Disorders Caused by Botulinum Toxin and Tetanus Toxin

Anaerobic organisms of the genus Clostridia (C) can cause significant human disease. Exotoxins secreted by C botulinum and C tetani cause botulism and tetanus, respectively (summarized in Table 156.1). Botulinum neurotoxin causes neuromuscular blockade by interfering with vesicular acetylcholine release, leading to cholinergic blockade at the neuromuscular junctions of skeletal muscle, and consequently, symmetric flaccid paralysis. Tetanus toxin prevents release of inhibitory neurotransmitters at central synapses, leading to overactivity of motor neurons and muscle rigidity and spasms. This chapter reviews clinical features of botulism and tetanus and discusses their pathophysiological basis.