Does social deprivation in 1, 2, 3 and 4-year-old Scottish infants influence the frequency isolation of caries-associated micro-organisms?

OBJECTIVES

The aim of this study was to determine if there are associations between the level of social deprivation/affluence and the frequency isolation of caries-associated micro-organisms (Streptococcus mutans, Streptococcus sobrinus, lactobacilli and yeasts) in a large cohort of infants examined annually from 1 to 4 years of age.

METHODS

DEPCAT was used to measure the socio-economic status of all consented infants (n=1099--1392) born in Dundee during a 1 year period (total n=1974). Caries-associated micro-organisms were cultured from saliva when the infants were 1, 2, 3 and 4 years of age. Standardised dental examinations were also carried out annually. Log linear analysis, which controlled for caries, was used to look for associations between DEPCAT and the isolation frequency of caries-associated micro-organisms.

RESULTS

When controlling for caries, there was an association between DEPCAT and the isolation frequency of yeasts when the infants were 1 and 2 but not when 3 and 4 years old, whereas lactobacilli were associated only when the infants were 3 and 4 years old. Correlations between S. mutans and social deprivation were usually dependent on the caries status of the infants.

CONCLUSIONS

The relationship between social deprivation and the isolation frequencies of caries-associated micro-organisms is complex with lactobacilli developing an association when the infants were 3 and 4 years old in contrast to yeasts which were only associated when the infants were 1 and 2 years old. Streptococcus mutans was associated with social deprivation when the infants were 2 years old and older, but dependent on caries status in the 3 and 4 year olds.

Mannosidase production by viridans group streptococci

The production of mannosidase activity by all currently recognized species of human viridans group streptococci was determined using an assay in which bacterial growth was dependent on the degradation of the high-mannose-type glycans of RNase B and subsequent utilization of released mannose. RNase B is an excellent substrate for the demonstration of mannosidase activity since it is a glycoprotein with a single glycosylation site which is occupied by high-mannose-type glycoforms containing five to nine mannose residues. Mannosidase activity was produced only by some members of the mitis group (Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus cristatus, Streptococcus infantis, Streptococcus parasanguinis, and Streptococcus pneumoniae) and Streptococcus intermedius of the anginosus group. None of the other species within the salivarius and mutans groups or Streptococcus peroris and Streptococcus sanguinis produced mannosidase activity. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, it was demonstrated that the Man(5) glycan alone was degraded while Man(6) to Man(9), which contain terminal alpha(1-->2) mannose residues in addition to the alpha(1-->3), alpha(1-->6), and beta(1-->4) residues present in Man(5), remained intact. Investigations on mannosidase production using synthetic (4-methylumbelliferone- or p-nitrophenol-linked) alpha- or beta-mannosides as substrates indicated that there was no correlation between degradation of these substrates and degradation of the Man(5) glycan of RNase B. No species degraded these alpha-linked mannosides, while degradation of the beta-linked synthetic substrates was restricted to strains within the Streptococcus anginosus, S. gordonii, and S. intermedius species. The data generated using a native glycoprotein as the substrate demonstrate that mannosidase production within the viridans group streptococci is more widely distributed than had previously been considered.

A clinical and microbiological study of approximal carious lesions. Part 1: the relationship between cavitation, radiographic lesion depth, the site-specific gingival index and the level of infection of the dentine

A clinical study was carried out to assess relationship between the presence of approximal cavitation, the radiographic depth of the lesion, the site-specific gingival index and the level of infection of the dentine. Adult patients assessed as needing operative treatment and presenting with approximal lesions visible in the outer third of dentine on bite-wing radiographs were included in the study. Direct lesion depth measurements were recorded from the radiographs and the site-specific gingival index adjacent to the lesion was noted. The presence or absence of a cavity was recorded on an impression following tooth separation. During operative treatment samples of dentine were taken on entry to the lesions to ascertain the level of infection of the dentine. Visual evaluation of 54 successfully recorded impressions revealed that 85% were cavitated. Cavitated lesions were found to have higher site-specific gingival index scores compared to non-cavitated lesions (p = 0.03). The probability of cavitation was greater for lesions >0.5 mm from the enamel-dentine junction on bite-wing radiographs (p<0.01). The level of infection of the dentine was significantly higher for cavitated lesions than for non-cavitated lesions (p = 0.02). However, the non-cavitated lesions were still infected.

A clinical and microbiological study of approximal carious lesions. Part 2: efficacy of caries removal following tunnel and class II cavity preparations

A randomized controlled clinical study was set up to assess caries removal following tunnel preparation (test group) and class II cavity preparation (control group). Sixty approximal lesions in adult posterior teeth, visible in the outer third of dentine on bite-wing radiographs, were referred for operative treatment. Initial dentine samples were taken on entry to the lesions in both groups. Following cavity preparation dentine samples were taken from beneath the marginal ridge in the tunnel group and at the cervical floor in both groups. Microbiological analysis was carried out to establish the level of infection of the dentine. The bacterial counts were high on entry to the lesions with a median log10 (CFU + 1) per sample of 3.07 (+/-1.24). Following cavity preparation bacterial counts at the cervical floor were significantly reduced in both amalgam and tunnel groups (p<0.00001). In the tunnel group, however, slightly increased bacterial counts were found beneath the marginal ridge compared to the cervical floor (p<0.01).

The isolation of Actinomyces naeslundii from sound root surfaces and root carious lesions

The isolation of Actinomyces naeslundii from sound, exposed root surfaces (n = 56) and soft and leathery root carious lesions (n = 71) was investigated. Root carious lesions were sampled after the removal of overlying plaque. Supragingival plaque or carious dentine was sampled using a sterile excavator, the samples were disaggregated and cultured on both selective and non-selective media. A. naeslundii isolates were identified to the genospecies using specific antisera. Significantly greater numbers and proportions of A. naeslundii genospecies 2 than A. naeslundii genospecies 1 were isolated from all sites sampled. There was no significant difference between the numbers and proportions of the two genospecies isolated from leathery and soft lesions. The relationship between the presence of A. naeslundii genospecies and aciduric and acidogenic organisms was investigated. Those sound exposed root surfaces from which A. naeslundii genospecies 1 and/or 2 were isolated yielded significantly lower numbers of lactobacilli and yeasts than the surfaces from which A. naeslundii were not isolated. This difference was also found in leathery lesions but not soft root carious lesions. The microflora of soft root carious lesions was found to comprise primarily gram-positive pleomorphic rods which formed 70+/-7.8% of the flora, while in plaque from exposed root surfaces and in infected dentine from leathery lesions the gram-positive pleomorphic rods represented only 35% of the flora.

Genotypic heterogeneity of Streptococcus oralis and distinct aciduric subpopulations in human dental plaque

The genotypic heterogeneity of Streptococcus oralis isolated from the oral cavity was investigated using repetitive extragenic palindromic PCR. Unrelated subjects harbored unique genotypes, with numerous genotypes being isolated from an individual. S. oralis is the predominant aciduric bacterium isolated from noncarious tooth sites. Genotypic comparison of the aciduric populations isolated at pH 5.2 with those isolated from mitis-salivarius agar (MSA) (pH 7.0) indicated that the aciduric populations were genotypically distinct in the majority of subjects (chi(2) = 13.09; P = 0.0031). Neither the aciduric nor the MSA-isolated strains were stable, with no strains isolated at baseline being isolated 4 or 12 weeks later in the majority of subjects. The basis of this instability is unknown but is similar to that reported for Streptococcus mitis. Examination of S. oralis strains isolated from cohabiting couples demonstrated that in three of five couples, genotypically identical strains were isolated from both partners and this was confirmed by using Salmonella enteritidis repetitive element PCR and enterobacterial PCR typing. These data provide further evidence of the physiological and genotypic heterogeneity of non-mutans streptococci. The demonstration of distinct aciduric populations of S. oralis implies that the role of these and other non-mutans streptococci in the caries process requires reevaluation.

Caries-associated micro-organisms in infants from different socio-economic backgrounds in Scotland

OBJECTIVES

The aims of this study were: (1) to compare the frequency of isolation of mutans streptococci, (Streptococcus mutans, Steptococcus sobrinus), lactobacilli and yeasts (caries-associated micro-organisms) in the saliva of 1-year-old infants with and without dental caries; and (2) to determine if socio-economic background influenced the frequency isolation of bacteria and caries status.

METHODS

1393 1-year-old consented infants, who comprised 70. 3% of children born in Dundee during a 1year period, had saliva samples taken (tongue-loop method) for microbiological culture and were examined for dental caries (d(1)-threshold: enamel and dentine diagnostic threshold). Thirty-nine infants were diagnosed with caries and the frequencies of isolation of caries-associated micro-organisms (and absolute microbial counts) were compared with infants who were caries-free. In addition, associations were sought between the infants' socio-economic background, the frequency of isolation of caries-associated micro-organisms and caries status.

RESULTS

Streptococcus mutans, lactobacilli and yeasts were isolated more frequently from those infants with caries compared to those who were caries-free (S. mutans: 29.7 vs 9.8%, P=0.0008; lactobacilli: 15.4 vs 4.3%, P=0.0073; yeasts: 23.7 vs 10.4%, P=0.0016-Fisher's exact test). There were no significant differences between the isolation frequencies of S. sobrinus (2.7 vs 1.3%, P=0.39) from those with and without caries. Significantly, more infants living in areas of high deprivation had caries compared to those from more affluent areas (DEPCAT 6 and 7 vs 1-5: 3.6 vs 1.9%, P=0.049), but, apart from yeasts, socio-economic background was not significantly associated with the isolation frequencies of any of the caries-associated micro-organisms.

CONCLUSIONS

In infants as young as 1year of age, salivary S. mutans, lactobacilli and yeasts but not S. sobrinus were isolated significantly more frequently from those with caries compared to those who were caries-free. Apart from yeasts, socio-economic background did not influence the frequency of isolation of caries-associated micro-organisms. However, infants living in areas of highest deprivation had significantly higher frequencies of caries compared to those from more affluent areas.

Detecting mannosidase activities using ribonuclease B and matrix-assisted laser desorption/ionization-time of flight mass spectrometry

Ribonuclease (RNase) B incubated with purified enzymes, whole bacterial cultures, or their separated components-cells and supernates-have been directly analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF) to detect exomannosidases and to evaluate their specificities and location. Enzymatic cleavage was monitored by observing changes in RNase B glycoform population. Thus a nonspecific alpha-(1 --> 2)-mannosidase activity converts the glycoprotein to its Man(5) form, identifiable by its mass of 14,899 [M + H](+); this species subsequently is converted, by the actions of alpha-(1 --> 3) and alpha-(1 --> 6)-mannosidases, to the Man(1) form via Man(4), Man(3), and Man(2). The Man(1) glycoform (which is readily isolated) has then similarly been used for identifying beta-(1 --> 4)-mannosidase and the derived Man(0) form has served in turn as a natural substrate for beta-(1 --> 4) N-acetylglucosaminidase producing a species possessing a single asparagine-linked GlcNAc residue (mass 13,886). Mannose liberated from the actions of mannosidases can, if desired, be quantified by, for example, chromatography. The actions and specificities of endoglycosidases such as a peptide-N-glycosidase F (PNGase F) and of endo-N-acetlyglucosaminidases (e.g., endo-F and endo-H), which respectively cleave between the GlcNAc&bond;Asn and GlcNAc&bond;GlcNAc bonds of N-linked glycoproteins, are also demonstrable by MALDI-ToF analysis of RNase B (and derived products). From these digests the completely deglycosylated polypeptide corresponding to RNase A in which Asn has been converted to Asp (mass 13,684) and a species corresponding to RNase A + GlcNAc (mass 13,886) are produced, together with their corresponding free oligosaccharides which are amenable to analysis by both MALDI-ToF and by HPLC.

Oral health in children undergoing liver transplantation

AIMS

To determine the prevalence of dental caries in children undergoing liver transplantation and to compare the plaque, gingivitis, and gingival overgrowth indices and oral mucosal lesions in children before and after liver transplantation.

PATIENTS AND METHODS

Patients undergoing liver transplantation at King's College Hospital were examined before transplantation, at 3 and 106 days post-transplantation. Healthy children from the Greenwich Health District, south-east London, were matched to the liver transplant patients by age, gender, socio-economic factors and the presence or absence of active dental caries.

RESULTS

Twenty-seven liver transplant patients (mean age: 7 years and 10 months; SD 3 years and 5 months) and 27 controls (mean age: 8 years and 6 months; SD 3 years and 7 months) were examined. The mean dmft and DMFT scores were 2.3 (SD 4.1) and 0.8 (SD 1.4), respectively, in the liver transplant patients, and 1.2 (SD 2.2) and 0.9 (SD 1.5), respectively, in the controls. There were no significant differences between either the mean plaque or gingivitis indices for the primary and permanent teeth in patients before and after transplantation. There were no significant differences between the liver transplant patients and the controls for either mean plaque or gingivitis indices at each examination time. Gingival overgrowth was present in 41% of liver recipients receiving cyclosporin with or without nifedipine, but not in the majority receiving tacrolimus at the final examination. Oral mucosal lesions were absent in both the patients and controls at each examination time.

CONCLUSIONS

The oral health of the children undergoing liver transplantation was inadequate. Funding and implementation of an oral health care programme must become a priority for all children before and after liver transplantation.

The oral microbiota of children undergoing liver transplantation

This study investigated the oral microbiota of children undergoing liver transplantation. Oral swabs were taken using a standardized procedure from 27 children before liver transplantation and at 3 and 100 days post-transplantation and from 27 healthy controls at baseline and 90 days. Viridans streptococci, yeasts, staphylococci, enterococci and Enterobacteriaceae were enumerated and identified using conventional techniques. The oral microbiota of the patients changed significantly immediately post-transplantation, but by the final examination, it had returned to baseline levels. The oral microbiota of the controls did not change significantly. The numbers and proportions of Streptococcus salivarius, Streptococcus sanguis and Streptococcus gordonii as percentages of the total streptococcal counts and of the total anaerobic counts decreased significantly 3 days post-transplantation (P < or = 0.006). There were no significant changes in the numbers and proportions of Streptococcus oralis and Streptococcus mitis isolated pre- and post-transplantation. The isolation frequencies and numbers of yeasts were significantly higher in patients than controls. Staphylococci were isolated in low numbers from all children. Enterococci and Enterobacteriaceae were isolated infrequently from patients.

Isolation and characterisation of sialidase from a strain of Streptococcus oralis

Streptococcus oralis, the most virulent of the viridans streptococci, produces a sialidase and this exo-glycosidase has been implicated in the disease process of a number of pathogens. The sialidase of S. oralis strain AR3 was purified in order to understand the characteristics of this putative virulence determinant. The enzyme isolated as a high mol. wt aggregate (c. 325 kDa) was purified 4520-fold from late exponential phase cultures by a combination of ultrafiltration, ammonium sulphate precipitation, ion-exchange and gel filtration chromatography. The sialidase component had a mol.wt of 144 kDa as determined by SDS-PAGE analysis. The purified sialidase released N-acetylneuraminic acid from a range of sialoglycoconjugates including human alpha1-acid glycoprotein, bovine submaxillary mucin, colominic acid and sialyl-alpha2,3- and sialyl-alpha2,6-lactose. Also, N-glycolylneuraminic acid was cleaved from bovine submaxillary mucin. The sialidase had a Km of 11.8 microM for alpha1-acid glycoprotein, was active over a broad pH range with a pH optimum of 6.0 and cleaved alpha2,3-, alpha2,6- and alpha2-8-sialyl glycosidic linkages with a marked preference for alpha2,3-linkages. The enzyme was competitively inhibited by the sialic acid derivative, 2,3-dehydro-N-acetylneuraminic acid, with a K(IC) of 1.2 microM. The characteristics of the purified sialidase would support a nutritional role for this enzyme that may be significant in the proliferation of this organism in the oral cavity and at extra-oral sites in association with life-threatening infections.

An evaluation of an oral health training programme for carers of the elderly in residential homes

OBJECTIVE

The objectives of this study were: to evaluate carers' knowledge of oral health; to provide a high quality, consistent, oral health training programme for carers in residential homes; to evaluate the quality of this programme by examining both carers' changes in knowledge and any changes in carers' behaviour as reported by residents and to assess any changes in the oral health of the elderly residents after one year.

DESIGN

A cross-sectional, multi-centre study using a carer training programme, evaluated by both a questionnaire conducted with carers and residents and oral examination of residents.

SETTING

In August 1996, 20 (20%) of the residential/nursing homes, in West Hertfordshire were chosen at random and all managers contacted and offered an oral examination for all their residents. Ten (10%) of the homes were also offered an oral health training programme for their carers. Eighteen homes accepted the oral examination for all consenting residents and 7 of the 10 homes offered accepted the carer training.

SUBJECTS

Thirty-nine carers from 7 of the residential homes attended an oral health training course and 213 elderly residents in the 18 homes were examined both at baseline and after 12 months.

RESULTS

Carers' baseline knowledge about oral health was poor; the oral health training programme was enjoyed and their knowledge gain after one week was high. However, the elderly residents perceived no change in the oral care given by carers either after one week or after one year and there was no measurable improvement in the oral health of residents after carer training, except for an increase in filled coronal surfaces. Few of the carers originally trained were still working in the same residential homes after one year.

CONCLUSION

Although the carer training programme was well received, no changes in oral health practice resulted. Barriers to practice of oral care by carers remained and training, even when including practical skills, evaluation by peers and a high knowledge gain, failed to reduce these barriers.

Production of an endo-beta-N-acetylglucosaminidase activity mediates growth of Enterococcus faecalis on a high-mannose-type glycoprotein

Enterococcus faecalis is associated with a high proportion of nosocomial infections; however, little is known of the ability of this organism to proliferate in vivo. The ability of RNase B, a model glycoprotein with a single N-glycosylation site occupied by a family of high-mannose-type glycans (Man(5)- to Man(9)-GlcNAc(2)), to support growth of E. faecalis was investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of RNase B demonstrated a reduction in the molecular mass of this glycoprotein during bacterial growth. Further analysis by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry revealed that this mass shift was due to the degradation of all high-mannose-type glycoforms to a single N-linked N-acetylglucosamine residue. High-pH anion-exchange chromatography analysis during exponential growth demonstrated the presence of RNase B-derived glycans in the culture supernatant, indicating the presence of an endoglycosidase activity. The free glycans were eluted with the same retention times as those generated by the action of Streptomyces plicatus endo-beta-N-acetylglucosaminidase H on RNase B. The cleavage specificity was confirmed by MALDI-TOF analysis of the free glycans, which showed glycan species containing only one N-acetylglucosamine residue. No free glycans were detectable after 5 h of bacterial growth, and we have subsequently demonstrated the presence of mannosidase activity in E. faecalis, which releases free mannose from RNase B-derived glycans. We propose that this deglycosylation of glycoproteins containing high-mannose-type glycans and the subsequent degradation of the released glycans by E. faecalis may play a role in the survival and persistence of this nosocomial pathogen in vivo.

Mechanisms of resistance to quinupristin-dalfopristin among isolates of Enterococcus faecium from animals, raw meat, and hospital patients in Western Europe

Twenty-eight quinupristin-dalfopristin-resistant isolates of Enterococcus faecium from hospital patients and nonhuman sources in European countries were studied. High-level resistance (MICs, >/=32 microg/ml) was associated with the presence of vat(E) (satG) (14 isolates ¿50%) or vat(D) (satA) (6 isolates ¿21%). These genes were not detected in eight (29%) isolates with lower levels of quinupristin-dalfopristin resistance (MICs, 4 to 16 microg/ml). This suggests the presence of further mechanisms of resistance to quinupristin-dalfopristin in E. faecium.

Composition of the oral streptococcal flora in healthy children

OBJECTIVES

To identify the predominant streptococcal species in the mouths of healthy children and to investigate the composition of the oral streptococcal flora over a period of 4 months.

PATIENTS AND METHODS

The subjects were 33 fit, healthy schoolchildren aged between 5 and 16 years. These children were part of a large study and were the matched controls for a group of subjects undergoing bone marrow transplantation. The oral flora was sampled using an oral rinse technique on two separate occasions 4 months apart. The outcome measures were the number of each streptococcal species per millilitre of oral rinse; the isolation frequency of each species; the proportion of each species as a percentage of both the total streptococcal count and the total anaerobic count.

RESULTS

The predominant species were Streptococcus salivarius, S. oralis and S. mitis. There was no significant variation in the composition of the oral streptococcal flora over the 4 month period.

CONCLUSIONS

The oral rinse technique provides a reliable method of sampling the streptococcal flora of children.

Attitudes of carers and the elderly occupants of residential homes to antimicrobial chewing gum as an aid to oral health

OBJECTIVE

The aim of this study was to investigate the attitudes of elderly residents to using an antimicrobial chewing gum as an aid to oral health, and the opinion of their carers on such a procedure.

DESIGN

A cross-sectional, multi-centre survey using a structured interview/questionnaire conducted with elderly residents and their carers.

SETTING

In January 1998, 9 residential/nursing homes were chosen at random from all the homes in West Hertfordshire, 207 residents were asked to chew two pieces of gum twice daily for 7 days.

SUBJECTS

The participants, 148 women and 59 men, were aged between 53-100 years (mean age 82.23 +/- 9.62 years). 47 carers, all female, were involved in distributing and collecting the gum.

RESULTS

122 residents (58.9%) were edentulous and 85 (41%) of the participants were partially dentate. Of those with teeth 23 (27%) had 21 teeth or more. 73 (35.2%) residents found that chewing the gum was difficult with 37 (17.9%) of this group being unable to chew (P < 0.0001 for those residents with no teeth/dentures or dentures unopposed by teeth or other dentures). 32 (18.6%) subjects disliked the flavour of the gum. Of the 170 residents who chewed the gum 99 (57.2%) found it reduced oral dryness and 78 (45.1%) reported it made their mouth feel healthy. 34 (53.6%) of the dentate and 47 (40.9%) of the edentate residents wished to keep using the gum (P < 0.05). 35 (74.5%) of the carers found it easy to distribute the gum and 29 (61.7%) thought that chewing gum was an acceptable method of maintaining oral health for residents.

CONCLUSION

The antimicrobial gum investigated in this study was acceptable to many elderly occupants and their carers, significantly improving perceived oral health and oral dryness of residents.

A study of small-colony, beta-haemolytic, Lancefield group C streptococci within the anginosus group: description of Streptococcus constellatus subsp. pharyngis subsp. nov., associated with the human throat and pharyngitis

beta-Haemolytic, Lancefield group C streptococci within the anginosus-species group were shown by genetic and phenotypic criteria to be heterogeneous and to constitute two distinct taxa related at subspecies level to Streptococcus constellatus and Streptococcus anginosus, respectively. The first group, referred to here as DNA group 1, comprised six strains with 86-100% intragroup overall genomic DNA relatedness; five of the strains were originally isolated from the human throat and one was from an abdominal mass. They shared 61-77% DNA relatedness (delta Tm values = 1.2-1.5 degrees C) with reference strains of S. constellatus and were clearly differentiated from S. constellatus (now named Streptococcus constellatus subsp. constellatus) by the ability to produce beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, beta-D-fucosidase, beta-D-galactosidase and beta-D-glucosidase. The name S. constellatus subsp. pharyngis is proposed for these strains on the grounds that they are genetically and phenotypically distinct and exhibit a predeliction for the human throat, being isolated also from cases of pharyngitis. The DNA G + C content is 35-37 mol%. The type strain is MM9889aT (= NCTC 13122T). The second group (DNA group 2) was formed by five beta-haemolytic, Lancefield group C strains originally isolated from various human infections. DNA group 2 strains (81-100% intragroup DNA relatedness) shared 60-72% DNA relatedness (delta Tm values = 2.1-4.1 degrees C) with S. anginosus strains NCTC 10713T and MAS 283 but were not clearly differentiated phenotypically from S. anginosus, showed no clear pattern of clinical association, and therefore are not formally proposed as a new subspecies here.

The influence of specific foods and oral hygiene on the microflora of fissures and smooth surfaces of molar teeth: A 5-day study

A group of 20 students, harbouring >10(4) mutans streptococci per millilitre of saliva, was enrolled into the study. Models for sampling, reproducibly, the dental plaque present in specific sites (fissure and smooth surface) on the dentition were developed and validated. Withdrawal of normal oral hygiene procedures for only 1 day resulted in approximately 10-fold increases in the number of micro-organisms recovered from both sites. The effect of supplementing the subjects' diets with particular food items given 5 times per day [lemonade (5.8% w/v sugars, 250 ml), biscuits (digestive biscuits, 67.6% w/w carbohydrate of which 22% w/w was sugars and 45.6% w/w was starch), caramel toffees and sugar lumps] on the number of micro-organisms recovered and on the composition of the flora at both sites was determined. Dental plaque samples were taken after 5 days and it was found that supplementation of the diet with toffee and sugar lumps resulted in significantly more micro-organisms at both sampling sites. The supplementation of the diets with lemonade or biscuits did not significantly alter the numbers of micro-organisms recovered from either site. The percentage composition of the plaque samples from both dental sites remained relatively unaffected by oral hygiene although there were lower levels of mutans streptococci which might be related to the use of an antimicrobial toothpaste containing fluoride, triclosan and zinc citrate. This study suggests that the cariogenicity of certain sucrose-containing foods may, in part, be due to the enhancement of plaque accumulation in addition to other effects on the percentage composition of the plaque which may become manifest on prolonged usage of these dietary foodstuffs. These observations are consistent with dietary survey findings which often find consumption of confectionery related to caries experience or incidence.

PCR-Based methods for genotyping viridans group streptococci

Standard repetitive extragenic palindromic (REP)-PCR, enterobacterial repetitive intergenic consensus-PCR, and Salmonella enteritidis repetitive element-PCR methods for bacterial strain typing were performed with DNA extracted by boiling members of each of the currently recognized species of human viridans group streptococci. Each of the methods was reproducible. The unique isolates (n = 72) from 15 species of viridans group streptococci were readily distinguishable, with no two isolates showing greater than 90% per cent similarity. The majority of strains exhibited much less than 90% similarity. Isolates identical by REP-PCR were also identical by the other two methods. These PCR-based typing methods, although they do not permit determination of the species of the isolates, are simple to perform and are suitable for clinical and ecological investigations of viridans group streptococci.

The pattern of change in salivary immunoglobulins and antibodies to S. mitis and S. oralis in children undergoing bone marrow transplantation: use of an indirect method of assessment

The objective of this study was to assess the pattern of change in salivary immunoglobulins and antibodies to S. mitis and S. oralis in 23 children following allogeneic bone marrow transplantation and their matched controls. To overcome the difficulty of obtaining a sufficient quantity of whole saliva from very young, sick children saliva was collected in a 5-ml oral rinse of sterile normal saline. It was not possible to measure the volume of whole saliva in each rinse and the concentration of the salivary immunoglobulins and bacterial antibodies were estimated from 1 ml of oral rinse. Despite these shortcomings a pattern of change in the mean concentrations of total salivary IgA, secretory IgA, antibodies to S. mitis and S. oralis and total IgG at specific event- related times during the transplantation period has been demonstrated. There was a significant increase in the concentration of salivary IgG 7 days post-transplantation, followed by significant decreases in total salivary IgA, secretory IgA and antibodies to S. mitis after recovery of the peripheral neutrophil count above 0.5 x 10(9). The concentrations of total IgA and antibodies to S. oralis was significantly greater in the transplant group 119 days post-transplantation.

The predominant Actinomyces spp. isolated from infected dentin of active root caries lesions

Actinomyces are Gram-positive pleomorphic rods (GPPR) which form a large proportion of the oral microflora of all mammals. They have been implicated in root caries, although their role in dental caries initiation and progression is not well-understood. Many studies have focused on Actinomyces naeslundii, but few reports have documented other members of the GPPR. Therefore, we investigated the GPPRs isolated from infected dentin of active root caries lesions (n = 9) to determine which species were the most frequently isolated. The GPPR were isolated under both aerobic and anaerobic conditions and identified by biochemical and physiological tests to the species level according to the new taxonomy. Of 654 GPPR isolates investigated, 607 were identified as belonging to the genus Actinomyces. Of these, 242 were identified as A. israelii, 225 as A. gerencseriae, 109 as A. naeslundii, 15 as A. odontolyticus, and 13 as A. georgiae. Individual strains of A. israelii (n = 56) and A. gerencseriae (n = 46) were also investigated at the DNA level by means of Repetitive Extragenic Palindromic polymerase chain-reactions (REP-PCR) for the study of clonal diversity. Although only a small number of isolates was investigated, REP-PCR showed that the genotypes of both A. gerencseriae and A. israelii populations were heterogeneous within individual root caries lesions. A. gerencseriae and A. israelii strains from the same lesions did not share the same REP-PCR patterns, showing the robustness of the identification scheme. A significantly greater proportion of A. gerencseriae was isolated from the aerobic plates (p < 0.05), while the proportion of A. israelii was significantly (p < 0.05) greater from anaerobic plates. The role of individual Actinomyces spp. in the root caries process remains unclear, since various populations of GPPRs were isolated from individual active root caries lesions.

Growth of Viridans streptococci on human serum alpha1-acid glycoprotein

Viridans streptococci have emerged as major opportunistic pathogens. We suggest that for these bacteria to proliferate in vivo and cause disease, they must utilize host tissue components. We have therefore examined the ability of all recognized species of viridans streptococci to liberate and utilize the constituent sugars of the glycans of the extensively sialylated human serum alpha1-acid glycoprotein (AGP) as the sole source of carbohydrate to support in vitro growth. Analysis of residual glycans following bacterial growth was performed by high-pH anion exchange chromatography with pulsed amperometric detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Only those species which produced sialidase-namely, Streptococcus oralis, S. intermedius, and S. defectivus--grew on AGP. The extent of degradation of glycans was dependent on the particular glycosidases produced by the bacteria. S. defectivus produced only a sialidase which released the terminal N-acetylneuraminic acid residues of the glycans, and the liberated sugar was utilized. S. intermedius also produced beta-galactosidase and beta-N-acetylglucosaminidase, which removed galactose and N-acetylglucosamine from desialylated glycans, all of which again were utilized by the organism. S. oralis produced beta-galactosidase, beta-N-acetylglucosaminidase, and alpha-fucosidase and novel alpha- and beta-mannosidases which were apparent only from the analysis of the residual sugars of AGP. S. oralis cleaved all the sugars from AGP except for 22% of the N-acetylglucosamine. The residual N-acetylglucosamine residues remaining were those linked to the asparagine of the peptide backbone. All the monosaccharides released by S. oralis from AGP, with the exception of fucose, were utilized. Sialidase production may be a key factor for growth of these species of viridans streptococci on glycoproteins in vivo, since they are commonly associated with extra-oral diseases, with S. oralis emerging as an important pathogen.