A client is brought to the emergency room with reports of facial muscle paralysis and increasing upper extremity weakness several hours after eating canned peppers. Histologic examination reveals a bacterial infection and further testing reveals a decrease in the release of the neurotransmitter acetylcholine from cholinergic neurons. What is the most likely cause of this illness?

The correct answer is Botulism exotoxin.

Explanation:

An exotoxin is a protein secreted extracellularly by a microorganism such as bacteria, protozoa and some fungi and algae. Exotoxins are very potent and can cause great damage to the host by destroying their cells or disrupting normal cell metabolism; they can be secreted, or, like some endotoxins, they can be released during cell lysis.

Most exotoxins can be destroyed by heat. They can exert effects locally or produce systemic effects. Among the best known are the botulinum toxin produced by Clostridium botulinum, the exotoxin of Corynebacterium diphtheriae that occurs in diphtheria disease.

Exotoxins are sensitive to antibodies produced by the immune system, but many are so toxic that they can be fatal to the host before the immune system has a chance to produce defenses against them.