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 Research shows that Streptococcus mutans, the bacteria that is a main cause of tooth decay or dental caries, is passed from mother to child, and also between nonrelative children. Any interaction that involves saliva, like sharing an ice cream cone or drinking from the same cup or straw as another child, can cause the microbes to be transferred. From Medical Xpress:

Research shows sharing of cavity-causing bacteria may not be only from mothers to children

New ongoing research from the University of Alabama at Birmingham Department of Biology and School of Dentistry is showing more evidence that children may receive oral microbes from other, nonrelative children. It was previously believed that these microbes were passed primarily from mother to child, but in a recent study presented at the American Society for Microbiology MICROBE 2016 Meeting in Boston, researchers found that 72 percent of children harbored at least one strain of the cavity-causing Streptococcus mutans not found in any cohabiting family members.

S. mutans is a bacterium that feeds on fermentable carbohydrates, in particular sucrose, that are frequently consumed by humans. After meals, S. mutans produces enamel-eroding acids, which makes S. mutans one of the main causes of tooth decay, or dental caries, in humans.

One hundred nineteen African-American children ages 12-18 months and 5-6 years who lived with at least one family member were a part of the study. The researchers collected samples from children periodically over the course of eight years. Momeni says that dental caries are more prevalent in minorities and low-socioeconomic groups.

"The literature tells us that we usually get this bacterium from our mothers," Momeni said. "This is because we most commonly have more interaction with our mothers when we are very young. However, our data supports that children who interact with other children at school or in nurseries can, and frequently do, contract this bacteria from each other." Momeni says any interaction that involves saliva, like sharing an ice cream cone or drinking after another child from the same cup or straw, can cause the microbes to be transferred.

Forty percent of the children in the study did not share any S. mutans strains with their mothers, and close to 20 percent of children shared these bacteria only with another child who lived in the household, such as a sibling or cousin. It is important to note that, for the strains of S. mutans not shared with anyone in the same household, approximately a third of the children had only a single isolate for a genotype, which could mean these rare strains may have nothing to do with the dental caries, and may be confounding the search for strains associated with the disease.

 The finding that the oral bacteria Streptococcus mutans, which is found in 10% of the population, is linked with hemorrhagic strokes is big. S. mutans is found in tooth decay or cavities (dental caries). The researchers found a link with cnm-positive S. mutans with both intracerebral hemorrhage (ICH) and also with cerebral microbleeds. Some risk factors for strokes have long since been known, such as high blood pressure and advanced age, but then there are those hemorrhagic strikes that don't seem to fit the norm, with no apparent risk factors. Well, apparently the presence of cnm-positive S. mutans is one. My understanding of what cnm-positive S. mutans means is S. mutans bacteria that carries the collagen-binding Cnm gene. This bacteria can be found in a person's saliva and in dental plaque, and swabs of both were taken for this study.

This study builds on other studies that find a link between the bacteria Streptococcus mutans and a number of systemic diseases, including bacteremia, infective endocarditis and hemorrhagic stroke. The researchers of this latest study suggest that infection with cnm-positive S. mutans causes constant inflammation (as shown by 2 inflammatory markers: CRP and fibrinogen), which then causes damage to blood vessels (endothelial damage) in the brain. Bottom line: take care of your teeth and gums. From Science Daily:

Oral bacteria linked to risk of stroke

In a study of patients entering the hospital for acute stroke, researchers have increased their understanding of an association between certain types of stroke and the presence of the oral bacteria (cnm-positive Streptococcus mutans).

In the single hospital study, researchers at the National Cerebral and Cardiovascular Center in Osaka, Japan, observed stroke patients to gain a better understanding of the relationship between hemorrhagic stroke and oral bacteria. Among the patients who experienced intracerebral hemorrhage (ICH), 26 percent were found to have a specific bacterium in their saliva, cnm-positive S. mutans. Among patients with other types of stroke, only 6 percent tested positive for the bacterium.

Strokes are characterized as either ischemic strokes, which involve a blockage of one or more blood vessels supplying the brain, or hemorrhagic strokes, in which blood vessels in the brain rupture, causing bleeding.

The researchers also evaluated MRIs of study subjects for the presence of cerebral microbleeds (CMB), small brain hemorrhages which may cause dementia and also often underlie ICH. They found that the number of CMBs was significantly higher in subjects with cnm-positive S. mutans than in those without. The authors hypothesize that the S. mutans bacteria may bind to blood vessels weakened by age and high blood pressure, causing arterial ruptures in the brain, leading to small or large hemorrhages.

"This study shows that oral health is important for brain health. People need to take care of their teeth because it is good for their brain and their heart as well as their teeth," Friedland said. "The study and related work in our labs have shown that oral bacteria are involved in several kinds of stroke, including brain hemorrhages and strokes that lead to dementia."

Multiple research studies have shown a close association between the presence of gum disease and heart disease, and a 2013 publication by Jan Potempa, Ph.D., D.Sc., of the UofL School of Dentistry, revealed how the bacterium responsible for gum disease worsens rheumatoid arthritisThe cnm-negative S. mutans bacteria is found in approximately 10 percent of the general population, Friedland says, and is known to cause dental cavities (tooth decay). Friedland also is researching the role of oral bacteria in other diseases affecting the brain.

Several interesting bacteria studies. Who knew that dental caries (tooth decay that causes cavities) is contagious? From Science Daily:

Bacteria can linger on airplane surfaces for days

Disease-causing bacteria can linger on surfaces commonly found in airplane cabins for days, even up to a week, according to research. In order for disease-causing bacteria to be transmitted from a cabin surface to a person, it must survive the environmental conditions in the airplane. In this study, MRSA lasted longest (168 hours) on material from the seat-back pocket while E. coli O157:H7 survived longest (96 hours) on the material from the armrest.

From Science Daily: Cavities are contagious, research shows

Dental caries, commonly known as tooth decay, is the single most common chronic childhood disease. In fact, it is an infectious disease, new research demonstrates. Mothers with cavities can transmit caries-producing oral bacteria to their babies when they clean pacifiers by sticking them in their own mouths or by sharing spoons. Parents should make their own oral health care a priority in order to help their children stay healthy.

From Science Daily: Physicians' stethoscopes more contaminated than palms of their hands

Although healthcare workers' hands are the main source of bacterial transmission in hospitals, physicians' stethoscopes appear to play a role. To explore this question, investigators assessed the level of bacterial contamination on physicians' hands and stethoscopes following a single physical examination. Two parts of the stethoscope (the tube and diaphragm) and four regions of the physician's hands (back, fingertips, and thenar and hypothenar eminences) were measured for the total number of bacteria present in a new study. The stethoscope's diaphragm was more contaminated than all regions of the physician's hand except the fingertips. Further, the tube of the stethoscope was more heavily contaminated than the back of the physician's hand.