Analytical and physiological variability of salivary microbial counts

Coffee pulp: From a by-product of coffee production to a potential anticariogenic mouth rinse! An in vivo study

Background and Objectives

Dental caries is a prevalent disease despite various efforts made toward its prevention. The drawbacks of the available preventive agents have led to the quest for a potentially more effective agent with fewer adverse effects. Coffee, a local produce of Coorg, is one such herbal alternative. This study aims to assess the potential antimicrobial activity of Robusta coffee pulp extracts on Streptococcus mutans.

Methodology

A total of 39 participants were divided into three groups with 13 participants each, after obtaining ethical clearance and informed consent: Group A (negative control), sterile water; Group B (positive control), 0.2% chlorhexidine mouth rinse; and Group C, 2.5% coffee pulp extract rinse (prepared according to minimum inhibitory concentration). The saliva samples were collected from the patients in a sterile Eppendorf tube at prerinse for baseline, at 1-h postrinse, and at the end of 2 weeks. The S. mutans colony count was done using image-based software analysis. The acquired data were statistically analyzed with one-way ANOVA and repeated measures ANOVA followed by post hoc Tukey's test.

Results

Coffee pulp mouth rinse (P = 0.035) and positive control (P = 0.036) groups showed a statistically significant reduction in the microbial count at 2 weeks postrinse (compared to the negative control group).

Conclusion and Clinical Relevance

The coffee pulp extract-based mouth rinse is a potential anticariogenic agent that offers few advantages over chlorhexidine as no instances of staining, altered taste, or any allergic reactions were reported by the subjects.

Comparative Evaluation of Efficacy of Green Tea Mouth Rinse and Green Tea Gel on the Salivary Streptococcus mutans and Lactobacillus Colony Count in 12-18-year-old Teenagers: A Randomized Clinical Trial

Aims:

Green tea is an antibacterial agent with no significant side effect. This feature makes green tea safe for children to use. The purpose of this study was to compare the effectiveness of green tea gel and mouth rinse on salivary level of Streptococcus mutans and Lactobacillus of teenagers aged 12–18 years.

Subjects and Methods:

In this randomized controlled clinical trial study, 30 children aged 12–18 years were included in the study according to the inclusion criteria and were randomly divided into two groups. Participants in mouth rinse group were asked to rinse their mouth with 0.5% green tea mouthwash twice a day for 2 weeks. In the gel group, participants were requested to brush their teeth with 0.5% green tea gel twice a day for 2 weeks. After 4 weeks of washout period, mouthwash group applied the gel and the gel group rinsed the mouthwash for 2 weeks and with the same instruction as mentioned. Colony count of S. mutans and Lactobacillus was determined before and after intervention and data were analyzed using t-test.

Results:

According to the independent t-test, there was no significant difference in the salivary levels of S. mutans before and after intervention regarding age and gender (P = 0.33). Results from paired t-test showed significant decrease in the mean count of S. mutans and Lactobacillus colonies in both groups before and after intervention (P < 0.001).

Conclusions:

Green tea gel and mouthwash contribute to a significant reduction of salivary levels of S. mutans and Lactobacillus colonies, with a greater effect of mouthwash than the green tea gel, which was not statistically significant.

Effect of Green Coffee Bean Extract on Streptococcus mutans Count: A Randomised Control Trial

INTRODUCTION

Mouth rinses have been popularly used as a supplementary oral hygiene aid. A lot of commercially available mouth rinses possess few adverse effects, which has necessitated the search for alternative and herbal mouth rinses.

AIM

The aim of the study was to assess the effect of rinsing with green coffee bean extract in comparison with chlorhexidine mouthwash and sterile water on salivary Streptococcus mutans count.

MATERIALS AND METHODS

A randomized parallel controlled clinical trial was planned and 45 subjects aged between 18-22 years were selected. The subjects were divided into three groups (n=15 in each group): Group A: Study group: 2% Green coffee bean extract, Group B: Positive control: 0.2% Chlorhexidine (CHX), Group C: Negative control: Sterile water. Group A subjects rinsed mouth with 5 ml of 2% Green coffee bean extract for one minute. Group B subjects rinsed mouth with 5 ml 0.2% CHX mouthwash for one minute. Group C subjects rinsed mouth with 5 ml of Sterile water for one minute twice daily for two weeks. Baseline samples (Pre rinse) were collected on day 1 and post rinsing saliva samples were collected after 14 days. The samples were cultured using Mitis Salivarius Agar enriched with Bacitracin and colonies were counted using a hand held digital colony counter. The statistical analysis was done using paired t-test, One-way variance ANOVA and Post-Hoc tests.

RESULTS

The Green coffee bean extract group showed a statistical significant reduction in Streptococcus mutans colony count before and after intervention which was comparable with CHX group.

CONCLUSION

Green coffee bean extract as a mouthwash can be explored as a safe and effective alternative to CHX mouthwash.

Effects of oral environment stabilization procedures on Streptococcus mutans counts in pregnant women

The aim of this study was to determine the effect of oral environment stabilization (OES) on the counting of Streptococcus mutans in high-caries-risk pregnant women participants of a prevention program in a public teaching institution. The sample was composed of 30 pregnant women aged 18 to 43 years, who looked for treatment at the Preventive Dentistry Clinic of the Araraquara Dental School, UNESP. Saliva samples were collected before and after the OES procedures and were forwarded to the pathology for observation and quantification of S. mutans CFU. There was a decrease in the number of S. mutans CFU, which was significantly different (p<0.0001) between samples. Considering the age group, 70.0% were between 18 to 30 years old and 30.0% belonged to the 31-43-year-old age group. Data related to the pregnancy period showed that 73.4% were in the second trimester, 13.3% in the first and 13.3% in third trimester. OES showed to be an effective clinical procedure in diminishing the number of S. mutans CFU in the saliva of high-caries-risk pregnant women. This management is simple and effective, corresponding to the basic treatment needs of pregnant women that search dental care in this public service.

Polymerase chain reaction detection of Lactobacillus acidophilus in human oral cavity and fecal samples after 2-week consumption of yoghurt

OBJECTIVE

To investigate whether short-term daily consumption of yoghurt leads to colonization by Lactobacillus acidophilus in a group of human subjects who were initially totally devoid of L. acidophilus in their oral cavities.

MATERIAL AND METHODS

Twenty-three volunteers consumed yogurt containing L. acidophilus during a 14-day trial stage. Oral and fecal samples were collected at the clearance stage and at the post-yoghurt intake stage until L. acidophilus was found. Standard polymerase chain reaction methods using specific primers were adopted for the detection and identification of L. acidophilus.

RESULTS

The isolation frequency decreased rapidly 72 h after stopping intake of yoghurt. After 1 week, L. acidophilus was absent in all oral samples. Non-significant differences were found between the survival rates of L. acidophilus in samples of saliva, plaque, tongue surface, and buccal mucosa. L. acidophilus was also found to remain in the gastrointestinal tract for longer than in the oral cavity.

CONCLUSION

Allochthonous L. acidophilus is not likely to permanently colonize the oral cavity and intestine.

Caries Prevalence Measured with QLF after Treatment with Fixed Orthodontic Appliances: Influencing Factors

Caries prevalence on the buccal surfaces of teeth in orthodontic patients was determined with QLF and visual examination immediately after removal of fixed appliances. The number of lesions found by QLF far outnumbered that found by visual examination, but the distribution pattern was similar. 97% of all subjects and on average 30% of the buccal surfaces in a person were affected. On average, in males 40% of surfaces and in females 22% showed white spots (p < 0.01). Caries prevalence was lower (p < 0.01) in incisors and cuspids than in molars and premolars. A positive correlation with caries prevalence was found for the bleeding scores 6 weeks after debonding and lactobacillus counts before debonding. Mutans streptococci counts, age, treatment duration, socioeconomic status and dietary habits showed no correlation with caries prevalence.

Microbiological composition of whole saliva and caries experience in minority populations

Microbiological factors in whole saliva, previously implicated in dental caries formation, were studied in four caries-positive adult ethnic groups: Asians, blacks, whites, and Hispanics. Whole saliva was collected from each patient and used for the enumeration of total cultivable microflora (T), streptococci, mutans streptococci (MS), and lactobacilli. In the female subgroup, statistically significant differences were found among the ethnic groups with regard to T in saliva. In the male subgroup, statistically significant differences were found among the ethnic groups with regard to MS in saliva. Statistically significant differences were also found among the ethnic groups in relation to caries score (DMFS), with the Hispanic group having the highest mean DMFS score; and among socioeconomic groups with regard to MS in saliva. Moreover, microbial composition (T and MS) of whole saliva and DMFS scores differed significantly (P < 0.05) among the ethnic groups studied.

Analyses of Streptococcus mutans in saliva with species-specific monoclonal antibodies

Three species-specific monoclonal antibodies (MAbs) against Streptococcus mutans were used to detect and quantify S. mutans levels in saliva. This study shows that MAb-based salivary S. mutans tests exhibit significantly higher specificity and sensitivity than the commonly used selective culture method. Examination of nearly 2,000 human saliva samples shows that S. mutans counts in human saliva vary from less than 10,000 to a high 36 million cells/mL. Over 15% of the saliva samples examined have salivary S. mutans counts over 500,000 cells/mL. When saliva samples were collected at different time points during a day, the number of salivary S. mutans in the same human subject varied, especially before and after sugar uptake. Additionally, data obtained from stimulated versus unstimulated saliva in the same human subjects differed greatly and appear to be completely uncorrelated. This study provides useful information and tools for analyzing the role of S. mutans in human dental caries.

A randomized clinical trial of the effect of yoghurt on the human salivary microflora

Yoghurt is active against some human pathogens, so this experiment tested whether it is also active against the salivary microflora. A clinical trial was designed, with volunteers aged between 23 and 37 years. Initially, for 8 weeks, they consumed neither yoghurt nor casein-free soybean ice cream (phase 1). They were then split randomly into test (yoghurt) and control (ice cream) groups and required to consume 125 g of these foods twice daily for 8 weeks (phase 2) and then to avoid them for the following 2 weeks (phase 3). Many potential sources of microbial fluctuation were standardized. Salivary samples were then collected at regular intervals of 2 weeks. For each group and phase, the mean logarithms of the salivary counts for total viable flora, oral streptococci, mutans streptococci, lactobacilli and Candida were calculated. The prevalence of Streptococcus thermophilus and Lactobacillus bulgaricus was also assessed. Twenty test and 22 control participants completed the study. At phase 2, the mean for mutans streptococci was lower in the test than in the control group (3.6 vs. 4.0 log colony-forming units/ml; P=0.02). Moreover, the mean had decreased in all test participants with high phase 1 means for lactobacilli as compared to only 36.4% of those with low phase 1 means (P=0.01). L. bulgaricus was transiently detected in three test participants during phase 2. These results suggest that yoghurt does have some activity against the salivary microflora, but this does not seem to be due to the installation of yoghurt microorganisms in the mouth.

The effects of gum chewing, four oral hygiene procedures, and two saliva collection techniques, on the output of bacteria into human whole saliva

Six healthy dentate individuals collected a 5-min sample of unstimulated whole saliva (UWS) and dilutions were plated out on blood agar and grown anaerobically for 48 h. The output of bacteria into saliva (counts/min) was calculated as the product of counts/ml and ml/min. The individuals repeated the collections at intervals of up to 7 h after (1) rinsing with water, (2) eating a meal plus tooth brushing, (3) a thorough dental prophylaxis, or (4) tongue brushing and scraping. They also collected saliva at intervals while chewing gum for 20 min, as did 10 individuals who chewed gum for 2 h. The original six individuals also collected UWS under "drooling" (no oral movements) and "spitting" conditions. Six edentulous individuals not wearing their dentures collected UWS before and after a water rinse. With the four oral hygiene procedures, bacterial outputs fell initially and then rose again, but a repeated-measures ANOVA revealed no significant differences in the effects of the four procedures. Gum chewing caused initial marked increases in the outputs of bacterial and epithelial cells, but these fell with time and reached a plateau after about 10 min at outputs above those in UWS. Samples collected by spitting contained up to 14 times more bacteria than those collected by drooling. Bacterial output by edentulous individuals did not differ from that in those with teeth. It is concluded that bacteria from the teeth and gingival crevices normally make only a small contribution to those in saliva, that various oral hygiene procedures have similar effects on bacterial output into saliva, and that saliva collection conditions should be standardized and specified.

Effect of whitening agents containing carbamide peroxide on cariogenic bacteria

PURPOSE

The purpose of this study was to investigate the in vitro antibacterial effects of three different carbamide peroxide products (Nitewhite, Opalescence, and Proxigel) on cariogenic microorganisms (mutans streptococci [MS] and lactobacilli), and to evaluate the effects of a 10% carbamide peroxide solution (Proxigel) on salivary levels of MS and lactobacilli clinically.

MATERIALS AND METHODS

Growth inhibition studies were performed to determine the concentration and exposure time of carbamide peroxide to give total inhibition of recoverable growth of MS and lactobacilli. Paraffin-stimulated saliva samples were collected from subjects before and after 6 weeks of treatment with 10% carbamide peroxide in bleaching trays, and levels of MS and lactobacilli were determined.

RESULTS

The growth inhibition studies showed no visible growth of MS or lactobacilli at 24-, 48-, or 72-hour incubation, after a 2-hour exposure to 1% carbamide peroxide. Identical results were obtained with all three carbamide peroxide products. In the clinical study, the mean salivary MS levels, expressed as logarithm colony-forming units per milliliter (CFU/mL), were 5.38 for the pretreatment samples and 5.23 for the post-treatment samples. The differences were not statistically significant (p > .05). However, there was a reduction in logarithm lactobacilli counts from a mean of 4.12 pretreatment to a mean of 2.74 post-treatment. This was statistically significant (p < .05).

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.

Whole mouth microbiota effects following subgingival delivery of sanguinarium

An increased incidence of antibiotic-resistant bacteria and yeast overgrowth has been reported following various periodontal treatments. The objective of this study was to detect possible overgrowth of opportunistic bacteria and fungi as well as changes in normal microbiota after application of a biodegradable delivery system containing 5% sanguinarium (ABDS-S) to one quadrant in a split-mouth study. An oral hygiene quadrant served as a control. The ABDS-S treated and control periodontal sites as well as the saliva of 17 subjects were sampled prior to treatment, immediately after ABDS-S removal at 7 days, and again at 30 and 60 days. At Day 7 sanguinarium-resistant bacteria increased in both control and ABDS-S periodontal sites as well as in the saliva. Enteric Gram-negative bacilli in both control and ABDS-S periodontal sites were 2.2 to 3.4 log colony forming units higher at Day 7 compared to baseline. This overgrowth was transient in that levels became undetectable at Days 30 and 60. No such overgrowth was observed for C. albicans or other fungi, or for S. aureus or other staphylococci in any periodontal sites. Levels of Actinomyces increased at Days 30 and 60 in both control and ABDS-S sites as well as saliva. These changes strongly suggest that a 7 day ABDS-S treatment in one quadrant of the mouth led to significant microbiota changes in the treated and control quadrants as well as in the saliva. Future microbial studies involving antimicrobials delivered by local delivery systems must consider the crossover effects of treatment inherent in the split-mouth design.

Inconsistent levels of mutans streptococci and lactobacilli measured in stimulated whole saliva

The counts of mutans streptococci (MS) and lactobacilli (LB) in saliva have been used for prediction of dental caries. The results have not justified putting the methods into clinical practice as the explanatory values of the bacteria for caries are low. There is therefore reason to question how representative the methods for sampling and estimation of those bacteria are. The aims of this study were to investigate if the variation in caries is better explained by the bacteria, estimated as means of numbers in double saliva samples, than by numbers in single samples, and to determine whether chewing on either the preferred or the non-preferred side influences the bacterial counts. Twenty-five healthy subjects were included in the study. Two saliva samples were collected with a 1-wk interval by chewing on a piece of sterile paraffin wax on the preferred side only. One month later this was repeated on the opposite side. In order to test if there were variations in the numbers of bacteria due to the laboratory methods, a paired cultivation of 20 samples was carried out. The results showed that the coefficients of variation (c.v.) for the differences between the individual double samples varied between 110 and 276% of the total mean of the double samples. The paired cultivation gave r values for MS of 0.93 and for LB of 0.99. Using double samples did not increase the explanatory values for caries. There were higher explanatory values for caries on the preferred side than on the non-preferred side, this being much more pronounced for lactobacilli than for mutans streptococci.

The oral prevalence of aerobic and facultatively anaerobic gram-negative rods and yeasts in Hong Kong Chinese

Saline oral rinse samples were obtained from 300 community-dwelling Hong Kong Chinese attending an outpatient dental clinic to determine the oral prevalence of aerobic and facultatively anaerobic Gram-negative rods (AGNR) and yeasts. The oral prevalence of AGNR was 41.7%. Enterobacteriaceae species comprised 73% of all AGNR isolated, with an overall prevalence of 32%. There was no difference in prevalence between females (n = 190) and males (n = 110). Morning samples (n = 154) yielded a significantly higher prevalence of AGNR (54.5%) and Enterobacteriaceae (42.2%) than afternoon samples (n = 146) (28.1 and 21.2%, respectively; p < 0.01, p < 0.01). Subjects over 50 yr had a significantly higher prevalence of AGNR than those aged 30-49 yr (p < 0.01). The most commonly isolated AGNR species were Enterobacter cloacae and Klebsiella pneumoniae pneumoniae. The oral prevalence of yeasts was 24%, with Candida albicans forming 77% of all yeasts isolated. Subjects taking medication (n = 38) or wearing dentures (n = 38) had a significantly higher oral yeast prevalence of 36.8 (p < 0.05) and 44.7% (p < 0.01), respectively. Yeast prevalence was significantly higher in subjects over 50 yr than those aged 30-49 yr (p < 0.05) and 15-29 yr (p < 0.05). Comparisons with previous studies suggest that the oral prevalence of AGNR in Chinese may be higher in Hong Kong than in other parts of the world.

Oral and oropharyngeal prevalence of Enterobacteriaceae in humans: a review

Members of the Enterobacteriaceae family are widely distributed in nature and exhibit substantial diversity in ecology, host range and pathogenic potential for man. While wide discrepancies in methodology exist between epidemiological studies, the available data indicate an increased prevalence of oral and/or oropharyngeal Enterobacteriaceae carriage in patients with illnesses of varying severity compared with healthy subjects. This paper reviews the prevalence of Enterobacteriaceae in the oral and oropharyngeal region of healthy human subjects and those affected by different disease entities, and discusses the complexities associated with collating and interpreting such data. The effect of antimicrobials and antiseptics on oral and oropharyngeal Enterobacteriaceae has also been reviewed, while highlighting the gaps in knowledge and future research directions.

The use of a concentrated oral rinse culture technique to sample oral candida and lactobacilli in children, and the relationship between candida and lactobacilli levels and dental caries experience: a pilot study

The purpose of this study was to test the suitability of a concentrated rinse culture technique, previously applied to adults, as a method for sampling the oral cavity of children on a community basis. The technique was used to assess the levels of oral candida and lactobacilli in the mouths of a group of 32 14- to 15-year-old children and to relate this to their past caries experience. Caries experience was assessed by means of a DMFS count. Each subject rinsed with 10 ml of buffered saline for 1 minute for microbial sampling. The oral rinse was concentrated by centrifugation and cultured on to selective media for candida and lactobacilli. The rinse technique proved simple and effective as a means of sampling the oral flora in children. The level of candida was more easily assessed and appeared to be a more useful indicator of microbial risk factors in caries than the lactobacilli count.

Intra- and inter-individual variation in salivary flow rate, buffer effect, lactobacilli, and mutans streptococci among 11- to 12-year-old schoolchildren

Both intra- and inter-individual variation in salivary flow rate, buffer effect, and the levels of salivary mutans streptococci and lactobacilli were analyzed in 128 11-year-old children. The follow-up period was 9 months, with six saliva samplings done at regular intervals. Inter-individual variation was relatively large in paraffin-stimulated salivary flow rate: low (< 1.0 ml/min) and high (> or = 2.0 ml/min) flow rates were measured in 18% and 13% of the children, respectively. Intraindividual variation during the follow-up period was found in 63% of the boys and in 73% of the girls. The buffer effect stayed stable in all samplings in 59% of the boys and in 42% of the girls. Buffer effect was significantly (p < 0.001) lower in girls than in boys. Mutans streptococci were analyzed by a chair-side method (Strip mutans test) and by cultivation on mitis-salivarius-bacitracin (MSB) agar plates. The results of the two methods correlated highly significantly (r = 0.79, p < 0.001). With the Strip mutans test no variation in test scores occurred in 49% of all subjects in all six samplings, whereas the respective percentage for MSB scores was only 19%. No variation in salivary lactobacilli occurred in only 18% of the subjects, and in 13% the intraindividual variation was as high as > or = 3 logs. These results show that in young teenagers with a developing dentition, simultaneous changes in behavioral, hormonal, and dietary factors make single-point measurements of salivary factors too unreliable for caries-diagnostic or predictive purposes.

Initial acquisition of mutans streptococci by infants: evidence for a discrete window of infectivity

Oral bacterial levels of 46 mother-child pairs were monitored from infant birth up to five years of age so that the acquisition of mutans streptococci (MS) by children could be studied. The initial acquisition of MS occurred in 38 children at the median age of 26 months during a discrete period we designated as the "window of infectivity". MS remained undetected in eight children (17%) until the end of the study period (median age of 56 mo). The levels of both MS and lactobacilli in saliva of mothers of children with and without MS were not significantly different. Comparisons between a caries-active cohort colonized by MS (nine of 38) and children without detectable MS revealed similar histories in terms of antibiotic usage, gestational age, and birth weight. Interestingly, half of the children between the ages of one and two years who were not colonized by MS were attended by caretakers other than the mother, while all of the caries-active children during this same time period were cared for by their mothers; the difference was statistically significant. Here we report for the first time that MS is acquired by infants during a defined period in the ontogeny of a child. Support for the notion of a discrete window of infectivity comes from other sources, including animal models.

Physiologic variation of sucrase activity and microbial counts in human saliva

Quantitation of salivary sucrase activity has been proposed as a method for the estimation of the level of sucrose consumption. The purpose of the present study was to investigate the physiologic variability of the sucrase activity and microbial counts in paraffin-wax-stimulated saliva of subjects with sound sucrose consumption habits. Variation was analyzed by repeated sampling studies. Intraday variability was investigated by serial analyses of 16 individuals who gave eight samples at 2-h intervals on a single day. Interday variation was studied by analyzing the morning value of 24 individuals on three consecutive days. Interday variability of salivary mutans streptococci, lactobacilli, and yeasts was tested using semiquantitative commercial test kits. The diurnal variation of sucrase activity revealed that the activity in the morning was significantly higher than at noon or at later sampling times of the day. Interday variation was considerable in subjects with high sucrase values. The day-to-day variability of the salivary microbes was considerable for lactobacilli and relatively small for yeasts. A weak positive correlation ranging from 0.732 to 0.741 was found between high sucrase activity values and salivary lactobacilli. Salivary samples should be collected in the morning to differentiate between subjects with high and low sucrase activities.

The efficacy of chlorhexidine gel in reduction of Streptococcus mutans and Lactobacillus species in patients treated with radiation therapy

Xerostomia may develop in patients with cancer who receive radiotherapy that includes the salivary glands in the field. These patients are at high risk of rampant dental caries. Streptococcus mutans and Lactobacillus species have been associated with dental caries. Quantitative counts of these organisms demonstrated high caries risk due to streptococci in 66% and due to lactobacilli in 100% of patients studied. Use of chlorhexidine rinse was shown to reduce S. mutans counts 1.1 logs and lactobacilli 1.1 logs. The use of chlorhexidine gel resulted in a reduction of S. mutans 1.2 logs and lactobacilli 2.2 logs. In the subjects using the rinse, caries risk due to streptococci was reduced to low levels in 44% and due to lactobacilli in only one subject, with reduction to moderate risk in one third and no change in risk in the remaining patients. The use of chlorhexidine gel was found to reduce the caries risk associated with streptococci to low levels in all patients, and the risk associated with lactobacilli to low and moderate risk in two thirds of patients.