The organism associated with a pseudomembrane in the throat and an exotoxin absorbed into the bloodstream causing a rapidly fatal hypertoxic disease is which?

• A. Arcanobacterium haemolyticum
• B. Staphylococcus aureus
• C. Streptococcus pyogenes
• D. Corynebacterium diphtheriae

Answer: (D)

Forming a pseudomembrane in the throat with potential rapid systemic toxicity points to a toxin-driven disease: diphtheria caused by Corynebacterium diphtheriae. This bacterium releases diphtheria toxin, an AB exotoxin that halts protein synthesis by ADP-ribosylating elongation factor-2, leading to local tissue necrosis and the characteristic fibrinous pseudomembrane. If the toxin enters the bloodstream, it can cause severe systemic effects such as myocarditis and neuropathies, which can be rapidly fatal if not treated. Vaccination with diphtheria toxoid provides protection, and antitoxin can be used if infection occurs. The other organisms may cause throat infections, but they do not produce this potent toxin or the distinctive pseudomembrane seen in diphtheria.