There are many bacteria that we know very little about but still exist in our bodies. H. pyloriCan cause stomach problems but most people have asymptomatic. Simply put, a mutual symbiosis has been established between us and them, with the difference that if the deal goes wrong they can hurt us or even kill us.

The average lifespan of a bacterium is about 20 minutes. But during this short-lived existence, a bacterium is capable of many things. Welcome to the world of opportunistic bacteria that are there without a problem until they see opportunity and ruin everything for you.

we are more than them

First of all, we must assume that bacteria are a part of us. So intricately it’s hard to decide if we’re more them than we are. Because we have 25,000 genes in our cells, but we have 20 times more genes. non-human genes comes from bacteria. Not in vain, there are as many human cells in our body as bacterial cells. According to the book’s author, Ed Young I contain many:

Humans have 1 cell bacteria for each of us, but they are lighter because they are significantly smaller. In total, the 39 billion calculated in recent estimates is equivalent to 1 or 2 kilos at most.

Also, bacteria are ubiquitous. Although they are only five micrometers long (five millionths of a metre), they represent one of the oldest, most resilient and widespread forms of life on our planet. To give you an idea of ​​its existence: we can find ten thousand bacteria in a simple grain of dust.

Therefore, they are not easy to destroy. They are an integral part of our body. In fact, if we destroyed them, we wouldn’t be able to survive because there are bacteria that are harmful to health, but others are helpful. Therefore, even after a shower or bath, we cannot destroy bacteria and other microbes that nest in our bodies: they can actually increase, because water itself carries bacteria, as Bill Bryson explains in your book. Human body. And antibacterial soaps? The problem with these soaps is that they kill bad bacteria as well as good bacteria on the skin. The same goes for hand sanitizers.

Fortunately, most of these bacteria are beneficial. Of the nearly one million microbes identified to date, only 1,415 are known to cause disease in humans, accounting for just one-third of all deaths worldwide.

opportunistic infections

Some of the infections that bacteria can cause us are due to a problem in our immune system rather than them. In other words, they are bacteria that live peacefully with us as long as we have a healthy immune system, but can attack us ruthlessly if something changes this situation. These are called “opportunistic infections.” As if we left the door of our castle open, the bacteria somehow seize the opportunity.

Here are some of the opportunistic bacteria that seem peaceful until we make it too easy for them:

• Clostridioides difficile. It colonizes the intestines of a small proportion (less than 5%) of healthy people. The disease caused C. difficile It usually occurs after taking antibiotics. It is transmitted from person to person by the fecal-oral route.

C. difficile growing on a blood agar plate.

Some people are carriers of bacteria. C. difficile in the intestines, but they never get sick. These are carriers of bacteria and can spread infections. Advanced age is a risk factor. In one study, the risk of contracting an infection C. difficile It was 10 times higher in people aged 65 and over than in younger people. To prevent this type of infection, therefore, it is usual to recommend hand washing and avoid using antibiotics when absolutely not necessary.

• Legionella pneumophila It is a bacterium that causes legionellosis or Legionnaires’ disease. It is a water-dwelling bacterium that reproduces at temperatures between 25°C and 45°C. Some infected individuals may have mild or no symptoms at all. About 5% to 30% of people who get legionellosis die, especially if antibiotic treatments are delayed. It is estimated that between 8,000 and 18,000 people have legionellosis each year in the United States.

• Pseudomonas aeruginosa It is a type of aerobic bacteria that is opportunistic in humans and plants. P. aeruginosa It is often pre-identified in vitro by its pearly appearance and grape-like odor and is often transmitted in hospital settings. These bacteria infect the blood, skin, bones, ears, eyes, urinary system, heart valves and lungs, as well as wounds (such as burns, injuries or surgical wounds).

The use of medical devices such as catheters placed in the bladder or veins, breathing tubes and mechanical ventilators increases the risk of infection. Sometimes the origin of the bacteria is unknown, as can happen in people who have too few white blood cells (leukocytes) in their blood after using chemotherapy for cancer treatment.

• staphylococcus aureus It is an anaerobic bacterium that is estimated to be present in one in three people, but this does not necessarily mean that they are infected. Usually harmless, but opportunistic and can sneak in and wreak havoc when the immune system is weakened.

Currently, this microorganism is the main cause of nosocomial infections, that is, those transmitted from patients admitted to a healthcare facility. This is facilitated by the fact that this species lives on both the mucous membranes and the skin of humans, allowing it to enter the patient’s bloodstream either directly from surgical wounds or through indirect contact with medical personnel, a contaminated object, or even another person. patient.

The S. aureus bacterium escapes destruction by human leukocytes.

• Escherichia coli It is a bacterium that is a member of the Enterobacteriaceae family and is part of the microbiota of the gastrointestinal tract. The way they reproduce and mutate is particularly surprising. Unsurprisingly, it can reproduce 72 times in a day, meaning that in three days it can accumulate as many new generations as we have achieved in the entire history of mankind. Theodor Escherich, the discoverer of Escherichia coli, once said: “It seems like a pointless and dubious exercise to study and explain the apparently random presence of bacteria in normal stool and intestinal tract. coincidences.”

• Helicobacter pylori: At the beginning of the 20th century, Helicobacter pylori It was the dominant microbe in almost everyone’s stomach. At the beginning of the 21st century, less than 6% of children in the United States, Sweden and Germany carried this organism. Several factors play a role for this decline, but antibiotics may be the main culprit.

Its eradication may affect the regulation of two hormones produced in the stomach that play a role in energy balance, ghrelin and leptin. And how H. pylori disappeared from people’s stomachs, there was an increase in gastroesophageal reflux and associated problems such as Barrett’s esophagus and esophageal cancer. People who do not have the bacteria are also more likely to develop childhood asthma, hay fever, or skin allergies. However, having it is also a risk if we have a weakened immune system: it causes hemorrhagic diarrhea and can sometimes lead to kidney failure and even death.

Helicobacter pylori, seen under the electron microscope, shows numerous flagella on the cell surface.

In addition to all the bacteria listed, about 4 in 10 women are given antibiotics during childbirth, meaning doctors are fighting babies’ germs as babies start getting them. We have no idea what the long-term health consequences of this might be, but they are unlikely to be good.

In fact, there are currently concerns that some beneficial bacteria are in danger of extinction. Bifidobacterium infantisAs Ed Young explains, an important microbe in breast milk is found in 90% of infants in developing countries, compared to only 30% in the developed world.

Research is also being done to find out if people behave differently after taking certain doses of antibiotics or probiotics. In one of the most promising studies, Kirsten Tillisch found that women who ate a serving of microbe-rich yogurt twice a day showed less activity in parts of the brain involved in processing emotions, compared to women who ate yogurt products.

The meaning of these differences is still a matter of debate, but they at least show that bacteria can influence human brain activity. The real test will be to show us that bacteria can help people cope with stress, anxiety, depression and other mental health issues. There are already some signs of success. Stephen Collins has completed a small clinical trial of a probiotic bacterium. reduces symptoms of depression in people with irritable bowel syndrome.

There is strong evidence that microbes in the female reproductive system affect reproductive health and help protect against disease. Finally, 80% of the air we breathe is nitrogen. For nitrogen to be useful to us, it has to take other forms like ammonia, and it’s bacteria that do the work for us. Without their help, the human species might not even exist.

So what are we going to do with them?

We are home to billions and billions of microscopic entities that are surprisingly beneficial to us, but also make us sick. They provide us with about 10% of our calories. by breaking down foods that we would not otherwise benefit from but could also kill us.

We both love and hate bacteria. So what can we do with them? Do they roam freely? kill them? A compromise solution might be to slow down dangerous bacteria, which may be more effective than killing them.

According to the researchers who suggested this solution: “We don’t need to kill bacteria to treat diseases and infections; we can simply reduce their speed and make them less powerful. That way, there’s very little chance of developing any resistance.” Whatever happens, they’re going to stay with us there because without them we wouldn’t be us.