What is the confirmation method for a diagnosis of diphtheria?

The confirmation method for a diagnosis of diphtheria relies on demonstrating toxin production by a suspicious isolate. The causative agent of diphtheria, Corynebacterium diphtheriae, produces a potent exotoxin that is responsible for the disease's pathogenic effects. When confirming a suspected case of diphtheria, testing for the presence of this toxin is critical, as it indicates that the isolate is not just a colony of C. diphtheriae but also one that can cause the disease.

Various methods can identify the presence of the toxin, including the Elek test, which involves inoculating a culture medium with a suspected strain and checking for the precipitation of toxin. This method not only confirms the bacteria's identity but also indicates its virulence based on toxin production. The clinical significance of detecting toxin production emphasizes its importance in diagnosis.

Other methods, such as the microscopic appearance of organisms stained with methylene blue or isolation on selective media like Tinsdale agar, can suggest the presence of C. diphtheriae but do not confirm whether the organism produces the toxin necessary for causing disease. Similarly, detection of β phage plaques in cultures pertains to certain bacteriophages affecting bacterial behavior but does not directly inform about the