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Santos HSDB, Damé-Teixeira N, Nagano MH, Do T, Parolo CCF, Maltz M, Arthur RA. Acid tolerance of Lactobacillus spp. on root carious lesions: A complex and multifaceted response. Arch Oral Biol 2023; 156:105820. [PMID: 37866118 DOI: 10.1016/j.archoralbio.2023.105820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/24/2023] [Accepted: 10/07/2023] [Indexed: 10/24/2023]
Abstract
Lactobacillus spp. are acidogenic and aciduric bacteria and are among the main cariogenic microorganisms associated with the carious process. OBJECTIVE This study aimed to identify genes involved in the acid-tolerance of Lactobacillus spp. and potential functions attributed to these genes within the metatranscriptome of sound root surfaces and carious root surfaces. DESIGN Genomic libraries were built from mRNA isolated from the biofilm samples (10 from sound root and 9 from carious root using Illumina HiSeq 2500). Reads generated by RNA-seq were mapped against 162 oral microbial genomes and genes potentially related to acid tolerance were manually extracted from the Lactobacillus spp. genomes using L. paracasei ATCC 344 as reference genome. The R package DESeq2 was used to calculate the level of differential gene expression between those two clinical conditions. RESULTS Fifteen Lactobacillus spp. genomes were identified and a total of 653 acid tolerance genes were overexpressed in carious root surfaces. Multiple functions, as translation, ribosomal structure and biogenesis, transport of nucleotides and amino acids, are involved in Lactobacillus spp. acid tolerance. Species-specific functions also seem to be related to the fitness of Lactobacillus spp. in acidified environments such as that of the cariogenic biofilm associated with carious root lesions. CONCLUSIONS The response of Lactobacillus spp. to an acidic environment is complex and multifaceted. This finding suggests several possible avenues for further research into the adaptive mechanisms of these bacteria.
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Affiliation(s)
- Heitor Sales de Barros Santos
- Preventive and Community Dentistry Department, Dental School, Federal University of Rio Grande do Sul (UFRGS), Ramiro Barcelos, 2492, Porto Alegre 90035-003, Brazil
| | - Nailê Damé-Teixeira
- Department of Dentistry, School of Health Sciences, University of Brasilia, Campus Universitario Darcy Ribeiro, 70910-900 Brasilia, Brazil; Division of Oral Biology, School of Dentistry, University of Leeds, Wellcome Trust Brenner Building, St. James' University Hospital, LS9 7TF Leeds, United Kingdom
| | - Martina Hitomi Nagano
- Preventive and Community Dentistry Department, Dental School, Federal University of Rio Grande do Sul (UFRGS), Ramiro Barcelos, 2492, Porto Alegre 90035-003, Brazil
| | - Thuy Do
- Division of Oral Biology, School of Dentistry, University of Leeds, Wellcome Trust Brenner Building, St. James' University Hospital, LS9 7TF Leeds, United Kingdom
| | - Clarissa Cavalcanti Fatturi Parolo
- Preventive and Community Dentistry Department, Dental School, Federal University of Rio Grande do Sul (UFRGS), Ramiro Barcelos, 2492, Porto Alegre 90035-003, Brazil
| | - Marisa Maltz
- Preventive and Community Dentistry Department, Dental School, Federal University of Rio Grande do Sul (UFRGS), Ramiro Barcelos, 2492, Porto Alegre 90035-003, Brazil
| | - Rodrigo Alex Arthur
- Preventive and Community Dentistry Department, Dental School, Federal University of Rio Grande do Sul (UFRGS), Ramiro Barcelos, 2492, Porto Alegre 90035-003, Brazil.
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Wen ZT, Huang X, Ellepola K, Liao S, Li Y. Lactobacilli and human dental caries: more than mechanical retention. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35671222 DOI: 10.1099/mic.0.001196] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Lactobacilli have been considered as major contributors to human dental caries for over a century. Recent in vitro model studies have shown that when compared to Streptococcus mutans, a keystone pathogen of human dental caries, the ability of lactobacilli to form biofilms is poor, although differences exist between the different major species. Further studies using molecular and bioinformatics approaches provide evidence that multiple mechanisms, including adhesin-receptor mediated physical contact with S. mutans, facilitate the adherence and establishment of lactobacilli on the tooth surface. There is also evidence that under conditions like continuous sugar consumption, weak acids and other antimicrobials such as bacteriocins from lactobacilli can become detrimental to the microbial community, especially those in the proximity. Details on the underlying mechanisms of how different Lactobacillus sp. establish and persist in the highly complex microbiota on the tooth surface await further investigation.
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Affiliation(s)
- Zezhang T Wen
- Department of Prosthodontics, School of Dentistry and Department of Microbiology, Immunology and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Xiaochang Huang
- Department of Prosthodontics, School of Dentistry and Department of Microbiology, Immunology and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA.,Present address: Analysis and Testing Center, Nanchang University, 235 Nanjing East Load, Qingshan Lake District, Nanchang, PR China
| | - Kassapa Ellepola
- Department of Prosthodontics, School of Dentistry and Department of Microbiology, Immunology and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA.,Present address: Department of Oral Biology, College of Dentistry, University of Illinois Chicago, Chicago, IL, USA
| | - Sumei Liao
- Department of Prosthodontics, School of Dentistry and Department of Microbiology, Immunology and Parasitology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Yihong Li
- Department of Public and Ecosystem Health, College of Veterinary Medicine, Cornel University, Ithaca, NY, USA
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A Two-Year Longitudinal Study of the Effectiveness of the CRT ® Bacteria Test in Evaluating Caries Risk in Three-Year-Old Children. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:7488855. [PMID: 34659437 PMCID: PMC8519682 DOI: 10.1155/2021/7488855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/22/2021] [Indexed: 11/17/2022]
Abstract
Objective To study the correlation between the level of infection with Streptococcus mutans (SM) and lactobacilli (LB) in saliva with existing status and the development of primary dental caries in 3-year-old children and to evaluate the results of CRT® bacteria as a Caries Risk Test. Methods A total of 140 3-year-old children were selected for the study. Oral examination was conducted and the levels of infection with SM and LB in saliva were measured using a CRT® bacteria test. Oral reexamination was conducted after two years. The prevalence rate of caries, the decayed-missing-filled tooth (dmft) and decayed-missing-filled surface (dmfs) indices, and Caries Severity Index (CSI) were calculated at the start and end of the two years. The indices were statistically analyzed. Results The caries prevalence rate, dmft, dmfs, and CSI increased with increasing levels of CRT-SM and CRT-LB at the start and end of the two years; the increases in dmft, dmfs, and CSI over the period were consistent with the increases in CRT-SM and CRT-LB levels, with all differences being highly statistically significant. The increase in caries prevalence rate over the two years was not statistically different for different CRT-SM and CRT-LB levels. CRT-SM and CRT-LB levels were highly positively correlated with dmft, dmfs, CSI and their increases over the two years. Levels of infection with oral SM and LB were found to be independent risk factors for primary dental caries, respectively. For an SM concentration in saliva of ≥104 CFU/mL and an LB concentration of <104 CFU/mL, the risk of caries increased by approximately 2.8-fold. When the concentration of LB in saliva was ≥104 CFU/mL and that of SM <104 CFU/mL, the risk of caries increased by approximately 3.9-fold. When the concentration of both SM and LB was ≥104 CFU/mL, the risk increased by approximately 10.9-fold. Conclusions Significant positive correlations were found between the level of infection with oral SM and LB and existing oral decay status and the trend in the development of primary dental caries. Infection with SM and LB significantly increased the risk of caries in primary teeth. The CRT® bacteria is a simple, convenient, reliable, and effective Caries Risk Test.
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Reis ACM, Bezerra DDS, Hart-Chú ENS, Stipp RN, Guedes SFDF, Neves BG, Rodrigues LKA. Quantification and gene expression of Lactobacillus casei group species associated with dentinal lesions in early childhood caries. Saudi Dent J 2021; 33:69-77. [PMID: 33551619 PMCID: PMC7848803 DOI: 10.1016/j.sdentj.2020.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 01/15/2020] [Accepted: 01/19/2020] [Indexed: 11/22/2022] Open
Abstract
Background Considering that the Lactobacillus casei group is strongly associated with caries progression, the use of lactobacilli as probiotics must be balanced due to their possible involvement in dental caries. Objective This study aimed to detect and quantify L. paracasei, L. rhamnosus, and L. casei group species in the active and arrested dentinal lesions of preschoolers. It also aimed to determine the expression profiles of lactobacilli genes related to adhesion, extracellular polymeric substance regulation, and pyruvate oxidation. Methods Total ribonucleic acid (RNA) was extracted from dentinal lesion samples (25 active, 13 arrested) of children between 2 and 5 years of age. The samples were converted to complementary deoxyribonucleic acid (cDNA), and quantitative polymerase chain reaction (qPCR) analyses were performed to quantify and determine the relative abundance (measured by percentage of total bacteria) of L. paracasei, L. rhamnosus, and L. casei group species. The expression profiles of L. paracasei/casei genes (spaC and spxB) and L. rhamnosus genes (spaE and wzb) were assessed. The Student t-test and the Mann-Whitney U test were used for comparisons. Results The L. casei group species were found to be part of the viable microbial community in dentinal caries. L. paracasei (p = 0.001), L. rhamnosus (p = 0.022), and L. casei (p = 0.004) group species were abundant in the active dentinal lesions compared to the arrested dentinal lesions. Only the wzb gene (p = 0.006) exhibited a statistically significant difference between the active and arrested lesions in terms of its expression profile; it was expressed to a higher extent in the active dentinal lesions. Conclusions The L. casei group species presented in large numbers in the active dentinal caries lesions, indicating that these microorganisms are related to caries activity, and the wzb gene may play an important role in caries progression.
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Affiliation(s)
- Ana Catarina Martins Reis
- Postgraduate Program in Medical Microbiology, Federal University of Ceará, R. Coronel Nunes de Melo 1315, 60430-270 Fortaleza, CE, Brazil
| | - Daniela da Silva Bezerra
- Unichristus Campus Ecological Park, Dental College, R. João Adolfo Gurgel, 133, 60190-180, Fortaleza, CE, Brazil
| | - Erika Nikitza Shiauha Hart-Chú
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, 13414-903 Piracicaba, SP, Brazil
| | - Rafael Nóbrega Stipp
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901, 13414-903 Piracicaba, SP, Brazil
| | | | - Beatriz Gonçalves Neves
- School of Dentistry, Federal University of Ceará, Rua Conselheiro José Júlio, S/N, 62010-080 Sobral, CE, Brazil
| | - Lidiany Karla Azevedo Rodrigues
- Postgraduate Program in Medical Microbiology, Federal University of Ceará, R. Coronel Nunes de Melo 1315, 60430-270 Fortaleza, CE, Brazil.,Postgraduate Program in Dentistry, Federal University of Ceará, R. Alexandre Baraúna, 949, 60430-160 Fortaleza, CE, Brazil
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Efficacy of Sea Salt-Based Mouthwash and Xylitol in Improving Oral Hygiene among Adolescent Population: A Pilot Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 18:ijerph18010044. [PMID: 33374694 PMCID: PMC7793524 DOI: 10.3390/ijerph18010044] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/11/2020] [Accepted: 12/17/2020] [Indexed: 11/16/2022]
Abstract
The scientific community has definitely demonstrated the importance of the use of mouthwash in daily oral hygiene. In our pilot study, we tested the effectiveness of a novel mouth rinse containing sea salt, xylitol, and lysozyme. Streptococcus mutans (S. mutans) growth, and plaque index in adolescent patients aged 14-17 years, were observed. The bacterial load was investigated by in vitro microbiological analysis; the plaque index was assessed through the O'Leary's Plaque Control Record (PCR). The study has shown that the use of a sea salt-based mouthwash in daily oral hygiene reduces the bacterial levels of S. mutans (p < 0.01) linked to the combined action of xylitol and lysozyme, together with the action of sea salt. Our preliminary data confirm and improve the main results reported in the scientific literature on the importance of the use of xylitol, lysozyme, and sea salt in oral health.
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Antão C, Teixeira C, Gomes M. Effect of Mode of Delivery on Early Oral Colonization and Childhood Dental Caries: A Systematic Review. PORTUGUESE JOURNAL OF PUBLIC HEALTH 2019. [DOI: 10.1159/000495804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Tao D, Li F, Feng X, Wong MCM, Lu H. Plaque biofilm microbial diversity in infants aged 12 months and their mothers with or without dental caries: a pilot study. BMC Oral Health 2018; 18:228. [PMID: 30594172 PMCID: PMC6311051 DOI: 10.1186/s12903-018-0699-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 12/18/2018] [Indexed: 11/30/2022] Open
Abstract
Background A number of studies on oral microbial diversity of early childhood caries (ECC) have tended to focus on mid- or late-stage of ECC, with a lack of research into early stage of tooth eruption and maternal influence. The aims of this study are to compare the supragingival plaque biofilm microbiota diversity between mothers with or without dental caries and their 12-month-old infants, and to explore the relationship of microbial diversity between infants and their mothers, using sequencing analysis. Methods Supragingival plaque biofilm samples were collected from 20 pairs of mothers and their infants aged 12 months (10 mothers with dental caries and their 10 infants vs. 10 caries-free mothers and their 10 infants). The basic information of the mothers and infants had been collected through self-completed questionnaire. Pooled plaque biofilm DNA was extracted and DNA amplicons of the V4-V5 hypervariable region of the bacterial 16S rRNA gene were generated. Ilumina Miseq PE300 was used for 16S rRNA sequencing. Results The results showed that high bacterial diversity was noted in the plaque biofilm of infants and their mothers with or without dental caries (dental caries mothers vs. caries-free mothers: 774 operational taxonomical units (OTUs) vs. 761 OTUs at a 3% divergence; infants whose mothers have dental caries vs. infants whose mothers are caries-free: 815 OTUs vs. 684 OTUs at 3% divergence). The Shannon microbial diversity index showed no statistically significant differences both on infants and their mothers between two groups (p > 0.05). Mother’s microbial diversity was higher than infants’ based on Shannon index (p < 0.05). Significant positive correlations were found between mothers’ and their infants’ Shannon index (r = 0.656, p = 0.002). Conclusion Oral microbial diversity is significantly different between mothers and infants regardless of dental caries status, but no significant difference was found between mothers with and without dental caries or between their infants. Mother’s oral microbial diversity has an overall impact on the infants aged 12 months. Electronic supplementary material The online version of this article (10.1186/s12903-018-0699-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Danying Tao
- Department of Preventive Dentistry, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, National Clinical Research Centre of Stomatology, 500 Quxi Road, Shanghai, 200011, China
| | - Fei Li
- Department of Preventive Dentistry, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, National Clinical Research Centre of Stomatology, 500 Quxi Road, Shanghai, 200011, China
| | - Xiping Feng
- Department of Preventive Dentistry, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, National Clinical Research Centre of Stomatology, 500 Quxi Road, Shanghai, 200011, China
| | - May Chun Mei Wong
- Dental Public Health, Faculty of Dentistry, University of Hong Kong, 34 Hospital Road, Hong Kong, China
| | - Haixia Lu
- Department of Preventive Dentistry, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, National Clinical Research Centre of Stomatology, 500 Quxi Road, Shanghai, 200011, China.
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The Influence of Type 1 Diabetes Mellitus on Dental Caries and Salivary Composition. Int J Dent 2018; 2018:5780916. [PMID: 30369949 PMCID: PMC6189668 DOI: 10.1155/2018/5780916] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/26/2018] [Indexed: 11/29/2022] Open
Abstract
Diabetes mellitus is the most common chronic disease that affects the oral health. The aim of the study is to evaluate the dental caries, salivary flow rate, buffer capacity, and Lactobacilli in saliva in children with type 1 diabetes mellitus compared to the control group. Methods. The sample consisted of 160 children of 10 to 15 years divided into two groups: 80 children with type 1 diabetes mellitus and 80 children as a control group. Dental caries was assessed using the DMFT index for permanent dentition. Stimulated saliva was collected among all children. Salivary flow rate and buffer capacity were measured, and the colonies of Lactobacillus in saliva were determined. The observed children have answered a number of questions related to their dental visits and parents' education. The data obtained from each group were compared statistically using the chi-square test and Mann–Whitney U-test. The significant level was set at p < 0.05. Results. DMFT in children with type 1 diabetes was significantly higher than that in the control group (p < 0.001). Diabetic children have a low level of stimulated salivary flow rate compared to control children (0.86 ± 0.16 and 1.10 ± 0.14). The buffer capacity showed statistically significant differences between children with type 1 diabetes and control group (p < 0.001). Also, children with type 1 diabetes had a higher count and a higher risk of Lactobacillus compared to the control group (p < 0.05 and p < 0.001). Conclusion. The findings we obtained showed that type 1 diabetes mellitus has an important part in children's oral health. It appears that children with type 1 diabetes are exposed to a higher risk for caries and oral health than nondiabetic children.
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Shahi S, Zununi Vahed S, Fathi N, Sharifi S. Polymerase chain reaction (PCR)-based methods: Promising molecular tools in dentistry. Int J Biol Macromol 2018; 117:983-992. [DOI: 10.1016/j.ijbiomac.2018.05.085] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/13/2018] [Accepted: 05/14/2018] [Indexed: 02/06/2023]
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Early childhood caries, salivary and microbiological aspects among 3- to 4-year-old children in Cali, Colombia. Eur Arch Paediatr Dent 2018; 19:347-352. [DOI: 10.1007/s40368-018-0365-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 05/29/2018] [Indexed: 10/28/2022]
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Piva F, Pereira JT, Luz PB, Hashizume LN, Hugo FN, Araujo FBD. A Longitudinal Study of Early Childhood Caries and Associated Factors in Brazilian Children. Braz Dent J 2017; 28:241-248. [DOI: 10.1590/0103-6440201701237] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 12/05/2016] [Indexed: 11/21/2022] Open
Abstract
Abstract Early childhood caries (ECC) affects children all over the world and has high prevalence and severity in preschool children. Different social, biological and behavioral factors compose a network of causal factors for ECC. The aim was to evaluate the association between socioeconomic variables and caries at baseline, and the presence of Streptococcus mutans and Lactobacillus spp. microorganisms with the progression of caries lesions after two years of follow-up in a group of children. At baseline, 163 children (3-4 years old) living in the areas of 12 primary care services of the Hospital Group Conceição (GHC, Porto Alegre, RS, Brazil) were evaluated. After two years, 119 children were re-evaluated. Clinical examinations were conducted by calibrated examiners using the ICDAS criteria. A sociodemographic questionnaire was applied to the children’s parents and saliva samples were collected from the children for microbiological analysis. Descriptive statistics and multivariate Poisson regression analysis were performed in the statistical analysis. The factors associated with the caries progression were marital status of mothers (p=0.040), higher S. mutans counts (p=0.031) and the presence of cavitated lesions at baseline (p<0.001). The caries lesions progression in preschool children enrolled in primary health care was directly associated with marital status, presence of cavitated lesions at baseline and higher S. mutans counts at two-year follow-up.
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Caufield PW, Schön CN, Saraithong P, Li Y, Argimón S. Oral Lactobacilli and Dental Caries: A Model for Niche Adaptation in Humans. J Dent Res 2015; 94:110S-8S. [PMID: 25758458 DOI: 10.1177/0022034515576052] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Lactobacilli have been associated with dental caries for over a century. Here, we review the pertinent literature along with findings from our own study to formulate a working hypothesis about the natural history and role of lactobacilli. Unlike most indigenous microbes that stably colonize a host, lactobacilli appear to be planktonic, opportunistic settlers that can gather and multiply only in certain restrictive niches of the host, at least within the oral cavity. We postulate that the following essential requirements are necessary for sustained colonization of lactobacilli in humans: 1) a stagnant, retentive niche that is mostly anaerobic; 2) a low pH milieu; and 3) ready access to carbohydrates. Three sites on the human body meet these specifications: caries lesions, the stomach, and the vagina. Only a handful of Lactobacillus species is found in caries lesions, but they are largely absent in caries-free children. Lactobacilli present in caries lesions represent both a major contributor to caries progression and a major reservoir to the gastrointestinal (GI) tract. We extend the assertion from other investigators that lactobacilli found in the GI tract originate in the oral cavity by proposing that lactobacilli in the oral cavity arise from caries lesions. This, in turn, leads us to reflect on the health implications of the lactobacilli in the mouth and downstream GI and to ponder whether these or any of the Lactobacillus species are truly indigenous to the human GI tract or the oral cavity.
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Affiliation(s)
- P W Caufield
- New York University College of Dentistry, New York, USA
| | - C N Schön
- New York University College of Dentistry, New York, USA
| | - P Saraithong
- New York University College of Dentistry, New York, USA
| | - Y Li
- New York University College of Dentistry, New York, USA
| | - S Argimón
- New York University College of Dentistry, New York, USA
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