important human pathogen of the genus is Corynebacterium diphtheriae , which causes diphtheria (2, 4). C. diphtheriae is genetically heterogeneous (5–8) and four biovars were defined: Gravis, Mitis, Belfanti and Intermedius (9–11), the latter being almost never reported in recent literature. In 2010, maltose-non fermenting strains of C. diphtheriae biovar Belfanti were reported from two cats in the USA, and were shown to have a divergent rpoB sequence (12).…”

Laboratory review of reference strains of Corynebacterium diphtheriae indicates mistyped intermedius strains

“…Anderson et al described three types of Corynebacterium diphthenae on the basis of cultural and biochemical differences and noted that the gravis strains caused the most severe cases of diphtheria (1,2,9). A number of characteristics, including colonial morphology on McLeod's tellurite chocolate agar that clearly distinguished the minute colonies of intermedius strains from the much larger mitis and gravis colonies, differentiated the biotypes of C. diphthenae.…”

“…d HI broth supplemented with 0.2% Tween 80 (14). e Description from McLeod, who used nutrient broth (9). f Methylene blue stain of overnight growth on Loeffler's slants (9).…”