DIAGNOSIS o Clinical: muscle weakness edema and a pseudomembranous material in the upper respiratory tract characterizes diphtheria o Laboratory: Tellurite media is the agar of choice for isolation of Corynebacteria, which produce jet black coloniesDIAGNOSIS ⚫ Clinical: Muscle weakness, edema and a pseudomembranous material in the upper respiratory tract characterizes diphtheria. ⚫ Laboratory: Tellurite media is the agar of choice for isolation of Corynebacteria, which produce jet black colonies