Pseudomonas aeruginosa in oral infections

Novel antimicrobial applications of copper oxide nanoparticles after combination with tissue conditioner used in complete prostheses

BACKGROUND

Tissue conditioners are used for treating and improving the tissues supporting complete dentures. On the other hand, recent advances in nanotechnology have revolutionized various fields of science, including dentistry. The present study aimed to investigate novel antimicrobial applications of copper oxide nanoparticle-based tissue conditioner used in complete prostheses.

METHODS

The present experimental study included 126 tissue conditioner samples with different concentrations of copper oxide nanoparticles (20%, 10%, 5%, 2.5%, 1.25%, 0.625%, and 0% w/w). The samples were incubated with Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans in 24-well plates for 24 h. Then, samples from the wells were re-incubated for 24 h, and the microorganisms were counted.

RESULTS

The culture media containing E. faecalis and P. aeruginosa showed significantly different growth between different nanoparticle concentrations following 24 h (P < 0.001), showing a reduction in bacterial growth with increased nanoparticle concentration. Both bacteria did not show any growth at the 20% concentration. However, C. albicans showed significant differences in growth between different nanoparticle concentrations following 48 h (P < 0.001), showing a reduction in growth with increased nanoparticle concentration. Also, the least growth was observed at the 20% concentration.

CONCLUSIONS

In conclusion, the CuO nanoparticles were prepared using a green synthesis methon in the suitable sizes. Moreover, the tissue conditioners containing CuO nanoparticles showed acceptable antimicrobial properties against E. faecalis, P. aeruginosa, and C. albicans.

Novel Options to Counteract Oral Biofilm Formation: In Vitro Evidence

Biofilm production on biotic and abiotic surfaces is crucial in the pathogenesis of most infections, particularly those occurring in the oral cavity. Its prevention and/or control may greatly facilitate the management of patients with oral diseases. Here, the antibiofilm activity of a biomimetic hydroxyapatite and a natural compound, MicroRepair (MicroR) and pomegranate (PomeGr), respectively, was assessed. By luminescence/fluorescence-based assays, Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) were tested for biofilm production in the presence of MicroR and/or PomeGr. We found that both MicroR and PomeGr could affected biofilm production; however, the efficacy of the two, given alone or in combination, varied according to the microbial agent considered. These data open to clinical studies aimed at defining the most efficacious protocols to counteract oral biofilm-associated infections.

The Antimicrobial, Antioxidative, and Anti-Inflammatory Effects of Polycaprolactone/Gelatin Scaffolds Containing Chrysin for Regenerative Endodontic Purposes

The appropriate endodontic material should eliminate the infection and inflammation to provide a situation for regeneration and healing of pulp tissue besides biomineralization. Chrysin is one of the active ingredients of plant flavonoids, which has significant anti-inflammatory and antimicrobial properties. In the present study, this natural substance was evaluated for antioxidant, anti-inflammatory, and mineralization properties on dental pulp stem cells (DPSCs). SEM, FTIR, and TGA tests were used to determine the successful synthesize of chrysin-loaded scaffolds. The antimicrobial effects of the synthesized scaffold against Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis were assessed by the agar diffusion test and live/dead assay. The proliferation of DPSCs on these scaffolds was determined by the MTT assay, DAPI staining, and DNA extraction. Moreover, the antioxidant and anti-inflammation activity of chrysin-loaded scaffolds on inflamed DPSCs was evaluated. Alkaline phosphatase activity and Alizarin Red S Stain tests were done to evaluate the mineralization of DPSCs seeded on these scaffolds. The chrysin-loaded scaffolds reported antimicrobial effects against evaluated bacterial strains. The proliferation of DPSCs seeded on these scaffolds was increased significantly (p < 0.05). The TNFα and DCF levels in inflamed DPSCs showed a significant decrease in the presence of chrysin-loaded scaffolds (p < 0.05). The ALP activity and formation of mineralized nodules of DPSCs on these scaffolds were significantly increased compared with the control group (p < 0.05). These results indicated that chrysin as an ancient therapeutic agent can accelerate the healing and regeneration of damaged pulp tissue, and this active ingredient can be a potential natural substance for regenerative endodontic procedures.

The Postmedieval Latvian Oral Microbiome in the Context of Modern Dental Calculus and Modern Dental Plaque Microbial Profiles

Recent advantages in paleomicrobiology have provided an opportunity to investigate the composition of ancient microbial ecologies. Here, using metagenome analysis, we investigated the microbial profiles of historic dental calculus retrieved from archaeological human remains from postmedieval Latvia dated 16–17th century AD and examined the associations of oral taxa and microbial diversity with specific characteristics. We evaluated the preservation of human oral microbiome patterns in historic samples and compared the microbial composition of historic dental calculus, modern human dental plaque, modern human dental calculus samples and burial soil microbiota. Overall, the results showed that the majority of microbial DNA in historic dental calculus originated from the oral microbiome with little impact of the burial environment. Good preservation of ancient DNA in historical dental calculus samples has provided reliable insight into the composition of the oral microbiome of postmedieval Latvian individuals. The relative stability of the classifiable oral microbiome composition was observed. Significant differences between the microbiome profiles of dental calculus and dental plaque samples were identified, suggesting microbial adaptation to a specific human body environment.

Propolis Affects Pseudomonas aeruginosa Growth, Biofilm Formation, eDNA Release and Phenazine Production: Potential Involvement of Polyphenols

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen responsible for a wide range of clinical conditions, from mild infections to life-threatening nosocomial biofilm-associated diseases, which are particularly severe in susceptible individuals. The aim of this in vitro study was to assess the effects of an Albanian propolis on several virulence-related factors of P. aeruginosa, such as growth ability, biofilm formation, extracellular DNA (eDNA) release and phenazine production. To this end, propolis was processed using three different solvents and the extracted polyphenolic compounds were identified by means of high performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis. As assessed by a bioluminescence-based assay, among the three propolis extracts, the ethanol (EtOH) extract was the most effective in inhibiting both microbial growth and biofilm formation, followed by propylene glycol (PG) and polyethylene glycol 400 (PEG 400) propolis extracts. Furthermore, Pseudomonas exposure to propolis EtOH extract caused a decrease in eDNA release and phenazine production. Finally, caffeic acid phenethyl ester (CAPE) and quercetin decreased upon propolis EtOH extract exposure to bacteria. Overall, our data add new insights on the anti-microbial properties of a natural compound, such as propolis against P. aeruginosa. The potential implications of these findings will be discussed.

The protective effects of antigen-specific IgY on pyocyanin-treated human lymphoma Raji cells

Background: Pyocyanin (PCN), a highly pathogenic pigment produced by Pseudomonas aeruginosa, induces caspase 3-dependent human B cell (Raji cells) death. The aim of the present study, therefore, was to assess whether antigen-specific IgY antibodies may be protective on PCN-induced Raji cell death.

Methods: Chickens were subcutaneously immunized with Freund's complete adjuvant containing PCN, and then given two boosted immunizations.  Anti-PCN IgY antibodies were purified from egg yolk and detected using an agar gel precipitation test (AGPT) and ELISA. Protective effects of antigen-specific IgY on Raji cells were tested using a cell viability assay.

Results: AGPT results showed the formation of strong immune complex precipitates, whilst ELISA further confirmed the presence of IgY antibodies specific to PCN at significant concentration. Further experiments showed that anti-PCN IgY antibodies significantly increased PCN-treated Raji cell viability in a dose-dependent fashion (p<0.05).

Conclusions: The results of the present study suggest that anti-PCN IgY antibodies may be protective on PCN-induced Raji cell death.

An in vitro Comparison of Antimicrobial Activity of Three Endodontic Sealers with Different Composition

AIMS

The aim of the study was to compare the antimicrobial property of newly introduced EndoSequence BC sealer with commonly used zinc oxide-eugenol-based sealer (Zical) and epoxy resin-based sealer (MM-Seal) against Candida albicans, Lactobacillus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

MATERIALS AND METHODS

The agar diffusion test was done to measure the antimicrobial activity of sealers. The sealers were put in the 4 mm wells prepared in the inoculated agar plates. The agar plates were incubated at 37°C for 24 hours and the zones of inhibition that appeared was measured. Chi-square test was done to evaluate intraobserver bias for all study samples. Intergroup comparison was done for all five parameters using Pearson correlation statistical analysis.

RESULTS

EndoSequence BC sealer showed maximum mean of diameter of zones of inhibition against all the microorganisms but with no statistically significant difference with other sealers. Zical did not show any zone of inhibition against the P. aeruginosa. MM-Seal did not show any inhibitory activity against the P. aeruginosa and C. albicans.

CONCLUSION

EndoSequence BC sealer showed antimicrobial activity against all the microorganisms and proved to be a better choice when compared with other two sealers.

CLINICAL SIGNIFICANCE

Antimicrobial properties of endodontic sealers are important to prevent the persistent infection of the complex root canals. EndoSequence BC sealer has been proved to be a better sealer in this aspect.

Microflora profiling of infected root canal before and after treatment using culture-independent methods

This study aimed to profile the microflora in infected root canals before and after root canal treatment using culture-independent methods. Six infected root canals in single-rooted teeth with periapical lesions from five subjects were included. Quantification of total bacteria was performed by real-time PCR with primers targeting 16S rRNA genes. PCR products with universal 16S rRNA gene primers were cloned and partially sequenced, and bacterial identification at the species level was performed by comparative analysis with the GenBank database. The concentration of extracted DNA before treatment was higher than that after root canal treatment, although the difference was not statistically significant. Sequence analysis revealed that oral bacteria such as Fusobacterium, Streptococcus, Olsenella, and Pseudoramibacter detected in cases before root canal treatment disappeared after treatment. These results suggest that the root canal microflora are distinct before and after root canal treatment, and that treatment changes the microflora in both quantity and quality.

Community-based interference against integration of Pseudomonas aeruginosa into human salivary microbial biofilm

As part of the human gastrointestinal tract, the oral cavity represents a complex biological system and harbors diverse bacterial species. Unlike the gut microbiota, which is often considered a health asset, studies of the oral commensal microbiota have been largely limited to their implication in oral conditions such as dental caries and periodontal disease. Less emphasis has been given to their potential beneficial roles, especially the protective effects against oral colonization by foreign or pathogenic bacteria. In this study, we used salivary microbiota derived from healthy human subjects to investigate protective effects against colonization and integration of Pseudomonas aeruginosa, an opportunistic bacterial pathogen, into developing or pre-formed salivary biofilms. When co-cultivated in saliva medium, P. aeruginosa persisted in the planktonic phase, but failed to integrate into the salivary microbial community during biofilm formation. Furthermore, in saliva medium supplemented with sucrose, the oral microbiota inhibited the growth of P. aeruginosa by producing lactic acid. More interestingly, while pre-formed salivary biofilms were able to prevent P. aeruginosa colonization, the same biofilms recovered from mild chlorhexidine gluconate treatment displayed a shift in microbial composition and showed a drastic reduction in protection. Our study indicates that normal oral communities with balanced microbial compositions could be important in effectively preventing the integration of foreign or pathogenic bacterial species, such as P. aeruginosa.

Evaluation of the subgingival microbiota of alcoholic and non-alcoholic individuals

OBJECTIVES

The aim of this study was to evaluate the composition of the subgingival microbiota of alcoholic and non-alcoholic individuals.

METHODS

The study was conducted with 49 alcoholic and 49 non-alcoholic males of the Philippe Pinel Institute, Rio de Janeiro, Brazil. The subjects were selected by convenience and two criteria were used to diagnose alcohol dependence: the CAGE (cut-down, annoyed, guilt, eyes-opener) questionnaire and the International Statistical Classification of Diseases, 10th edition (WHO). Subgingival biofilm samples were obtained from 4 sites, 2 with probing depth (PD) ≥ 4 mm and 2 sites with PD < 4 mm. The presence and levels of 45 bacterial taxa were analysed using the checkerboard technique.

RESULTS

The prevalence of bacterial species was not significantly different between groups. However, alcoholics showed significantly higher mean counts of Aggregactibacter actinomycetemcomitans, Fusobacterium nucleatum nucleatum, and Porphyromonas gingivalis (adjusted p < 0.001). Moreover, alcoholics harboured significantly higher mean levels of Capnocytophaga sputigena, Fusobacterium nucleatum vincentii, F. nuc. nucleatum, Gemella morbillorum, Neisseria mucosa, P. gingivalis, Streptococcus gordonii, and Tannerella forsythia at sites with PD < 4 mm or ≥ 4 mm compared to non-alcoholics (p ≤ 0.001). Of interest, shallow sites of alcoholics presented significantly higher mean levels of F. nuc. vincentii, F. nuc nucleatum, P. gingivalis, and T. forsythia than sites with PD ≥ 4 mm of non-alcoholics (p ≤ 0.001).

CONCLUSIONS

Alcoholics and non-alcoholics present a diverse and complex microbiota; however, alcoholics harbour significantly higher levels of periodontopathic species in the subgingival microbiota than non-alcoholics.