Scrombroid toxicity results from bacterial decarboxylation of histidine.

• A. True
• B. False
• C. Bacterial hydrolysis of histamine
• D. Histidine deamination

Answer: (A)

Histamine formation by bacteria is the key driver of scromboid toxin poisoning. Bacteria on improperly stored or spoiled fish produce the enzyme histidine decarboxylase, which converts the amino acid histidine in fish tissue into histamine. The histamine then accumulates in the fish and, when consumed, causes the characteristic rapid onset of flushing, headache, palpitations, and other symptoms. Cooking does not reliably destroy histamine, so proper refrigeration and handling of fish to prevent histamine formation is essential.

The other options don’t fit because hydrolysis of histamine would break it down rather than create it, and histidine deamination would convert histidine into a different compound (urocanic acid) without producing histamine.