Corynebacterium genus is named using the Greek word "korynee" which means club-shaped and "bacterium" which translates to rod-shaped. Corynebacterium species are short gram-positive rods often in irregular, club-shaped, or V-shaped arrangements. [Cells tend to lie parallel (palisades) or at acute angles (coryneform).] These organisms can undergo snapping after cell division from which they will form the characteristic palisades or "Chinese letter" shapes. Cells vary in diameter (0.3 to 1μm) and length (1.0 to 8.0 μm). They do not form spores or branches as with actinomycetes. There are other organisms that may also have similar shapes and are often called 'coryneform' or 'diphtheroid'.
Corynebacterium species are catalase-positive with a variety of biochemical reactions. Most Corynebacterium species contain mycolic acid in the cell wall and can be lipophilic or non-lipophilic. The growth of lipophilic species is enhanced when 0.1% Tween 80 is added to the media. According to Aoki and colleagues, as of January 2021, 137 Corynebacterium species have been recognized.2
2. Aoki T, Kitazawa K, Deguchi H, Sotozono C. Current evidence for Corynebacterium on the ocular surface. Microorganisms. 2021;9(2):254. doi:10.3390/microorganisms9020254
