Impact of chlorhexidine digluconate and temperature on curli production in <em>Escherichia coli</em>—consequence on its adhesion ability

Abstract

Chlorhexidine-Digluconate (CHX-Dg) is a biocide widely used as disinfectant or antiseptic in clinical and domestic fields. It is often found in the formulation of solutions to treat superficial wounds. Nevertheless, few studies have focused on its effects on Escherichia coli while this bacterium is commonly involved in mixed infections. Therefore, the impact of CHX-Dg and temperature on E. coli was investigated; particularly the curli production. In accordance with bibliographic data, the curli production decreased when the temperature of the culture was shift from 30 °C to 37 °C. The bacterial adhesion to abiotic surfaces was also reduced. Surprisingly, the curli production at 37 °C was maintained in presence of antiseptic and the bacterial adhesion was improved at a very low concentration (1 µg ml −1 ) of CHX-Dg. Complementary investigations with a cpxR mutant demonstrated that the CpxA/R-TCS (Two-Component System) is involved in the temperature-dependent control of the curli expression. Indeed, the curli production was not altered by the growth temperature in the mutant. Otherwise, no relationship between CHX-Dg and the Cpx-TCS was shown. A subsequent proteomic investigation revealed the alteration of the production of 44 periplasmic and outer membrane proteins in presence of CHX-Dg. These proteins are involved in the transport of small molecules, the envelope integrity, the stress response as well as the protein folding.

3D Porous Collagen Matrices—A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

“…In fact, the broad-spectrum antimicrobial bioactivity of chlorhexidine ( CH ) has been reported in countless studies over a long period of time, more than six decades, but recent works are focused on designing novel CH -loaded carriers/materials/composites able to supply topically a tunable amount of active component ( CH –copper composite as micrometer sized particles with synergetically enhanced activity compared to that silver particles [ 43 ]; CH -loaded biocompatible gelatin fibers with antimicrobial activity demonstrated against both Gram-negative and Gram-positive bacteria [ 44 ]; CH -loaded nanocarriers— CH -containing shellac nanoparticles exhibiting enhanced bioactivity of CH [ 45 ], CH -loaded copolymer nanogel carriers superficially functionalized with a cationic polyelectrolyte with amplified and broad biocidal action [ 46 ], nanoparticles of amorphous calcium phosphate containing CH with a beneficial action of inhibiting collagen type I degradation and promoting its mineralization at the adhesive–dentin interface, with a direct consequence in slowing down the aging of the resin–dentine contact [ 47 ]; bioresorbable polylactide-based and collagen-based membranes previously soaked in CHDG solution displaying a certain retardation of bacterial colonization when the membranes were exposed to oral activity [ 48 ]). In addition, other relatively newly obtained results deal specifically with CH action in treatment concerning curli production and biofilm formation ( E. colli ) [ 49 ], with new formulations of CH -based mouth rinse with bioactivity against pathogenic bacteria such as P. mutans and P. gingivalis [ 50 ], or in the wound healing of human gingival tissue that has been post-surgically affected [ 36 ]. Last but not least, other works proved that some enzymatically treated undesirable oral biofilms can be disrupted and removed under the action of low concentrations of aqueous CHDG solutions (<0.1%) [ 37 ], and, what is truly noteworthy, the bacteria ( P. aeruginosa , S. aureus ) killed by CHDG may behave similarly to zombie cells, which possess high biocidal activity against the next generation of viable bacteria [ 51 ].…”