The false widow spider has received a lot of negative press over the years but they’re not entirely deserving of their malevolent reputation. These spiders do sometimes administer venom when they bite humans but usually the worst symptoms you can expect to suffer from this is pain comparable to a wasp sting. However, new research has recognized an alternative complication for a patient with a false widow bite as it’s been discovered that these spiders can transfer antibiotic-resistant bacteria. The study, published in the journal Scientific Reports, found that many spider bites are capable of transferring bacteria when they munch on a human and that previous assumptions that venom would neutralize it were false.
The research was carried out by a team of zoologists and microbiologists from NUI Galway who focused on spider bite reactions reported by people living in Ireland and Britain in the past decade. There are over 650 species of spider in the UK alone, but according to the researchers, only 10 species that are common in North-western Europe have strong enough fangs to pierce our skin and administer their venom, and only one is considered of medical significance to clinicians receiving patients presenting with a spider bite: the invasive noble false widow spider.
For most patients, such a bite will result in redness and pain, but some have exhibited severe and debilitating symptoms from a "skin-eating" condition that can be difficult to manage. In cases where this happened, it was previously thought that bacteria got into the bite as the result of a secondary infection, most likely from the patient scratching the affected area.
To investigate this, the team looked for evidence of pathogenic bacteria on false widows and some other European spiders. Their results showed that two native spiders, Amaurobius similis and Eratigena atrica, were capable of transmitting bacteria in their bites. The false widows were found to be carriers of 22 species of bacteria that had the potential to infect humans. Of the bacteria, Pseudomonas putida, Staphylococcus capitis, and Staphylococcus edaphicus had the highest rate of antibiotic resistance.
The researchers hope their work will better inform clinicians treating troublesome spider bites in identifying that not only do biting spiders carry bacteria that can be transmitted to humans but that some of these won’t respond to commonly used antibiotics.
"The diversity of microbes never ceases to amaze me,” said Dr Aoife Boyd, director of the Pathogenic Mechanisms Group at NUI Galway's School of Natural Sciences, and senior author of the study. “The power to survive and thrive in every environment is shown here by the presence of antimicrobial resistance bacteria even in spider venom. Antimicrobial resistance (AMR) is an urgent and growing problem worldwide. A One Health approach interconnecting human, animal and environmental health is the only way to tackle the problem."