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BACKGROUND: Staphylococcus aureus is a common pathogen with strains that are resistant to existing antibiotics. MurJ from S. aureus (SaMurJ), an integral membrane protein functioning as Lipid II flippase, is a potential target for developing new antibacterial agents against this pathogen. Successful expression and purification of this protein shall be useful in the development of drugs against this target. OBJECTIVE: In this study, we demonstrated the optimized expression and purification procedures of SaMurJ, identified suitable detergent for extracting and solubilizing the protein, and examined the peptidisc system to generate a detergent-free environment. METHODS: SaMurJ fused with N-terminal ten-His tag was expressed without induction. Six detergents were selected for screening the most efficient candidate for extraction and solubilization of the protein. The thermostability of the detergent-solubilized protein was assessed by evaluated temperature incubation. Different ratios of peptidisc bi-helical peptide (NSPr) to SaMurJ were mixed and the on-bead peptidisc assembly method was applied. RESULTS: SaMurJ expressed in BL21(DE3) was confirmed by peptide fingerprinting, with a yield of 1 mg SaMurJ per liter culture. DDM was identified as the optimum detergent for solubilization and the nickel affinity column enabled SaMurJ purification with a purity of ~88%. However, NSPr could not stabilize SaMurJ. CONCLUSION: The expression and purification of SaMurJ were successful, with high purity and good yield. SaMurJ can be solubilized and stabilized by a DDM-containing buffer.

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PURPOSE: Staphylococcus aureus is the critical pathogenic bacterium of eczema. The relationship between nasal colonization by S. aureus and eczema has not been well studied. We aimed to evaluate the associations between nasal colonization by S. aureus and eczema of multiple body sites, including persistent and ever-reported eczema. We further examined the associations between eczema and different subtypes of S. aureus, that is, methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). METHODS: The real-world data from the US National Health and Nutrition Examination Survey were used. The associations were calculated using survey-weighted multinomial logistic regression models and further calculated in subgroups stratified by demographic factors. RESULTS: In total, 2,941 adults were included. The prevalence rate of S. aureus nasal carriage was significantly higher in adults with persistent hand eczema (51.0%) than in those with ever-reported hand eczema (23.3%) and never eczema (26.9%). S. aureus nasal colonization was associated with an approximately two-fold increased risk of persistent hand eczema (odds ratios ranges in different models: 2.86-3.06) without significant heterogeneity in the association by demographic factors. No significant associations between S. aureus nasal colonization and persistent eczema of other body sites or ever-reported eczema of multiple body sites (including hands) were observed. Furthermore, similar significant association between nasal colonization of MSSA and persistent hand eczema was seen; the association was much stronger (odds ratios ranges in different models: 4.64-6.54) for MRSA, although with borderline significant. CONCLUSIONS: Nasal colonization of S. aureus was associated with increased risk of persistent hand eczema. Our findings imply that preventive measures targeting S. aureus for the anterior nares should be considered in preventing and treating eczema.

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BACKGROUND: Nowadays, the emergence of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) strains has dramatically restricted the treatment options against this microorganism. AIM: In this study, we aimed to discover new drug targets and inhibitors against S. aureus. METHODS: This study consists of two major sections. In the upstream evaluation, after a comprehensive coreproteome analysis, essential cytoplasmic proteins with no similarity to the human proteome were selected. Then the S. aureus metabolome-specific proteins were selected, and novel drug targets were identified using the DrugBank database. In the downstream analysis, a structure-based virtual screening approach was performed to reveal potential hit compounds against adenine N1 (m(m1A22)-tRNA methyltransferase (TrmK) using the StreptomeDB library and AutoDock Vina software. The compounds with a binding affinity > -9 kcal/mol were analyzed based on ADMET properties. Finally, the hit compounds were selected based on Lipinski's rule of five (RO5). RESULTS: Three proteins, including glycine glycosyltransferase (FemA), TrmK, and heptaprenyl pyrophosphate synthase subunit A (HepS1), were selected as feasible and promising drug targets based on PDB file availability and their essential role in the survival of the S. aureus. Finally, seven hit compounds, including Nocardioazine_ A, Geninthiocin_D, Citreamicin_delta, Quinaldopeptin, Rachelmycin, Di-AFN_A1 and Naphthomycin_ K were introduced against the binding cavity of TrmK, as a feasible drug target. CONCLUSION: The results of this study provided three feasible drug targets against S. aureus. In the following, seven hit compounds were introduced as potential inhibitors of TrmK, and Geninthiocin_D was identified as the most desirable agent. However, in vivo and in vitro investigations are needed to confirm the inhibitory effect of these agents on S. aureus.

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AIM: This study aims to assess the antimicrobial efficacy and impact on color stability of Thymus (T.) vulgaris solution compared to conventional disinfectants on maxillofacial silicones. MATERIALS AND METHODS: Various solutions were evaluated, including T. vulgaris solutions at 5 and 10%, saline (control), chlorhexidine (4%), and soap water. The substrates were MDX4-4210 silicone elastomers, and the microorganisms tested were Candida (C.) albicans and Staphylococcus (S.) aureus. The viability of microorganisms was determined through an 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay, and color stability was measured using a spectrophotometer with X-Rite Europe software. Statistical analysis was performed using the Kruskal-Wallis test, Mann-Whitney U post hoc test, and Wilcoxon Signed Rank test. RESULTS: Soap water demonstrated superior disinfectant action against both microorganisms, while T. vulgaris solutions at 5 and 10% exhibited comparable antimicrobial efficacy. Chlorhexidine and 10% T. vulgaris solution showed minimal color changes in the silicone material. In contrast, soap water and the 5% T. vulgaris solution resulted in clinically unacceptable color alterations. CONCLUSION: This study underscores the potential of T. vulgaris as an herbal disinfectant for combating microbial biofilms on maxillofacial silicones, particularly at concentrations of 5 and 10%. The importance of maintaining color stability is emphasized, with Chlorhexidine and the 10% T. vulgaris solution demonstrating effective preservation of esthetics. These findings suggest the viability of considering T. vulgaris as an alternative disinfectant in clinical settings for maxillofacial silicone prostheses. CLINICAL SIGNIFICANCE: Maxillofacial silicones are vital in restoring aesthetic features for individuals with facial trauma, congenital deformities, or post-surgical interventions. Yet, biofilm-related infections jeopardize their durability and visual integrity. Clinically, T. vulgaris signifies a potential advance in prosthodontic care, offering valuable insights for improving antimicrobial performance and aesthetic durability in maxillofacial prostheses. How to cite this article: Peter M, Kanathila H, Bembalagi M, et al. An In Vitro Comparative Evaluation of Conventional and Novel Thymus vulgaris Derived Herbal Disinfectant Solutions against Pathogenic Biofilm on Maxillofacial Silicones and Its Impact on Color Stability. J Contemp Dent Pract 2023;24(12):967-973.

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Among central nervous system (CNS) infections (e.g., meningitis, brain abscess, ventriculitis, transverse myelitis), those caused by Staphylococcus aureus (SA) are particularly challenging both in management and treatment, with poor clinical outcomes and long hospital stay. It has been estimated that SA is responsible for around 1%-7% of meningitis (up to 19% in healthcare-associated meningitis). Recent neurosurgical procedures and immunocompromisation are major risk factors for SA CNS infections. Hand hygiene, surveillance nasal swabs and perioperative prophylaxis are crucial points for effective SA infections prevention. In case of SA-CNS infections, pending microbiological results, anti-methicillin-resistant SA (MRSA) antibiotic, with good CNS penetration, should be included, with prompt de-escalation as soon as MRSA is ruled out. Consultation with an expert in antimicrobial therapy is recommended as well as prompt source control when feasible. In this narrative review, we reviewed current literature to provide practical suggestions on diagnosis, prevention, management, and treatment of SA CNS infections.

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AIM: The higher success rate (>90%) of dental implants over 5 years has made this treatment option favorable for dental surgeons as well as for patients. The present in vitro study was conducted to assess microleakage and microgap of two dissimilar internal implant-abutment associations. MATERIALS AND METHODS: Forty dental implants were divided into two groups: trilobe internal connection fixtures in group I and internal hexagonal geometry fixtures in group II. For the immersion of implant abutment assemblies, sterilized tubes containing 4 mL of Staphylococcus aureus broth culture were incubated at 37°C for 2 weeks. Gram's stain and biochemical reactions were used for identification of colonies. RESULTS: The mean log10 colony-forming unit (CFU) in group I was 8.6 and was 9.3 in group II. The disparity among two groups was found to be significant (p < 0.05). The mean microgap in group I was 7.2 µm and was 10.4 µm in group II. The disparity among the two groups was found to be significant (p < 0.05). CONCLUSION: Authors found that microscopic space between implant and abutment may be the site of penetration of bacteria. There was significant higher log10 CFU in dental implant fixtures with an internal hexagonal geometry compared to the dental implant fixtures with a trilobe internal connection. CLINICAL SIGNIFICANCE: Microscopic space between implant and abutment may be the site of penetration of bacteria. This information will help to avoid microleakage to improve implant success rate.

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AIMS: The present study aims at recording the antibacterial efficacy of various disinfectants used at different time periods against Staphylococcus aureus and viridans streptococcal species of bacteria isolated from complete dentures. MATERIALS AND METHODS: Fifty complete denture patients were selected for the study and swabs were collected from their complete denture surfaces. The isolated bacteria were subjected to six experimental groups which includes four groups of chemical denture disinfectants and two tree extracts groups. Isolation of the bacteria S. aureus and viridians streptococcal species was done by means of selective media and confirmed by means of biochemical tests. The bacteria were subjected to biofilm assays. The biofilm-forming bacteria with optical density (O.D.) values of more than 1.5 were selected for the study. About 150 acrylic specimens were fabricated and were contaminated by the 2 isolated bacteria mentioned above. The contaminated samples were disinfected by immersion for 10, 20, and 30 minutes in six disinfectants, namely: (1) 1% sodium hypochlorite, (2) 2% chlorhexidine, (3) 2% glutaraldehyde, (4) 3.8% sodium perborate, (5) 2% aalam extract, and (6) 2% neem extract. RESULTS: ANOVA test was performed for both S. aureus and viridans streptococcal species with regard to various synthetic and tree extracts as well as time duration of disinfection. F values for disinfection vs S. aureus is 205.4 (p < 0.001) and the relevant Scheffe post hoc test values is in the following order: 3 < 1, 4 < 6, 2 < 5. F values for disinfection vs viridans streptococcal species is 364.7 (p < 0.001) and the relevant Scheffe post hoc test values is in the following order: 3 < 4 < 1, 6, 2 < 5. CONCLUSION: For biofilm-forming S. aureus, 2% glutaraldehyde showed best antibacterial efficacy which was followed by 1% sodium hypochlorite and 3.8% sodium perborate. When it comes to biofilm-forming viridans streptococcal species, 2% glutaraldehyde showed best antibacterial efficacy. Next to 2% glutaraldehyde, 3.8% sodium perborate exhibited good disinfection potential. CLINICAL SIGNIFICANCE: Complete denture patients have a plethora of microorganisms habitating their complete dentures. Some bacteria are capable of causing systemic illness such as aspiration pneumonia and endocarditis. Hence, constant removal and disinfection of biofilms from the denture surface is vital to the local and systemic wellness of the patient. The most common bacteria capable of causing pneumonia and endocarditis that are isolated from complete dentures include S. aureus and viridans streptococcal species. The present study evaluates antibacterial efficacy of different disinfection agents especially against these biofilm-forming bacteria for different time periods. How to cite this article: Andonissamy L, Karthigeyan S, Ali SA, et al. Effect of Chemical Denture Disinfectants and Tree Extracts on Biofilm-forming Staphylococcus aureus and Viridans Streptococcus Species Isolated from Complete Denture. J Contemp Dent Pract 2019;20(11):1307-1314.

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