Microorganisms surround us everywhere and live in our body, being an integral part of it and the world as a whole. However, not all of them are dangerous to our he alth; on the contrary, those bacteria that make up the normal microflora of various human organs resist foreign microbes and prevent infections. In addition, an important element of protection is the immune system, however, when it is weakened, even opportunistic flora can cause diseases. One of their brightest representatives is streptococcus viridans, which will be discussed.
Basic information
Otherwise referred to as "green streptococcus", it is a normal inhabitant of the human oral cavity, where it is localized on the teeth and gums and often causes caries. This is because the structure of streptococcus viridans has a special surface protein that is able to bind saliva and thus attach to the tooth. And when sucrase enters with food, it turns it into lactic acid, corroding enamel. It got its interesting name because it was bacteriologically sown onThese bacteria form a green zone of hemolysis around their colony in the blood agar medium. However, there are other groups of them, these are hemolytic streptococci (completely hemolyze the environment) and non-hemolytic (do not have hemolytic enzymes). In comparison with the first streptococcus group viridans are not so dangerous to the human body and are much less virulent. However, when immunity is weakened, they actively multiply and have a pathogenic effect, causing opportunistic infections, and not always of a mild course.
Microbiology
Now let's take a closer look at what streptococcus viridans is. If we talk about these bacteria from a microbiological point of view, then they are spherical or ovoid gram-positive cocci that do not form spores. They belong to the group of facultative anaerobes and belong to the Streptococcaceae family. To find out what streptococcus viridans looks like, what it is, just look through a light microscope. So you can see that most often they are arranged in pairs or assembled in chains, but at the same time remain motionless. Their danger to our immunity lies in the fact that they are able to form a capsule that protects them from phagocytosis by specialized blood cells, and can also easily turn into an L-form, thus changing, and therefore can hide from the components of our defense system for a long time.
Inoculation and virulence
The nutritional needs of these bacteria, unlike staphylococci, are quite complex. They grow well only on those media in the preparation of which whole blood or serum was used, and they also definitely need carbohydrates for nutrition. That is why blood agar is most often used for bacteriological culture of green streptococci. In the external environment, they are quite stable, so, for example, on dried biomaterials (blood, pus, sputum), they can remain viable for several more months. During pasteurization, disinfection, they die, but not immediately. So, when they are heated to a temperature of 60 degrees Celsius, their death occurs only after half an hour, and when using des. funds - in 15 minutes.
Epidemiology
The fact that among the usual microflora of the human body, along with many bacteria, streptococcus viridans is also the norm. However, this applies only to a certain amount of its strain, and it can be replenished from infected people, that is, carriers of streptococci or already sick with one of the many forms of infection (tonsillitis, scarlet fever, pneumonia, etc.). At the same time, patients with lesions of the upper respiratory tract are most dangerous, since they release much more streptococci into the environment. Hence the main route of infection is airborne, that is, when talking, sneezing, coughing, kissing, etc.; in some cases, alimentary (with food) and contact (dirty hands) are also possible. Thus, it is known that many group A streptococcican retain their virulent properties for a long time when they get on products that are, in fact, a favorable environment for them. These include eggs, milk, ham and shellfish.
Complications
The most formidable disease caused by viridescent and non-hemolytic streptococci is infective endocarditis. The fact is that when the mucous membrane of the oral cavity (gums, tongue) is injured with a toothbrush, floss or with stomatitis, streptococcus viridans enter the local, and then the systemic circulation. Once they reach the heart, they are able to attach to and colonize the valves. This is how the disease develops. It begins, as a rule, with general manifestations: weakness, malaise, fever. This is primarily due to the fact that it is more often caused by moderately or slightly virulent strains.
Clinic and outcomes
If highly pathogenic bacteria become the cause of infective endocarditis, then the disease begins acutely and is accompanied by a febrile temperature, up to forty degrees. At the same time, muscle and joint pains occur in parallel, and heart murmurs are heard on auscultation. The danger of this disease lies in the destruction of the endocardium, that is, the deformation of the valves with the appearance of bacterial vegetations on them. With their exfoliation, microbial vascular embolism develops, leading to heart attacks and strokes. In addition, aneurysms of large arteries, brain abscesses, meningitis, encephalopathy and heart failure can form.
