Pathogenic potential of Escherichia coli clinical strains from orthopedic implant infections towards human osteoblastic cells.
Escherichia coli is one of the first causes of Gram-negative orthopedic implant infections (OII), but little is known about the pathogenicity of this species in such infections that are increasing due to the ageing of the population. We report how this pathogen interacts with human osteoblastic MG-63 cells in vitro, by comparing 20 OII E. coli strains to two Staphylococcus aureus and two Pseudomonas aeruginosa strains. LDH release assay revealed that 6/20 (30%) OII E. coli induced MG-63 cell lysis whereas none of the four control strains was cytotoxic after 4 h of coculture. This high cytotoxicity was associated with hemolytic properties and linked to hlyA gene expression. We further showed by gentamicin protection assay and confocal microscopy that the non-cytotoxic E. coli were not able to invade MG-63 cells unlike S. aureus strains (internalization rate <0.01% for the non-cytotoxic E. coli versus 8.88 ± 2.31% and 4.60 ± 0.42% for both S. aureus). The non-cytotoxic E. coli also demonstrated low adherence rates (<7%), the most adherent E. coli eliciting higher IL-6 and TNF-α mRNA expression in the osteoblastic cells. Either highly cytotoxic or slightly invasive OII E. coli do not show the same infection strategies as S. aureus towards osteoblasts.
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France Department of Bacteriology-Hygiene, Nantes University Hospital, F-44000 Nantes, France.
Lise
L
Crémet
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Alexis
A
Broquet
INSERM, UMR 957, Pathophysiology of Bone Resorption Laboratory and Therapy of Primary Bone Tumors, Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Bénédicte
B
Brulin
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Cédric
C
Jacqueline
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Sandie
S
Dauvergne
INSERM, UMR 957, Pathophysiology of Bone Resorption Laboratory and Therapy of Primary Bone Tumors, Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Régis
R
Brion
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France Department of Bacteriology-Hygiene, Nantes University Hospital, F-44000 Nantes, France INSERM, UMR 957, Pathophysiology of Bone Resorption Laboratory and Therapy of Primary Bone Tumors, Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France Intensive Care Unit, Anesthesia and Critical Care Department, Nantes University Hospital, F-44000 Nantes, France.
Karim
K
Asehnoune
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France Department of Bacteriology-Hygiene, Nantes University Hospital, F-44000 Nantes, France.
Stéphane
S
Corvec
INSERM, UMR 957, Pathophysiology of Bone Resorption Laboratory and Therapy of Primary Bone Tumors, Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France.
Dominique
D
Heymann
UPRES EA3826, Laboratory of Clinical and Experimental Therapeutics of Infections., Medicine Faculty, University of Nantes, 1, rue G. Veil, F-44000 Nantes, France nathalie.caroff@univ-nantes.fr.
Nathalie
N
Caroff
D001422:Bacterial Adhesion; D002460:Cell Line; D002470:Cell Survival; D018920:Coculture Techniques; D004705:Endocytosis; D004926:Escherichia coli / Q000302:isolation & purification / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000633:toxicity; D020869:Gene Expression Profiling; D006460:Hemolysin Proteins / Q000633:toxicity; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D018613:Microscopy, Confocal; D009985:Orthopedics; D010006:Osteoblasts / Q000382:microbiology* / Q000502:physiology; D016459:Prosthesis-Related Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity; D013211:Staphylococcus aureus / Q000472:pathogenicity; D013514:Surgical Procedures, Operative / Q000009:adverse effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; C508600:IL6 protein, human; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D007770:L-Lactate Dehydrogenase
E. coli; TNF-α; alpha-hemolysin; cytotoxicity; human osteoblasts; internalization