Why bacteria are not bad

Sakshi Sharma and Jyoti Vakhlu
Human being can be defined biologically as living organism developed from a fertilised egg that contains genes contributed by both – father and mother. A growing band of biologists, however, find this definition incomplete. They see human beings not just as individuals, but as a habitat (ecosystem). In their view, the descendant of the fertilised egg is merely one component of the human system. The other component is trillions of microbes which are the smallest living beings, not visible to naked eye and can only be seen with a microscope. These microbes, each equally an individual, are found in a person’s gut, his mouth, his scalp, his skin and all of the crevices and orifices that subtend from his body’s surface. Microbes can creep into our bodies in many different ways without getting noticed. Microbes reside on human body the way humans reside on earth, with an only difference that human being are important for the health of earth, in fact,  contrary is true. The four main types of microbes are bacteria, viruses, fungi and protozoa. The ones that need to be washed away regularly, called as ‘keetanu’ (bad microorganisms), are just a fraction of the total microorganism associated with the human body. Bacteria have always been considered villains to human health as they cause a number of serious diseases such as pneumonia, meningitis, strep throat, food poisoning and many more. These bad bacteria are the reason why we attentively disinfect our hands and wipe down our kitchen and washrooms, as well as any other places where microbes tend to congregate. We also have developed a wide range of antibiotics and disinfectants, which are drugs designed to kill the bacteria that cause disease. Of course, all this is important to stay healthy and clean, but surprisingly over-cleaning and disinfection may also lead to health challenges as 99% of microbes associated with human beings are important for a healthy human life. Same is true of other living beings but the focus of present article is effect of bacteria on human health.  The reason that bacteria are viewed as bad is, because scientists initially never thought that bacteria can be responsible for anything good. This is a result of flawed perception.
It has been now established scientifically that human body contains over 100 trillion microbial cells, that’s 10 times the number of human cells. How can body hold that many microbial cells? Don’t forget how tiny they are: a single microbe is one-thousandth the size of a regular human cell. Not only do we live in harmony with these beneficial microbes, but they are actually essential to our survival. The microbes associated with human body are referred collectively as Human microbiome and the collective genome of these microbes is now thought to be ‘second human genome”.  Any human being receives his first dose of microbes during his birth. The foetus inside mother’s womb is considered free of microbes. Immediately after birth, microbes enter the newborns’ bodies. Depending on how and where the birth occurs, newborns are colonized by different types of microbes. During natural childbirth babies are covered in a film of microbes as they pass through the birth canal. Babies delivered by caesarean section are colonized by a very different set of species, mainly by environment and skin microbes. So babies who are born at home are exposed to different types of microbes than babies born in hospitals. These very first differences-vaginal vs. c. section birth, home vs. hospital are measurable and have long lasting impact on human health. After birth, babies pick up microbes from the environment to which they are exposed and by breastfeeding. Humans do not produce all the molecular tools (enzymes, vitamins antibodies) that are required by them to survive. They are dependent on microbes for these functions.  Human being can not digest the food they eat on their own. Good bacteria help our bodies digest food and absorb nutrients, and they produce several vitamins in the intestinal tract-including folic acid, niacin, and vitamins B6 and B12. They also help turn what’s left over into waste. Beneficial bacteria may also protect us against their dangerous relatives that cause disease, by crowding them out in the gut, producing acids that inhibit their growth, and stimulating the immune system to fight them off. Researchers have been studying good bacteria more thoroughly in recent years. When helpful bacteria multiply and thrive in our bodies, they act as our protectors. But sometimes, we put the population of beneficial bacteria at risk. Some diseases may be the result of disturbance of the microbial community. In this case, the symptoms are not caused by a particular microbe, but by altered proportions of various normal inhabitant microbes or altered behaviours of the inhabitant microbial communities under conditions of stress. For example, the discomfort that many people experience after taking broad-spectrum antibiotics is the result of a disturbance of the normal microbial community in the gut that leads to gastrointestinal inflammation and diarrhoea, and sometimes sets the stage for infections by harmful bacteria. Scientists believe that using antibiotics too often might kill off good bacteria, leading to obesity due to inefficient digestion.  Most common side effect referred due to overuse of antibiotics is that the pathogenic bacteria becomes resistant to the drug and hence the drug is rendered ineffective and pathogen dangerous.
Studies have shown that good bacteria may help prevent diseases like diabetes and asthma, make the immune system function correctly and even ward off certain types of cancer. Bacteria living on your skin might also help prevent infections. Microbes influence how much energy we burn and how much fat we store. There is even evidence that the microbes in our guts send signals that can affect our brain function. These signals may affect development of human brain and subsequently our moods and behaviour as adults.
Drug companies may one day sell medicines that treat illnesses by increasing the amount of particular types of good bacteria in the body. Food manufacturers have already started making foods intended to increase the good bacteria in the body. These products – from yogurt to cereal to drinks – contain probiotics. Probiotics are defined as live microorganisms, which, when administered in adequate amounts, may confer a health benefit. Early research suggests that probiotics may help to prevent colds and the flu, treat diarrhoea, reduce certain types of cancer and even prevent certain types of skin problems.
The microbes associated with human body are without any doubt crucial for human health. Exactly how, to what extent, and what areas of human health are influenced by them is yet to be established. But human life without microbial association is not possible and hence the scientific world considers humans as “superorganisms” a communal group of human and microbial cells – living and working together in harmony.

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