Staphylococcus aureus Cell Wall Phenotypic Changes Associated with Biofilm Maturation and Water Availability: A Key Contributing Factor for Chlorine Resistance

Abstract

Staphylococcus aureus biofilms are resistant to both antibiotics and disinfectants. As Staphylococci cell walls are an important defence mechanism, we sought to examine changes to the bacterial cell wall under different growth conditions. Cell walls of S. aureus grown as 3-day hydrated biofilm, 12-day hydrated biofilm, and 12-day dry surface biofilm (DSB) were compared to cell walls of planktonic organisms. Additionally, proteomic analysis using high-throughput tandem mass tag-based mass spectrometry was performed. Proteins involved in cell wall synthesis in biofilms were upregulated in comparison to planktonic growth. Bacterial cell wall width (measured by transmission electron microscopy) and peptidoglycan production (detected using a silkworm larva plasma system) increased with biofilm culture duration (p < 0.001) and dehydration (p = 0.002). Similarly, disinfectant tolerance was greatest in DSB, followed by 12-day hydrated biofilm and then 3-day biofilm, and it was least in the planktonic bacteria––suggesting that changes to the cell wall may be a key factor for S. aureus biofilm biocide resistance. Our findings shed light on possible new targets to combat biofilm-related infections and hospital dry surface biofilms.

Susceptibility of Salmonella enterica Typhimurium dry surface biofilms to disinfection

“…Treatment of hydrated biofilms with formulation B without wiping did not significantly reduce viable bacteria remaining on the coupon ( p > 0.05; Figure 1a). Since hydrated biofilms have previously been shown to be easily disturbed by mechanical removal compared to DSB (Parvin et al, 2023), adding a mechanical wiping step against the hydrated biofilms was not studied.…”

How biofilm changes our understanding of cleaning and disinfection

“…It has also been suggested EPS is a major DSB mechanim of resistance to disinfection [ 81 ]. Changes to the bacterial cell structure in S. aureus DSB, notably the thickness of the cell wall, has been associated with a decreased susceptibility to sodium hypochlorite [ 93 ].…”

Resveratrol and Resveratrol-Loaded Galactosylated Liposomes: Anti-Adherence and Cell Wall Damage Effects on Staphylococcus aureus and MRSA

“…LG-RSV RSV hands RSV loaded in LG liposomes behaves exactly the opposite; it reduces the biofilm of S. aureus wild type and MRSA bacteria but does not inhibit their planktonic growth. In order to clarify this finding it will be necessary to deepen the analysis of the cell wall phenotype and the ultrastructure differences existing between planktonic and biofilm staphylococci and focus on the RSV interaction with these two diverse cell wall structures [46][47][48]. The search for new antimicrobials often focuses on the possible damage induced by these compounds on the bacterial cell wall, as documented for many new synthetic and natural products [49,50].…”