The Anti-Adhesive Activity of Double-Etched Titanium (DAE) as a Dental Implant Surface

This work aimed to compare the capability of Streptococcus oralis to adhere to a novel surface, double-etched titanium (DAE), in respect to machined and single-etched titanium. The secondary outcome was to establish which topographical features could affect the interaction between the implant surface and bacteria. The samples’ superficial features were characterized by using scanning electron microscopy and energy dispersive x-ray spectrometry (EDS) and the wetting properties were tested through sessile methods. The novel surface, the double-etched titanium (DAE), was also analyzed with atomic force microscopy. S. oralis was inoculated on discs previously incubated in saliva, and then the colony-forming units (CFUs), biomass, and cellular viability were measured at 24 and 48h. SEM observation showed that DAE was characterized by higher porosity and oxygen (%) in the superficial layer and the measurement of the wetting properties showed higher hydrophilicity. Atomic force microscopy (AFM) confirmed the presence of a higher superficial nano-roughness. Microbiological analysis showed that DAE discs, coated by pellicle’s proteins, were characterized by significantly lower CFUs at 24 and 48 h with respect to the other two groups. In particular, a significant inverse relationship was shown between the CFUs at 48 h and the values of the wetted area and a direct correlation with the water contact angle. The biomass at 24 h was slightly lower on DAE, but results were not significant concerning the other groups, both at 24 and 48 h. The DAE treatment not only modify the superficial topography and increased hydrophilicity, but it also increase the Oxygen percentage in the superficial layer, that could contribute to the inhibition of S. oralis adhesion. DAE can be considered a promising treatment for titanium implants to counteract a pioneer microorganism colonization, such as S. oralis

Pistacia vera L. oleoresin and levofloxacin is a synergistic combination against resistant Helicobacter pylori strains.

The increasing multidrug resistance in Helicobacter pylori, also correlated to its biofilm-forming ability, underlines the need to search novel strategies to improve the eradication rate. Natural compounds are proposed as antibiotic-resistant-breakers capable to restore the efficacy of conventional drugs. Aim of this work was to evaluate the capability of Pistacia vera L. oleoresin (ORS) to synergize with levofloxacin (LVX) against resistant H. pylori strains. The antimicrobial activity of P. vera L. ORS and LVX and their combinations was determined by MIC/MBC (in neutral and acidic environments) and checkerboard tests. The anti-biofilm effect was determined by biomass quantification. In vivo Galleria mellonella model was used to confirm in vitro data. Pistacia vera L. ORS and LVX MICs ranged respectively from 780 to 3120 mg/l and from 0.12 to 2.00 mg/l, at pH 7.0 and 5.5. MBCs were similar to MICs. Pistacia vera L. ORS was able to synergize with LVX, restoring its effectiveness in LVX resistant strains. Pistacia vera L. ORS, LVX and their synergistic combinations displayed significant biofilm reduction. Pistacia vera L. ORS and LVX, showed protective effect against H. pylori infection on G. mellonella (62% and 63% of survival, respectively). Pistacia vera L. ORS can be considered a promising potentiator to restore the effectiveness of LVX tackling the H. pylori antibiotic resistance phenomenon

The Effect of a Silver Nanoparticle Polysaccharide System on Streptococcal and Saliva-Derived Biofilms

In this work, we studied the antimicrobial properties of a nanocomposite system based on a lactose-substituted chitosan and silver nanoparticles: Chitlac-nAg. Twofold serial dilutions of the colloidal Chitlac-nAg solution were both tested on Streptococcus mitis, Streptococcus mutans, and Streptococcus oralis planktonic phase and biofilm growth mode as well as on saliva samples. The minimum inhibitory and bactericidal concentrations of Chitlac-nAg were evaluated together with its effect on sessile cell viability, as well as both on biofilm formation and on preformed biofilm. In respect to the planktonic bacteria, Chitlac-nAg showed an inhibitory/bactericidal effect against all streptococcal strains at 0.1% (v/v), except for S. mitis ATCC 6249 that was inhibited at one step less. On preformed biofilm, Chitlac-nAg at a value of 0.2%, was able to inhibit the bacterial growth on the supernatant phase as well as on the mature biofilm. For S. mitis ATCC 6249, the biofilm inhibitory concentration of Chitlac-nAg was 0.1%. At sub-inhibitory concentrations, the Streptococcal strains adhesion capability on a polystyrene surface showed a general reduction following a concentration-dependent-way; a similar effect was obtained for the metabolic biofilm activity. From these results, Chitlac-nAg seems to be a promising antibacterial and antibiofilm agent able to hinder plaque formation

Searching for New Tools to Counteract the Helicobacter pylori Resistance: The Positive Action of Resveratrol Derivatives

The drug-resistance phenomenon in Helicobacter pylori underlines the need of novel strategies to improve the eradication rate including alternative treatments combining antibiotic and non-antibiotic compounds with synergistic action. In this study, the antibacterial (MIC/MBC) and anti-virulence effects (biofilm reduction and swarming motility inhibition) of resveratrol-RSV and new synthetized RSV-phenol derivatives, with a higher bioavailability, alone and combined with levofloxacin-LVX were evaluated against resistant H. pylori clinical strains. The experiments were confirmed in vivo using the Galleria mellonella model. Among the studied RSV derivatives, RSV-3 and RSV-4 possessed higher antibacterial activity with respect to RSV (MICs from 6.25 to 200 µg/mL and from 3.12 to 200 µg/mL, respectively). RSV, RSV-3, and RSV-4 were able to synergize with LVX restoring its effect in two out of seven clinical resistant strains tested for the study. RSV, RSV-3, and RSV-4, alone and with LVX at sub-MIC and sub-synergistic concentrations, significantly reduced the biofilm formation. Moreover, RSV-3 and RSV-4 reduced the H. pylori swarming motility on soft agar. RSV, RSV-3, and RSV-4 were non-toxic for G. mellonella larvae and displayed a protective effect against H. pylori infection. Overall, RSV–phenol derivatives should be considered interesting candidates for innovative therapeutic schemes to tackle the H. pylori antibiotic resistance

Additional file 1: Figure S1. of Enterococcus hirae biofilm formation on hospital material surfaces and effect of new biocides

In vitro effect of LH IDROXI FAST and LH ENZYCLEAN SPRAY on mature biofilm of S. aureus ATCC 6538. Top; the untreated and treated biofilms were analyzed for the biomass production, after 48 h of incubation at 37 °C on polystyrene surface, through Cristal Violet staining method. The results were expressed as average of OD595 values of three experiments (mean value ± SD). Symbol represents result statistically significant (p ˂ 0.05). Down; representative images of the in vitro mature biofilms at 37 °C on polystyrene surface untreated (a) and treated with LH IDROXI FAST (b) and LH ENZYCLEAN SPRAY (c). Biofilms were cultured for 48 h, stained with live/dead reagents, and visualized with the optical microscope fluorescence. Sessile population in biofilms stained in red (propidium iodide) expresses a compromised membrane integrity (damaged), whereas green stained bacteria (SYTO 9) remained viable. Both biocides reduced significantly S. aureus ATCC 6538 biomasses even exerting a killing effect. Original magnification ×1000. (ZIP 114 kb

Physicochemical properties of carvacrol codrug 4.

<p>^aValues are means of three experiments, standard deviation is given in parentheses.</p><p>Physicochemical properties of carvacrol codrug 4.</p

Transmission electron microscopy demonstrating the effects of carvacrol codrug 4 on <i>S</i>. <i>aureus</i> ATCC 29213 (B), <i>E</i>. <i>coli</i> ATCC 8739 (D), <i>C</i>. <i>albicans</i> ATCC 10231 (F), and untreated cultures (control), respectively (A, C, and E).

<p>Microorganisms incubated for 3 h in media containing 12.5 mg/mL [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120937#pone.0120937.ref045" target="_blank">45</a>] of carvacrol codrug <b>4</b> (B, D, and F). Irregular features of septa in <i>S</i>. <i>aureus</i> ATCC 29213 (B: arrows); numerous electron-dense bubbles protrude from the cell surface (higher magnification b 140000x and c 110000x) in <i>E</i>. <i>coli</i> ATCC 8739 treated (D) and electron-dense granules of the substance internalized into the cytoplasm (d 110000x); integrity of the membrane (a 110000x) in the controls (C); disintegration of membrane in <i>C</i>. <i>albicans</i> ATCC 10231 (F).</p

Kinetic data for hydrolysis of carvacrol codrug 4 at 37°C.^a

<p>^aValues are means of three experiments, standard deviation is given in parentheses.</p><p>^bAbbreviations: SGF, simulated gastric fluid; SIF, simulated intestinal fluid.</p><p>Kinetic data for hydrolysis of carvacrol codrug 4 at 37°C.<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120937#t004fn001" target="_blank">^a</a></p