title: Serratia marcescens is injurious to intestinal epithelial cells.
abstract: Diarrhea causes substantial morbidity and mortality in children in low-income countries. Although numerous pathogens cause diarrhea, the etiology of many episodes remains unknown. Serratia marcescens is incriminated in hospital-associated infections, and HIV/AIDS associated diarrhea. We have recently found that Serratia spp. may be found more commonly in the stools of patients with diarrhea than in asymptomatic control children. We therefore investigated the possible enteric pathogenicity of S. marcescens in vitro employing a polarized human colonic epithelial cell (T84) monolayer. Infected monolayers were assayed for bacterial invasion, transepithelial electrical resistance (TEER), cytotoxicity, interleukin-8 (IL-8) release and morphological changes by scanning electron microscopy. We observed significantly greater epithelial cell invasion by S. marcescens compared to Escherichia coli strain HS (p = 0.0038 respectively). Cell invasion was accompanied by reduction in TEER and secretion of IL-8. Lactate dehydrogenase (LDH) extracellular concentration rapidly increased within a few hours of exposure of the monolayer to S. marcescens. Scanning electron microscopy of S. marcescens-infected monolayers demonstrated destruction of microvilli and vacuolization. Our results suggest that S. marcescens interacts with intestinal epithelial cells in culture and induces dramatic alterations similar to those produced by known enteric pathogens.
authors.affiliation: a Department of Pediatrics ; University of Virginia School of Medicine ; Charlottesville , VA USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Ochieng
authors.forename: Nadia
authors.initials: N
authors.lastname: Boisen
authors.forename: Brianna
authors.initials: B
authors.lastname: Lindsay
authors.forename: Araceli
authors.initials: A
authors.lastname: Santiago
authors.forename: Collins
authors.initials: C
authors.lastname: Ouma
authors.forename: Maurice
authors.initials: M
authors.lastname: Ombok
authors.forename: Barry
authors.initials: B
authors.lastname: Fields
authors.forename: O Colin
authors.initials: OC
authors.lastname: Stine
authors.forename: James P
authors.initials: JP
authors.lastname: Nataro
mesh_terms: D002460:Cell Line; D003106:Colon / Q000378:metabolism / Q000382:microbiology*; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology*; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D016868:Serratia Infections / Q000378:metabolism / Q000382:microbiology*; D012706:Serratia marcescens / Q000502:physiology*
chemical_list: D016209:Interleukin-8
keywords: CFU, colony forming units; Chemokine; ELISA, enzyme linked immunosorbent assay; IL-8, interleukin-8; LDH, lactate dehydrogenase; Serratia marcescens; T84 cells; TEER, transepithelial electric resistance; TNFα, Tumor necrotic factor-α; adhesion; cytotoxicity; invasion; pathogenicity; polarized monolayer