Antibacterial activity of snake, scorpion and bee venoms: a comparison with purified venom phospholipase A 2 enzymes

Aims:  Venoms of snakes, scorpions, bees and purified venom phospholipase A 2 (PLA 2 ) enzymes were examined to evaluate the antibacterial activity of purified venom enzymes as compared with that of the crude venoms. Methods and Results:  Thirty‐four crude venoms, nine purified PLA 2 s and two l ‐amino acid oxidases (LAAO) were studied for antibacterial activity by disc‐diffusion assay (100  μ g ml −1 ). Several snake venoms ( Daboia russelli russelli , Crotalus adamanteus , Naja sumatrana , Pseudechis guttata , Agkistrodon halys , Acanthophis praelongus and Daboia russelli siamensis ) showed activity against two to four different pathogenic bacteria. Daboia russelli russelli and Pseudechis australis venoms exhibited the most potent activity against Staphylococcus aureus , while the rest showed only a moderate activity against one or more bacteria. The order of susceptibility of the bacteria against viperidae venoms was – S. aureus  >  Proteus mirabilis  >  Proteus vulgaris  >  Enterobacter aerogenes  >  Pseudomonas aeruginosa and Escherichia coli . The minimum inhibitory concentrations (MIC) against S. aureus was studied by dilution method (160–1·25  μ g ml −1 ). A stronger effect was noted with the viperidae venoms (20  μ g ml −11 ) as compared with elapidae venoms (40  μ g ml −1 ). The MIC were comparable with those of the standard drugs (chloramphenicol, streptomycin and penicillin). Conclusion:  The present findings indicate that viperidae ( D. russelli russelli ) and elapidae ( P. australis ) venoms have significant antibacterial effects against gram (+) and gram (−) bacteria, which may be the result of the primary antibacterial components of laao , and in particular, the PLA 2 enzymes. The results would be useful for further purification and characterization of antibacterial agents from snake venoms. Significance and Impact of the Study:  The activity of LAAO and PLA 2 enzymes may be associated with the antibacterial activity of snake venoms.