Metal-ion susceptibility of oral bacterial species

Abstract

Summary Aims: This study aimed to evaluate the effect of lead (Pb) on growth of bacterial species related to dental diseases in vitro. Methods and Results: The effects of lead acetate on representative species of the oral flora were examined at 0·1–10 mmol l−1 and compared with the effect of silver nitrate and ferrous sulfate. The minimal inhibitory concentration of lead acetate was between 0·15 and 5 mmol l−1 for the bacterial strains tested. The minimal bactericidal concentration of lead acetate for most oral species was detected in the range of 5–10 mmol l−1. Silver nitrate at a concentration of 1·25 mmol l−1 was sufficient to exhibit antibacterial activity against almost all bacteria tested. Ferrous sulfate had the lowest effect. Conclusions: The study indicated a general antimicrobial effect of lead on oral bacterial species in the range of 0·15–10 mmol l−1. The toxicity of silver nitrate was the highest, whereas that of ferrous sulfate was the lowest. Gram‐positive species had a tendency to be less susceptible for metals than Gram‐negatives. Significance and Impact of the Study: The study shows that it is possible that microbiological changes may occur in the dental plaque in children because of toxic exposure of environmental lead.

The antibacterial effects of silver, titanium dioxide and silica dioxide nanoparticles compared to the dental disinfectant chlorhexidine onStreptococcus mutansusing a suite of bioassays

“…MIC values for AgNO 3 have not been previously reported for saline–BHI media, but the value here is much lower than those reported in other growth media for S. mutans (e.g., 20 mg l −1 in tryptone–glucose–Marmite medium, 24 h incubation time, Thibodeau et al 1978; 100 mg l −1 in basal medium, 24 h incubation time, Youravong et al 2011), suggesting that Ag was more bioavailable in the media used in the present study. Reports of MIC values for 24 h exposures of S. mutans to sub-100 nm-sized Ag NPs also vary (e.g., 67 mg l −1 , particles size: 9 nm, S. mutans inoculum: 6 × 10 5 CFU/ml −1 in BHI + 2% sucrose, Espinosa-Cristobal et al 2009; 4.9 ± 2.7 mg l −1 , particle size: 25 nm, S. mutans inoculum: 1.5 × 10 5 CFU/ml −1 in saline–phosphate buffer solution, Hernandez-Sierra et al 2008).…”

Silver diamine fluoride (SDF) used in childhood caries management has potent antifungal activity against oral Candida species

“…Silver is a broad-spectrum chemical with excellent anti-biofilm properties, and hence widely integrated into indwelling devices such as orthopedic prostheses, cardiac devices, and surgical instruments [16][17][18]. In dentistry too, the susceptibility of several species of oral microbiota to silver-ions has been reported [19,20], as a result of which it is now incorporated into some dental materials [21]. The exact mechanisms by which particulate silver kills bacteria and fungi are unclear, but it is known that silver causes microbial death by binding to microbial cell wall and membrane components thus causing toxicity and death of the organisms [22].…”

Salivary lead in relation to caries, salivary factors and cariogenic bacteria in children

“…Although this association was only marginally significant (P = 0.06), this is probably because the PbS concentrations were not high enough to inhibit oral bacterial species. In a recent in vitro study, Youravong et al 38 reported minimal inhibitory concentrations (MICs) of lead on oral bacteria in the range of 0.15-5 mM and minimal bactericidal concentrations (MBCs) in the range of 5-10 mM. The MIC and MBC values of mutans streptococci were 2.5 mM and 10 mM respectively, while the MBC of L. acidophilus was 5 mM.…”