Bacteria are found in and on humans in a wide variety. While some bacteria promote health, other bacteria can be detrimental to health. Bacteria should not be confused with bacilli, a rod-shaped genus of motile bacteria.
What are bacteria?
Schematic diagram of the components and structure of a bacterium. Click to enlarge. Bacteria are microorganisms and reach an average size of 0.5 to 5 micrometers. Bacteria are unicellular and reproduce by simple cell division. Unlike many living cells, bacteria do not have a nucleus. Depending on their shape and structure, bacteria can be divided into three basic types. These basic types include the cocci (e.g. staphylococci), the rods (e.g. bacilli or salmonella) and the helical bacteria. The term cocci is derived from the Greek and means berries or spheres. The approximate diameter of these bacteria is one micrometer. Bacteria called rods are rod-shaped according to their naming. The coils of helical bacteria are often clearly visible under a light microscope.
Meaning and function
In the healthy body, bacteria perform many important functions. For example, many types of health-promoting bacteria are found in the human intestine. In their interaction, these bacteria form the so-called intestinal flora, which has a beneficial effect on digestive processes. Approximately 99% of all microorganisms in the human body are found here. A large number of bacteria are also found on the human skin, where they form the so-called skin flora. Among other things, the skin flora takes on the task of protecting the skin and also the organism from invading, pathogenic (disease-causing) germs. Other health-promoting bacteria are found in the small intestine, the pharynx, the oral cavity or on the mucous membrane of the female vagina. In order for health-promoting bacteria to be able to perform their tasks without restriction, it is important that the bacterial flora of the organism is properly composed; beneficial bacteria must be present in a constant and sufficient quantity for this purpose. Many bacteria are capable of producing enzymes or antibiotically active substances that are important for humans. This property is also used in medicine. For example, bacteria such as Escherichia coli are used to produce drugs such as antibiotics or insulin. This is done by specifically utilizing the metabolism of the corresponding bacteria. Bacteria in the human body that bring neither scientifically measurable benefit nor measurable harm are referred to as commensals. Furthermore, there are bacteria in the human body that draw nutrients from the body but can also prevent harmful bacteria from colonizing. These forms of bacteria are therefore called symbionts.
Diseases
Bacilli or rod-shaped bacteria or are rod-shaped bacteria. Click to enlarge. Occasionally, bacteria that are actually beneficial to health can also have harmful effects on the body. This is the case, for example, when bacteria leave their actual environment in the human body and enter a different environment. For example, beneficial bacteria from the colon can lead to bladder infections in the urinary tract. In addition to beneficial bacteria, there are a large number of bacteria that damage the human body and are therefore also referred to as pathogens. The harmful influence of such bacteria comes from the so-called bacterial toxins secreted by bacteria. Various toxins secreted by living bacteria can, for example, trigger infectious diseases such as scarlet fever, tetanus (also known as tetanus), whooping cough or diphtheria (a disease of the upper respiratory tract). Toxins can also be emitted from dying bacteria as they break down. For example, a certain form of typhoid fever can be caused by salmonella (rod-shaped bacteria). Some bacteria can release toxins so potent that these substances are used as biological weapons. Depending on their form, pathogenic bacteria can be transmitted from one person to another by various routes.Bacteria can be transmitted through the air, through water, or through various body fluids such as saliva, urine, or blood. Bacteria are also capable of mutating within certain periods of time, so that they can no longer be combated with drugs such as certain antibiotics, for example. These bacteria develop so-called resistance and therefore represent a major health threat. On the latter, you can also read our articles: MRSA infection and ESBL infection.