CORYNEBACTERIA

CORYNEBACTERIA Morphology • Are gram positive bacilli • Have some swellings/ club shaped at the end • Polymorphic show variation in shape and size. Some are so short, others large • Stain irregularly due to the nature of their cell wall • They do not form spores • Do not have capsules, non motile • Facultative anaerobes • Several species Corynebacteria diphtheria This is the main pathogenic species in human • Collectively known as diptheroids or coryneform • It easily gets decolorized during gram staining and can be confused to be gram negative • They contain metachromatic granules/volutin in their cytoplasm to store metabolites • The organisms arrange themselves in pairs attached at one end and look like a bean • Others arrange themselves in a parallel arrangement known as palisade arrangement • They tend to look like Chinese alphabets but this is seen in the critical stage