Which statement about Scombroid (scrombrotoxin) poisoning is incorrect?

• A. Fish usually smell obviously spoiled before accumulation of toxic levels occur
• B. It is due to poor handling and improper (delayed) chilling after harvest
• C. Histamine is produced through bacterial decarboxylation of histidine
• D. Toxin production is associated with Lactobacillus, Clostridial and Proteus species of bacteria

Answer: (A)

Histamine poisoning comes from bacteria in improperly handled fish that convert histidine into histamine using histidine decarboxylase. The key idea is that toxin buildup does not depend on the fish smelling obviously spoiled, because histamine can accumulate even when odor or appearance seems acceptable. Cooking does not reliably destroy histamine, so even well-cooked fish can cause symptoms if histamine levels were high. The incorrect statement wrongly suggests that an obvious spoilage smell is a prerequisite for toxic histamine levels. In contrast, delayed chilling after harvest allows bacteria to proliferate and produce histamine, and the chemistry is driven by bacterial decarboxylation of histidine. The bacteria commonly implicated include Proteus species (and related Enterobacteriaceae), which aligns with the notion that certain microbes are associated with histamine production.