The Biology of Streptococcus mutans.

As a major etiological agent of human dental caries, Streptococcus mutans resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, S. mutans is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of S. mutans have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms. In these areas of research, S. mutans has served as a model organism for ground-breaking new discoveries that have, at times, challenged long-standing dogmas based on bacterial paradigms such as Escherichia coli and Bacillus subtilis. In addition to sections dedicated to carbohydrate metabolism, biofilm formation, and stress responses, this article discusses newer developments in S. mutans biology research, namely, how S. mutans interspecies and cross-kingdom interactions dictate the development and pathogenic potential of oral biofilms and how next-generation sequencing technologies have led to a much better understanding of the physiology and diversity of S. mutans as a species.

Biology of Oral Streptococci.

Bacteria belonging to the genus Streptococcus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of the oral microbiota. In this article, we discuss the different oral environments inhabited by streptococci and the species that occupy each niche. Special attention is given to the taxonomy of Streptococcus, because this genus is now divided into eight distinct groups, and oral species are found in six of them. Oral streptococci produce an arsenal of adhesive molecules that allow them to efficiently colonize different tissues in the mouth. Also, they have a remarkable ability to metabolize carbohydrates via fermentation, thereby generating acids as byproducts. Excessive acidification of the oral environment by aciduric species such as Streptococcus mutans is directly associated with the development of dental caries. However, less acid-tolerant species such as Streptococcus salivarius and Streptococcus gordonii produce large amounts of alkali, displaying an important role in the acid-base physiology of the oral cavity. Another important characteristic of certain oral streptococci is their ability to generate hydrogen peroxide that can inhibit the growth of S. mutans. Thus, oral streptococci can also be beneficial to the host by producing molecules that are inhibitory to pathogenic species. Lastly, commensal and pathogenic streptococci residing in the oral cavity can eventually gain access to the bloodstream and cause systemic infections such as infective endocarditis.

Progress dissecting the oral microbiome in caries and health.

Recent rapid advances in "-omics" technologies have yielded new insights into the interaction of the oral microbiome with its host. Associations of species that are usually considered to be acid-tolerant with caries have been confirmed, while some recognized as health-associated are often present in greater proportions in the absence of caries. In addition, some newly identified bacteria have been suggested as potential contributors to the caries process. In spite of this progress, two major challenges remain. The first is that there is a great deal of heterogeneity in the phenotypic capabilities of individual species of oral bacteria. The second is that the most abundant taxa in oral biofilms display remarkable phenotypic plasticity, i.e., the bacteria associated most strongly with health or with caries can morph rapidly in response to alterations in environmental pH, carbohydrate availability and source, and oxygen tension and redox environment. However, new technologic advances coupled with "old-fashioned microbiology" are starting to erode the barriers to a more complete understanding of oral biofilm physiology and ecology, and in doing so are beginning to provide insights for the creation of novel cost-effective caries control therapies.

Increasing incidence of invasive pneumococcal disease and pneumonia despite improved vaccination uptake: surveillance in Hull and East Yorkshire, UK, 2002-2009.

Introduction of pneumococcal polysaccharide (PPV23) and conjugate vaccine (PCV7) programmes were expected to change the epidemiology of invasive pneumococcal disease (IPD) and pneumonia in the UK. We describe the epidemiology of IPD and hospitalization with pneumonia using high-quality surveillance data over an 8-year period, 2002-2009. Although PPV23 uptake increased from 49% to 70% and PCV7 uptake reached 98% by 2009, the overall incidence of IPD increased from 11.8/100 000 to 16.4/100 000 (P=0.13), and the incidence of hospitalization with pneumonia increased from 143/100 000 to 207/100 000 (P<0.001). Although a reduction in the proportion of IPD caused by PCV7 serotypes was observed, concurrent increases in PPV23 and non-vaccine serotype IPD contributed to an increased IPD burden overall. Marked inequalities in the geographical distribution of disease were observed. Existing vaccination programmes have, so far, not been sufficient to address an increasing burden of pneumococcal disease in our locality.

A whole water catchment approach to investigating the origin and distribution of Cryptosporidium species.

AIMS: Investigating the distribution and origin of Cryptosporidium species in a water catchment affected by destocking and restocking of livestock as a result of a foot and mouth disease epidemic. METHODS AND RESULTS: Surface water, livestock and wildlife samples were screened for Cryptosporidium and oocysts characterised by sequencing SSU rRNA and COWP loci, and fragment analysis of ML1, ML2 and GP60 microsatellite loci. Oocyst concentrations in water samples (0-20.29 per 10 l) were related to rainfall events, amount of rainfall and topography. There was no detectable impact from catchment restocking. Cryptosporidium spp. found in water were indicative of livestock (Cryptosporidium andersoni and Cryptosporidium parvum) and wildlife (novel genotypes) sources. However, C. andersoni was not found in any animals sampled. Calf infections were age related; C. parvum was significantly more common in younger animals (<4 weeks old). Older calves shared Cryptosporidium bovis, Cryptosporidium ryanae and C. parvum. Wildlife shed C. parvum, Cryptosporidium ubiquitum, muskrat genotype II and deer genotype. CONCLUSIONS: Several factors affect the occurrence of Cryptosporidium within a catchment. In addition to farmed and wild animal hosts, topography and rainfall patterns are particularly important. SIGNIFICANCE AND IMPACT OF THE STUDY: These factors must be considered when undertaking risk-based water safety plans.

Psychosocial impact of the summer 2007 floods in England.

BACKGROUND: The summer of 2007 was the wettest in the UK since records began in 1914 and resulted in severe flooding in several regions. We carried out a health impact assessment using population-based surveys to assess the prevalence of and risk factors for the psychosocial consequences of this flooding in the United Kingdom. METHODS: Surveys were conducted in two regions using postal, online, telephone questionnaires and face-to-face interviews. Exposure variables included the presence of flood water in the home, evacuation and disruption to essential services (incident management variables), perceived impact of the floods on finances, house values and perceived health concerns. Validated tools were used to assess psychosocial outcome (mental health symptoms): psychological distress (GHQ-12), anxiety (GAD-7), depression (PHQ-9) and probable post-traumatic stress disorder (PTSD checklist-shortform). Multivariable logistic regression was used to describe the association between water level in the home, psychological exposure variables and incident management variables, and each mental health symptom, adjusted for age, sex, presence of an existing medical condition, employment status, area and data collection method. RESULTS: The prevalence of all mental health symptoms was two to five-fold higher among individuals affected by flood water in the home. People who perceived negative impact on finances were more likely to report psychological distress (OR 2.5, 1.8-3.4), probable anxiety (OR 1.8, 1.3-2.7) probable depression (OR 2.0, 1.3-2.9) and probable PTSD (OR 3.2, 2.0-5.2). Disruption to essential services increased adverse psychological outcomes by two to three-fold. Evacuation was associated with some increase in psychological distress but not significantly for the other three measures. CONCLUSION: The psychosocial and mental health impact of flooding is a growing public health concern and improved strategies for minimising disruption to essential services and financial worries need to be built in to emergency preparedness and response systems. Public Health Agencies should address the underlying predictors of adverse psychosocial and mental health when providing information and advice to people who are or are likely to be affected by flooding.

Effects of emissions from different type of residential heating upon cyclic guanosine monophosphate (cGMP) in blood platelets of residents.

We hypothesized that different types of residential heating would be associated with different levels of indoor carbon monoxide (CO) and further that this might result in a differential in the concentration of cyclic 3':5' guanosine monophosphate (cGMP) in blood platelets in exposed residents. Individuals, who were recruited from homes using different fuel for heating, donated a venous blood sample in the winter and in the summer. In the winter the median blood platelet cGMP value for the group using liquid propane gas (LPG) was 65% higher than for the group using piped natural gas for heating (p <0.001). Also in the group using LPG, the median concentration of cGMP in the winter was 39% higher than the summer median (p < 0.003). The mean indoor concentrations of CO were measured over a period of 1 week during the winter and were <1 ppm. We conclude that observed differences were associated with emissions from different types of heating but that CO exposure alone is too low to explain these.

Alerting and Surveillance Using Poisons Information Systems (ASPIS): outcomes from an international working group.

BACKGROUND: In recent years, awareness of the risks of chemical and poison exposure has increased, and a number of highly publicized terrorist events have heightened community fears. In particular, there is concern surrounding the potential risk of a covert release, which underpins the need to develop robust methods of population surveillance. AIMS AND METHODS: This article outlines the proceedings of a working group and focuses on the need for greater international cooperation and understanding of existing toxicological surveillance systems in a variety of countries. Poison control centers have well-established local networks and experienced staff, which make them well-placed to detect chemical and poison release. This needs further development to ensure timely detection of signals, which might be better achieved by robust international networks and consistent use of data collection tools. We illustrate some of the strengths and weaknesses of existing surveillance methods, and present a position statement on the minimum dataset required by future surveillance systems. CONCLUSIONS: Poison control centers provide a useful platform for developing surveillance activity. Having proposed a number of common aims and objectives, it is hoped that these consensus statements will inform decision makers and stimulate discussion of how international toxicological surveillance programs might best be developed.

Effects on patients with asthma of eradicating visible indoor mould: a randomised controlled trial.

BACKGROUND: It is not clear whether associations between respiratory symptoms and indoor mould are causal. A randomised controlled trial was conducted to see whether asthma improves when indoor mould is removed. METHODS: Houses of patients with asthma were randomly allocated into two groups. In one group, indoor mould was removed, fungicide was applied and a fan was installed in the loft. In the control group, intervention was delayed for 12 months. Questionnaires were administered and peak expiratory flow rate was measured at baseline, 6 months and 12 months. RESULTS: Eighty-one houses were allocated to the intervention group and 83 to the control group; 95 participants in 68 intervention houses and 87 in 63 control houses supplied follow-up information. Peak expiratory flow rate variability declined in both groups, with no significant differences between them. At 6 months, significantly more of the intervention group showed a net improvement in wheeze affecting activities (difference between groups 25%, 95% CI 3% to 47%; p = 0.028), perceived improvement of breathing (52%, 95% CI 30% to 74%; p<0.0001) and perceived reduction in medication (59%, 95% CI 35% to 81%; p<0.0001). By 12 months the intervention group showed significantly greater reductions than the controls in preventer and reliever use, and more improvement in rhinitis (24%, 95% CI 9% to 39%; p = 0.001) and rhinoconjunctivitis (20%, 95% CI 5% to 36%; p = 0.009). CONCLUSIONS: Although there was no objective evidence of benefit, symptoms of asthma and rhinitis improved and medication use declined following removal of indoor mould. It is unlikely that this was entirely a placebo effect.

The influence of local politicians on pedestrian safety.

AIM: To determine whether local politicians influence the distribution of traffic calming measures. METHODS: Longitudinal ecological study in two UK cities. Local political constituencies were categorized by representation by members of the cabinet structure as a marker of influence. The density of traffic calming features per political area, adjusted for the historical pattern of road injuries, was compared between cabinet represented and non-represented areas. RESULTS: Traffic calming density was significantly associated with cabinet representation status, adjusted for historical collision risk (risk ratio 2.77, 95% confidence interval 1.37 to 5.61). CONCLUSION: These results support the hypothesis that senior local politicians are effective advocates for enhancing safety in their areas.

Exposure to school children as a risk factor in a community outbreak of hepatitis A in young adults: a case control study.

To investigate risk factors during a community outbreak of hepatitis A we carried out a case- control study of 35 cases and 49 matched controls using an interviewer-administered questionnaire on clinical history, travel, household details including domestic toilet facilities, infectious contacts, and food history. Of 99 cases notified in the city during the outbreak year, 50 (51%) were young adults age 15-34 years. Hepatitis A infection was independently associated with household contact with a case (P=0.0005), and sharing a household with children in primary school (OR 3.4, 95% CI 1.2-9.5, P=0.008) with risk increasing with number of primary-school pupils in the household (chi(2) for linear trend 6.47, P=0.01). We concluded that in a population with a low prevalence of hepatitis A, adults who live in the same household as primary-school-age children are at increased risk of acquiring the infection during community outbreaks.

A case-control study of domestic kitchen microbiology and sporadic Salmonella infection.

The microbiology of domestic kitchens in the homes of subjects who had suffered sporadic Salmonella infection (cases) was compared with control domestic kitchens. Case and control dishcloths and refrigerator swabs were examined for the presence of Salmonella spp., total Enterobacteriaceae counts and total aerobic colony counts. Salmonella spp. were isolated from both case and control dishcloths and refrigerators but there were no significant differences between the two groups. Colony counts were similar in case and control dishcloths and refrigerator swabs. There was no relationship between the total counts and presence of Salmonella . There was no evidence that cases of Salmonella infection were more likely to have kitchens which were contaminated with these bacteria or have higher bacterial counts than controls. Total bacterial counts were poor indicators of Salmonella contamination of the domestic kitchen environment. Further factors which could not be identified by a study of this design may increase risk of Salmonella food poisoning. These factors may include individual susceptibility of the patient. Alternatively, sporadic cases of Salmonella food poisoning may arise from food prepared outside the home.

Traffic calming policy can reduce inequalities in child pedestrian injuries: database study.

OBJECTIVES: To determine whether area wide traffic calming distribution reflects known inequalities in child pedestrian injury rates. To determine whether traffic calming is associated with changes in childhood pedestrian injury rates. DESIGN: Small area ecological study, longitudinal analysis of injury rates with cross sectional analysis of traffic calming and method of travel to school. SETTINGS: Two cities in the United Kingdom. PARTICIPANTS: 4-16 year old children between 1992 and 2000. MAIN OUTCOME MEASURES: Area wide traffic calming distribution by area deprivation status and changes in injury rate/1000. RESULTS: The most deprived fourth of city A had 4.8 times (95% CI 3.71 to 6.22) the number of traffic calming features per 1000 population compared with the most affluent fourth. Injury rates among the most deprived dropped from 9.42 to 5.07 from 1992-94 to 1998-2000 (95% CI for change 2.82 to 5.91). In city B, the traffic calming ratio of the most to least deprived fourth was 1.88 (95% CI 1.46 to 2.42); injury rates in the deprived areas dropped from 8.92 to 7.46 (95% CI for change -0.84 to 3.77). Similar proportions of 9-12 year olds walked to school in both cities. CONCLUSIONS: Area wide traffic calming is associated with absolute reductions in child pedestrian injury rates and reductions in relative inequalities in child pedestrian injury rates.

Laboratory testing policies and their effects on routine surveillance of community antimicrobial resistance.

OBJECTIVE: To investigate the effects of laboratory testing policies, particularly selective testing, rule-based reporting and isolate identification, on estimates of community antimicrobial resistance. MATERIALS AND METHODS: Antibiotic resistance estimates were analysed from an all-Wales dataset for approximately 300 000 community isolates of common pathogens. RESULTS: Selective testing policies were often associated with markedly increased resistance, particularly for second-line testing. Site-specific testing tended to yield variant resistance estimates for eye and ear isolates. Estimates from rule-based reporting deviated markedly from test-result-based reporting. Urinary isolates reported as Escherichia coli showed greater susceptibility than those reported as undifferentiated urinary 'coliforms'. The proportion of isolates tested for an antibiotic by a laboratory was a useful indicator of selective testing in this dataset. Selective testing policies had invariably been applied where the proportion of isolates of a species tested against an antibiotic was <90%. As this proportion fell with increasingly selective policies, divergence from pooled-all-Wales non-selective estimates tended to increase, with a bias to increased resistance. CONCLUSIONS: Selective testing, rule-based reporting and urinary coliform identification policies all had significant effects upon resistance estimates. Triage based upon the proportion of isolates tested seemed a useful tool in assigning analysis resources. Where <20% of isolates were tested, selective policies with inherent bias to increased resistance were common, the low number of isolates gave high potential sampling errors, and little confidence could be placed in the resistance estimate. Where 20-90% of isolates were tested, detailed analysis sometimes revealed resistance estimates that might be usefully retrieved. Where >/=90% of isolates were tested, there was no evidence of selective testing, and inter-laboratory variation in estimates appeared to be safely ascribable to other effects, e.g. methodology or real variation in resistance levels.

Effectiveness of rugby headgear in preventing soft tissue injuries to the head: a case-control and video cohort study.

OBJECTIVE: To determine if headgear use by rugby players was associated with a reduced risk of head or facial laceration, abrasion, or fracture. METHODS: An emergency department based case-control study in South Wales, UK, with cases being rugby players treated for superficial head and facial injuries and controls being their matched opponents during the game. A review of videos of the 41 games in the 1999 Rugby World Cup was also carried out to compare with the case-control study. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to measure association between exposure (headgear wearing) and outcome (head and facial injuries). RESULTS: In the case-control study, 164 pairs were analysed, with headgear worn by 12.8% of cases and 21.3% of controls. Headgear use was associated with substantial but non-significant reductions in superficial head (OR = 0.43, 95% CI 0.13 to 1.19) and facial (OR = 0.57, 95% CI 0.21 to 1.46) injuries. The video study followed 547 players over 41 games, during which there were 47 bleeding injuries to the head. Headgear use significantly reduced the risk of bleeding head injury in forwards (OR = 0.14, 95% CI 0.01 to 0.99, p = 0.02), but not in backs. There was also a higher risk of facial injury among forwards, but this was not significant. CONCLUSIONS: The combined results suggest that headgear can prevent certain types of superficial head injuries in players at all levels of the game, but the evidence is strongest for superficial head injury in elite forwards. A randomised controlled trial would be the best way to study this further.

Risk factors for salmonella food poisoning in the domestic kitchen--a case control study.

Domestic kitchen food handling risk factors for sporadic salmonella food poisoning are largely unknown. We compared food consumption and food handling practices, opportunities for cross contamination and refrigerator temperature control, in 99 households in South East Wales in 1997/8 with a case of salmonella food poisoning, and control households matched for electoral ward. On univariate analyses, cases were significantly more likely than control respondents to have purchased free-range eggs in the preceding week, and more likely than control households to have handled frozen whole chicken in the previous week, and to handle raw chicken portions at least weekly. In multivariate analysis, only consumption of raw eggs and handling free-range eggs were significant risk factors, independent of the age structure of the family and of the season.

The seasonal distribution of campylobacter infection in nine European countries and New Zealand.

In all temperate countries campylobacter infection in humans follows a striking seasonal pattern, but little attention has been given to exploring the epidemiological explanations. In order to better characterize the seasonal patterns, data from nine European countries and New Zealand have been examined. Several European countries with weekly data available showed remarkably consistent seasonal patterns from year to year, with peaks in week 22 in Wales, week 26 in Scotland, week 32 in Denmark, week 30 in Finland and week 33 in Sweden. In Europe, the seasonal peak was most prominent in Finland and least prominent in Scotland and Austria. In New Zealand the seasonality was less consistent since the peak was more prolonged. Possible explanations for the seasonal peaks are discussed. Research into the causes of campylobacter seasonality should help considerably in elucidating the sources of human infection.

Development and use of a population based injury surveillance system: the all Wales Injury Surveillance System (AWISS).

This report details the development and use of a population based emergency room surveillance system in the UK. Despite some difficulties in accessing high quality data the system has stimulated a considerable number of research and intervention projects. While surveillance systems with high quality data collection and coding parameters remain the gold standard, imperfect systems, particularly if population based, can play a substantial part in stimulating injury prevention initiatives.

Short report: Is regional paediatric surveillance useful? Experience in Wales.

The Welsh Paediatric Surveillance Unit was established in 1994 to monitor the incidence and prevalence of a number of uncommon disorders of childhood in Wales. Its work complements that of the British Paediatric Surveillance Unit. Information from consultant paediatricians is obtained by means of a monthly card return system; return rate is over 90%.