Phospholipase A2 (PLA₂) as an Early Indicator of Envenomation in Australian Elapid Snakebites (ASP-27)

• Main Authors: Geoffrey K. Isbister, Nandita Mirajkar, Kellie Fakes, Simon G. A. Brown, Punnam Chander Veerati
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Biomedicines
• Subjects: snakebite; envenomation; phospholipase; diagnosis; antivenom; venom
• Online Access: https://www.mdpi.com/2227-9059/8/11/459

Early diagnosis of snake envenomation is essential, especially neurotoxicity and myotoxicity. We investigated the diagnostic value of serum phospholipase (PLA₂) 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 PLA₂ activity using a Cayman sPLA₂ 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 <i>Pseudonaja</i> spp. (33), <i>Notechis scutatus</i> (24), <i>Pseudechis porphyriacus</i> (19) and <i>Tropidechis carinatus</i> (17). There was a significant difference in median PLA₂ activity between non-envenomated (9 nmol/min/mL; IQR: 7–11) and envenomated patients (19 nmol/min/mL; IQR: 10–66, <i>p</i> < 0.0001) but <i>Pseudonaja</i> spp. were not different to non-envenomated. There was a significant correlation between venom concentrations and PLA₂ activity (r = 0.71; <i>p</i> < 0.0001). PLA₂ 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 <i>Pseudonaja</i>. PLA₂ activity was a good early predictor of envenomation in most Australian elapid bites. A bedside PLA₂ activity test has potential utility for early case identification but may not be useful for excluding envenomation.