Animal venoms are considered sterile sources of antimicrobial compounds with strong membrane-disrupting activity against multidrug-resistant bacteria. However, venomous bite wound infections are common in developing nations. New research led by the University of Westminster and Northumbria University provides evidence that spider and snake venoms host diverse, viable microbiota, with isolates genetically adapted to venom antimicrobials of medical interest against multidrug resistance. The results challenge perceptions on the sterility of venom and absence of primary infection risk upon envenomation, pointing to modern nucleic acid technologies to better inform envenomation care and antibiotic use.
In contrast to the generally held view that venoms are both antimicrobial and sterile, despite contrasting reports since the 1940s, Esmaeilishirazifard et al. show that microorganisms can viably colonize venoms of both vertebrates and invertebrates. Image credit: Pete Wardell / CDC.
“Notwithstanding their 3 to 5% mortality, the 2.7 million envenomation-related injuries occurring annually — predominantly across Africa, Asia, and Latin America — are also major causes of morbidity,” said Dr. Sterghios Moschos, a researcher at the University of Westminster and Northumbria University, and colleagues.
“Venom toxin-damaged tissue will develop infections in some 75% of envenomation victims, with Enterococcus faecalis being a common culprit of disease.”
“However, such infections are generally considered to be independent of envenomation.”
In the study, the authors investigated the envenomation organ and venom microbiota of five snake and two spider species.
They found viable microorganisms in the venoms of the black-necked spitting cobra (Naja nigricollis) and the Indian ornamental tarantula (Poecilotheria regalis).
Among the bacterial isolates recovered from the cobra venom, they identified two venom-resistant types of a bacterium species called Enterococcus faecalis.
“Common diagnostic tools failed to identify these bacteria correctly — if you were infected with these, a doctor would end up giving you the wrong antibiotics, potentially making matters worse,” Dr. Moschos said.
“When we sequenced their DNA we clearly identified the bacteria and discovered they had mutated to resist the venom.”
“This is extraordinary because venom is like a cocktail of antibiotics, and it is so thick with them, you would have thought the bacteria would not stand a chance.”
“Not only did they stand a chance, they had done it twice, using the same mechanisms.”
“We also directly tested the resistance of Enterococcus faecalis, one of the species of bacteria we found in the venom of black-necked spitting cobras, to venom itself and compared it to a classic hospital isolate: the hospital isolate did not tolerate the venom at all, but our two isolates happily grew in the highest concentrations of venom we could throw at them.”
The findings appear this week in the journal Microbiology Spectrum.
_____
Elham Esmaeilishirazifard et al. Bacterial Adaptation to Venom in Snakes and Arachnida. Microbiology Spectrum, published online May 23, 2022; doi: 10.1128/spectrum.02408-21
Source link: https://www.sci.news/biology/venom-bacteria-10836.html
