The Science of Sourdough and How a Jar of Microbes Could Help Keep Your Bread Fresher Longer (McGill OSS)

7 minute read

Its catapult to popularity may have been triggered by the pandemic-induced yeast shortages, but even months later, when instant yeast is once again available at most grocery stores, sourdough’s contemporary stardom is barely starting to fade. Sure, many of us turned to making a sourdough starter to simultaneously combat yeast scarcity and our newfound fear of going to the grocery store. But lots of us have kept up with our strange new hobby of mixing water with flour and leaving it on the counter for reasons beyond just the practical.

Read the entire article here: https://mcgill.ca/oss/article/nutrition-technology/science-sourdough-and-how-jar-microbes-could-help-keep-your-bread-fresher-longer

No Need to Shave the World: Why Your Beard Is Not a Problem in the Age of COVID

6 minute read
originally posted here: https://mcgill.ca/oss/article/health/no-need-shave-world-why-your-beard-not-problem-age-covid

In 1843 a letter to the editor entitled “The growth of the beard medically considered” published in the Boston Medical and Surgical Journalargued that beards were medicinally beneficial, and that “the practice of shaving the beard, and thus depriving the face, throat and chest of that efficient protection which nature has provided” was responsible for the “numerous diseases of the respiratory organs with which mankind are afflicted.”

Yet, by 1916 beards had lost their safeguarding status. Edwin F. Bowers (who would go on to invent the pseudoscience of reflexology) wrote in an article for McClure’s Magazine that “there is no way of computing the number of bacteria and noxious germs that may lurk in the Amazonian jungles of a well-whiskered face, but their number must be legion.”

It was only two years later that the 1918 Spanish Flu pandemic hit, and any possible disease vector, including beards, was targeted in bids to quell the number of sick individuals. Given that we’re currently in the midst of what the United Nations is calling “a global health crisis unlike any” it seems inevitable that beards once again fall under the literal microscope as potential germ gardens.

Luckily, given the scientific advances that have taken place since the last few hundred years, we don’t need to rely on racially contentious observations like this one from 1843: “those nations where the hair and beard are worn long, they are more hardy and robust and much less subject to diseases, particularly of a pulmonary character, than those who shave.”

Let’s see what science has to say about how pathogenic your facial hair might be.

Does facial hair collect more germs than a smooth face?

The real question of hair’s cleanliness isn’t whether or not it can harbour microbes. Unfortunately, just like any other surface, it most certainly can. What we really care about is whether a beard contains more germs than a clean-shaven face.

A 1967 study saw four volunteers’ beards or clean-shaven faces sprayed with a bacterial solution and swabs taken from their skin 30 minutes and six hours after, either with or without letting them wash their faces with soap. They found that while there were more bacteria on clean-shaven faces than on beards before washing, more bacteria were removed by washing a clean-shaven face compared to washing a beard. So even though the beards didn’t accumulate more bacteria than the face, they did retain it through the wash.

A 2014 study reinforced the finding that facial hair doesn’t accumulate more bacteria than non-hairy facial skin. Researchers took swabs from the cheeks and upper lips of 199 healthcare workers who had facial hair and 209 who didn’t. The results showed that clean-shaved healthcare workers were actually more likely to harbour certain types of bacteria than their fur-faced coworkers. Similarly, a 2015 study of 118 mustachioed and 123 non-mustachioed men found that “nasal S. aureus [a bacterium] carriage is similar in men with and without a mustache.”

So even though beards may retain bacteria through a wash (highlighting the importance of washing your beard well), there’s no evidence that they accumulate or harbour larger bacterial populations than smooth faces.

Does facial hair spread more germs than a smooth face? 

The other piece of this facial hair puzzle is whether or not people with beards spread more microbes than those without. This question has been at the forefront of a debate over whether or not doctors, nurses, surgeons and other healthcare workers should be allowed to have facial hair. Some people fear that their beards and mustaches could be contaminated and lead to infected patients. Others worry that strict facial hair rules unnecessarily limit a doctor’s personal choices.

Part of why this debate rages on is due to some conflicting study results. A study published in 2000 by McLure et al. compared the bacterial shedding of 10 bearded, 10 clean-shaven and 10 female subjects. The researchers had the volunteers wear a surgical mask either while talking and moving their faces such that the mask “wiggled” around or while still. They held agar plates just below their chins to collect any bacteria that fell off and then cultured these colonies and quantitated them. The results showed that with or without mask wiggling, bearded subjects shed more bacteria than clean-shaven ones.

However, a 2016 study by Parry et al. using the same methods found no difference in the amounts of bacteria shed by bearded versus clean-shaven subjects regardless of whether they wore a surgical mask, a surgical mask plus a hood (shown below), or nothing.

Image source: http://www.healio.com/doiresolver?doi=10.3928/01477447-20160301-01

Unfortunately, this leaves us at the familiar scientific dead-end: more research is needed. Without another study, preferably one with a much larger sample size than the 30 and 20 of these trials, it’s difficult to know which results to trust. Both researchers present reasonable explanations for their results. McLure et al. suggest that beards “may act as a reservoir for bacteria and dead organic material which can be easily dislodged with movement of the face mask,” whereas the daily act of shaving helps to remove the “superficial layer of skin containing bacteria” and thus give clean-shaven men fewer microbes to shed.

On the other hand, Parry et al. suggest that daily shaving can cause micro-cuts on the face that can serve as hiding places for bacteria. They also pondered if their results could be due to beard lengths. They showed that longer beards shed less than shorter beards when the subjects wore masks and hoods, which they hypothesize is due to longer beard hair being less abrasive and therefore leading to fewer shed bacteria. Unfortunately, since McLure did not report their participants’ beard lengths, it’s not possible to know for sure.

But wait, what about viruses?

To throw another wrench in the interpretation of these results, allow me to point out that all these studies measured the amounts of bacteria on participants’ faces or beards. However, the current COVID-19 pandemic is being caused by a virus, not a bacterium. While this distinction may not seem important, there are a lot of differences between these two types of microbes: in particular, size! As you can see below, the size range for bacteria is roughly 500-5000 nanometres, but for viruses is only roughly 100-800 nanometres, making them quite a bit smaller. The SARS-CoV-2 virus (at the time known as 2019-nCoV) has been reported to be 60-140 nm in diameter, making it a particularly small virus, as viruses go.

Image source: https://www.researchgate.net/figure/Relative-sizes-of-major-host-cells-and-their-components-versus-those-of-bacteria-and_fig4_325937574

In the end, there’s no compelling evidence that beards foster bacteria, but we cannot really say if they do lead to increased bacterial shedding. And as far as viruses are concerned, we have no evidence at all.

The good news is, that if you’re practicing proper social distancing, washing your hands often and not exposing yourself to others unnecessarily, you and your beard are unlikely to encounter the SARS-CoV-2 virus at all. So, if you’re doing your part to flatten the curve by staying home, keeping your beard should be fine. However, healthcare workers should consider the role that their facial hair may play in transmitting microbes and take care to wash it very thoroughly whenever possible. However, I do expect that, given that many facial hairstyles can interfere with special masks called respirators, many have already done a spring shave.

Image source: https://www.cdc.gov/niosh/npptl/pdfs/FacialHairWmask11282017-508.pdf

You’re probably storing leftovers wrong (especially if it’s rice)

3 minute read
Originally posted here: https://mcgill.ca/oss/article/did-you-know-health/youre-probably-storing-leftovers-wrong-especially-if-you-eat-rice

If, like me, you aim to cook dinners that provide both your next day’s lunch as well as a freezer portion to be thawed at some future date, you may want to stop. At least with rice.

Uncooked rice can contain spores of Bacillus cereus, a bacterium that can cause two different types of food poisoning. The first type is characterized by vomiting (and thus is called the emetic form). It results from consuming a toxin produced by the bacteria while they’re growing in your food and has a short incubation time of 1-5 hours. The second is characterized by diarrhea (and is non-surprisingly called the diarrhoeal form). It results from a toxin that is produced in your small intestine as the bacteria grow there and has a longer incubation time of 6-15 hours.

The two forms are commonly associated with different types of foods. The diarrhoeal form has been linked with foodstuff like soupsmeatvegetablesand milk products including formula. The emetic form comes from a more limited list of culprits, as it’s mostly associated with starchy foods that have been improperly stored like rice, pasta, pastries or sauces.

But what does “improperly stored” actually mean?

If a raw food is contaminated with B. cereus (as much rice is) and then cooked, some spores will remain in the cooked product (unless you’re in the habit of heating your rice to above 100 ˚C for extended periods of time). These spores, If left standing in temperatures between 10 ˚C and 50 ˚C, such as on your stove or countertop, find themselves in their ideal environment (wet and warm) to germinate, grow and produce the toxin that will make you sick.

It doesn’t take long for the spores to reproduce either. A colony of B. cereuscan double in size within 20 minutes if kept at 30˚C. The routine reheating of your food will not help to deactivate the toxin or kill the bacteria. Since this bacteria and its toxin are so resistant to heat your only hope of dodging food poisoning is to avoid allowing the bacteria to germinate.

To sidestep a nasty bout of illness caused by B. cereus you should aim to eat your food as soon as possible after it is cooked. If you can’t do that, then hot foods should be kept above 60˚C and cold foods, below 5˚C. Meats and vegetables should be cooked to an internal temperature of 60˚C and kept there for at least 15 seconds. Frozen foods should ideally be thawed in the fridge or as a part of the cooking process.

If storing leftovers for later, they should be rapidly cooled in the fridge as fast as possible (according to the NHS, within 1 hour is best). You should avoid storing hot leftovers in deep dishes or stacking containers together, as it will cause the food to cool slower. When reheating leftovers make sure they reach an internal temperature of at least 74˚C and don’t keep them for more than seven days, even in the fridge.

When dealing with high-risk ingredients (like rice, grains and other starchy foods) it’s best to not keep leftovers at all. But if you do, try not to keep them for more than one day, and never reheat them more than once. Even freezingdoesn’t kill bacteria but rather just stops them from multiplying, so, by all means, freeze your leftover curry, but make fresh rice when it’s time to eat it again.

Considering the amount of improperly stored rice I now know I’ve eaten it seems almost a miracle that I haven’t gotten sick yet. Then again, food poisoning with B. cereus is often confused with the 24-hour flu, so I may have already paid for my mistakes without even knowing it.

Let’s all learn from my mistakes and start storing our leftovers properly.

Rust Doesn’t Give You Tetanus

1 minute read
Originally posted here: https://mcgill.ca/oss/article/did-you-know/rust-doesnt-cause-tetanus

Ever step on a rusty nail? It was, in all likelihood, rapidly followed by your parents dragging you to the doctor’s office for a painful (but safe!) tetanus shot. The memory of my first tetanus shot is preceded by an exploring an abandoned barn and getting cut by a stray wire fence. If it had happened in my own home it wouldn’t have even deserved a band-aid, but the threat of rust sent us to the doctor’s office.

But it turns out that injuries caused by rusty objects aren’t any worse than injuries caused by any other discarded object.

Tetanus, or lockjaw, is a bacterial infection caused by Clostridium tetani, an extremely hardy rod-shaped bacterium found in animal digestive tracts and soil worldwide. Tetanus is fatal in about 10% of cases but causes muscle spasms, fever and trouble swallowing in all cases.

The reason we associate tetanus with rust is because it’s often found in soil that’s rich in organic material like manure or dead leaves. Old houses, cars or other discarded items left in nature for long enough will rust (if they’re metal) and collect bacteria like Clostridium tetani, but the relationship between rust and tetanus-causing bacteria is purely correlative, not causative. Humans can be exposed to Clostridium tetani in a variety of non-rusty ways, such as when cleaning animal cages, when bitten by infected animals, or if exposed to contaminated heroin.

So if your skin is pierced from anything from your own kitchen knife to a rusty gnarled screw, or if you begin working on a farm, it’s worth making sure that your tetanus shot is up to date. After all, (in Canada at least) it’s free and lasts an entire decade.

Your Pet Cat May Be a Bit More Dangerous Than You Think

2 minute read
Originally posted here: https://mcgill.ca/oss/article/did-you-know-general-science/your-pet-cat-may-be-bit-more-dangerous-you-think

Cat scratch disease (CSD) is an infection resulting from a scratch or bite of a cat (or, in rarer cases, dogs or other animals). It is not the same thing as Cat Scratch Fever, an album by Ted Nugent, although CSD can cause a fever, as well as swollen lymph nodes, lethargy, neuroretinitis and headaches.

CSD is the result of an infection by Bartonella henselae, a bacterium commonly transmitted to cats via the cat flea (yes, cats and dogs usually have different fleas). Rarely, ticks and spiders can also carry the bacterium, and transmit it directly to humans.

Kittens are more likely to carry Bartonella henselae than adult cats due to their underdeveloped immune systems, and are much more likely to bite or scratch their owners while learning how to play gently. But anyone who is exposed to cats of any age should take care to clean any wounds well to avoid risk. Bartonella henselae can also be transmitted to humans via cats’ saliva, so as sweet as it may seem that Fluffy is licking your wounds for you, probably best to wash it and wear a Band-Aid.

For veterinarians, CSD is actually considered an occupational hazard. Vets are frequently in close proximity to many cats, oftentimes cats that are acting aggressively and are more likely to bite or scratch. One study found Bartonella DNA in 32 of the 114 veterinarian patients they tested.

CSD is diagnosed via blood test, or simply by considering the symptoms of the patient, the most obvious of which is a swollen blister or sore and red area surrounding the infected bite or cut. Those who are immunocompromised (such as patients with HIV), very young or very old are more likely to be infected, and rates of infection generally increase during spring in North America, likely due to the birth of many new kittens.

So while they may be as cute as anything, cats do still pose a risk to their owners, and not only because they may destroy your favourite furniture.

The kitty in the picture is named Jean-Charles and he is available for adoption from the Réseau Secours Animal in Monteal now!

Killer Tampons from Outer Space or Why We Don’t Hear About Toxic Shock Syndrome Anymore

5 minute read
Originally published here: https://mcgill.ca/oss/article/health-history/killer-tampons-outer-space-or-why-we-dont-hear-about-toxic-shock-syndrome-anymore

In the early 1980’s and 90’s toxic shock syndrome was on everybody’s mind. Its prevalence dominated headlines, inspiring fear in every tampon-using woman across North America. Young adults going through puberty were taught to watch out for toxic shock syndrome like it was hiding beneath every tampon wrapper.

My mom, going through puberty in the mid 80’s, was inundated with warnings to not leave tampons in too long and to always pay attention to new or unexplained rashes. But by the time I hit puberty in the early 2010’s the flood of warnings had slowed to a trickle. I was made aware that toxic shock syndrome was a risk, but also that it was rare, unlikely and treatable. Almost a decade later I don’t think I’ve heard the words toxic shock syndrome in years.

So what happened? How did people stop dying of toxic shock syndrome, or if they didn’t, why did we stop hearing about it?

What is toxic shock syndrome?

Toxic shock syndrome or TSS is an infection caused by Staphylococcus aureus, the same bacterium responsible for “staph infections” on the skin.S. aureusis normally present in human’s respiratory tracts and on their skin, but it’s what’s called an opportunistic pathogen. Given an opening (a compromised immune system or an injury on the skin),S. aureuswill infect its host, causing all sorts of nasty effects from pimples to pneumonia.

TSS is a condition resulting from an S. aureus infectionIt can occur because S. aureus contain what are called superantigensAntigens are substances that T-cells (a type of white blood cell and main player in our immune systems) bind to. Normally, some T-cells bind to antigens and then display them on their surface, to show other T-cells that the infection is being dealt with. Superantigens, however, skip this displaying step, causing more T-cells than usual (or necessary) to be activated.

These activated T-cells then go on to release cytokines, little proteins that cause inflammation. Normally, inflammation is actually a good sign. It’s the result of the body increasing blood flow to an injured area in order to heal it. But too many T-cells release too many cytokines which cause too much inflammation in a process called a cytokine storm. As the name suggests, it’s not good. Cytokine storms are associated with fevers, fatigue, nausea, rashes, diarrhea and dizziness, which are also the symptoms of TSS.

TSS is a tampon disease, right?

In 1983 over 2,200 cases of TSS were examined, and it was determined that 90% of the patients were menstruating when they fell ill. Of these menstruating patients, 99% of them were using tampons.

But TSS is not exclusive to tampons. It was first identified in five non-menstruating boys and girls in 1978. From 2001 to 2011 there were 11 cases of TSS associated with bandages used to treat burns in children, and in 2003, a man died as a result of TSS after having tattoo work done.

It’s estimated that 25-35% of TSS cases are unrelated to menstruation. These cases of nonmenstrual TSS can be caused by S. aureus or by Streptococcus pyogenes, and have a mortality rate 6 to 12 times higher than menstrual TSS. While the incidence of menstrual TSS has fallen sharply since its heyday in the 80s, the incidence of nonmenstrual TSS has remained essentially constant.

If nonmenstrual TSS is more prevalent and more dangerous, why do we only associate TSS with tampons?

Well for one, because the nonmenstrual TSS is still fairly rare. With an incidence rate of 2-4 cases per 100,000 people, nonmenstrual TSS is less common than dysentery (5.39 cases per 100,000) or Lyme disease (8.3 cases per 100,000).

Mostly, though, we don’t hear about nonmenstrual TSS because of the epidemic of menstrual TSS that took place in the early 80s.

Modern tampons were first patented in 1931, but not produced until Gertrude Tendrich bought the patent in 1933. They didn’t rise to mainstream popularity until WWII when women entering the workforce began to use them en masse.

Those tampons, marketed largely by the same brands as today (Tampax and o.b.), were made of cotton and rayon and were fairly similar to the tampons of today. One brand, however, decided to explore other materials to make their tampons more absorbent.

Rely tampons utilized compressed polyester beads and carboxymethylcellulose instead of cotton. These tampons were super-absorbent, holding nearly 20 times their own weight in blood, and opened inside the vagina to form a sort of cup to help prevent leakage. While these sound like fantastic features for a tampon, they turned out to also be fantastic features for a bacterial infection. 

Menstrual blood is not as acidic as the vagina normally, so during menstruation the pH of the vagina is raised, which can hinder its ability to kill bacteria. But that shouldn’t matter, so long as there are no cuts inside the vagina for bacteria to enter, right?

Well, the super-absorbent nature of Rely tampons meant that the vagina was left much dryer than usual. This caused tiny ulcerations to form when tampons were inserted or removed, giving bacteria the opening they needed. Couple this with the fact that people could leave Rely tampons in for longer (thereby maximizing the bacteria’s time to grow and infect) and you have the epidemic of TSS that occurred in 1980.

Rely tampons were recalled on September 22nd 1980, but cases of TSS kept occurring. It wasn’t until 1984 that researchers realized that TSS was associated with the use of any high absorbency tampon, cotton or polyester.

I don’t want TSS! What should I do?

First, don’t panic. TSS is really rare. While several high profile cases of TSS have occurred recently, the rates of TSS are lower than ever.

Tampon companies and government agencies have worked together to identify a strategy of use that minimizes your risk. Their recommendations are as follows:

  1. Use the lowest absorbency tampon that you can.
  2. Change your tampon every 4-8 hours.
  3. Wash your hands before inserting a tampon.
  4. Do not use tampons when you’re not on your period.

Can’t I just use a menstrual cup to avoid any risk of TSS?

Menstrual cups lessen the risk of TSS, but they don’t eliminate it. While it’s true they don’t absorb any blood, and therefore don’t cause vaginal dryness leading to ulcerations, they can be really difficult to put it, especially for new users, leading to scratches or cuts on the vaginal wall.

Case in point, a 37-year-old woman was diagnosed with TSS in 2015 after using a menstrual cup for the first time.

If you’re not going to change your tampon every 8 hours, you should consider a menstrual cup. They are approved by Health Canada to stay in the vagina for up to 12 hours at a time, making them great options for those who work 8-hour days or are just forgetful.

But do still remember to wash your hands before inserting the cup, and make sure to sanitize it between cycles.

If you’d like to learn more about TSS, click here for a short but very informative video.

Did you know that some bacteria can eat cleaning products?

Originally posted here: https://mcgill.ca/oss/article/did-you-know-technology/did-you-know-some-bacteria-can-eat-cleaning-products

Have you ever noticed the message on the front of a Lysol bottle: “Kills 99.9% of viruses and bacteria”?

Well, that 0.1% is causing NASA some real issues. In order to prevent our organic matter from infiltrating other planets, and vice versa, NASA aims to provide what they call “planetary protection.” If a bacterium from Earth made it to Mars it may severely hinder any chance we have of finding native Martian life, so NASA takes every precaution to prevent cross-planetary contamination.

Hence the need for cleanrooms, inside which visitors must wear a face mask, hood, booties and coveralls, and still can’t come closer than several feet away from the probes and rovers contained within.

But despite everyone’s best efforts, some bacteria will always be present. Specifically, the bacteria that are the most hardy, having survived many rounds of chemical and UV cleansings.

In an environment that clean, however, these bacteria can’t dine on their usual fare of decaying plant and animal matter. So, in order to survive, they’ve actually developed the ability to eat the cleaning materials!

One study showed that Acinetobacter bacteria, a particularly persistent and troublesome bacterium for hospitals, is able to survive on only ethanol and can degrade cleaning products. These troublesome microbes are resistant to radiation, hydrogen peroxide, high pressures and high temperatures.

In 2014 Koichi Wakata, a Japanese astronaut, proved that microbes are making it to space. He swabbed fifteen surfaces around the International Space Station and brought them back to Earth. From these swabs more than 12 000 microbes were identified!

It is important to remember though that the vast majority of these, just like the majority of microbes on your skin, phone and counter, are totally harmless. If even NASA’s cleanrooms can’t be microbe free, your home will never be either, and that’s ok.