Extracellular DNA Impedes the Transport of Vancomycin in Staphylococcus epidermidis Biofilms Preexposed to Subinhibitory Concentrations of Vancomycin

Abstract

This study provides an explanation of the eDNA-based mechanism of antibiotic tolerance in sub-MIC-vancomycin-treated S. epidermidis biofilms, which might be an important factor for the persistence of biofilm infections.

Sub-inhibitory tigecycline concentrations induce extracellular matrix binding protein Embp dependent Staphylococcus epidermidis biofilm formation and immune evasion

“…The release of eDNA could be of significant importance for induction of an antibiotic-tolerant state, as evidence indicates that eDNA can bind antibiotics, soak them within the biofilm matrix [55], and render biofilm forming S. epidermidis less susceptible to e.g. vancomycin [56]. Moreover, inhibitors of protein biosynthesis used above their MIC have been shown to support the emergence of persister cells in E. coli [57].…”

Extracellular DNA in oral microbial biofilms

“…For example, DNase I increases the susceptibility of nontypeable Haemophilus influenzae to ampicillin and ciprofloxacin and partially sensitises biofilm cells of Mycobacterium tuberculosis to isoniazid [51,52]. Vancomycin binds 100 times more tightly to DNA than to its cellular target, the dAla-d-Ala C terminus of the peptidoglycan pentapeptide, and eDNA protects Staphylococcus epidermidis biofilms from vancomycin [53]. Extracellular DNA protects P. aeruginosa biofilm cells from tobramycin [54].…”

Critical review on biofilm methods

“…This procedure couples green SYTO-9 (cell permeant) and red propidium iodide (cell impermeant) so that bacteria with a compromised membrane appear yellow or red, while the live viable cells appear green. This labeling can be used for example to analyze the spatial distribution of viable bacteria (Hope et al, 2002), observe the existence of localized cell death in biofilms and their regulation (Asally et al, 2012;Ghosh et al, 2013;Guilbaud et al, 2015;Webb et al, 2003), and to assess the effect of several antimicrobials on cell viability (Bridier et al, 2012;Doroshenko et al, 2014;Marchal et al, 2011;Verma et al, 2010). However, CLSM imagining with live/dead staining should be carefully analyzed since differentiation between the red or green channels is often biased by the intensity of the lasers used.…”