title: Schistosoma-associated Salmonella resist antibiotics via specific fimbrial attachments to the flatworm.
abstract: BACKGROUND
  Schistosomes are parasitic helminths that infect humans through dermo-invasion while in contaminated water. Salmonella are also a common water-borne human pathogen that infects the gastrointestinal tract via the oral route. Both pathogens eventually enter the systemic circulation as part of their respective disease processes. Concurrent Schistosoma-Salmonella infections are common and are complicated by the bacteria adhering to adult schistosomes present in the mesenteric vasculature. This interaction provides a refuge in which the bacterium can putatively evade antibiotic therapy and anthelmintic monotherapy can lead to a massive release of occult Salmonella.
  
  
  RESULTS
  Using a novel antibiotic protection assay, our results reveal that Schistosoma-associated Salmonella are refractory to eight different antibiotics commonly used to treat salmonellosis. The efficacy of these antibiotics was decreased by a factor of 4 to 16 due to this association. Salmonella binding to schistosomes occurs via a specific fimbrial protein (FimH) present on the surface on the bacterium. This same fimbrial protein confers the ability of Salmonella to bind to mammalian cells.
  
  
  CONCLUSIONS
  Salmonella can evade certain antibiotics by binding to Schistosoma. As a result, effective bactericidal concentrations of antibiotics are unfortunately above the achievable therapeutic levels of the drugs in co-infected individuals. Salmonella-Schistosoma binding is analogous to the adherence of Salmonella to cells lining the mammalian intestine. Perturbing this binding is the key to eliminating Salmonella that complicate schistosomiasis.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, 1600 SE 16th St., Ames, IA 50011, USA.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Barnhill
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Novozhilova
authors.forename: Tim A
authors.initials: TA
authors.lastname: Day
authors.forename: Steve A
authors.initials: SA
authors.lastname: Carlson
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D012475:Salmonella / Q000187:drug effects* / Q000502:physiology*; D012547:Schistosoma / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents