Similarity of bacteriocin activity profiles of mutans streptococci within the family when the children acquire the strains after the age of 5

Acquisition and establishment of the oral microbiota

Acquisition and establishment of the oral microbiota occur in a dynamic process over various stages and involve close and continuous interactions with the host and its environment. In the present review, we discuss the stages of this process in chronological order. We start with the prenatal period and address the following questions: ‘Is the fetus exposed to maternal microbiota during pregnancy?’ and ‘If so, what is the potential role of this exposure?’ We comment on recent reports of finding bacterial DNA in placenta during pregnancies, and provide current views on the potential functions of prenatal microbial encounters. Next, we discuss the physiological adaptations that take place in the newborn during the birth process and the effect of this phase of life on the acquisition of the oral microbiota. Is it really just exposure to maternal vaginal microbes that results in the difference between vaginally and Cesarian section‐born infants? Then, we review the postnatal phase, in which we focus on transmission of microbes, the intraoral niche specificity, the effects of the host behavior and environment, as well as the role of genetic background of the host on shaping the oral microbial ecosystem. We discuss the changes in oral microbiota during the transition from deciduous to permanent dentition and during puberty. We also address the finite knowledge on colonization of the oral cavity by microbes other than the bacterial component. Finally, we identify the main outstanding questions that limit our understanding of the acquisition and establishment of a healthy microbiome at an individual level.

Dental Neglect

Dental neglect can be an indicator of general child neglect. Inadequately treated dental disease may have significant long-term impacts on the physical and psychological well-being of children. Primary care providers play a critical role in the prevention of dental neglect, and should be aware of the manifestations of dental caries and dental trauma. When diagnosing dental neglect, health professionals should ensure the child's caregivers have demonstrated an understanding of the condition, its consequences, and the recommended treatment and then failed to comply with the treatment. Attempts should be made to eliminate any barriers preventing caretakers from complying with professional advice. Dental neglect is a form of child maltreatment and, if suspected, should be reported to the appropriate child protective agencies.

Knowledge, Attitude, and Practice of Mothers towards Infant Oral Healthcare

Background

Among all the oral diseases, dental caries is the most common chronic disease affecting the children. Early childhood caries is one of the most severe forms of dental caries affecting the children less than 3 years. Though dental caries is preventable, not much importance has been given to the preventive aspect of dental caries. This is because of the lack of oral health education. Vertical colonization occurs from caregiver usually mother to the child. Since mother play an important role in a child's life, their knowledge about child's oral health will have a significant impact on the child's oral health status. A proper knowledge for the mothers regarding infant's oral health care will be beneficial in reducing the burden of dental caries in children. Hence a study was conducted to evaluate the mother's knowledge, attitude and practice towards infant oral health care.

Material and methods

A cross-sectional study was conducted among a convenient sample of 185 first time mothers with a child aged 9 to 24 months of age visiting Department of Pediatrics and Department of Pedodontics and Preventive Dentistry. Permission to carry out the study was obtained from the Institutional Ethical Board. Data were collected using a structured questionnaire. The questionnaire used in this study was divided into two sections. The first section contained demographic details and the second section contained knowledge about primary teeth and practice of oral health care. All the participants fulfilling the inclusion criteria were enrolled. The purpose of the study and the questionnaire were explained to each participant. The questionnaire was completed and returned before leaving the clinic. The data were analyzed using Statistical Package for the Social Sciences (SPSS) version 22.

Results

Total 52.5% of the mothers responded that first tooth erupt after 6 months. A total of 86.5% of the mothers were not aware of the first dental visit. 77.8% did not agree that caries causing bacteria is transferred from mother to the child; 53% mothers did not agree that night time bottle feeding causes dental caries and 78.4% disagreed that nocturnal breastfeeding can cause dental caries in children. A total of 65.4% mothers feel dental check-up is not necessary when the first tooth erupt, and 95.7% mother did not have any information on infant oral health care. 72.4% of mothers started using toothbrush and paste after all the primary teeth erupted and only 5.9% of the mother had the knowledge about proper dispensing of toothpaste for children.

Conclusion

Overall knowledge and attitude of mothers towards oral health care of children is poor. Health care professionals like a gynecologist, pediatrician Anganwadi workers who contact first-time mothers need to be trained to disseminate appropriate infant oral health care information. The mother needs to be educated about oral health during their antenatal check upHow to cite this article: Dhull KS, Dutta B, Devraj IM, Samir PV. Knowledge, Attitude, and Practice of Mothers towards Infant Oral Healthcare. Int J Clin Pediatr Dent. 2018;11(5):435-439.

Mother-to-child transmission of mutans streptococci

Mutans streptococci (MS) are the major group of pathogens implicated in dental caries. Like other infectious diseases, transmission of the causative microorganisms is the initial and essential step that should be understood relative to disease control and prevention. This review summarizes current knowledge regarding MS transmission, especially from mothers to their children. Included are methods used to study transmission, sources of MS, initial acquisition, factors concerning transmission and prevention of transmission. Information accumulated over many decades showed the involvement of MS transmission in the pathogenesis of caries, hence several preventive measurements have been proposed. Nevertheless, some essential aspects remain to be elucidated for more benefits of practical application.

Mother-to-child transmission of Streptococcus mutans: a systematic review and meta-analysis

OBJECTIVES

A systematic review was performed with the aim of determining whether there is scientific evidence of the transmission of Streptococcus mutans from mother to child.

DATA

The eligibility criteria, based on the PECO strategy, were the following: observational human studies whose subjects were mother and child pairs (P) contaminated by S. mutans (E); comparison according to the presence or absence of S. mutans (C); and whether there is transmission (O). The qualitative analysis was performed by assessing the risk of bias of the included studies, while quantitative synthesis was performed through comprehensive Meta-Analysis software (p<0.05).

SOURCES

Two reviewers performed the database search of studies published between January 1950 and May 2014. The strategy included observational studies that assessed the vertical transmission of S. mutans from mothers to children through analyzing genetic strains.

STUDY SELECTION

It was found 166 non-duplicated studies. However, after reviewing the articles in full and applying the eligibility criteria, 36 papers were selected for qualitative analysis and 19 for quantitative analysis. The cumulative meta-analysis demonstrated vertical transmission of S. mutans from mother to child (p<0.001).

CONCLUSIONS

The present systematic review and meta-analysis demonstrated evidence of vertical transmission of S. mutans from mother to child because there was an association between S. mutans n mothers and their respective children.

CLINICAL SIGNIFICANCE

The knowledge of the S. mutans strains is important because the virulence of the microorganisms is varied; also, the virulence affects the dental caries evolution rate, being more or less aggressive.

Caries-risk profile variations after short-term use of 5000 ppm fluoride toothpaste

OBJECTIVE

To assess the caries risk following 6 weeks' use of 5000 ppm F toothpaste using 'Cariogram' software.

MATERIALS AND METHODS

A total of 34 participants, 17 mothers and their teenage children, were enrolled in a 6-week clinical trial in which they were given 5000 ppm F toothpaste. They were followed consecutively for 6 weeks with visits that were 2 weeks apart (four in total). A clinical examination was done at baseline and salivary chair-side tests to record the buffer capacity and mutans streptococci (MS) and lactobacilli (LB) counts were performed at each visit. Based on these data, seven caries-related variables were collected and inserted into the Cariogram software to calculate the actual chance of avoiding caries.

RESULTS

The use of 5000 ppm F toothpaste resulted in a statistically significant modification of the caries-risk profile, increasing the actual chance of avoiding caries in the future among the mothers and teenagers at each visit following baseline (p < 0.01). The changes essentially related to the salivary parameters (buffer capacity, MS and LB counts). A statistically significant linear trend was observed for MS counts (p < 0.01) and the number of subjects with a salivary concentration of MS < 10(3) increased at each visit. The same trend was also observed for LB and buffer capacity scores (p = 0.04 and p = 0.03, respectively).

CONCLUSIONS

The short-term use of 5000 ppm F toothpaste is able to reduce the caries risk, which can be clearly demonstrated using 'Cariogram' software.

Chair-side quantitative oral-microflora screening for assessing familial correlation of periodontal status and caries prevalence

Aim: Our goal was to investigate the relationship between clinical status and the presence of carious or periodontal pathogens among parent-child familial pairs. Clinical practices of risk assessment with consideration of familial pathogen interaction might reduce the need for therapy, improve patient outcomes, and ultimately reduce oral disease burden. Materials and Methods: In this study, we enrolled 30 parent-child pairs, with the children exhibiting complete deciduous dentition or mixed dentition with only permanent first molars. Clinical statuses were evaluated using caries and periodontal disease indicators, including the sum of decay and the number of missing or filled teeth (DMFT) for adults, decay, extraction caused by dental disease, and filled teeth (deft), for children, probing depth, and plaque control record (PCR). Supra- and sub-gingival bacteria were determined based on semi-quantitative measurements of microbial infection by using data from the Dentocult^® SM test (caries-related organisms) and the PerioCheck^® test (periodontal disease-related organisms). Results: No statistically significant relationship was detected between the prevalence of periodontal pathogens and that of cariogenic pathogens in the oral cavity. However, the clinical status of caries (DMFT) was negatively correlated with the clinical status of periodontal disease (pocket depth) in parents who were infected with dominant periodontal pathogens (r = −0.59, p<0.01). Parents’ DMFT scores were positively correlated with children’s deft and PCR scores. PCR and deft scores of children appeared to decrease significantly with the parent’s pocket depth. Conclusion: The study showed that the quantity of caries pathogens were not significant related to periodontal pathogens, but the caries clinical outcome is negative related with periodontal clinical outcome between familial pairs.

Comparative analysis of colony counts of different species of oral streptococci in saliva of dentulous, edentulous and in those wearing partial and complete dentures

OBJECTIVES

To study and compare the number of colony forming units of Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mitis and Streptococcus milleri in dentulous, edentulous and in those wearing partial and complete dentures by using semi-quantitative culture method of saliva samples with calibrated standard loop.

MATERIALS

Sterile specimen collection bottles, Mitis salivarius agar plates, Standard loop, Candle jar, Incubator, Colony counter.

METHODOLOGY

Study population consisted of 100 subjects with 25 in each group, with an age range of 40 to 80 years, who were attending the Department of Community Dentistry and Prosthodontics at MNR Dental College, Sangareddy, Hyderabad. Unstimulated saliva samples were collected from patients and inoculated on to Mitis salivarius agar plates using calibrated standard loop. The plates were then incubated anaerobically at 37°C for 24 hours and left at room temperature for further 24 hours. Using a colony counter, the number of colonies of each species was counted.

RESULTS

Streptococcus mutans and Streptococcus mitis predominates in the dentulous group, Streptococcus sanguis in complete denture group, Streptococcus salivarius in edentulous group and Streptococcus milleri in removable partial denture group.

CONCLUSION

The results of our study are in accordance with the previous studies, which have sought to differentiate different groups of mutans streptococci using a simple calibrated standard loop.

Recovery of mutans streptococci on MSB, SB-20 and SB-20M agar media

OBJECTIVE

The recovery of mutans streptococci in saliva and dental biofilm samples depends, in part, on the culture medium used. In this study, we compared (i) the culture media Sucrose-Bacitracin agar (SB-20), Modified SB-20 (SB-20M) and Mitis Salivarius Bacitracin agar (MSB) in the count of colony forming units (cfu) of mutans streptococci and (ii) in the morphological and biochemical differentiation between Streptococcus mutans and Streptococcus sobrinus.

DESIGN

Samples of non-stimulated saliva from 20 children were plated on SB-20, SB-20M and MSB, and incubated in microaerophilia at 37°C for 72h. Identification of microorganisms was based on analysis of colony morphology under stereomicroscopy. The biochemical identification of colonies was done by biochemical tests using sugar fermentation, resistance to bacitracin and hydrogen peroxide production.

RESULTS

There was no significant difference (p>0.05) in the number of cfu of mutans streptococci recovered on SB-20 and SB-20M agar. Comparing the media, SB-20 and SB-20M yielded a larger number of mutans streptococci colonies (p<0.05) and were more effective than MSB in the identification of S. sobrinus (p<0.05), but not of S. mutans (p>0.05).

CONCLUSION

There was no significant difference between SB-20 and SB-20M culture media in the count of mutans streptococci, demonstrating that the replacement of sucrose by coarse granular cane sugar did not alter the efficacy of the medium. Compared with MSB, SB-20 and SB-20M allowed counting a larger number of mutans streptococci colonies and a more effective morphological identification of S. sobrinus.

Studies on strains of Streptococcus mutans isolated from caries-active and caries-free individuals in Iceland

Background

Dental caries has been strongly associated with mutans streptococci, particularly Streptococcus mutans and S. sobrinus. Many studies have linked these organisms to the carious process and counts of mutans streptococci have been used to monitor caries risk. The high levels of caries generally found in Iceland have enabled several studies to be performed on the variation within strains of S. mutans.

Methods

This paper reports some studies showing phenotypic differences between strains of S. mutans that were related to whether the strain was isolated from an individual with active caries or from a caries-free subject.

Results

Strains from individuals with active caries generally adhered better to apatite, were more vigorous in decalcifying apatite and had bacteriocin-like activity that was likely to help the strain compete successfully with other strains, for example in the dental plaque biofilm.

Conclusions

Phenotypic differences exist between strains of S. mutans depending on the caries activity of the individual from whom the strain was isolated.

Mutacins of Streptococcus mutans

The colonization and accumulation of Streptococcus mutans are influenced by various factors in the oral cavity, such as nutrition and hygiene conditions of the host, salivary components, cleaning power and salivary flow and characteristics related with microbial virulence factors. Among these virulence factors, the ability to synthesize glucan of adhesion, glucan-binding proteins, lactic acid and bacteriocins could modify the infection process and pathogenesis of this species in the dental biofilm. This review will describe the role of mutacins in transmission, colonization, and/or establishment of S. mutans, the major etiological agent of human dental caries. In addition, we will describe the method for detecting the production of these inhibitory substances in vitro (mutacin typing), classification and diversity of mutacins and the regulatory mechanisms related to its synthesis.

Horizontal transmission of mutans streptococci in children

It has not been established whether transmission of mutans streptococci occurs between unrelated children older than 4 years of age. The aim of the study was to investigate the possible transmission of mutans streptococci genotypes from child to child in kindergarten. We studied 96 children (ages 5-6 yrs) in three San Francisco Bay Area public schools. Mutans streptococci colonies from each child were isolated from selective culture on Mitis Salivarius Sucrose Bacitracin agar. We used arbitrary primed polymerase chain reactions to determine the mutans streptococci genotypes. Two children (not siblings) in each of the three schools (6%) shared an identical amplitype of S. mutans, unique to each pair. The 19 S. sobrinus amplitypes were found in 12 children, and all were unique to each child. The presence of matching genotypes of S. mutans demonstrates horizontal transmission of this species between unrelated children aged 5-6 years.

Comparative whole-genome analysis of Streptococcus mutans isolates within and among individuals of different caries status

INTRODUCTION

Genotypic analyses of Streptococcus mutans using fingerprinting methods depend on a few genetic loci being different but do not reveal the underlying genome-wide differences between strains.

METHODS

We used comparative genomic hybridization (CGH) with 70-mer oligonucleotide microarrays containing open reading frames (ORFs) from S. mutans strain UA159 to examine the genetic diversity of 44 isolates from nine children selected from a local study population in Eastern Iowa.

RESULTS

Unique strains (clones) within each child initially identified by arbitrary-priming polymerase chain reaction were confirmed by CGH. There was a wide range of variation in the hybridization patterns of the 1948 ORFs among the test isolates examined. Between 87 and 237 ORFs failed to give a positive signal among individual isolates. A total of 323 of the UA159 ORFs were absent from one or more of the test strains. These 323 variable genes seemed to be distributed across the entire UA159 genome and across all the predicted functional categories.

CONCLUSION

This set of very close geographically and temporally collected S. mutans isolates had a degree of gene content variation as high as a previously examined global set of strains. Comparing the frequency of these variable genes, the majority of which have unknown function, among strains of different origins (i.e. different caries status) could help to determine their relevance in S. mutans cariogenicity.

Evidence-based caries, risk assessment, and treatment

Dental caries is a dietary and host-modified biofilm disease process, transmissible early in life that, if left untreated, will cause destruction of dental hard tissues. If allowed to progress, the disease will result in the development of caries lesions on tooth surfaces, which initially are noncavitated (eg, white spots), and eventually can progress to cavitation. The "medical model," where the etiologic disease-driving agents are balanced against protective factors, in combination with risk assessment, offers the possibility of patient-centered disease prevention and management before there is irreversible damage done to the teeth. This article discusses how to use evidence supporting risk assessment and management strategies for the caries process.

Case definition, aetiology and risk assessment of early childhood caries (ECC): a revisited review

AIM

To provide a review of the existing literature on early childhood caries (ECC) with particular reference on the nomenclature, case definition, epidemiology, etiology and risk assessment.

METHODS

An electronic search was used to identify and critically review papers that have been published and are pertinent to the above issues, evaluate and compile the reported evidence.

RESULTS

The term ECC has been adopted to more accurately describe dental caries that affects primary dentitions, replacing previously used terminology that associated the disease with the nursing habit. Suggested ECC case definition uses caries patterns as defining criteria, however, further refinement to include different clinical expressions of a varying severity is necessary. Significant percentages of preschool child populations are affected by ECC today, with the disease concentrating disproportionately in deprived families. Early colonization by mutans streptococci (MS) is associated with increased ECC development, with bacteria being transmitted in both vertical and horizontal ways. Dietary factors related to sugar consumption predispose to early MS colonization and establishment and increase the risk for ECC development, being part of the causal chain. Inappropriate bottle and breast-feeding behaviors also increase the risk, without showing a direct causal relationship. High risk children belong to ethnic minority groups and to low income families with poor parental behaviors and attitudes.

CONCLUSIONS

Further high-quality studies are needed to explore the role bacteria other than MS may play in caries initiation and progression, elucidate the interaction of the saliva immune defence system with a potentially defective tooth, and investigate the effect distant behavioral factors have on the causal chain that leads to ECC development.

Frequency and expression of mutacin biosynthesis genes in isolates of Streptococcus mutans with different mutacin-producing phenotypes

The aim of this study was to analyse the frequency and expression of biosynthesis genes in 47 Streptococcus mutans isolates with different mutacin-producing phenotypes. Detection of the frequency and expression of genes encoding mutacin types I, II, III and IV were carried out by PCR and semi-quantitative RT-PCR, respectively, using primers specific for each type of biosynthesis gene. In addition, a further eight genes encoding putative bacteriocins, designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened. There was a high phenotypic diversity; some Streptococcus mutans isolates presented broad antimicrobial spectra against other Streptococcus mutans clinical isolates, including bacteria resistant to common antibiotics, as well as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Streptococcus pyogenes. The expression frequency of the bsm gene was higher than that of the previously characterized mutacins (I-IV). There was no positive correlation between the number of indicator strains inhibited (antimicrobial spectra) and the number of biosynthesis genes expressed (Spearman correlation test, r=-0.03, P>0.05). In conclusion, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened, reveals a broad repertoire of genetic determinants encoding antimicrobial peptides that can act in different combinations.

Assessment of genes associated with Streptococcus mutans biofilm morphology

Streptococcus mutans, the major pathogen responsible for dental caries in humans, is a biofilm-forming bacterium. In the present study, 17 different pulsed-field gel electrophoresis patterns of genomic DNA were identified in S. mutans organisms isolated clinically from whole saliva. The S. mutans isolates showed different abilities to form biofilms on polystyrene surfaces in semidefined minimal medium cultures. Following cultivation in a flow cell system in tryptic soy broth with 0.25% sucrose and staining using a BacLight LIVE/DEAD system, two strains, designated FSC-3 and FSC-4, showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy. Further, image analyses of spatial distribution and architecture were performed to quantify the merged green (live cells) and red (dead cells) light. The light intensity of the FSC-3 biofilm was greater than that of the FSC-4 biofilm in the bottom area but not in the top area. S. mutans whole-genome array results showed that approximately 3.8% of the genes were differentially expressed in the two strains, of which approximately 2.2%, including bacitracin transport ATP-binding protein gene glrA and a BLpL-like putative immunity protein gene, were activated in FSC-3. In addition, about 1.6% of the genes, including those associated with phosphotransferase system genes, were repressed. Analyses of the glrA-deficient strains and reverse transcription-PCR confirmed the role of the gene in biofilm formation. Differential assessment of biofilm-associated genes in clinical strains may provide useful information for understanding the morphological development of streptococcal biofilm, as well as for colonization of S. mutans.

Mutacin production in Streptococcus mutans genotypes isolated from caries-affected and caries-free individuals

Relationships between genetic diversity and mutacin production in Streptococcus mutans were evaluated in 319 clinical isolates from eight caries-affected and eight caries-free individuals. The isolates were submitted to mutacin typing and AP-PCR (arbitrarily primed polymerase chain reaction) assay. The mutacin production was detected for 12 Streptococcus sp. indicator strains. Results showed significant variations in the mutacin production profiles and the inhibitory spectra of both groups. A possible association was seen between mutacin activity and the distinct patterns of Streptococcus sp. colonization in the two groups. Genotyping by AP-PCR using the primers OPA-02 and OPA-13 revealed 101 distinct genotypes against 48 phenotypes identified by mutacin typing. No correlation was observed between the inhibitory spectra of mutacin and genotypic similarities based on AP-PCR analyses. According to our results, strains of the same S. mutans genotype showed different mutacin profiles, suggesting a high degree of interstrain diversity. In conclusion, mutacin production seems to be of clinical importance in the colonization of S. mutans and is highly diversified in the S. mutans species.

Transmission of Streptococcus mutans in a group of Turkish families

BACKGROUND/AIMS

To investigate the transmission of Streptococcus mutans in a group of Turkish families using AP-polymerase chain reaction (PCR) detection.

METHODS

Eight mothers who had high S. mutans levels in unstimulated saliva and 8 children aged between 2 and 3 years participated in the study. Plaque samples from each child were collected with the tips of sterile toothpicks for S. mutans counts. Although not part of the original study design, S. mutans samples were also obtained from the unstimulated saliva of the three fathers who shared the same households. Three typical isolates of S. mutans were isolated from TYCSB agar of each subject and identified by sugar fermentation tests. S. mutans ATCC 10449 was used as the reference strain. AP-PCR was conducted with OPA-05 primer.

RESULTS

All of the mothers and fathers shared the similar genotypes within their children. The fathers also harbored similar genotypes to their spouses.

CONCLUSION

The mothers or the fathers could be the source for the transmission of S. mutans to their children.

Longitudinal study of transmission, diversity, and stability of Streptococcus mutans and Streptococcus sobrinus genotypes in Brazilian nursery children

The aim of this study was to perform a follow-up evaluation of the Streptococcus mutans and Streptococcus sobrinus colonization profile of children's oral cavities, which included the pattern of vertical transmission from mother to child, genotypic diversity, and stability of the strains. The subjects were 16 mother-child pairs, who were monitored for 20 months. Samples of saliva, tongue dorsum, alveolar ridge mucosa, and dental plaque from the children were collected bimonthly. Saliva samples from the mothers were also collected. After isolation and identification, the arbitrarily primed PCR method was performed for the genotypic characterization of S. mutans (968 isolates) and S. sobrinus (111 isolates). At the time the strains were acquired, the children harbored one to four distinct genotypes of S. mutans and only one genotype of S. sobrinus. Although S. mutans prevalence and genotypic diversity were greater than those of S. sobrinus, the presence of matching genotypes of S. mutans and S. sobrinus was similar (in 81.25 and 83.33% of mother-child pairs, respectively), suggesting vertical transmission for both species. This longitudinal study showed an increase in genotypic diversity of S. mutans in the oral cavity during the follow-up period: most of the initially acquired genotypes persisted, normally those genotypes transmitted by the mother, and some were lost during follow-up; new strains were also acquired. In conclusion, S. mutans and S. sobrinus genotypes acquired from maternal or alternative sources may show effective persistence in the oral cavity and/or transitory detection in the children's mouths, reflecting the continuous development of oral microbiota in children.

Colonization of Streptococcus mutans and Streptococcus sobrinus Genotypes and Caries Development in Children to Mothers Harboring Both Species

The major route of early acquisition of mutans streptococci in humans is a vertical transmission from mother to child. The purpose of this longitudinal study was to examine the acquisition, distribution and persistence of Streptococcus mutans and Streptococcus sobrinus in children whose mothers harbored both species and to study the caries incidence in relation to colonization of these bacteria. Fifteen mother-child pairs were followed during the child's first 7 years. Stimulated salivary samples were taken from the mothers and the children. Plaque samples were also collected from the teeth and the tongue of the children. The samples were analyzed by cultivating techniques together with genomic fingerprinting and hybridizing. The caries experience was evaluated on the sampling occasions and retrospectively using the records of caries registrations from the community clinics. During the 7-year period 10 of the 15 children acquired mutans streptococci. Only 4 of them were colonized by both S. mutans and S. sobrinus despite the fact that their mothers harbored both species. In 2 of the children S. sobrinus was found later than S. mutans. A total of 26 genotypes were found in the children and 9 of them were identical to their mothers. New genotypes and a gain-loss pattern were noted especially in the children but also in their mothers. The groups of teeth first positive for the two species were the deciduous molars. The caries experience was low during the study period with 8 children showing no caries.

Different bacteriocin activities of Streptococcus mutans reflect distinct phylogenetic lineages

Bacteriocins produced by mutans streptococci are known as mutacins. In this study 16 broadly active mutacin-producing Streptococcus mutans strains from New Zealand, North America and Europe were classified into four groups (A-D) on the basis of differences in their activity in deferred antagonism tests against either the homologous producer strain (to test for presence of self-immunity) or indicator strains Staphylococcus aureus 46 and Enterococcus faecium TE1. Two of the strains included in the study (UA140 and UA96) were representatives of the group I and II mutacin producer strains previously described by Caufield and co-workers. One of the New Zealand isolates of group A (S. mutans strain N) appeared to produce inhibitory activity similar to that of the group I prototype strain UA140. Four other New Zealand isolates of group B (S. mutans strains M19, M34, B34 and D14) had mutacin II-like activity. The group B mutacin producers differed from the group A mutacin producers in their additional activity against Staph. aureus 46. Seven S. mutans strains (M46, B46, B57, M12, M28, B28 and 13M) were distinguished from the group A and group B mutacin producers in that they inhibited E. faecium TE1. These were called group C mutacin producers. Strains H7 and H23 resembled the group C strains in their action on both indicator strains TE1 and 46. However, these two strains failed to exhibit immunity to their own inhibitory products in the deferred antagonism test and were separately classified as group D mutacin producers. Phylogenetic analysis of the strains by several genotypic and phenotypic characteristics revealed that the mutacin groups were associated with distinct evolutionary lineages of S. mutans.