Bacteria are different from viruses. After all, they are full-fledged living organisms that can provide for themselves and reproduce their own kind, well, of course, with sufficient nutrition. Some of their species, getting into the human body, find conditions suitable for their vital functions and begin to multiply actively, and, as a result, bacterial diseases arise.
Until the beginning of the last century, the tactics of combating pathogenic bacteria did not differ in anything from the fight against viruses and consisted in helping the body defeat the disease on its own. Since then, the possibilities of medicine have significantly increased, both in treatment and in the diagnosis of pathologies such as bacterial diseases. Scientists have created a number of groups of drugs that can destroy microbes without harming the human body, for example, sulfonamides (Etazol, Penicillin, Biseptol) and antibiotics (Tetracycline, Penicillin, Gentamicin).
But microorganisms also did not completely give up, began to mutate, gradually acquiring resistance to these medicinal substances, forcing people to invent more and more new drugs. In addition to constantly increasing resistance to drugs, bacteria present another unpleasant surprise - an ever-increasing number of types of microorganisms that are considered conditionally pathogenic, and previously practically did not cause pathology, and nowadays they constantly become the causes of human suffering. Bacteria are very diverse species, respectively, are very diverse and bacterial diseases caused by them. These microorganisms differ from each other not only in size, but also in structure, and reproduction, and nutrition. There are round cocci (meningo-, stafilo-, strepto- and so on), elongated - various sticks (whooping cough, intestinal, dysentery), as well as irregular shapes and equipped with all kinds of flagella, growths and the like.
Bacterial diseases, unlike viral ones, do not have such a pronounced tropism to individual human organs. But nevertheless, some “preferences” for individual microbes have, for example, meningococcus - the meninges, and whooping cough - the epithelium of the respiratory tract and vice versa certain diseases, such as bacterial bronchitis, can be caused by various pathogens (hemolytic streptococcus, pneumococcus, Staphylococcus aureus and so on). But staphylococci nest anywhere and can cause a wide variety of diseases.
But the bacterium in itself does little harm to the human body. And the products of their vital activity are harmful - toxins. And each bacterium has its own special, and the symptoms that accompany bacterial diseases are determined precisely by their effect on the body. On these toxic substances, however, as on the membrane of a pathogenic cell and on its various outgrowths, be it cilia, flagella or something like that, the human immune system produces specific antibodies designed to protect his body from harmful effects. In addition to these protective substances, phagocytes, special cells-eaters, also participate in the fight against pathogens.
Most toxins are released during the death of bacterial cells and its subsequent destruction. And they are destroyed constantly, both due to the short life span and due to the fact that immunity and the same antibiotics fight against them. These substances are called endotoxins, that is, inside, there are also exotoxins that the microbe constantly releases into the environment during its life. By the way, exotoxins are the most powerful poisons of all that are known to mankind.