Inhibitory capacity of Rhus coriaria L. extract and its major component methyl gallate on Streptococcus mutans biofilm formation by optical profilometry: Potential applications for oral health

Streptococcus mutans (S. mutans) bacterium is the most well recognized pathogen involved in pathogenesis of dental caries. Its virulence arises from its ability to produce a biofilm and acidogenicity, causing tooth decay. Discovery of natural products capable to inhibit biofilm formation is of high importance for developing health care products. To the best of our knowledge, in all previous scientific reports, a colorimetric assay was applied to test the effect of sumac and methyl gallate (MG) on S. mutans adherence. Quantitative assessment of the developed biofilm should be further performed by applying an optical profilometry assay, and by testing the effect on both surface roughness and thickness parameters of the biofilm. To the best of our knowledge, this is the first study to report the effect of sumac extract and its constituent MG on biofilm formation using an optical profilometry assay. Testing antibacterial activity of the sumac extract and its fractions revealed that MG is the most bioactive component against S. mutans bacteria. It reduced S. mutans biofilm biomass on the polystyrene surface by 68‑93%, whereas 1 mg/ml MG was able to decrease the biofilm roughness and thickness on the glass surface by 99%. MG also prevented a decrease in pH level by 97%. These bioactivities of MG occurred in a dose‑dependent manner and were significant vs. untreated bacteria. The findings are important for the development of novel pharmaceuticals and formulations of natural products and extracts that possess anti‑biofilm activities with primary applications for oral health, and in a broader context, for the treatment of various bacterial infections.The present study was supported by the Al‑Qasemi Research Foundation, the Ministry of Science, Technology and Space (Israel) and the Faculty of Medicine, Vilnius University (Lithuania)

Successful use of extracorporeal membrane oxygenation in a human immunodeficiency virus infected patient with severe acute respiratory distress syndrome

Introduction We report a case of an adult patient with human immunodeficiency virus (HIV), acute respiratory distress syndrome (ARDS) and ventilator associated pneumonia (VAP) caused by multidrug resistant (MDR) bacteria that was successfully managed with veno-venous extracorporeal membrane oxygenation (ECMO). Case report A 25 year old male with no significant past medical history had been admitted to a local hospital due to dyspnea and fever. His pulmonary function subsequently failed necessitating mechanical ventilation (MV) and introduction of ECMO support. The patient was transported for 300 km by road on ECMO to a tertiary medical center. The diagnosis of ARDS, HIV infection and MDR bacterial and fungal VAP was made. Patient was successfully treated with antiretroviral therapy (ART), anti-infective agents and 58 days of veno-venous ECMO support, with complete resolution of the respiratory symptoms. Conclusion HIV infected patients with ARDS and MDR bacterial VAP whose HIV replication is controlled by ART could be successfully managed with ECMO

Antisense Oligonucleotide in Fluoride Mouthwash Inhibits Mutans Streptococci Biofilm Formation

Objectives To test if a new biofilm-inhibiting antisense phosphorothioate oligodeoxyribonucleotide (PS-ODN) targeting simultaneously the selected homologous region of Streptococcus mutans glucosyltransferase (gtf) B, gtfC and Streptococcus sobrinus gtfI mRNAs is compatible with a sodium fluoride (NaF) mouthwash in suppressing streptococci biofilm formation in vitro. Methods Mixed cultures of S. mutans UA159 and S. sobrinus SL1 bacteria were grown anaerobically on vertical glass slides in 24-well cell culture plates containing Todd Hewitt broth with 1% sucrose and sterile-filtered human saliva (1:10) or 10% heat-inactivated horse serum under exposure to 10 µM of PS-ODN (5ʹ-GCAGACCATTGCTTAATCT-3ʹ) and 22.6 ppm of fluoride resulting from mouthwash (% w/v): 0.06% PS-ODN, 0.05% NaF, 0.1% saccharin-Na, 0.2% menthol. Untreated bacteria and bacteria exposed to mouthwash without PS-ODN, served as controls. After 24 h of incubation, glass slides were air-dried and further used for quantitative evaluation of biofilm applying optical profiler Sensofar PLµ 2300 and Gwyddion 2.27 software. Data obtained from two experiments (n=12, surface roughness; n=10, biofilm thickness) were analyzed using SPSS 23.0 program. Results The PS-ODN in combination with NaF mouthwash decreased surface roughness (parameter Rq) of the biofilm-covered glass slides by 62% and 75% versus untreated bacteria (p<0.05) in medium containing saliva and serum, respectively. This combination also reduced biofilm thickness by 88% and 78% versus untreated bacteria (p0.05), whereas it reduced biofilm thickness by 38% and 22% versus untreated bacteria (p<0.05) in medium with saliva and serum, respectively. Conclusions The antisense PS-ODN is compatible with a NaF mouthwash and significantly inhibits mutans group streptococci biofilm formation on glass, and the combination might therefore be used as antibiofilm and/or anticaries agent in mouthwash formulations

Alkyl Gallates as Potential Antibiofilm Agents: A Review

Biofilms, which consist of microorganisms embedded in a polymer-rich matrix, contribute to a variety of infections and increase antimicrobial resistance. Thus, there is a constant need to develop new chemotherapeutic agents to combat biofilms. This review article focuses on the use of alkyl gallates, gallic acid and its esters (methyl, ethyl, propyl, butyl, hexyl, octyl, and dodecyl gallate), most of which are found in plants, to inhibit biofilm formation. The studies under review reveal that alkyl gallates have the capacity to prevent biofilm development and eradicate mature biofilms through mechanisms that suppress the synthesis of the extracellular polymeric matrix, inhibit quorum-sensing signaling, and alter the microbial cell membrane. The effects are stronger the greater the length of the alkyl chain. Moreover, the alkyl gallates’ preventive activity against biofilm formation occurs at doses below the minimum inhibitory concentration. More importantly, combining alkyl gallates with antimicrobials or blue-light irradiation produces a synergistic effect on the inhibition of biofilm formation that can be used to treat infections and overcome microbial resistance

Inhibitory Effects of Ethyl Gallate on <i>Streptococcus mutans</i> Biofilm Formation by Optical Profilometry and Gene Expression Analysis

This study aimed to test the effectiveness of ethyl gallate (EG) against S. mutans biofilm formation on solid surfaces (polystyrene, glass) and acidogenicity, and to examine the effect on expression of related genes. The biofilm that is formed by S. mutans bacteria was evaluated using colorimetric assay and optical profilometry, while the pH of the biofilm growth medium was measured with microelectrode. The expression of genes encoding glucan binding protein B (gbpB), glucosyltranferases B, -C, -D (gtfB, -C, -D) and F-ATPase (atpD, atpF) was assessed using a quantitative reverse transcription-polymerase chain reaction (RT-qPCR). It was revealed that all of the EG concentrations significantly suppressed S. mutans biofilm build-up on polystyrene and glass surfaces, and inhibited acidogenicity, in a dose-dependent manner, compared to the activity of untreated bacteria (p &lt; 0.05). The highest concentration of EG (3.53 mM) reduced biofilm formation on polystyrene and glass surfaces by 68% and more than 91%, respectively, and prevented a decrease in pH levels by 95%. The RT-qPCR data demonstrate that the biofilm-producing bacteria treated with EG underwent significant gene expression changes involving the gtfC (a 98.6 increase in fold change), gtfB gene (a 47.5 increase in fold change) and the gbpB gene (a 13.8 increase in fold change). However, for the other genes tested (gtfD, atpD and atpF), the EG treatments did not produce significant expression change compared to the control. EG produced significant gene expression change in three genes&#8212;gtfC, gtfB, and gbpB; it has the capacity to inhibit S. mutans biofilm formation on solid surfaces (polystyrene, glass), as well as acidogenicity. Therefore, EG might be used as an antibiofilm and/or anticaries agent for oral formulations in order to reduce the prevalence of dental caries