An in-vitro examination of the effect of vinegar on discharged nematocysts of Chironex fleckeri.

OBJECTIVE To determine the effect acetic acid (vinegar) has on discharged nematocysts in a simulated sting from Chironex fleckeri. METHOD This research was performed in 2 parts: 1 C. fleckeri tentacles placed on amniotic membrane were electrically stimulated, and venom washings collected before and after application of vinegar. Lyophilised venom washings were run through a fast-performance protein liquid chromatography column to confirm the venom profile, with a quantitative measure of venom from each washing calculated using UNICORN™ software. 2 The toxicity of the washings was determined by application to human cardiomyocytes, with percentage of cell detachment providing a measure of cell mortality, and hence toxicity. RESULTS Part 1: There was a 69 ± 32% (F = 77, P < 0.001) increase in venom discharge after vinegar was applied compared to post electrical stimulation. Part 2: Venom collected after the administration of vinegar demonstrated the same toxicity as venom from electrically stimulated C. fleckeri tentacles and milked venom, causing cell mortality of 59 ± 13% at 10 µg ml⁻¹ compared to 57 ± 10% and 65 ± 7% respectively. CONCLUSION This in-vitro research suggests that vinegar promotes further discharge of venom from already discharged nematocysts. This raises concern that vinegar has the potential to do harm when used as first aid in C. fleckeri envenomation.