Effects of Subinhibitory Concentrations of Chemical Agents on Hydrophobicity and in vitro Adherence of Streptococcus mutans and Streptococcus sanguis

Abstract

The aim of this investigation was to determine whether sublethal concentrations of chlorhexidine (Cx), hexetidine (Hx), cetylpyridinium chloride (Cc), sodium dodecyl sulfate (SDS), sanguinarine (Sg), sodium fluoride (NaF), and ammonium fluoride (NH₄F) could affect hydrophobicity and adhesion of Streptococcus sanguis and Streptococcus mutans to saliva-coated hydroxyapatite (S-HA). Determination of the minimum inhibitory concentrations (MICs) showed that both species were susceptible to all agents tested. Growth in the presence of sub-MIC concentrations of Cx, SDS, Cc, NaF, or NH₄F did not change significantly the hydrophobicity of S. sanguis cells when compared to the control which lacked any agent. However, growth in the presence of Hx or Sg resulted in a significant reduction in their hydrophobicity. Sub-MIC levels of SDS or Sg in the growth medium resulted in S. mutans cells with increased affinity for hexadecane compared with the control. The adherence of S. sanguis was changed significantly only by Hx or Sg, resulting in less cells adhering to S-HA. However, S. mutans cells previously incubated with NaF, NH₄F, or Sg showed a higher adherence to S-HA than the control. The mechanisms of interference with adherence are at present not completely understood. Thus, antimicrobial agents at sub-MIC concentrations can interfere selectively with hydrophobicity and/or adhesion of oral streptococci.

The in vitro antibiofilm activity of selected culinary herbs and medicinal plants against Listeria monocytogenes

“…It can therefore be postulated that pretreatment of the surface with plant extracts produced an unfavourable film that promotes detachment, thereby reducing the surface adhesion. Milk constituents and chitosan have been reported to inhibit cell attachment (Cai et al 1994;Sharon and Ofek 2002). Some researchers have also demonstrated the success of coating medical devices with biocides such as silver to reduce microbial adhesion (Klueh et al 2000;Hashimoto 2001).…”

Silicone colonization by non-Candida albicans Candida species in the presence of urine

“…It is well known that cell surface properties, such as hydrophobicity and zeta potential, play an important role in adhesion of micro-organisms to the surface of medical devices (Cai et al, 1994;Anil et al, 2001;Henriques et al, 2002). As a result, we investigated the relationship between adhesion and hydrophobicity and zeta potential parameters (Table 1).…”

Cranberry high molecular weight constituents promote Streptococcus sobrinus desorption from artificial biofilm

“…Milk constituents [20], low molecular weight chitosan [21], and antibacterial agents at sub-inhibitory concentrations [22] were found to promote detachment of bacteria from biofilm. Other researchers have focused on polymers, such as polyvinylmethylether maleic acid copolymer [23], which act as anti-adhesive agents.…”