Abstract
Animal venoms are considered sterile sources of antimicrobial compounds with strong membrane disrupting activity against multi-drug resistant bacteria. However, bite wound infections are common in developing nations. Investigating the oral and venom microbiome of five snake and two spider species, we evidence viable microorganisms potentially unique to venom for black-necked spitting cobras (Naja nigricollis). Among these are two venom-resistant novel sequence types of Enterococcus faecalis; the genome sequence data of these isolates feature an additional 45 genes, nearly half of which improve membrane integrity. Our findings challenge the dogma of venom sterility and indicate an increased primary infection risk in the clinical management of venomous animal bite wounds.
One Sentence Summary Independent bacterial colonization of cobra venom drives acquisition of genes antagonistic to venom antimicrobial peptides.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
We have added significant new data in our manuscript consisting of 1) MIC curves of the venom-derived E. faecalis isolates vs V583 demonstrating venom tolerance and 2) expanding pangenomic comparisons to 723 additional published E. faecalis genomes, in an attempt to identify the source of the venom-tolerant isolates. These isolates show no, or >30% inhibition by venom at 50mg/ml, where V583 shows an MIC of 11.7 mg/ml and an NIC 2.78 mg/ml. In addition, we redefine the pangenome of E. faecalis at 26,412 genes with a core genome of 342 highly conserved genes and 865 genes present in over 99% of strains. Maximum likelihood trees also failed to place the venom-derived strains within clades identified from within the UK or with any environmental or other link to the source snakes demonstrating independent adaptation to the venom milieu.
