Confocal laser scanning microscopy analysis of S. epidermidis biofilms exposed to farnesol, vancomycin and rifampicin

Abstract

BackgroundStaphylococcus epidermidis is the major bacterial species found in biofilm-related infections on indwelling medical devices. Microbial biofilms are communities of bacteria adhered to a surface and surrounded by an extracellular polymeric matrix. Biofilms have been associated with increased antibiotic tolerance to the immune system. This increased resistance to conventional antibiotic therapy has lead to the search for new antimicrobial therapeutical agents. Farnesol, a quorum-sensing molecule in Candida albicans, has been described as impairing growth of several different microorganisms and we have previously shown its potential as an adjuvant in antimicrobial therapy against S. epidermidis. However, its mechanism of action in S. epidermidis is not fully known. In this work we better elucidate the role of farnesol against S: epidermidis biofilms using confocal laser scanning microscopy (CLSM).Findings24 h biofilms were exposed to farnesol, vancomycin or rifampicin and were analysed by CLSM, after stained with a Live/Dead stain, a known indicator of cell viability, related with cell membrane integrity. Biofilms were also disrupted by sonication and viable and cultivable cells were quantified by colony forming units (CFU) plating. Farnesol showed a similar effect as vancomycin, both causing little reduction of cell viability but at the same time inducing significant changes in the biofilm structure. On the other hand, rifampicin showed a distinct action in S. epidermidis biofilms, by killing a significant proportion of biofilm bacteria.ConclusionsWhile farnesol is not very efficient at killing biofilm bacteria, it damages cell membrane, as determined by the live/dead staining, in a similar way as vancomycin. Furthermore, farnesol might induce biofilm detachment, as determined by the reduced biofilm biomass, which can partially explain the previous findings regarding its role as a possible chemotherapy adjuvant.

Farnesol increases the susceptibility of Burkholderia pseudomallei biofilm to antimicrobials used to treat melioidosis

“…In addition, it has been reported that farnesol is capable of disaggregating bacterial biofilm structure, reducing its biomass (Cerca et al 2012), and allowing the contact of antibiotics with the cells entrapped within the biofilm structure (Katragkou et al 2014). The results of the present research corroborate these findings, since the microscopic analyses of mature B. pseudomallei biofilms revealed that exposure to MBEC concentrations of farnesol promoted disaggregation of the matrix and, consequently, destruction of the biofilm.…”

“…In addition, it has been reported that farnesol is capable of disaggregating bacterial biofilm structure, reducing its biomass (Cerca et al . ), and allowing the contact of antibiotics with the cells entrapped within the biofilm structure (Katragkou et al . ).…”

Bacteriophage-encoded virion-associated enzymes to overcome the carbohydrate barriers during the infection process

“…For more detailed analysis of the cleavage specificity, the lists of biochemistry techniques were implemented, such as 1 H NMR spectroscopy, FABMS, MALDI MS, GC MS, ESI-MS, and EIMS (Thurow et al 1974; Linnerborg et al 2001). There is also the possibility to measure biofilm thickness by confocal laser scanning microscopy (CLSM) (Cerca et al 2012), scanning electron microscopy (SEM), or atomic force microscopy (Chatterjee et al 2014). A fully electric tuning fork resonance frequency measurement system designed by Piasecki et al (2015) offered an effective mass measurement in a novel approach to evaluate the bacterial biofilm parameters such as mass, viscosity, and density.…”

Screening of biofilm formation by beneficial vaginal lactobacilli and influence of culture media components

“…; Cerca et al . ). Therefore, biofilm‐forming strains could be responsible for the recurrence of urogenital infections (UGI) (Harriott et al .…”

“…The micro-organisms included in biofilms show a different behaviour than planktonic cells and thus are more resistant to conventional treatments with antimicrobials, being able to evade the host's immune system more easily (Dales et al 2009;Cerca et al 2012). Therefore, biofilmforming strains could be responsible for the recurrence of urogenital infections (UGI) (Harriott et al 2010;Swidsinski et al 2011).…”