The electron transport chain sensitisesStaphylococcus aureus and Enterococcus faecalis to the oxidative burst
File(s)
Accepted version
Author(s)
Painter, KL
Hall, A
Ha, KP
Edwards, A
Type
Journal Article
Abstract
Small colony variants (SCVs) of Staphylococcus aureus typically lack a functional electron transport chain and cannot produce virulence factors such as leukocidins, hemolysins or the anti-oxidant staphyloxanthin. Despite this, SCVs are associated with persistent infections of the bloodstream, bones and prosthetic devices. The survival of SCVs in the host has been ascribed to intracellular residency, biofilm formation and resistance to antibiotics. However, the ability of SCVs to resist host defences is largely uncharacterised. To address this, we measured survival of wild-type and SCV S. aureus in whole human blood, which contains high numbers of neutrophils, the key defense against staphylococcal infection. Despite the loss of leukcocidin production and staphyloxanthin biosynthesis, SCVs defective for heme or menquinone biosynthesis were significantly more resistant to the oxidative burst than wild-type bacteria in human blood or the presence of purified neutrophils. Supplementation of the culture medium of the heme-auxotrophic SCV with heme, but not iron, restored growth, hemolysin and staphyloxanthin production, and sensitivity to the oxidative burst. Since Enterococcus faecalis is a natural heme auxotroph and cause of bloodstream infection, we explored whether restoration of the electron transport chain in this organism also affected survival in blood. Incubation of E. faecalis with heme increased growth and restored catalase activity, but resulted in decreased survival in human blood via increased sensitivity to the oxidative burst. Therefore, the lack of functional electron transport chains in SCV S. aureus and wild-type E. faecalis results in reduced growth rate but provides resistance to a key immune defence mechanism.
Date Issued
2017-10-09
Date Acceptance
2017-09-28
Citation
Infection and Immunity, 2017, 85 (12)
ISSN
0019-9567
Publisher
American Society for Microbiology
Journal / Book Title
Infection and Immunity
Volume
85
Issue
12
Copyright Statement
Copyright © 2017 American Society for Microbiology.
Sponsor
The Royal Society
Grant Number
RG2011R2
Subjects
Science & Technology
Life Sciences & Biomedicine
Immunology
Infectious Diseases
small-colony variant
Staphylococcus aureus
Enterococcus faecalis
neutrophil
oxidative burst
bacteremia
enterococcus
SMALL-COLONY VARIANTS
STREPTOCOCCUS-FAECALIS
HEMB MUTANTS
INTRACELLULAR PERSISTENCE
ANTIBIOTIC-RESISTANCE
FIBRONECTIN-BINDING
CYSTIC-FIBROSIS
VAR ZYMOGENES
SOS RESPONSE
INFECTIONS
06 Biological Sciences
11 Medical And Health Sciences
07 Agricultural And Veterinary Sciences
Microbiology
Publication Status
Published
Article Number
e00659-17
Date Publish Online
2017-10-09