Mecanismos de transmisión de bacterias que podemos reducir


In a conventional handshake we share
around 124 MILLION forming units of bacterial colonies.
If instead of doing that, you high 5, only around 40% of the handshake bacteria are transmitted. If you make a greeting “fists”, less than 10% of the bacteria from a handshake is transmitted No, I haven’t made up the numbers … and when I say 124 million units of formation of
bacterial colonies, we are not even counting “all bacteria”, just
the bacteria that could still breed.
And will that be too much, way too much? Should I be worried? Is it true what they say about
humans being more bacteria than actual human cells? Colleagues interested in forming opinions
based on scientific evidence and hard data. Welcome … I am Science Reyes, I mean …
Cinthia Reyes … Perhaps you have ever heard that
microbes that survive in and around our body are more numerous than our
own cells, in fact the popular number says there are 10 bacteria per human cell
… If you have ever doubted this saying, let me tell you that…. you were right, it is
exaggerated! An analysis you find in an open access article
published in 2016 in Plos Biology magazine estimates that for a
70 kilogram man, the cell count in his entire body should be around
3 x 10 ^ 13 cells. This is not a simple estimate because the
density of your lungs is not the same as the density of your bones, they are different cells
and structures, which also differ from muscle cells. and body fat …
Anyway, this article approximates that the number of bacteria of that same reference subject
should be 3.8 x 10 ^ 13 … So it’s not a 10 to 1 ratio, it’s about 1 bacterium per 1 human cell …
so partially yes, we are a set of walking bacteria …
If for a moment you came up with the idea: ah, so that’s why I can’t lose weight …
sorry to disappoint you, the bacteria in the same reference subject would have a “dry” weigh of around
200 grams … the heaviest part of our bodies, in general are the bones
and muscles You are probably wondering: and where
are all those bacteria? why don’t we live sick? Isn’t bath supposed to get rid of those? For starters, not all bacteria make us sick.
Many bacteria are indeed necessary for our digestive processes and that’s why
most of them are concentrated in the colon. That’s why maybe you had already heard commercial products that claim to help your intestinal flora or
keep a “healthy microbiota in your intestine ”… some of these bacteria
help us synthesize compounds like the vitamin K2 or some types of vitamin B. There are bacteria that live for example in the
surface of our skin, which do not help us but they don’t make us sick either. I commented a very specific case
of this type in the video about the antiperspirants, in relation to the
sweat smell. With so many bacteria involved in our
life, it’s important to know what to expect of them … that’s why there have been initiatives
as the Human Microbiota Project that worked between 2007 and 2016. This project had
by objective to sequence the genes of the microbes that typically live in our mouth, skin,
nose, digestive tract, etc. Thanks to this project, we now know that some bacteria
of the mouth are associated with atherosclerosis and other cardiovascular problems.
In fact, just at the beginning of last year, Nature magazine published about a
recent finding of almost 2000 new species of bacteria in the intestines of humans
that had not been previously identified. So, should we worry or not
about bacteria? You may not remember it, but in this
video I talked about the advantages of changing to silicone sponges, because of the bacteria encountered in regular sponges. In the case of our body, it is estimated that
one third of the bacteria that travel with us, as the are concentrated in our
colon … are discarded, when the colon discards … in the bathroom … and at least I ran into a
2005 study in which they say that 49% of the discarded bacteria remain intact.
If we have learned anything from the historical cholera epidemic events, influenza
and other pathogens throughout history, is that hygiene and the transmission of pathogens should not be ignored. At the beginning of the 20th century, during industrial revolution, life expectancy was below 50 years in almost every place in the world where we have data It was the discovery of penicillin, and
its subsequent purification to produce it massively in 1945 what marks the beginning
of the era of antibiotics with which we begin to defend ourselves against bacteria
pathogens. Life expectancy, according to the CDC in the United States in 2017 is
estimated at an average of 78.6 years. Before the discovery of penicillin,
there is a lot of literature that points out that we already knew that soap washing processes helped
to reduce the spread of diseases. Today, even with antibiotics, the ideal situation
is not to need them and not to abuse their consumption. Therefore, hygiene issues that
allow us to reduce the transmission of bacteria are still important.
In some previous videos I already talked a little bit about how soaps work to
remove the dirt (and I have not forgotten that I still owe you a video on this topic) …
but an important step in the washing to which sometimes we don’t give so much importance is drying.
The transmission of bacteria is easier in wet surfaces rather than dry surfaces.
Hence, drying our hands after washing them well is very important. What is better to dry our hands? Towel
cloth, paper, air dryer? To answer this question, I rely on a
article that makes an analysis of 12 different studies that had already been
published in scientific journals. In these 12 studies, the researchers analyzed
the effectiveness of the type of drying with respect to: drying speed, drying level, removal
of bacteria and prevention of crossover contamination. The following options were compared: Dry hands with paper
With cloth towels With hot air dryer, which can
be operated with a switch or a proximitysensor And a new type of dryer they call “jet air dryier” that does not heat the air, but
makes it go through a filter. Drying efficiency
The most efficient method of all is: drying with towel
After 10 seconds of towel drying, the remaining moisture in the skin was reduced
in the experiments up to 4%, at 15 seconds with the towel, drying managed
reach up to 1% humidity. Hot air drying required 45 seconds
to lower the moisture in the skin to 3%. Drying with paper or
“Jet air dryer” machines drying, would lowers moisture in the skin up to 10% in ten secons.
BUT … we must emphasize that researchers also took into account
how long did people last drying their hands. On average, men dry for 3.5 seconds
in cloth towels and 17 seconds in hot air dryers Women dry for 5.2 seconds on towels of fabric and 13.3 seconds in hot air dryers. And as I had told you, the hot air dryers
were slower, they are not a very useful method considering the
drying time for average men (according to these experiments) … in
contrast, drying with paper or towel even with reduced times, for both sexes you can
achieve up to 90% drying. In terms of bacteria count,
In one of the studies that were reviewed, the researchers used a method to count the amount of bacteria on hands before and after using
paper towels, hot air and jet air spryer …
Paper towels are the ones that reduce the more bacteria left
in the hands. Hot air dryers do not reduce …
in fact, they increase the count of bacteria that people have.
The jet air dryers, also increase the bacteria count, but less
than hot air dryers. These experiments were done with new equipment, so the reason why there is more bacteria after using the dryers,
is not that the dryers were “contaminated.” But in another one of the studies it actually turned out
that the hot air dryer was the most effective to remove rotavirus (which are the type of virus that makes us sick with the flu), Escherichia colli … and here, the worst method of all was the cloth towel. There are studies where there is no statistically significant difference
between the different methods. There are studies where the friction of the hands
during drying actually increases the count of bacteria, other where the paper towel
is better in terms of friction in the fingers to reduce bacteria but not in
hand palms … Now, about cross contamination …
Public restrooms are places where it occurs because when you flush it:
there is a turbulent flow that results in Spray fluid can be spread
to move around an area of up to 6 square meters, and of course this spray can
contain pathogenic bacteria (that’s why it is recommended to lower the lid before flushing it,
and that is why some people recommend not having the toothbrush always exposed,
there in the bathroom sink). In this case, the hot air dryer
seems to be the champion … the champion in dispersing bacteria while paper towels
don’t have that problem. And there will be other variables in specific cases, depending on whether there is air conditioning in place or not … You will notice that there is not a very clear agreement …
and so it happens sometimes in science … starting with the fact that not all researchers follow
the same protocol. Finally, the conclusion of those who reviewed
these studies, points out that the highest amount of evidence evaluated and available from the
bacteria transmission point of view makes us think that the best choice is:
To dry our hands with paper towel. After watching this video it doesn’t come as surprise that hands washing is usually a prevention measure for several different diseases as we also mention on
influenza and a recently appeared disease I won’t mention ’cause it’s being censored. Remember you can
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