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Singh S, Bolla N. Endocator-paradigm shift in the evaluation of microbial load in root canals. JOURNAL OF CONSERVATIVE DENTISTRY AND ENDODONTICS 2024; 27:111-112. [PMID: 38463470 PMCID: PMC10923219 DOI: 10.4103/jcde.jcde_8_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 01/10/2024] [Indexed: 03/12/2024]
Affiliation(s)
- Shishir Singh
- Department of Conservative Dentistry and Endodontics, Terna Dental College, Nerul, Navi Mumbai, Maharashtra, India
| | - Nagesh Bolla
- Department of Conservative Dentistry and Endodontics, Sibar Dental College, Guntur, Andhra Pradesh, India
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2
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Usta SN, Solana C, Ruiz-Linares M, Baca P, Ferrer-Luque CM, Cabeo M, Arias-Moliz MT. Effectiveness of conservative instrumentation in root canal disinfection. Clin Oral Investig 2023; 27:3181-3188. [PMID: 36867258 PMCID: PMC10264279 DOI: 10.1007/s00784-023-04929-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/22/2023] [Indexed: 03/04/2023]
Abstract
OBJECTIVES The impact of conservative instrumentation on the disinfection of root canals with different curvatures has not yet been determined. This ex vivo study aimed to evaluate and compare the effect of conservative instrumentation with TruNatomy (TN) and Rotate and a conventional rotary system, ProTaper Gold (PTG), on root canal disinfection during chemomechanical preparation of straight and curved canals. MATERIALS AND METHODS Ninety mandibular molars with straight (n = 45) and curved (n = 45) mesiobuccal root canals were contaminated with polymicrobial clinical samples. Teeth were divided into three subgroups (n = 14) according to the file systems and the curvature. Canals were instrumented with TN, Rotate, and PTG, respectively. Sodium hypochlorite and EDTA were used as irrigants. Intracanal samples were taken before (S1) and after (S2) instrumentation. Six uninfected teeth were used as negative controls. The bacterial reduction between S1 and S2 was measured by ATP assay, flow cytometry, and culture methods. Kruskal-Wallis and ANOVA tests were followed by the Duncan post hoc test (p < 0.05). RESULTS Bacterial reduction percentages were similar for the three file systems in straight canals (p > 0.05). However, PTG showed a lower reduction percentage of intact membrane cells in flow cytometry than TN and Rotate (p = 0.036). For the curved canals, no significant differences were obtained (p > 0.05). CONCLUSION Conservative instrumentation of straight and curved canals using TN and Rotate files resulted in similar bacterial reduction compared to PTG. CLINICAL RELEVANCE The disinfection efficacy of conservative instrumentation is similar to conventional instrumentation in straight and curved root canals.
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Affiliation(s)
- Sıla Nur Usta
- Department of Endodontics, Gulhane Faculty of Dentistry, University of Health Sciences, Etlik, Keçiören, 06018 Ankara Turkey
| | - Carmen Solana
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Matilde Ruiz-Linares
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Pilar Baca
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Carmen María Ferrer-Luque
- Department of Stomatology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
| | - Monica Cabeo
- Department of Microbiology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
| | - Maria Teresa Arias-Moliz
- Instituto de Investigación Biosanitaria Ibs.GRANADA, Granada, Spain
- Department of Microbiology, School of Dentistry, University of Granada, Campus de Cartuja, Colegio Máximo S/N., 18071 Granada, Spain
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3
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Son HB, Bae WB, Jhee KH. Enhanced Antibacterial Activity of Sodium Hypochlorite under Acidic pH Condition. MICROBIOLOGY AND BIOTECHNOLOGY LETTERS 2022; 50:211-217. [DOI: 10.48022/mbl.2204.04014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/26/2022] [Accepted: 05/31/2022] [Indexed: 09/01/2023]
Affiliation(s)
- Hyeon-Bin Son
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Won-Bin Bae
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Kwang-Hwan Jhee
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
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4
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Chahal G, Quintana-Hayashi MP, Gaytán MO, Benktander J, Padra M, King SJ, Linden SK. Streptococcus oralis Employs Multiple Mechanisms of Salivary Mucin Binding That Differ Between Strains. Front Cell Infect Microbiol 2022; 12:889711. [PMID: 35782137 PMCID: PMC9247193 DOI: 10.3389/fcimb.2022.889711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
Streptococcus oralis is an oral commensal and opportunistic pathogen that can enter the bloodstream and cause bacteremia and infective endocarditis. Here, we investigated the mechanisms of S. oralis binding to oral mucins using clinical isolates, isogenic mutants and glycoconjugates. S. oralis bound to both MUC5B and MUC7, with a higher level of binding to MUC7. Mass spectrometry identified 128 glycans on MUC5B, MUC7 and the salivary agglutinin (SAG). MUC7/SAG contained a higher relative abundance of Lewis type structures, including Lewis b/y, sialyl-Lewis a/x and α2,3-linked sialic acid, compared to MUC5B. S. oralis subsp. oralis binding to MUC5B and MUC7/SAG was inhibited by Lewis b and Lacto-N-tetraose glycoconjugates. In addition, S. oralis binding to MUC7/SAG was inhibited by sialyl Lewis x. Binding was not inhibited by Lacto-N-fucopentaose, H type 2 and Lewis x conjugates. These data suggest that three distinct carbohydrate binding specificities are involved in S. oralis subsp. oralis binding to oral mucins and that the mechanisms of binding MUC5B and MUC7 differ. Efficient binding of S. oralis subsp. oralis to MUC5B and MUC7 required the gene encoding sortase A, suggesting that the adhesin(s) are LPXTG-containing surface protein(s). Further investigation demonstrated that one of these adhesins is the sialic acid binding protein AsaA.
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Affiliation(s)
- Gurdeep Chahal
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | | | - Meztlli O. Gaytán
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children´s Hospital, Columbus, OH, United States
| | - John Benktander
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Medea Padra
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Samantha J. King
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children´s Hospital, Columbus, OH, United States
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, United States
- Infectious Diseases Institute, The Ohio State University, Columbus, OH, United States
- *Correspondence: Sara K. Linden, ; Samantha J. King,
| | - Sara K. Linden
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
- *Correspondence: Sara K. Linden, ; Samantha J. King,
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5
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Recent Advances in the Application of Essential Oils as Potential Therapeutic Candidates for Candida-Related Infections. Appl Microbiol 2022. [DOI: 10.3390/applmicrobiol2020030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Candidiasis (oral, vulvovaginal, or systemic bloodstream infections) are important human fungal infections associated with a high global prevalence in otherwise healthy adults but are also opportunistic infections in immunocompromised patients. With the recent discovery of the multidrug resistant—and often difficult to treat—Candida auris, as well as the rising costs associated with hospitalisations and the treatment of infections caused by Candida species, there is an urgent need to develop effective therapeutics against these pathogenic yeasts. Essential oils have been documented for many years as treatments for different ailments and are widely known and utilised in alternative and complementary therapies, including treating microbial infections. This review highlights knowledge from research on the effects of medicinal plants, and in particular, essential oils, as potential treatments against different Candida species. Studies have been evaluated that describe the experimental approaches used in investigating the anticandidal effects of essential oils (in vivo and in vitro), the established mode of action of the different compounds against different Candida species, the effect of a combination of essential oils with other compounds as potential therapies, and the evidence from clinical trial studies.
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6
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Hou C, Yin F, Wang S, Zhao A, Li Y, Liu Y. Helicobacter pylori Biofilm-Related Drug Resistance and New Developments in Its Anti-Biofilm Agents. Infect Drug Resist 2022; 15:1561-1571. [PMID: 35411160 PMCID: PMC8994595 DOI: 10.2147/idr.s357473] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/05/2022] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori is one of the most common pathogenic bacterium worldwide, infecting about 50% of the world’s population. It is a major cause of several upper gastrointestinal diseases, including peptic ulcers and gastric cancer. The emergence of H. pylori resistance to antibiotics has been a major clinical challenge in the field of gastroenterology. In the course of H. pylori infection, some bacteria invade the gastric epithelium and are encapsulated into a self-produced matrix to form biofilms that protect the bacteria from external threats. Bacteria with biofilm structures can be up to 1000 times more resistant to antibiotics than planktonic bacteria. This implies that targeting biofilms might be an effective strategy to alleviate H. pylori drug resistance. Therefore, it is important to develop drugs that can eliminate or disperse biofilms. In recent years, anti-biofilm agents have been investigated as alternative or complementary therapies to antibiotics to reduce the rate of drug resistance. This article discusses the formation of H. pylori biofilms, the relationship between biofilms and drug resistance in H. pylori, and the recent developments in the research of anti-biofilm agents targeting H. pylori drug resistance.
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Affiliation(s)
- Chong Hou
- Department of Gastroenterology, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, 264100, People’s Republic of China
| | - Fangxu Yin
- Department of Thyroid and Breast Surgery, Binzhou Medical University Hospital, Binzhou, Shandong, 256603, People’s Republic of China
| | - Song Wang
- Department of Thyroid and Breast Surgery, Binzhou Medical University Hospital, Binzhou, Shandong, 256603, People’s Republic of China
| | - Ailing Zhao
- Department of Gastroenterology, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, 264100, People’s Republic of China
| | - Yingzi Li
- Department of Gastroenterology, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, 264100, People’s Republic of China
| | - Yipin Liu
- Department of Gastroenterology, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, 264100, People’s Republic of China
- Correspondence: Yipin Liu, Department of Gastroenterology, Yantai Affiliated Hospital of Binzhou Medical University, No. 717 Jinbu Street, Muping District, Yantai, Shandong, 264100, People’s Republic of China, Tel +86-18953595711, Email
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7
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Boutsioukis C, Arias-Moliz MT, Chávez de Paz LE. A critical analysis of research methods and experimental models to study irrigants and irrigation systems. Int Endod J 2022; 55 Suppl 2:295-329. [PMID: 35171506 PMCID: PMC9314845 DOI: 10.1111/iej.13710] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 11/28/2022]
Abstract
Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-omputed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.
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Affiliation(s)
- C Boutsioukis
- Department of Endodontology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - M T Arias-Moliz
- Department of Microbiology, Faculty of Dentistry, University of Granada, Granada, Spain
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8
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Abdulkareem A, Abdulbaqi H, Gul S, Milward M, Chasib N, Alhashimi R. Classic vs. Novel Antibacterial Approaches for Eradicating Dental Biofilm as Adjunct to Periodontal Debridement: An Evidence-Based Overview. Antibiotics (Basel) 2021; 11:antibiotics11010009. [PMID: 35052887 PMCID: PMC8773342 DOI: 10.3390/antibiotics11010009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/10/2021] [Accepted: 12/20/2021] [Indexed: 12/14/2022] Open
Abstract
Periodontitis is a multifactorial chronic inflammatory disease that affects tooth-supporting soft/hard tissues of the dentition. The dental plaque biofilm is considered as a primary etiological factor in susceptible patients; however, other factors contribute to progression, such as diabetes and smoking. Current management utilizes mechanical biofilm removal as the gold standard of treatment. Antibacterial agents might be indicated in certain conditions as an adjunct to this mechanical approach. However, in view of the growing concern about bacterial resistance, alternative approaches have been investigated. Currently, a range of antimicrobial agents and protocols have been used in clinical management, but these remain largely non-validated. This review aimed to evaluate the efficacy of adjunctive antibiotic use in periodontal management and to compare them to recently suggested alternatives. Evidence from in vitro, observational and clinical trial studies suggests efficacy in the use of adjunctive antimicrobials in patients with grade C periodontitis of young age or where the associated risk factors are inconsistent with the amount of bone loss present. Meanwhile, alternative approaches such as photodynamic therapy, bacteriophage therapy and probiotics showed limited supportive evidence, and more studies are warranted to validate their efficiency.
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Affiliation(s)
- Ali Abdulkareem
- College of Dentistry, University of Baghdad, Medical City of Baghdad, Baghdad 10011, Iraq; (H.A.); (N.C.); (R.A.)
- Correspondence:
| | - Hayder Abdulbaqi
- College of Dentistry, University of Baghdad, Medical City of Baghdad, Baghdad 10011, Iraq; (H.A.); (N.C.); (R.A.)
| | - Sarhang Gul
- College of Dentistry, University of Sulaimani, Sulaymaniyah 40062, Iraq;
| | - Mike Milward
- College of Dentistry, University of Birmingham, Birmingham B5 7EG, UK;
| | - Nibras Chasib
- College of Dentistry, University of Baghdad, Medical City of Baghdad, Baghdad 10011, Iraq; (H.A.); (N.C.); (R.A.)
| | - Raghad Alhashimi
- College of Dentistry, University of Baghdad, Medical City of Baghdad, Baghdad 10011, Iraq; (H.A.); (N.C.); (R.A.)
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9
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Evolution of Antibacterial Drug Screening Methods: Current Prospects for Mycobacteria. Microorganisms 2021; 9:microorganisms9122562. [PMID: 34946162 PMCID: PMC8708102 DOI: 10.3390/microorganisms9122562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/01/2021] [Accepted: 12/08/2021] [Indexed: 12/25/2022] Open
Abstract
The increasing resistance of infectious agents to available drugs urges the continuous and rapid development of new and more efficient treatment options. This process, in turn, requires accurate and high-throughput techniques for antimicrobials’ testing. Conventional methods of drug susceptibility testing (DST) are reliable and standardized by competent entities and have been thoroughly applied to a wide range of microorganisms. However, they require much manual work and time, especially in the case of slow-growing organisms, such as mycobacteria. Aiming at a better prediction of the clinical efficacy of new drugs, in vitro infection models have evolved to closely mimic the environment that microorganisms experience inside the host. Automated methods allow in vitro DST on a big scale, and they can integrate models that recreate the interactions that the bacteria establish with host cells in vivo. Nonetheless, they are expensive and require a high level of expertise, which makes them still not applicable to routine laboratory work. In this review, we discuss conventional DST methods and how they should be used as a first screen to select active compounds. We also highlight their limitations and how they can be overcome by more complex and sophisticated in vitro models that reflect the dynamics present in the host during infection. Special attention is given to mycobacteria, which are simultaneously difficult to treat and especially challenging to study in the context of DST.
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10
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Uematsu T, Matsuura T, Suzuki F, Aoki S, Suzuki M, Goto Y. [Evaluation of Hygiene in Dry Powder Steroid Drug Inhalers Used by Elderly Asthma Patients]. YAKUGAKU ZASSHI 2020; 140:789-798. [PMID: 32475929 DOI: 10.1248/yakushi.19-00243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dry powder inhalers (DPI) are frequently used by asthmatic patients, and the usage rate increases every year. The pharmacists at our hospital provided initial inhalation instructions on how the inhaler must be used but did not elaborate on the cleaning of the device. Therefore, the cleaning status of the inhaler is unknown, and there is a possibility of bacterial growth. This study investigated the cleaning status and hygiene of steroid drug inhalers used by elderly asthma patients. We administered a questionnaire to investigate the inhaler cleaning status after inhalation, and conducted a cross-sectional survey on hygiene using ATP measurement and bacterial culture examination. Considering the responses by 53 patients, it became clear that the ATP values of patients who answered "never cleaned" after inhalation were significantly higher than those who answered "cleaned every time". Moreover, some bacteria were detected in 62% of inhalers; 4 patients' inhalers contained bacteria other than normal oral microbial flora. In conclusion, because the inhalers used by elderly patients are in poor hygienic conditions, we must give cleaning instructions accordingly. We believe that it is necessary to give proper medical instructions along with instructions on the cleaning method with dry cloth.
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Affiliation(s)
- Takuya Uematsu
- Department of Hospital Pharmacy, Juntendo University Shizuoka Hospital
| | - Toru Matsuura
- Department of Hospital Pharmacy, Juntendo University Shizuoka Hospital
| | - Fuhito Suzuki
- Department of Hospital Pharmacy, Juntendo University Shizuoka Hospital
| | - Suzuka Aoki
- Department of Hospital Pharmacy, Juntendo University Shizuoka Hospital
| | - Misako Suzuki
- Department of Clinical Laboratory, Juntendo University Shizuoka Hospital
| | - Yukiko Goto
- Department of Clinical Laboratory, Juntendo University Shizuoka Hospital
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11
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Esteban Florez FL, Hiers RD, Zhao Y, Merritt J, Rondinone AJ, Khajotia SS. Optimization of a real-time high-throughput assay for assessment of Streptococcus mutans metabolism and screening of antibacterial dental adhesives. Dent Mater 2020; 36:353-365. [PMID: 31952798 PMCID: PMC7042092 DOI: 10.1016/j.dental.2019.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/17/2019] [Accepted: 12/18/2019] [Indexed: 12/25/2022]
Abstract
Objective. The present work shows the optimization of a high-throughput bioluminescence assay to assess the metabolism of intact Streptococcus mutans biofilms and its utility as a screening method for nanofilled antibacterial dental materials. Methods. The assay was optimized by monitoring changes in bioluminescence mediated by variation of the experimental parameters investigated (growth media and sucrose concentration, inoculum:D-Luciferin ratio, dilution factor, inoculum volume, luminescence wavelength, replicate and luciferase metabolic activity). Confocal microscopy was then used to demonstrate the impact of biofilm growth conditions on the 3-D distribution of extracellular polymeric substance (EPS) within Streptococcus mutans biofilms and its implications as confounding factors in high-throughput studies (HTS). Results. Relative Luminescence Unit (RLU) values from the HTS optimization were analyzed by multivariate ANOVA (α = 0.05) and coefficients of variation, whereas data from 3-D structural parameters and RLU values of biofilms grown on experimental antibacterial dental adhesive resins were analyzed using General Linear Models and Student–Newman–Keuls post hoc tests (α = 0.05). Confocal microscopy demonstrated that biofilm growth conditions significantly influenced the quantity and distribution of EPS within the 3-D structures of the biofilms. An optimized HTS bioluminescence assay was developed and its applicability as a screening method in dentistry was demonstrated using nanofilled experimental antibacterial dental adhesive resins. Significance. The present study is anticipated to positively impact the direction of future biofilm research in dentistry, because it offers fundamental information for the design of metabolic-based assays, increases the current levels of standardization and reproducibility while offering a tool to decrease intra-study variability.
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Affiliation(s)
- Fernando Luis Esteban Florez
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
| | - Rochelle Denise Hiers
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
| | - Yan Zhao
- The University of Oklahoma Health Sciences Center, Department of Biostatistics and Epidemiology, College of Public Health, 801 NE 13th Street, Oklahoma City, OK, 73126, USA.
| | - Justin Merritt
- Oregon Health & Science University, Department of Restorative Dentistry, School of Dentistry, MRB424, 3181 SW Sam Jackson Park Rd., Portland, OR, 97239, USA.
| | - Adam Justin Rondinone
- Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, TN, 37831, USA.
| | - Sharukh Soli Khajotia
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
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12
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Iwawaki Y, Muraoka Y, Higashiyama H, Kishimoto T, Liu L, Goto T, Ichikawa T. Comparison between Two Assessment Tests for Oral Hygiene: Adenosine Triphosphate + Adenosine Monophosphate Swab Test and Bacteria Number Counting by Dielectrophoretic Impedance Measurement. Dent J (Basel) 2019; 7:dj7010010. [PMID: 30717111 PMCID: PMC6473332 DOI: 10.3390/dj7010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/12/2019] [Accepted: 01/16/2019] [Indexed: 11/16/2022] Open
Abstract
Objective assessments of oral hygiene are important to prevent oral and systemic diseases. Two objective assessment tests are available to assess oral hygiene; (1) the adenosine triphosphate (ATP) + adenosine monophosphate (AMP) swab test, which incorporates a luciferase assay and (2) a bacteria count using the dielectrophoretic impedance measurement (DEPIM) method. In this study, we compared the two tests using a subjective visual assessment by professional clinicians and investigated the clinical significance of these tests. Twenty-seven young participants (mean age 26.3 ± 3.2 years) and twenty-seven older participants (mean age 75.1 ± 5.9 years) were recruited. Oral bacteria were sampled from three areas, including the tongue dorsum, the buccal mucosa, and the faucal mucosa, and saliva was obtained using a cotton swab. The amount of ATP + AMP and the number of bacteria were measured by each specific apparatus. Additionally, one examiner assessed the overall condition of oral hygiene using the visual analog scale (VAS). In the ATP + AMP swab test, the means were highest in saliva. For the bacteria count, the means were higher in the tongue dorsum and saliva and lower in the faucal and buccal mucosa. The results of the subjective assessment of oral hygiene indicated that the VAS-value was 3.78 ± 0.97 for the young group and 3.35 ± 0.81 for the older group. No significant difference was observed between the two groups. Additionally, no significant relationship between the values of the ATP + AMP swab test and the bacteria count was found for any of the four sample sites. In the older group, the subjective assessment of oral hygiene was significantly correlated with the values of the ATP + AMP swab test (multiple correlation coefficient = 0.723, p = 0.002). In conclusion, the values provided by the ATP + AMP swab test were not always correlated to the bacteria count. The results of this study suggest that the subjective assessment of oral hygiene was more highly correlated with the results of the ATP + AMP swab test, as compared to the bacterial count assay.
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Affiliation(s)
- Yuki Iwawaki
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Yuki Muraoka
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Hiroaki Higashiyama
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Takahiro Kishimoto
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Lipei Liu
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Takaharu Goto
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
| | - Tetsuo Ichikawa
- Department of Prosthodontics and Oral Rehabilitation, Tokushima University, Graduate School of Biomedical Sciences, 3-18-15, Kuramoto, Tokushima 770-8504, Japan.
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Roy R, Tiwari M, Donelli G, Tiwari V. Strategies for combating bacterial biofilms: A focus on anti-biofilm agents and their mechanisms of action. Virulence 2018; 9:522-554. [PMID: 28362216 PMCID: PMC5955472 DOI: 10.1080/21505594.2017.1313372] [Citation(s) in RCA: 698] [Impact Index Per Article: 116.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. The biofilm matrix surrounding bacteria makes them tolerant to harsh conditions and resistant to antibacterial treatments. Moreover, the biofilms are responsible for causing a broad range of chronic diseases and due to the emergence of antibiotic resistance in bacteria it has really become difficult to treat them with efficacy. Furthermore, the antibiotics available till date are ineffective for treating these biofilm related infections due to their higher values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), which may result in in-vivo toxicity. Hence, it is critically important to design or screen anti-biofilm molecules that can effectively minimize and eradicate biofilm related infections. In the present article, we have highlighted the mechanism of biofilm formation with reference to different models and various methods used for biofilm detection. A major focus has been put on various anti-biofilm molecules discovered or tested till date which may include herbal active compounds, chelating agents, peptide antibiotics, lantibiotics and synthetic chemical compounds along with their structures, mechanism of action and their respective MICs, MBCs, minimum biofilm inhibitory concentrations (MBICs) as well as the half maximal inhibitory concentration (IC50) values available in the literature so far. Different mode of action of anti biofilm molecules addressed here are inhibition via interference in the quorum sensing pathways, adhesion mechanism, disruption of extracellular DNA, protein, lipopolysaccharides, exopolysaccharides and secondary messengers involved in various signaling pathways. From this study, we conclude that the molecules considered here might be used to treat biofilm-associated infections after significant structural modifications, thereby investigating its effective delivery in the host. It should also be ensured that minimum effective concentration of these molecules must be capable of eradicating biofilm infections with maximum potency without posing any adverse side effects on the host.
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Affiliation(s)
- Ranita Roy
- a Department of Biochemistry , Central University of Rajasthan , Ajmer , India
| | - Monalisa Tiwari
- a Department of Biochemistry , Central University of Rajasthan , Ajmer , India
| | - Gianfranco Donelli
- b Microbial Biofilm Laboratory, IRCCS Fondazione Santa Lucia , Rome , Italy
| | - Vishvanath Tiwari
- a Department of Biochemistry , Central University of Rajasthan , Ajmer , India
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Evaluation of an Amplified ATP Bioluminescence Method for Rapid Sterility Testing of Large Volume Parenteral. J Pharm Innov 2018. [DOI: 10.1007/s12247-018-9344-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Wilson C, Lukowicz R, Merchant S, Valquier-Flynn H, Caballero J, Sandoval J, Okuom M, Huber C, Brooks TD, Wilson E, Clement B, Wentworth CD, Holmes AE. Quantitative and Qualitative Assessment Methods for Biofilm Growth: A Mini-review. RESEARCH & REVIEWS. JOURNAL OF ENGINEERING AND TECHNOLOGY 2017; 6:http://www.rroij.com/open-access/quantitative-and-qualitative-assessment-methods-for-biofilm-growth-a-minireview-.pdf. [PMID: 30214915 PMCID: PMC6133255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Biofilms are microbial communities attached to a surface and embedded in an extracellular polymeric substance which provides for the protection, stability and nutrients of the various bacterial species indwelling. These communities can build up in a variety of different environments from industrial equipment to medical devices resulting in damage, loss of productivity and disease. They also have great potential for economic and societal benefits as bioremediation agents and renewable energy sources. The great potential benefits and threats of biofilms has encouraged researchers across disciplines to study biofilm characteristics and antibiofilm strategies resulting in chemists, physicists, material scientists, and engineers, to develop beneficial biofilm applications and prevention methods. The ultimate outcome is a wealth of knowledge and innovative technology. However, without extensive formal training in microbes and biofilm research, these scientists find a daunting array of established techniques for growing, quantifying and characterizing biofilms while trying to design experiments and develop innovative laboratory protocols. This mini-review focuses on enriching interdisciplinary efforts and understanding by overviewing a variety of quantitative and qualitative biofilm characterization methods to assist the novice researcher in assay selection. This review consists of four parts. Part 1 is a brief overview of biofilms and the unique properties that demand a highly interdisciplinary approach. Part 2 describes the classical quantification techniques including colony forming unit (CFU) counting and crystal violet staining, but also introduces some modern methods including ATP bioluminescence and quartz crystal microbalance. Part 3 focuses on the characterization of biofilm morphology and chemistry including scanning electron microscopy and spectroscopic methods. Finally, Part 4 illustrates the use of software, including ImageJ and predictive modeling platforms, for biofilm analysis. Each section highlights the most common methods, including literature references, to help novice biofilm researchers make choices which commensurate with their study goals, budget and available equipment.
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Affiliation(s)
- Christina Wilson
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Rachel Lukowicz
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Stefan Merchant
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Helena Valquier-Flynn
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Jeniffer Caballero
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Jasmin Sandoval
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Macduff Okuom
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Christopher Huber
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Tessa Durham Brooks
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | - Erin Wilson
- Department of Chemistry, Westminster College, New Wilmington, Pennsylvania
| | - Barbara Clement
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
| | | | - Andrea E Holmes
- Department of Chemistry, Biology, Physics & Engineering, Doane University, Crete, Nebraska
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16
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Removal and killing of multispecies endodontic biofilms by N-acetylcysteine. Braz J Microbiol 2017; 49:184-188. [PMID: 28916389 PMCID: PMC5790572 DOI: 10.1016/j.bjm.2017.04.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 01/11/2017] [Accepted: 04/21/2017] [Indexed: 01/07/2023] Open
Abstract
Removal of bacterial biofilm from the root canal system is essential for the management of endodontic disease. Here we evaluated the antibacterial effect of N-acetylcysteine (NAC), a potent antioxidant and mucolytic agent, against mature multispecies endodontic biofilms consisting of Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans and Enterococcus faecalis on sterile human dentin blocks. The biofilms were exposed to NAC (25, 50 and 100 mg/mL), saturated calcium hydroxide or 2% chlorhexidine solution for 7 days, then examined by scanning electron microscopy. The biofilm viability was measured by viable cell counts and ATP-bioluminescence assay. NAC showed greater efficacy in biofilm cell removal and killing than the other root canal medicaments. Furthermore, 100 mg/mL NAC disrupted the mature multispecies endodontic biofilms completely. These results demonstrate the potential use of NAC in root canal treatment.
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17
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Lin NJ. Biofilm over teeth and restorations: What do we need to know? Dent Mater 2017; 33:667-680. [PMID: 28372810 DOI: 10.1016/j.dental.2017.03.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 03/09/2017] [Indexed: 12/29/2022]
Abstract
OBJECTIVE The goal of this manuscript is to provide an overview of biofilm attributes and measurement approaches in the context of studying biofilms on tooth and dental material surfaces to improve oral health. METHODS A historical perspective and terminology are presented, followed by a general description of the complexity of oral biofilms. Then, an approach to grouping measurable biofilm properties is presented and considered in relation to biofilm-material interactions and material design strategies to alter biofilms. Finally, the need for measurement assurance in biofilm and biofilm-materials research is discussed. RESULTS Biofilms are highly heterogeneous communities that are challenging to quantify. Their characteristics can be broadly categorized into constituents (identity), quantity, structure, and function. These attributes can be measured over time and in response to substrates and external stimuli. Selecting the biofilm attribute(s) of interest and appropriate measurement methods will depend on the application and, in the case of antimicrobial therapies, the strategic approach and expected mechanism of action. To provide measurement assurance, community accepted protocols and guidelines for minimum data and metadata should be established and broadly applied. Consensus standards may help to streamline testing and demonstration of product claims. SIGNIFICANCE Understanding oral biofilms and their interactions with tooth and dental material surfaces holds great promise for enabling improvements in oral and overall human health. Both substrate and biofilm properties should be considered to develop a more thorough understanding of the system.
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Affiliation(s)
- Nancy J Lin
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8543, USA.
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18
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New 1,4-dihydro[1,8]naphthyridine derivatives as DNA gyrase inhibitors. Bioorg Med Chem Lett 2017; 27:1162-1168. [DOI: 10.1016/j.bmcl.2017.01.073] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/21/2017] [Accepted: 01/24/2017] [Indexed: 01/27/2023]
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19
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Lomakina GY, Modestova YA, Ugarova NN. Bioluminescence assay for cell viability. BIOCHEMISTRY (MOSCOW) 2016; 80:701-13. [PMID: 26531016 DOI: 10.1134/s0006297915060061] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Theoretical aspects of the adenosine triphosphate bioluminescence assay based on the use of the firefly luciferin-luciferase system are considered, as well as its application for assessing cell viability in microbiology, sanitation, medicine, and ecology. Various approaches for the analysis of individual or mixed cultures of microorganisms are presented, and capabilities of the method for investigation of biological processes in live cells including necrosis, apoptosis, as well as for investigation of the dynamics of metabolism are described.
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Affiliation(s)
- G Yu Lomakina
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.
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20
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Cytotoxicity of three commercial mouthrinses on extracellular matrix metabolism and human gingival cell behaviour. Toxicol In Vitro 2016; 34:88-96. [DOI: 10.1016/j.tiv.2016.03.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 03/14/2016] [Accepted: 03/25/2016] [Indexed: 11/19/2022]
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21
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Quantifying implant-associated biofilms: Comparison of microscopic, microbiologic and biochemical methods. J Microbiol Methods 2016; 130:61-68. [PMID: 27444546 DOI: 10.1016/j.mimet.2016.07.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/17/2016] [Accepted: 07/18/2016] [Indexed: 01/10/2023]
Abstract
Biofilm-associated infections pose severe problems in modern implant medicine. Screening for new implant materials with antibacterial properties requires reliable quantification of colonizing bacteria. There are many different methods to quantify biofilms on solid surfaces in vitro, employing different (bio-)chemical/microbiological reference parameters. It is therefore difficult to compare studies with different quantification techniques. Here, we have evaluated commonly used microscopic, microbiologic and biochemical methods to quantify bacterial biofilms, in order to clarify their comparability and applicability. Two bacterial species frequently involved in biofilm-associated infections, Staphylococcus aureus and Aggregatibacter actinomycetemcomitans, were used as model organisms; their initial adhesion and biofilm formation on titanium and on antibacterial copper were analyzed using the following methods: LIVE/DEAD fluorescence staining and confocal laser-scanning microscopy, ultrasonic or a newly developed enzymatic detachment followed by standard plate counting (CFU method), a resazurin-based assay, the BacTiter-Glo™ assay and crystal violet staining. The methods differed greatly in complexity, reliability and the applicability to initial adhesion and biofilm formation. To screen biofilm formation on a multitude of surfaces, the resazurin-based and the BacTiterGlo™ assay are well suited. LIVE/DEAD staining and confocal laser-scanning microscopy can be applied for a more detailed analysis of both, initial adhesion and biofilm formation. When using the CFU method for screening purposes, the introduced enzymatic detachment procedure is to be favored over ultrasonic detachment. There is not one single method, which is suitable for all purposes. The appropriate biofilm quantification method has to be chosen on the basis of the specific scientific question.
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Tepper B, Howard B, Schnell D, Mills L, Xu J. In vitro method for prediction of plaque reduction by dentifrice. J Microbiol Methods 2015; 118:85-92. [PMID: 26151407 DOI: 10.1016/j.mimet.2015.06.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 06/26/2015] [Accepted: 06/27/2015] [Indexed: 01/01/2023]
Abstract
An in vitro Particle Based Biofilm (PBB) model was developed to enable high throughput screening tests to predict clinical plaque reduction. Multi-species oral biofilms were cultured from pooled stimulated human saliva on continuously-colliding hydroxyapatite particles. After three days PBBs were saline washed prior to use in screening tests. Testing involved dosing PBBs for 1min followed by neutralization of test materials and rinsing. PBBs were then assayed for intact biofilm activity measured as ATP. The ranking of commercial dentifrices from most to least reduction of intact biofilm activity was Crest ProHealth Clinical Gum Protection, Crest ProHealth, Colgate Total and Crest Cavity Protection. We demonstrated five advantages of the PBB model: 1) the ATP metric had a linear response over ≥1000-fold dynamic range, 2) potential interference with the ATP assay by treatments was easily eliminated by rinsing PBBs with saline, 3) discriminating power was statistically excellent between all treatment comparisons with the negative controls, 4) screening test results were reproducible across four tests, and 5) the screening test produced the same rank order for dentifrices as clinical studies that measured plaque reduction. In addition, 454 pyrosequencing of the PBBs indicated an oral microbial consortium was present. The most prevalent genera were Neisseria, Rothia, Streptococcus, Porphyromonas, Prevotella, Actinomyces, Fusobacterium, Veillonella and Haemophilus. We conclude these in vitro methods offer an efficient, effective and relevant screening tool for reduction of intact biofilm activity by dentifrices. Moreover, dentifrice rankings by the in vitro test method are expected to predict clinical results for plaque reduction.
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Affiliation(s)
- Bruce Tepper
- Microbiology Capability Organization, The Procter & Gamble Company, 8700 Mason-Montgomery Road, Mason, OH 45040, USA.
| | - Brian Howard
- Life Sciences Innovation, The Procter & Gamble Company, 8700 Mason-Montgomery Road, Mason, OH 45040, USA.
| | - Daniel Schnell
- Statistics and Data Management, The Procter & Gamble Company, 8700 Mason-Montgomery Road, Mason, OH 45040, USA
| | - Lisa Mills
- Microbiology Capability Organization, The Procter & Gamble Company, 8700 Mason-Montgomery Road, Mason, OH 45040, USA
| | - Jian Xu
- Single-Cell Center and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
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Effects of azithromycin, metronidazole, amoxicillin, and metronidazole plus amoxicillin on an in vitro polymicrobial subgingival biofilm model. Antimicrob Agents Chemother 2015; 59:2791-8. [PMID: 25733510 DOI: 10.1128/aac.04974-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 02/24/2015] [Indexed: 01/30/2023] Open
Abstract
Chronic periodontitis is one of the most prevalent human diseases and is caused by dysbiosis of the subgingival microbiota. Treatment involves primarily mechanical disruption of subgingival biofilms and, in certain cases, adjunctive use of systemic antibiotic therapy. In vitro biofilm models have been developed to study antimicrobial agents targeting subgingival species. However, these models accommodate a limited number of taxa, lack reproducibility, and have low throughput. We aimed to develop an in vitro multispecies biofilm model that mimics subgingival plaque, to test antimicrobial agents. Biofilms were cultivated using the Calgary Biofilm Device and were exposed to amoxicillin (AMX), metronidazole (MTZ), azithromycin (AZM), and AMX-MTZ at four different concentrations for 12, 24, or 36 h. Chlorhexidine (CHX) (0.12%) was used as the positive control. The compositions of the biofilms were analyzed by checkerboard DNA-DNA hybridization, and the percent reduction in biofilm metabolic activity was determined using 2,3,5-triphenyltetrazolium chloride and spectrophotometry. Thirty-five of the 40 species used in the inoculum were consistently recovered from the resulting in vitro biofilms. After 36 h of exposure at the 1:27 dilution, AMX-MTZ reduced metabolic activity 11% less than CHX (q = 0.0207) but 54% more than AMX (q = 0.0031), 72% more than MTZ (q = 0.0031), and 67% more than AZM (q = 0.0008). Preliminary evidence of a synergistic interaction between AMX and MTZ was also observed. In summary, we developed reproducible biofilms with 35 subgingival bacterial species, and our results suggested that the combination of AMX and MTZ had greater antimicrobial effects on these in vitro multispecies biofilms than expected on the basis of the independent effects of the drugs.
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