Phospholipase A2 (PLA(2)) as an Early Indicator of Envenomation in Australian Elapid Snakebites (ASP-27)

Early diagnosis of snake envenomation is essential, especially neurotoxicity and myotoxicity. We investigated the diagnostic value of serum phospholipase (PLA(2)) in Australian snakebites. In total, 115 envenomated and 80 non-envenomated patients were recruited over 2 years, in which an early blood sample was available pre-antivenom. Serum samples were analyzed for secretory PLA(2) activity using a Cayman sPLA(2) assay kit (#765001 Cayman Chemical Company, Ann Arbor MI, USA). Venom concentrations were measured for snake identification using venom-specific enzyme immunoassay. The most common snakes were Pseudonaja spp. (33), Notechis scutatus (24), Pseudechis porphyriacus (19) and Tropidechis carinatus (17). There was a significant difference in median PLA(2) activity between non-envenomated (9 nmol/min/mL; IQR: 7–11) and envenomated patients (19 nmol/min/mL; IQR: 10–66, p < 0.0001) but Pseudonaja spp. were not different to non-envenomated. There was a significant correlation between venom concentrations and PLA(2) activity (r = 0.71; p < 0.0001). PLA(2) activity was predictive for envenomation; area under the receiver-operating-characteristic curve (AUC-ROC), 0.79 (95% confidence intervals [95%CI]: 0.72–0.85), which improved with brown snakes excluded, AUC-ROC, 0.88 (95%CI: 0.82–0.94). A cut-point of 16 nmol/min/mL gives a sensitivity of 72% and specificity of 100% for Australian snakes, excluding Pseudonaja. PLA(2) activity was a good early predictor of envenomation in most Australian elapid bites. A bedside PLA(2) activity test has potential utility for early case identification but may not be useful for excluding envenomation.