Among the huge variety of microorganisms, you can meet both friends who provide the vital activity of our body, and worst enemies. Such life forms are divided into bacteria, viruses, fungi and protozoa. Sometimes these microorganisms are combined with the word "microbes". Bacteria are the causative agents of many diseases, some species pose a serious danger to human life. However, those organisms that live in the human body, on the contrary, help the organs cope with their functions.
Bacteria, their structure
Bacteria are the simplest unicellular organisms. They are small in size (0.5-10 microns) and have different shapes. The cell of these organisms consists of a shell and cytoplasm. The cell membrane plays an important role in the exchange of substances with the environment. The cytoplasmic membrane is tightly attached to the membrane and consists of proteins, lipids and enzymes. It is responsible for the processes of excretion and entry of substances into the cell, being an osmotic barrier. The main component of the cytoplasm is protein. It is here that the energy processes that ensure the vital activity of the cell take place. Bacteria do not have a well-formed nucleus. Instead, there is a nuclear substance that contains DNA and RNA.
Chemical composition of the cell
The main component of a bacterial cell is water. It occupies 80% of the total mass of the microorganism. However, in disputes, its content is much less - about 20%. Many bacteria tolerate water reduction (drying) quite well. At the same time, metabolic processes slow down, and they stop multiplying. In addition, the cell contains proteins, carbohydrates, fats, as well as minerals and nucleic acids.
Movement of bacteria
Bacterial cells move thanks to a special organ - flagella. These are thin thread-like formations, their number and location are varied. Their thickness is approximately 0.01-0.03 microns. At the same time, several types are distinguished. If there is only one flagellum and it is located at one pole, such bacteria are called monothoric. Microorganisms that have a bundle of flagella at one of the poles are monopolar lophotrichous. Those bacteria that have bundles at the poles are called amphitriches. But if the entire surface of the cell is covered with flagella, then these are peritrichous. Another way bacteria move is by gliding. It is believed that this is due to the fact that the cells contract in waves.
How microorganisms reproduce. Sporulation
The way bacteria reproduce is quite simple. Its essence lies in the fact that the cell is divided into two, reaching a certain size. First, it lengthens, then a transverse septum appears, sets of cells diverge at the poles. If favorable conditions are created, then the division of bacteria can occur every 20 minutes. But most organisms die under the influence of the environment. To endure adverse conditions, bacteria are able to form spores. In this state, they are able to survive for thousands of years. Even in ancient mummies bacterial spores have been found. They are formed in several types: inside, in the middle or at the end of the cell.
Morphology of bacteria
Depending on the shape, bacteria are classified into the following types:
- Spherical. These bacteria are the causative agents of various diseases. These include staphylococci (have the shape of grapes), streptococci (form a long chain). The latter microorganisms are the cause of inflammatory processes and diseases such as tonsillitis, otitis, pneumonia. Staphylococcal bacteria are the causative agents of diseases of the alimentary tract, purulent processes. The most dangerous representative is Staphylococcus aureus.
- Rod-shaped. This species has the shape of a cylinder. Often they form disputes. Such microorganisms are called bacilli. Similar bacteria are the causative agents of anthrax.
- Spiral. They got their name because of the shape with curls. They includespirilla, which are a fairly harmless organism. Spirochetes look like a thin twisted thread. These bacteria are known to cause syphilis.
- Vibrios. Representatives of this category have a slightly curved shape. They have a characteristic feature: such pathogenic bacteria are stable in an alkaline environment. They cause diseases like cholera.
- Mycoplasmas. A feature of this type is the absence of a cell membrane. Outside the body of the host, they are not capable of life. The question of which disease is caused by mycoplasma bacteria has a fairly simple answer: they mainly provoke the appearance of diseases in cattle or plants.
Cholera
One of the most dangerous infections is cholera. It affects the digestive organs and causes severe intoxication of the body. What bacteria are the causative agents of cholera? These microorganisms were discovered by Robert Koch. Vibrio cholerae has the shape of a slightly curved rod. A distinctive feature of these bacteria is their high mobility. Vibrio cholerae enter the small intestine and become fixed there. There they produce protein toxins, as a result of which the water-s alt balance is disturbed, the body is severely dehydrated. Bacteria are characterized by resistance to an alkaline environment, but acid is harmful to them. In addition, despite the fact that low temperatures are well tolerated by them, boiling kills Vibrio cholerae instantly. Infection is possible through contact with a sick person, through food or water. The incubation period is 5 days.
Pneumonia
Inflammation of the lungs is a fairly serious disease that can lead to death. Children are particularly susceptible to pneumonia. It can be caused not only by viruses. The answer to the question of which bacteria are the causative agents of the disease is known: these are pneumococci (up to 90%). Staphylococci (about 5%) and streptococci also provoke the appearance of inflammatory processes. Bacteria reside in the nasal passages and throat.
The most common symptoms of pneumonia are high fever, shortness of breath, general intoxication of the body. One of the most dangerous is intrauterine pneumonia. It can be provoked by group B streptococci, Staphylococcus aureus. Often this disease occurs as a result of the flu. Bacterial pneumonia is treated with antibiotics. In especially severe cases, such as the young age of the patient, hospitalization is necessary. As methods of prevention use vaccination, promotion of breastfeeding up to six months (exclusively mother's milk). It is also important to monitor personal hygiene and clean indoor air.
Chlamydia
It has only recently been established that chlamydia is a bacterium. Which disease is caused by this type of bacteria? First of all, they can cause eye conjunctivitis, urogenital infection, trachoma. A special type of chlamydia causes pneumonia and acuterespiratory diseases. Once in the host cells, microorganisms begin to divide. The entire cycle takes approximately 72 hours, as a result of which the affected cell is destroyed. This infection is especially dangerous for women. It plays a significant role in the formation of infertility. If there was an infection with chlamydia of the fetus, then the probability of his death is high. That is why it is important to undergo a study even before planning a pregnancy, since such an infection is often asymptomatic.
Causative agents of scabies and other diseases
Quite often amateurs wonder if bacteria are the causative agents of scabies. This, of course, is not true. A disease such as scabies provokes a tick, which, when it comes into contact with the skin, begins to multiply intensively, thereby causing itching. But already a complication of this disease - pyoderma, that is, a purulent lesion of the skin - can cause bacteria of the coccus group. As a treatment, special ointments are used, and clothes and linen are disinfected.
Relevant and the question of what bacteria are the causative agent of hepatitis? Basically, hepatitis is a common name for inflammatory diseases of the liver. They are mainly caused by viruses. However, there is also bacterial hepatitis (with leptospirosis or syphilis). Leptospira, treponema - these bacteria are the causative agents of hepatitis.
Another serious disease is malaria. The disease is transmitted to humans by insect bites (malarial mosquitoes). It is accompanied by fever, enlargementliver (possibly spleen), high temperature. If you do not start treatment on time, then a fatal outcome is possible. The causative agents are malaria bacteria of the genus Plasmodium. To date, 4 types of such microorganisms are known. The most dangerous is the one that can cause tropical malaria. As you can see, bacteria are the causative agents of diseases that have serious complications and require medical attention.
