Purpose: To elucidate the causative agent, two suspected fried fish sticks were collected from the suspected kitchen. Additionally, the 16 other raw fish stick samples were purchased from seven retail stores in southern Taiwan and processed for analyses.
Methods: The leftovers of the victims’ fried fish sticks and the 16 raw fish stick samples were tested to determine the occurrence of histamine, chemical and microbiological quality, and histamine-forming bacteria. Moreover, the fish species of suspected samples were identified as milkfish (Chanos chanos) by using PCR direct sequence analysis.
Results: The two suspected fried fish sticks contained 86.6 and 235.0 mg/100 g of histamine, levels which greater than the potential hazard action level (50 mg/100 g) in most illness cases. In addition, four of 16 tested raw milkfish stick samples (25%) had histamine levels greater than the FDA guideline of 5.0 mg/100g for scombroid fish and/or product. Ten isolates isolated from raw milkfish stick samples were proven to be prolific histamine-formers with ability to produce 373-1261 ppm of histamine in trypticase soy broth (TSB) supplemented with 1.0% L-histidine (TSBH).
Significance: Given the allergy-like symptoms of the victims and the high histamine content in the suspected fried milkfish sticks, this foodborne poisoning was strongly suspected to be caused by histamine intoxication.