Decrease of Staphylococcus aureus Virulence by Helcococcus kunzii in a Caenorhabditis elegans Model

Frontiers in Cellular and Infection Microbiology

Cattoir, Vincent⁴  Visvikis, Orane⁵  Ngba Essebe, Christelle⁷  Lemichez, Emmanuel^1,10  Dunyach-Remy, Catherine^1,13  Vergne, Anne^1,14  Fines-Guyon, Marguerite^1,16  Sotto, Albert^1,18  Lavigne, Jean-Philippe^1,19  Lecoustumier, Alain^2,20 

[1] EntéGram Positif), Caen, France;de Caen Normandie, Caen, France;de Montpellier, Nîet de la Recherche MéCNR de la RéInstitut National de la SantéLaboratoire de Biologie MéService de Microbiologie, CHU de Caen, Caen, France;Team Microbial Toxins in Host Pathogen Interactions, Centre MéUniversitéculaire, C3M, Institut National de la Santédecine Molédecine, Universitédicale, CH Cahors, Cahors, France;dicale, U1047, UFR de Médicale, U1065, Nice, France;diterranéen de Mémes, France;res chez les Bactéries àrocoques et Résistance aux Antibiotiques (Laboratoire Associésistances Particuliè

关键词: attenuation;    Caenorhabditis elegans;    Co-infection;    Helcococcus kunzii;    Staphylococcus aureus;    Virulence;   

DOI  :  10.3389/fcimb.2017.00077

学科分类：生物科学（综合）

来源: Frontiers

【 摘 要 】

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 aureus is the most prevalent pathogen isolated. Its association with Helcococcus kunzii, commensal Gram positive cocci, is frequently described. The aim of this study was to assess the impact of co-infection on virulence of both H. kunzii and S. aureus strains in a Caenorhabditis elegans model. To study the host response, qRT-PCRs targeting host defense genes were performed. We observed that H. kunzii strains harboured a very low (LT50: 5.7 days ±0.4) or an absence of virulence (LT50: 6.9 days ±0.5). In contrast, S. aureus strains (LT50: 2.9 days ±0.4) were significantly more virulent than all H. kunzii (P<0.001). When H. kunzii and S. aureus strains were associated, H. kunzii significantly reduced the virulence of the S. aureus strain 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 of S. aureus led to a strong induction of defense genes (lys-5, sodh-1 and cyp-37B1) while H. kunzii did not. No statistical difference of host response genes expression was observed when C. elegans were infected with either S. aureus alone or with S. aureus + H. kunzii. Moreover, two well-characterized virulence factors (hla and agr) present in S. aureus were down-regulated when S. aureus were co-infected with H. kunzii. This study showed that H. kunzii decreased the virulence of S. aureus without modifying directly the host defense response. Factor(s) produced by this bacterium modulating the staphylococci virulence must be investigated.

【 授权许可】

CC BY