An evaluation of associated bacteria and methicillin-resistant Staphalococcus aureus (MRSA) pathogen transfer capabilities of Tegenaria agrestis (Agelenidae), with hemolytic venom analysis

The introduced European spider Tegenaria agrestis has been implicated as a spider of medical importance in the Pacific Northwest since the late 1980s. Venom analysis has not shown any components that would support the hypothesis that this spider is capable of producing necrotic lesions. Recent events have shown bacterial infections being misdiagnosed as spider bites, in particular the pathogenic bacteria methicillin-resistant Staphylococcus aureus (MRSA). This study examines three aspects of the potential medical importance of Washington State collected hobo spiders: an assessment of the bacterial fauna associated with spider to determine if it carries any pathogenic bacteria; the ability of the spiders to acquire and transfer MRSA; and a hemolytic venom assay. Ten genera of ubiquitous bacteria were found on the exterior surface of the spider including: Bacillus spp., Paenibacillus sp., Aeromonas sp., Arthrobacter sp., Pseudomonas spp., Pantoea sp., Staphylococcus sp., Rahnella sp., a bacterium in the order Actinomycete, and Exiguobacterium. Spiders exposed to MRSA did not carry or transfer the pathogen after one hour. The hemolytic venom assay produced negligible results. These findings do not support the ongoing belief that the hobo spider is a medical concern.