The potency of herbal extracts and its green synthesized nanoparticle formulation as antibacterial agents against Streptococcus mutans associated biofilms

This study aims to determine the effects of the extracts of Streblus asper, Cymbopogon citratus, Syzygium aromaticum and its formulation of green synthesized silver nanoparticle (AgNPs) on Streptococcus mutans growth and biofilm formation. The ethanolic extracts of S. asper, C. citratus, S. aromaticum, and a mix of the three herbs demonstrated antibacterial activity against S. mutans isolates by reducing bacterial biofilm formation and decreasing bacterial cell surface hydrophobicity. The formulated AgNPs from the ethanolic extracts could enhance the antibacterial activities of the plant extracts. Molecular docking found the best interaction between luteolin isolated from C. citratus and glucosyltransferase protein (GtfB), assuming the promising anti-biofilm activity. The scanning electron microscopy revealed morphological changes in the biofilm structure and a significant decrease in the biofilm area of the AgNPs treated. The study suggested that the extracts and its application could be used as natural alternative agents with multi-action against S. mutans infections.

Correlation of vascular structural changes in a cadaveric model and obesity-related cardiovascular non-communicable diseases

INTRODUCTION

Carrying excess body weight is a vital risk factor for obesity-related chronic diseases affecting blood vessels. Obesity influences cardiovascular noncommunicable diseases (NCDs) via vascular structural changes, which involve alterations in lipids, blood pressure, coagulation, fibrinolysis, and inflammation, leading to endothelial dysfunction due to vascular remodelling and stiffness. Small peripheral vessels are the first to be impacted; however, it is unclear whether this change is followed by microscopic changes in the aorta.

OBJECTIVES

To determine the correlation of vascular structure with the incidence of NCDs and subcutaneous fat thickness and to study micro-scale changes in vascular structure, especially concerning collagen in the aorta, using a cadaveric model.

METHODS

Twenty-four cadaveric models were classified into a control group and an NCD group. The subcutaneous fat thickness was measured on the arm, anterior abdomen, and thigh. The aorta was collected and stained with haematoxylin, eosin, and Masson's trichrome for collagen evaluation. The vessel thickness was morphometrically analysed. Scanning electron microscopy was performed to identify the extracellular matrix organization in the vessel.

RESULTS

Disorganization of the extracellular matrix and fragments of the vascular wall were found in the NCDs group. The tunica intima of the NCDs group represented endothelial dysfunction with macrophage foam cells. The thickness of the tunica intima of the NCDs group slightly increased without being significantly different compared to control group with 144.63 ± 124.38 µm. and 105.60 ± 27.49 µm, respectively. However, the thickness of tunica media of the NCDs group significantly decreased compared to control group with 956.58 ± 27.80 µm. and 1167.43 ± 48.6 µm, respectively. Collagen deposits in the aortic wall significantly increased by 15% in the NCDs group especially in tunica media by 17.4% compared to control. The results showed a correlation between the amount of collagen fibre and subcutaneous fat on the thigh.

CONCLUSION

There was a change toward irregular microstructural patterns and increased collagen fibres in NCDs. In addition, there was a correlation between collagen fibre density and the subcutaneous fat thickness of the thigh in cadavers with a history of NCDs.

Rub and Rinse Contact Lenses Before Wearing as a Protective Regimen Against Contact Lens-Related Eye Infections

Purpose

Data on contact lens (CL) users in Thailand are limited, and previous reports have mainly focused on young populations. This study aims to determine demographic data, hygienic behaviour, and complications related to the usage of CLs in the general population.

Methods

This was a cross-sectional survey conducted from November 2020 to March 2021 using an anonymous questionnaire. Information on the demographic traits of the participants, characteristics of CL use, and CL care behaviours was collected. The responses were summarised and presented as a total behaviour score. Regression analysis was performed to evaluate the potential risk factors for a history of CL-related eye infections.

Results

A total of 134 CL wearers were recruited. Of all the participants, 83.58% were female and 16.42% were male. The average age was 31.14±10.69 years old. The total behaviour score showed that 62.69% of the population had good CL behaviour, while 37.31% exhibited poor CL behaviour. More than 50% of participants practised appropriate CL handling. Common unfavourable behaviours (>50%) reported were not using CL care solution to clean the storage case, not rubbing and rinsing the lens before storage, exposure to water during wear, use of makeup around the ocular area, and missing annual eye exams. Other less common but important instances of mishandling included using tap water to clean the lenses, topping off old CL solution, and exceeding the recommended planned-replacement period. However, no behaviours were significantly associated with a history of CL-related eye infections. Rubbing and rinsing CLs before wearing them was found to be a protective factor against a history of eye infections.

Conclusion

Rubbing and rinsing CLs before wearing should be mentioned as an additional recommendation for the user.

Bacterial microbiota of the contact lens surface and associated care behaviours

Introduction

Contact lens (CL) wear has been reported to cause changes to the microbiome of the ocular surface. More insight into the alteration of this microenvironment can help to understand the pathogenesis of CL-related eye infections. Knowledge of the relationship between the CL wearer's behaviours and pathogens would help health care providers focus on each step of proper CL care. This study aims to determine the behaviours that might be associated with the community of bacteria on CL.

Methods

A cross-sectional design was performed using anonymous questionnaires to obtain demographic data and assess hygiene practices among volunteering wearers. The CLs used were collected to evaluate the prevalence of pathogenic bacteria associated with ocular infections by PCR and microbiota analysis.

Results

The bacterial microbiota study revealed a total of 19 genera and 26 isolated strains from 20 eligible CLs. Enterobacter, Staphylococcus, and Achromobacter were the main genus in this subject population. Staphylococcus pasteuri and Achromobacter agilis were the most common pathogens at 65% and 35%, respectively. Enterobacter mori, a nonpathogenic organism, was found to be the most predominant strain, accounting for 27.51% of the total bacterial constituents. The risk behaviour of CL wear that was significantly associated with A. agilis contamination was cleaning the CL case with tap water (P value = 0.04).

Conclusions

This is the first study focusing on the association between the culture selected microbial community on the CL surface and compehensive behavioural characteristics. Environmental contamination was the main source of microbes found on CL surfaces. An emphasis in patient education should be placed on careful handling during the CL care routine and managing the hygiene of the surroundings.

Influence of Contact Lens Materials and Cleaning Procedures on Bacterial Adhesion and Biofilm Formation

Purpose

The present study aimed to compare the existing soft contact lens (CL) materials regarding their influence on bacterial biofilm formation and adhesion susceptibility. Then, the study was designed to investigate the effectiveness of various disinfecting solutions and evaluate the ability of cleaning regimens in terms of anti-bacterial adhesion and biofilm removal on different soft CL materials.

Methods

Bacterial biofilm formation on CLs was evaluated by biomass assay. Adhesion assay and standard plate count were carried out at time-interval periods within 24 h. Various CL disinfecting procedures were assessed for their efficacy to remove biofilm and reduce bacterial adhesion. Scanning electron microscopy (SEM) was performed for the morphological assessment of bacterial biofilm.

Results

Printed hydroxyethyl methacrylate (HEMA) CLs significantly demonstrated more biofilm staining and bacterial attachment when compared with non-printed HEMA CLs, while the Filcon II 3 and Nesofilcon A CLs possessed less biofilm biomass and adherent cells. Staphylococcus aureus and Pseudomonas aeruginosa represented the highest biofilm producing bacteria on HEMA-based materials in this study. The disinfecting regimen with the highest efficacy was the two-step system, first using multipurpose disinfecting solution containing edetate disodium and sorbic acid (MPDS+EDSA), followed by soaking in multipurpose solution (MPS). The regimen demonstrated the greatest effect against the pre-formed biofilm and the adhesion activity of S. aureus and P. aeruginosa on the soft CLs. The SEM micrographs confirmed the morphological changes of bacterial biofilm after disinfecting and revealed that the two-step system treated CLs displayed less adherent bacteria.

Conclusion

HEMA-based soft CLs may facilitate bacterial biofilm formation and adhesion capability. The two-step system was the most effective regimen for biofilm removal, where the soaking period in the disinfecting solution of the no-rub regimen should last more than 6 h to remove pre-formed biofilm.

Purification and Evaluation of N-benzyl Cinnamamide from Red Seaweed Gracilaria fisheri as an Inhibitor of Vibrio harveyi AI-2 Quorum Sensing

Previously, we reported that the ethanol extract from red seaweed Gracilaria fisheri effectively decreased biofilm formation of Vibrio harveyi. In this study, the anti-biofilm active compounds in the ethanol extract were isolated and their structures identified. The anti-biofilm fractionation assay for minimum inhibitory concentration (MIC) produced two fractions which possessed maximal inhibitory activities toward the biofilm formation of V. harveyi strains 1114 and BAA 1116. Following chromatographic separation of the bioactive fractions, two pure compounds were isolated, and their structures were elucidated using FTIR, NMR, and HR-TOF-MS. The compounds were N-benzyl cinnamamide and α-resorcylic acid. The in vitro activity assay demonstrated that both compounds inhibited the biofilm formation of V. harveyi and possessed the anti-quorum sensing activity by interfering with the bioluminescence of the bacteria. However, the N-benzyl cinnamamide was more potent than α-resorcylic acid with a 10-fold lesser MIC. The present study reveals the beneficial property of the N-benzyl cinnamamide from the ethanol extract as a lead anti-microbial drug against V. harveyi.

Ethanolic extract of red seaweed Gracilaria fisheri and furanone eradicate Vibrio harveyi and Vibrio parahaemolyticus biofilms and ameliorate the bacterial infection in shrimp

Bacteria respond to host immunity for their proliferation and survival by cell-cell communications such as biofilm formation, bioluminescence, and secreting virulence factors. In the biofilm form, bacteria are more resistant to various antimicrobial treatments and withstand the host's immune system. The approaches of deciphering biofilm formation for treating bacterial infections are therefore highly desirable. Recently, we have reported that the ethanolic extract of the red seaweed Gracilaria fisheri (G. fisheri) enhanced immune activities and inhibited growth of the luminescent bacteria Vibrio harveyi in shrimp. We undertook the present research study in order to evaluate and compare the effectiveness of the ethanolic extract from G. fisheri and furanone, a known biofilm inhibitor, in inhibiting the formation of clinically important Vibrio biofilms. The results showed that sub-lethal concentrations of both the ethanolic extracts (5, 10 and 100 μg ml^-1) and furanone (5 μM) inhibited biofilm formation by V. harveyi and Vibrio parahaemolyticus and also light production (luminescence) in V. harveyi. It is known that V. harveyi mediated light production via autoinducer AI-2 pathway, we further determined whether the inhibitory effect of the extract was involved the AI-2 signaling. The bioluminescence assay was conducted in an AI-2 deletion mutant V. harveyi. Supplementation of the AI-2 containing media with the extract or furanone impaired the light production in the mutant V. harveyi suggesting that the extract interfered AI-2 mediated light production similar to furanone. In vivo challenge study showed that the low concentrations (Sub MICs) of the ethanolic extract and furanone decreased bacterial adhesion and colonization in the surfaces of stomach lumen, down-regulated expression of a virulence factor, and protected shrimp against mortality from V. harveyi and V. parahaemolyticus infection. In conclusion, the present results suggest a potential application of the low concentrations of the ethanolic extract of G. fisheri as an efficient approach for treating biofilm-associated Vibrio diseases in aquacultures.