Introduction of Diphtheria bacillus and Diphtheroids
Table of Contents
Diphtheria bacillus is also known as Klebs-Löffler bacillus and it is a Gram-positive nonmotile, club-shaped bacillus of Corynebacterium diphtheriae. C. diphtheriae is a causative agent of Diphtheria (a serious infection of the mucous membranes of the nose and throat). Diphtheroids are non-diphtherial species and they are part of normal human skin flora having property of aerobic, non-sporulating, pleomorphic Gram-positive rods which are more uniformly stained than C. diphtheriae, lack the metachromatic granules and are arranged in a palisade manner as shown in the figure.
Differences between Diphtheria bacillus and Diphtheroids
Differences between Diphtheria bacillus and Diphtheroids are as follows-
|1||Gram Reaction||Weakly Gram-positive||Strongly Gram-positive|
|3.||Arrangement of bacilli||Chinese letter pattern||Palisade arrangement|
|5.||Size and shape||Long and Chinese letter arrangement, slender||Short and thick bacilli|
|6.||Culture on a basal medium like|
peptone water and nutrient agar
|7.||Tellurite blood agar||Generally rough colony||Smooth colony|
|8.||Glucose and sucrose fermentation||Glucose only||Both glucose and sucrose|
|10.||Organisms||Corynebacterium diphtheriae||Corynebacterium pseudotuberculosis, Corynebacterium renale, C. bovis, C. striatum, C. minutissimum, C. pseudodiphtheriticum, C. haemolyticum, etc|
|11.||Pathogenicity||Highly pathogenic||Less pathogenic or commensals of the skin and mucous membranes|
|12.||Infection||Diphtheria||Usually nosocomial infections|
Keynotes diphtheria bacillus and Diphtheroids
- The toxin gene is encoded by a prophage called corynephage β.
- The common symptoms of diphtheria include pharyngitis, fever, and swelling of the neck.
- The Elek immunodiffusion test is the most common in vitro assay for the toxigenicity of C. diphtheriae.
- Gravis, intermedius, mitis, and belfanti are biotypes of C. diphtheriae.
- Albert’s stain is used for diphtheria bacillus staining.