Synanthropic spiders, including the global invasive noble false widow Steatoda nobilis, are reservoirs for medically important and antibiotic resistant bacteria.

The false widow spider Steatoda nobilis is associated with bites which develop bacterial infections that are sometimes unresponsive to antibiotics. These could be secondary infections derived from opportunistic bacteria on the skin or infections directly vectored by the spider. In this study, we investigated whether it is plausible for S. nobilis and other synanthropic European spiders to vector bacteria during a bite, by seeking to identify bacteria with pathogenic potential on the spiders. 11 genera of bacteria were identified through 16S rRNA sequencing from the body surfaces and chelicerae of S. nobilis, and two native spiders: Amaurobius similis and Eratigena atrica. Out of 22 bacterial species isolated from S. nobilis, 12 were related to human pathogenicity among which Staphylococcus epidermidis, Kluyvera intermedia, Rothia mucilaginosa and Pseudomonas putida are recognized as class 2 pathogens. The isolates varied in their antibiotic susceptibility: Pseudomonas putida, Staphylococcus capitis and Staphylococcus edaphicus showed the highest extent of resistance, to three antibiotics in total. On the other hand, all bacteria recovered from S. nobilis were susceptible to ciprofloxacin. Our study demonstrates that S. nobilis does carry opportunistic pathogenic bacteria on its body surfaces and chelicerae. Therefore, some post-bite infections could be the result of vector-borne bacterial zoonoses that may be antibiotic resistant.

Survival, Biofilm Formation, and Growth Potential of Environmental and Enteric Escherichia coli Strains in Drinking Water Microcosms.

UNLABELLED: Escherichia coli is the most commonly used indicator for fecal contamination in drinking water distribution systems (WDS). The assumption is that E. coli bacteria are of enteric origin and cannot persist for long outside their host and therefore act as indicators of recent contamination events. This study investigates the fate of E. coli in drinking water, specifically addressing survival, biofilm formation under shear stress, and regrowth in a series of laboratory-controlled experiments. We show the extended persistence of three E. coli strains (two enteric isolates and one soil isolate) in sterile and nonsterile drinking water microcosms at 8 and 17°C, with T90 (time taken for a reduction in cell number of 1 log10 unit) values ranging from 17.4 ± 1.8 to 149 ± 67.7 days, using standard plate counts and a series of (reverse transcription-)quantitative PCR [(RT-)Q-PCR] assays targeting 16S rRNA, tuf, uidA, and rodA genes and transcripts. Furthermore, each strain was capable of attaching to a surface and replicating to form biofilm in the presence of nutrients under a range of shear stress values (0.6, 2.0, and 4.4 dynes [dyn] cm(-2); BioFlux system; Fluxion); however, cell numbers did not increase when drinking water flowed over the biofilm (P > 0.05 by t test). Finally, E. coli regrowth within drinking water microcosms containing polyethylene PE-100 pipe wall material was not observed in the biofilm or water phase using a combination of culturing and Q-PCR methods for E. coli The results of this work highlight that when E. coli enters drinking water it has the potential to survive and attach to surfaces but that regrowth within drinking water or biofilm is unlikely. IMPORTANCE: The provision of clean, safe drinking water is fundamental to society. WDS deliver water to consumers via a vast network of pipes. E. coli is used as an indicator organism for recent contamination events based on the premise that it cannot survive for long outside its host. A key public health concern therefore arises around the fate of E. coli on entering a WDS; its survival, ability to form a biofilm, and potential for regrowth. In particular, if E. coli bacteria have the ability to incorporate and regrow within the pipe wall biofilm of a WDS, they could reinoculate the water at a later stage. This study sheds light on the fate of environmental and enteric strains of E. coli in drinking water showing extended survival, the potential for biofilm formation under shear stress, and importantly, that regrowth in the presence of an indigenous microbial community is unlikely.