title: Decrease ofStaphylococcus aureusVirulence byHelcococcus kunziiin aCaenorhabditis elegansModel.
abstract: Social bacterial interactions are considered essential in numerous infectious diseases, particularly in wounds. Foot ulcers are a common complication in diabetic patients and these ulcers become frequently infected. This infection is usually polymicrobial promoting cell-to-cell communications.Staphylococcus aureusis the most prevalent pathogen isolated. Its association withHelcococcus kunzii, commensal Gram-positive cocci, is frequently described. The aim of this study was to assess the impact of co-infection on virulence of bothH. kunziiandS. aureusstrains in aCaenorhabditis elegansmodel. To study the host response, qRT-PCRs targeting host defense genes were performed. We observed thatH. kunziistrains harbored a very low (LT50: 5.7 days ± 0.4) or an absence of virulence (LT50: 6.9 days ± 0.5). In contrast,S. aureusstrains (LT50: 2.9 days ± 0.4) were significantly more virulent than allH. kunzii(P< 0.001). WhenH. kunziiandS. aureusstrains were associated,H. kunziisignificantly reduced the virulence of theS. aureusstrain in nematodes (LT50 between 4.4 and 5.2 days;P< 0.001). To evaluate the impact of these strains on host response, transcriptomic analysis showed that the ingestion ofS. aureusled to a strong induction of defense genes (lys-5, sodh-1, andcyp-37B1) whileH. kunziidid not. No statistical difference of host response genes expression was observed whenC. eleganswere infected with eitherS. aureusalone or withS. aureus+H. kunzii. Moreover, two well-characterized virulence factors (hlaandagr) present inS. aureuswere down-regulated whenS. aureuswere co-infected withH. kunzii. This study showed thatH. kunziidecreased the virulence ofS. aureuswithout modifying directly the host defense response. Factor(s) produced by this bacterium modulating the staphylococci virulence must be investigated.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de Montpellier Nîmes, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Ngba Essebe
authors.affiliation: Team Microbial Toxins in Host Pathogen Interactions, Centre Méditerranéen de Médecine Moléculaire, C3M, Institut National de la Santé et de la Recherche Médicale, U1065 Nice, France.
authors.forename: Orane
authors.initials: O
authors.lastname: Visvikis
authors.affiliation: Service de Microbiologie, CHU de CaenCaen, France; CNR de la Résistance aux Antibiotiques (Laboratoire Associé Entérocoques et Résistances Particulières chez les Bactéries à Gram Positif)Caen, France.
authors.forename: Marguerite
authors.initials: M
authors.lastname: Fines-Guyon
authors.affiliation: Laboratoire de Biologie Médicale, CH Cahors Cahors, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Vergne
authors.affiliation: Service de Microbiologie, CHU de CaenCaen, France; CNR de la Résistance aux Antibiotiques (Laboratoire Associé Entérocoques et Résistances Particulières chez les Bactéries à Gram Positif)Caen, France; Université de Caen NormandieCaen, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Cattoir
authors.affiliation: Laboratoire de Biologie Médicale, CH Cahors Cahors, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Lecoustumier
authors.affiliation: Team Microbial Toxins in Host Pathogen Interactions, Centre Méditerranéen de Médecine Moléculaire, C3M, Institut National de la Santé et de la Recherche Médicale, U1065 Nice, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lemichez
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Maladies Infectieuses et Tropicales, CHU CarémeauNîmes, France.
authors.forename: Albert
authors.initials: A
authors.lastname: Sotto
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Microbiologie, CHU CarémeauNîmes, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Lavigne
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, UFR de Médecine, Université de MontpellierNîmes, France; Service de Microbiologie, CHU CarémeauNîmes, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Dunyach-Remy
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000276:immunology / Q000382:microbiology*; D060085:Coinfection / Q000382:microbiology* / Q000473:pathology*; D004195:Disease Models, Animal; D000068536:Bacillota / Q000472:pathogenicity*; D020869:Gene Expression Profiling; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology* / Q000473:pathology*; D056265:Microbial Interactions; D060888:Real-Time Polymerase Chain Reaction; D016019:Survival Analysis; D014774:Virulence
keywords: Caenorhabditis elegans; Helcococcus kunzii; Staphylococcus aureus; attenuation; co-infection; virulence