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Some information about toothbrushes and bacteria. From Science Daily:

Clean before you clean: What's on your toothbrush just might surprise you

Do you know Staphylococci, coliforms, pseudomonads, yeasts, intestinal bacteria and -- yes -- even fecal germs may be on your toothbrush?

Appropriate toothbrush storage and care are important to achieving personal oral hygiene and optimally effective plaque removal, says Maria L. Geisinger, DDS, assistant professor of periodontology in the School of Dentistry at the University of Alabama at Birmingham.

"The oral cavity is home to hundreds of different types of microorganisms, which can be transferred to a toothbrush during use," Geisinger said. "Furthermore, most toothbrushes are stored in bathrooms, which exposes them to gastrointestinal microorganisms that may be transferred via a fecal-oral route. The number of microorganisms can vary wildly from undetectable to 1 million colony-forming units (CFUs). Proper handling and care of your toothbrush is important to your overall health."

What constitutes proper care and handling? Geisinger answers several questions that may help better protect families from toothbrush germs.

Q. Can bacteria from your toilet really reach your toothbrush?

A. "The short answer is 'yes.' Enteric bacteria, which mostly occur in the intestines, can transfer to toothbrushes and thus into your mouth. This may occur through inadequate hand-washing or due to microscopic droplets released from the toilet during flushing. The topic of dirty toothbrushes was a recent subject of the popular Discovery Channel show "Mythbusters," when 24 toothbrushes were tested, and all of them demonstrated enteric microorganisms -- even those that had not been inside of a bathroom. In fact, toothbrushes may be contaminated with bacteria right out of the box, as they are not required to be packaged in a sterile manner."

Q. What is the proper way to clean your toothbrush to help remove germs?

A. "You should thoroughly rinse toothbrushes with potable tap water after brushing to remove any remaining toothpaste and debris. Additionally, soaking toothbrushes in an antibacterial mouth rinse has been shown to decrease the level of bacteria that grow on toothbrushes."

Q. How should you to store your toothbrush to avoid germ and bacteria buildup?

A. "The American Dental Association recommends that you not store your toothbrush in a closed container or routinely cover your toothbrush, as a damp environment is more conducive to the growth of microorganisms. Also, storing toothbrushes in an upright position and allowing them to air dry until the next use is recommended, if possible. If more than one brush is stored in an area, keeping the toothbrushes separate can aid in preventing cross-contamination."

Another reason to wash your hands before handling food. From The Scientist:

Money Microbiome

Analyzing the genetic material on 80 $1 bills sampled from a Manhattan bank, researchers from New York University (NYU) have discovered a diverse array of microbes, most of which are relatively harmless to humans, but a few that may leave you washing your hands after every cash transaction. It total, they found more than 3,000 bacterial types, including some drug-resistant species, and known microbes accounted for just 20 percent of the non-human DNA the researchers isolated; the rest belongs to as-yet unidentified species.

The most abundant species the researchers identified were those that cause acne, followed by benign skin flora. More alarming discoveries included pathogenic Staphylococcus species as well as bacteria associated with gastric ulcers, pneumonia, and food poisoning. The researchers also found DNA from antibiotic-resistance genes, such as those carried by the deadly methicillin-resistantStaphylococcus aureus (MRSA).

The researchers even found evidence of anthrax, although Carlton notes this shouldn’t necessarily be cause for concern. “Anthrax is a very common bacteria in soil."

Nevertheless, the microbial diversity identified highlights the likelihood that cash—one of the most common items to be distributed internationally—could spread disease around the world.2010 study that investigated currencies from 10 different countries, including Australia, China, the U.K., Ireland, Mexico, and the U.S., found similarly dirty money, and the authors recommended “that current guidelines as they apply in most countries with regard to the concurrent hygienic handling of foods and money should be universally adopted.”

Flatulence is good, and up to 18 a day is totally normal! From NPR:

Got Gas? It Could Mean You've Got Healthy Gut Microbes

We know that air often comes after eating nutrient-packed vegetables, such as cabbage, kale and broccoli. And researchers have found that fiber-rich foods, like beans and lentils, boost the levels of beneficial gut bacteria after only a few days, as we reported in December.

So all this got us wondering: Could passing gas, in some instances, be a sign that our gut microbes are busy keeping us healthyAbsolutely, says Purna Kashyap, a gastroenterologist at the Mayo Clinic in Rochester, Minn. "Eating foods that cause gas is the only way for the microbes in the gut to get nutrients," he says. "If we didn't feed them carbohydrates, it would be harder for them to live in our gut."

And we need to keep these colon-dwelling critters content, Kashyap says. When they gobble up food — and create gas — they also make molecules that boost the immune system, protect the lining of the intestine and prevent infections.

"A healthy individual can have up to 18 flatulences per day and be perfectly normal," he adds.

Gas gets into the digestive tract primarily through  two routes: Swallowing air (which we all do when we eat and chew gum) and your microbiome. That's the collection of organisms in the GI tract that scientists and doctors are currently all fired up about. (Check our colleague Rob Stein's recent series on it.) That microbiome includes hundreds of different bacteria. But there are also organisms from another kingdom shacking up with them: the archaea.

All these microbes are gas-making fools. They eat up unused food in your large intestine, like fiber and other carbohydrates we don't digest, and churn out a bunch of gases as waste. But that's not all they make. They also produce a slew of molecules (called short chain fatty acids) that may promote the growth of other beneficial bacteria and archaea.

And the more fiber you feed these friendly inhabitants, the more types of species appear, studies have found. "Undigested carbohydrates allow the whole ecosystem to thrive and flourish," Kashyap says. Most gas made by the microbiome is odorless. It's simply carbon dioxide, hydrogen or methane. But sometimes a little sulfur slips in there."That's when it gets smelly," Kashyap says.

But here's the hitch: Many of the smelly sulfur compounds in vegetables have healthful properties. Take for instance, the broccoli, mustard and cabbage family. These Brassica vegetables are packed with a sulfur compound, called sulforaphane, that is strongly associated with a reduced risk of cancer. Another possible benefit of a little smelly gas? It may reduce the total volume of air in the gut, Kashyap says. 

This study suggests another reason to avoid Triclosan. From Science Daily:

In lab tests, the antimicrobial ingredient triclosan spurs growth of breast cancer cells

Some manufacturers are turning away from using triclosan as an antimicrobial ingredient in soaps, toothpastes and other products over health concerns. And now scientists are reporting new evidence that appears to support these worries. Their study, published in the ACS journal Chemical Research in Toxicology, found that triclosan, as well as another commercial substance called octylphenol, promoted the growth of human breast cancer cells in lab dishes and breast cancer tumors in mice.

Kyung-Chul Choi and colleagues note that hormonal imbalances seem to play a role in the development of breast cancer. Given that link, researchers are investigating whether endocrine-disrupting chemicals (EDCs), which are compounds that act like hormones, might spur cancer cell growth. EDCs have become ubiquitous in products, in the environment and even in our bodies. Research has found that two EDCs -- triclosan, an antimicrobial ingredient in many products, including soaps, cosmetics and cutting boards; and octylphenol, which is in some paints, pesticides and plastics -- have accumulated in the environment. Additionally, triclosan is reportedly in the urine of an estimated 75 percent of Americans. Choi's team wanted to see what effect the two compounds have on breast cancer cells.

In tests on human breast cancer cells and in special immunodeficient mice with tissue grafts, the scientists found that both agents interfered with genes involved with breast cancer cell growth, resulting in more cancer cells. Mice that were exposed to the two compounds had larger and denser breast cancer tumors than the control group. "Although the doses of EDCs were somewhat high, we did this to simulate their effects of daily exposure, as well as body accumulation due to long-term exposure, simultaneously in animal experiments," said Choi. "Thus, exposure to EDCs may significantly increase the risk of breast cancer development and adversely affect human health," the researchers state in the paper.

Excerpts from a very interesting NPR interview with Dr. Martin Blaser and his views on the human microbiome. His recently published book is Missing Microbes: How the Overuse of Antibiotics is Fueling Our Modern Plagues. From NPR News:

Modern Medicine May Not Be Doing Your Microbiome Any Favors

There are lots of theories about why food allergies, asthma, celiac disease and intestinal disorders like Crohn's disease have been on the rise. Dr. Martin Blaser speculates that it may be connected to the overuse of antibiotics, which has resulted in killing off strains of bacteria that typically live in the gut.

Blaser is an expert on the human microbiome, which is the collection of bacteria, viruses, fungi and other microbes that live in and on the body. In fact, up to 90 percent of all the cells in the human body aren't human at all — they're micro-organisms. Blaser is the director of NYU's Human Microbiome Program and a former chairman of medicine there. His new book is called Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues.

"Since World War II, we've seen big rises in a number of diseases: asthma, allergies, food allergies, wheat allergy, juvenile diabetes, obesity. ... These are all diseases that have gone up dramatically in the last 50 or 70 years. One of the questions is: Why are they going up? Are they going up for 10 different reasons, or perhaps there is one reason that is fueling all of them."

"My theory is that the one reason is the changing microbiome; that we evolved a certain stable situation with our microbiome and with the modern advances of modern life, including modern medical practices, we have been disrupting the microbiome. And there's evidence for that, especially early in life, and it's changing how our children develop."

"There's a choreography; there's a normal developmental cycle of the microbiome from birth over the first few years of life, especially the first three years, [that] appear[s] to be the most important. And that's how nature has, how we have, evolved together so that we can maximize health and create a new generation, which is nature's great purpose. And because of modern practices, we have disrupted that. And then the question is: Does that have consequence[s]?"

"As far as we know, when the baby is inside the womb it is apparently sterile. ... The big moment of truth is when the membranes rupture, the water breaks, and the baby starts coming out. And that's where they first get exposed to the bacteria of the world, and the first bacteria they're exposed to is their mother's bacteria in the birth canal. So as labor proceeds, the babies are in contact with the microbes lining their mother's vagina and, as they're going out, they're covered by these bacteria. They swallow the bacteria; it's on their skin. ..."

"That's their initial exposure to the world of bacteria. That's how mammals have been doing it for the last 150 million years, whether they're dolphins or elephants or humans. ... And we know a little about what those bacteria are. The most common bacteria are lactobacillus and there's evidence that over the course of pregnancy the microbiome in the vagina changes, just as many other parts of the body are changing. The microbiome is changing in its composition in terms of maximizing lactobacilli, and these are bacteria that eat lactose, which is the main component of milk. So the baby's mouth is filled with lactobacilli. The first thing that happens is they go up against their mom's breast and they inoculate the nipple with lactobacilli and now milk and lactobacilli go into the new baby and that's the foundation for their microbiome and that's how they start their life. ..."

"You could project that if they didn't acquire these organisms or they didn't acquire them normally or at the normal time, then the foundations might be a little shaky."

"Shortly after birth, they compared the microbiomes in the babies that came out. The babies that were born vaginally, their microbiome, not surprisingly, looked like the mom's vagina everywhere in the body — in their GI tract, on their skin, in their mouth. But the babies born by C-section, their microbiome looked like skin and it didn't even necessarily look like the mom's skin, maybe it was somebody else in the operating room. So it's clear that the microbiome is different immediately depending on the kind of birth."

"What I can tell you is that our immune system is quite complex. There are many kinds of immune cells. There are cells that strongly recognize foreign substances, there are ones that try to damp [the immune system] and down-regulate it. There's what we call innate immunity, which is the immunity we're all born with, and then there's adaptive immunity — the immunity that develops when we experience different kinds of exposures. So it's very complex."

"There are many different probiotics.  I think I can say three things: The first is that they're almost completely unregulated; second is that they seem to be generally safe; and third is that they're mostly untested. ... I'm actually a big believer in probiotics; I think that's going to be part of the future of medicine, that we're going to understand the science of the microbiome well enough so that we can look at a sample from a child and say this child is lacking such-and-such an organism and now we're going to take it off the shelf and we're going to give it back to that child. ... "

An argument for the need for human exposure to the microbes in rural environments. However, the role of diesel exhaust and other urban air pollutants is not discussed here (for example, diesel exhaust is linked to asthma). From Science Daily:

Rural microbes could boost city dwellers' health, study finds

The greater prevalence of asthma, allergies and other chronic inflammatory disorders among people of lower socioeconomic status might be due in part to their reduced exposure to the microbes that thrive in rural environments, according to a new scientific paper co-authored by a University of Colorado Boulder researcher.

The article, published in the journal Clinical & Experimental Immunology, argues that people living in urban centers who have less access to green spaces may be more apt to have chronic inflammation, a condition caused by immune system dysfunction.

When our immune systems are working properly, they trigger inflammation to fight off dangerous infections, but the inflammation disappears when the infection is gone. However, a breakdown in immune system function can cause a low level of inflammation to persist indefinitely. Such chronic inflammation can cause a host of health disorders.

Some scientists have hypothesized that the increase of chronic inflammation in wealthier Western countries is connected to lifestyles that have essentially become too clean. The so-called "hygiene hypothesis" is based on the notion that some microbes and infections interact with the immune system to suppress inflammation and that eliminating exposure to those things could compromise your health.

The authors agree that microbes and some types of infections are important because they can keep the immune system from triggering inflammation when it's not necessary, as happens with asthma attacks and allergic reactions.

But they say the infections that were historically important to immune system development have largely been eliminated in developed countries. The modern diseases we pick up from school, work and other crowded areas today do not actually lead to lower instances of inflammatory disorders.

During our evolutionary history, the human immune system was exposed to microbes and infections in three important ways: commensal microbes were passed to infants from their mothers and other family members; people came into contact with nonpathogenic microbes in the environment; and people lived with chronic infections, such as helminths, which are parasitic worms found in the gut and blood.

In order for those "old infections" to be tolerated in the body for long periods of time, they evolved a mechanism to keep the human immune system from triggering inflammation. Similarly, environmental bacteria, which were abundant and harmless, were tolerated by the immune system. According to Rook, a professor at UCL, "Helminthic parasites need to be tolerated by the immune system because, although not always harmless, once they are established in the host efforts by the immune system to eliminate them are futile, and merely cause tissue damage."

In contrast, relatively modern "crowd infections," such as measles or chicken pox, cause an inflammatory response. The result is that either the sick person dies or the infection is wiped out by the inflammation and the person becomes immune from having the same infection again in the future.

Collectively, the authors refer to the microbes and old infections that had a beneficial impact on the function of our immune systems as "old friends." Exposure to old friends plays an important role in guarding against inflammatory disorders, the authors said. Because the "old infections" are largely absent from the developed world, exposure to environmental microbes -- such as those found in rural environments, like farms and green spaces -- has likely become even more important.

The authors say this would explain why low-income urban residents -- who cannot easily afford to leave the city for rural vacations -- are more likely to suffer from inflammatory disorders. The problem is made worse because people who live in densely populated areas also are more likely to contract crowd infections, which cause more inflammation.

Important to know about this nasty bacterial strain for those who use contact lenses. From Science Daily:

Bacteria survive longer in contact lens cleaning solution than previously thought, study shows

Each year in the UK, bacterial infections cause around 6,000 cases of a severe eye condition known as microbial keratitis -- an inflammation and ulceration of the cornea that can lead to loss of vision. The use of contact lenses has been identified as a particular risk factor for microbial keratitis. New research, presented today at the Society for General Microbiology Annual Conference in Liverpool, shows that a bacterial strain associated with more severe infections shows enhanced resistance to a common contact lens disinfectant solution.

Researchers from The University of Liverpool and The Royal Liverpool University NHS Trust tested different strains of the keratitis-causing bacterium Pseudomonas aeruginosa for their ability to survive in a commonly used contact lens cleaning solution. The team compared nine clinical strains of P. aeruginosa, taken from hospital patients in the UK, with P. aeruginosa strain 9027, the standard strain used by lens solution manufacturers.

The results showed that the majority of clinical strains tested were killed within 10 minutes of being immersed in the contact lens solution, comparable with the standard reference strain. However, one clinical isolate, P. aeruginosa strain 39016 -- associated with a more severe case of keratitis with a prolonged healing time -- was able to survive for over four hours, much longer than the reference strain.

Professor Craig Winstanley, who led the research, says: "Microbial keratitis can be devastating for a patient -- it is important that the risk of developing this condition is reduced in contact lens wearers by improving contact lens disinfectant solutions."

Another reason to avoid products with Triclosan. From Science Daily:

Antimicrobial from soaps promotes bacteria buildup in human noses

An antimicrobial agent found in common household soaps, shampoos and toothpastes may be finding its way inside human noses where it promotes the colonization of Staphylococcus aureus bacteria and could predispose some people to infection

Triclosan, a human-made compound used in a range of antibacterial personal care products such as soaps, toothpastes, kitchen surfaces, clothes and medical equipment, was found in nasal passages of 41% of adults sampled. A higher proportion of subjects with triclosan also had S. aureus colonization. S. aureus could promote infection in some populations such as people undergoing surgery.

Triclosan has been around for the past 40 years, says senior study author Blaise Boles, PhD, an assistant professor of molecular, cellular and developmental biology at the university, and has been incorporated into many antibacterial household products within the past decade. Other studies have found traces of triclosan in human fluids including serum, urine and milk, and studies in mammals have found that high concentrations of triclosan can disrupt the endocrine system and decrease heart and skeletal muscle function.

"It's really common in hand soaps, toothpastes and mouthwashes but there's no evidence it does a better job than regular soap," Boles says. "This agent may have unintended consequences in our bodies. It could promote S. aureus nasal colonization, putting some people at increased risk for infection."

Additional experiments found that S. aureus grown in the presence of triclosan was better able to attach to human proteins, and that rats exposed to triclosan were more susceptible to S. aureus nasal colonization.

This study reevaluates how far airborne pathogens in coughs and sneezes can travel. From MIT News:

In the cloud: How coughs and sneezes float farther than you think

The next time you feel a sneeze coming on, raise your elbow to cover up that multiphase turbulent buoyant cloud you’re about to expel. That’s right: A novel study by MIT researchers shows that coughs and sneezes have associated gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously realized.

“When you cough or sneeze, you see the droplets, or feel them if someone sneezes on you,” says John Bush, a professor of applied mathematics at MIT, and co-author of a new paper on the subject. “But you don’t see the cloud, the invisible gas phase. The influence of this gas cloud is to extend the range of the individual droplets, particularly the small ones.”

Indeed, the study finds, the smaller droplets that emerge in a cough or sneeze may travel five to 200 times further than they would if those droplets simply moved as groups of unconnected particles — which is what previous estimates had assumed. The tendency of these droplets to stay airborne, resuspended by gas clouds, means that ventilation systems may be more prone to transmitting potentially infectious particles than had been suspected.

With this in mind, architects and engineers may want to re-examine the design of workplaces and hospitals, or air circulation on airplanes, to reduce the chances of airborne pathogens being transmitted among people.

“You can have ventilation contamination in a much more direct way than we would have expected originally,” says Lydia Bourouiba, an assistant professor in MIT’s Department of Civil and Environmental Engineering, and another co-author of the study.

Indeed, the cough or sneeze resembles, say, a puff emerging from a smokestack.

“But by elucidating the dynamics of the gas cloud, we have shown that there’s a circulation within the cloud — the smaller drops can be swept around and resuspended by the eddies within a cloud, and so settle more slowly. Basically, small drops can be carried a great distance by this gas cloud while the larger drops fall out. "

Specifically, the study finds that droplets 100 micrometers — or millionths of a meter — in diameter travel five times farther than previously estimated, while droplets 10 micrometers in diameter travel 200 times farther. Droplets less than 50 micrometers in size can frequently remain airborne long enough to reach ceiling ventilation units.

A cough or sneeze is a “multiphase turbulent buoyant cloud,” as the researchers term it in the paper, because the cloud mixes with surrounding air before its payload of liquid droplets falls out, evaporates into solid residues, or both.

This exciting research opens a whole new way of thinking about the female breast and breast cancer. First of all, note that even our breasts have a microbiome (the microbial community). Key finding: the breast microbial population (specifically the bacteria) is different in healthy breasts (in the breast tissue) as compared to cancerous breasts. From Science Daily:

First look at breast microbiota raises tantalizing questions

The female breast contains a unique population of microbes relative to the rest of the body, according to the first-ever study of the breast microbiome. That study sought to lay the groundwork for understanding how this bacterial community contributes to health and disease, says first author Camilla Urbaniak, a PhD student at the University of Western Ontario. 

"Proteobacteria was the dominant phylum in healthy breast tissue," says Urbaniak, noting that it is found only in small proportions at other sites in the body. That may reflect the fact that breast tissue produces high concentrations of fatty acids, and these bacteria are fatty acid metabolizers. Proteobacteria is also the predominant phylum in human milk.

"The fact that beneficial bacteria, such as Lactobacillus and Bifidobacteria, were also detected makes us wonder whether their presence might be protective for both mother and child," says principal investigator Gregor Reid of the University of Western Ontario. Breast milk is one of the initial sources of gastrointestinal (GI) bacteria for newborns, and their GI microbiota are different if they are formula fed, says Urbaniak.

Conversely, Escherichia and Bacillus predominated in cancerous breasts.

"Strains of Escherichia have been shown to have mutagenic and carcinogenic activity in the gut and the bladder," says Urbaniak.

In the study, the investigators collected breast tissue from 81 women. Ten of these had undergone breast reduction, and their breast microbiota served as controls. The remaining women had had benign or cancerous tumors. The tissue collected from these women was taken from about five centimeters from the tumor, from what is known as "normal adjacent" tissue. Bacterial censuses were taken using a molecular technique known as 16S ribosomal sequencing, and with cultures.

Studies of the microbiome in other parts of the body, most notably the gastrointestinal tract, have shown that certain changes in bacterial populations can lead to a variety of ills, from obvious gastrointestinal conditions such as inflammatory bowel disease to those more unexpected, such as diabetes, obesity, cancer and even neurological conditions.

The complete reference: C. Urbaniak, J. Cummins, M. Brackstone, J. M. Macklaim, G. B. Gloor, C. K. Baban, L. Scott, D. M. O'Hanlon, J. P. Burton, K. P. Francis, M. Tangney, G. Reid.Bacterial microbiota of human breast tissueApplied and Environmental Microbiology, 2014; DOI: 10.1128/AEM.00242-14