Streptococcus - what is it? Types of streptococci

Many people heard about the existence of streptococcal infection and even faced it. But very few seriously thought about what a streptococcus is, what is it? But the knowledge of the features of life and the activities of the enemy is already half the victory. The science of microbiology deals with streptococci. In it, as in any other field of knowledge, there are many complex and incomprehensible terms. In this article, we will try to explain in an accessible language what dangerous streptococcus is, what it is, whether it is possible and necessary to fight it and by what methods the therapy is carried out.

"Portrait" of a parasite

A person daily and every second encounters thousands of microorganisms, which can only be examined under a microscope. A striking representative of this huge army of parasites is streptococcus. What is it, and maybe, who? What type of living beings should he include? Let's start in order.

Streptococci are bacteria that look like microscopic balls with a radius of up to 0.5 microns. A ball is one cell of a bacterium and a whole organism. Streptococci are kept in pairs in pairs, or in groups, connected in a chain. They are absolutely immobile, because they have neither a cilium, nor tails, nor flagella. They are moved only by external interference, for example, when coughing with a stream of air. Once in a new environment, the bacterium streptococcus almost immediately begins to multiply. It does this by simple cell division. The structure of her cell is such that it is able to form the so-called L-form (ie, almost without the cell wall). This tricky property causes easy patency of the pathogen through bacterial filters and a very low sensitivity to the drugs. To better "get to know" with such a representative of the world of microorganisms as streptococcus (what is it, we have already discussed), we list its physical characteristics. So, these parasites:

- Anaerobic (ie, they do well without oxygen);

- Gram-positive (the term refers not to weight, but to staining the bacteria by the method of the scientist Gram) - this property is used to diagnose diseases;

- chemoorganotrophic (feed on organic matter);

- Asporogenous (do not form a dispute);

- parasitic.

Features of life activity

In humans and animals, streptococci live massively and parasitize in the oral cavity, nasopharynx, gastrointestinal tract, large intestine, but they can get into any organ with blood or other ways and start their pathogenic activity there. In addition, streptococci are found in environments around us, such as dust, any surfaces, sputum, dried pus. Despite the fact that parasites form L-form and seem to be unprotected, getting rid of them is quite difficult. These bacteria are able to survive in the frost, "hold" 30 minutes at a temperature of up to +55 degrees, and solutions of the mercaptans and carbolic acid kill them in only 15 minutes. But there are types of streptococci with even wider limits of viability. In the dried fragments of pus, sputum (dried and fresh), all kinds of microorganisms retain their viability indefinitely. But the greatest activity these pathogens show at a temperature of the environment of +37 ^о С and pH, close to neutral or weakly alkaline (values from 6.9 to 7.6). For information, water at room temperature has a pH of 7, and in saliva, most people have a pH of 7-7.4, that is, they are ideal for the development of streptococci in them. Particularly great fecundity of bacteria is manifested if they enter a medium containing blood, blood serum, glucose, because this is their most favorite food. Here they very quickly grow to huge colonies. If you place different types of streptococci in blood agar (a specially prepared solution containing the blood of some animals), some of them will not change the color of the agar, others will form around the colonies the zones of complete decay of erythrocytes (hemolysis), the third will decorate the captured place with green color. In less favorable conditions for them (for example, in dust) colonies of streptococci are much less (up to 2.5 mm), the touch is often smooth, sometimes rough, outwardly translucent and shiny. In liquids, microorganisms tend to settle at the walls of the vessels or on the bottom, leaving the medium transparent.

The biggest harm from streptococci is that they release very dangerous toxins that cause poisoning of the victim's body and even capable of leading to death.

What are streptococci?

There are several generally recognized classifications. According to Brown and Sottmuller, the entire army of streptococci is divided into 3 main groups:

1. Hemolytic.

2. Greening.

3. Nonhemolytic.

The most dangerous are hemolytic streptococci, but not all are pathogenic. At the same time among the harmless non-hemolytic there are quite "serious" parasites.

In connection with the difficulties in determining the harmfulness of streptococcus, another classification was proposed. It was developed independently by Rebecca Lensfield and Frederick Griffith. They were based on the antigenic structure of pathogens, thanks to which they were divided into 17 species or groups, denoted by Latin letters. The first - A streptococcus, the second B, the third C, the fourth D and so on, to the group of S-streptococcus. For people, the first four are the most unpleasant. We will discuss them in more detail and start with the answer to the question: "Streptococcus of group A - what is it?" Why from him? Firstly, because it is the first in the list, and secondly, because it is the most dangerous parasite that causes a whole "bunch" of diseases in a person. So…

Group A streptococci

Bacteria of this group are not only the most dangerous, but also the most numerous. In total, 53 species of these microorganisms were found in man, and 49 of them belong to group A. They are found in respiratory organs, in the mouth, in the intestines, on the genital organs, and by means of blood, where the parasites very easily penetrate, are transferred to any part Body and in any organ. Another name for these bacteria is Streptococcus pyogenes, that is, pyogenic streptococcus. What it is? Since the Greek pyon is translated as "pus". From the name it is clear that pyogenic streptococci cause diseases accompanied by purulent discharge (purulent infections). This is not their only dangerous property. Such microorganisms provoke complications after the transfer of the underlying disease - rheumatism and acute glomerulonephritis (kidney damage). The main characteristic of all streptococci A-group is the presence of M-protein in the walls of their cells, and it occurs in 80 variations. This substance protects streptococci from phagocytes existing in a person's blood to eat foreign bodies. In addition, each representative of pathogens of group A has a capsule, which also protects them from phagocytes. Such morphological features of streptococci are "guilty" in the fact that a person who has recovered from something develops immunity only to the type of parasite that this disease caused. That is, if your angina is caused by a-streptococcus with the M1 protein, then immunity will only be to this bacterium, and to the pathogen with the M2 protein will no longer exist, which means that you can again get sore throat. The figures in this case determine the type of bonds in the protein.

Hemolytic Streptococcus: What is it?

The term "hemolytic" means destroying blood cells. If the parasite causes complete hemolysis (complete destruction of all blood cells around it), it is called beta-hemolytic. Almost all representatives of the first four groups (A, B, C, D) are just such. They cause the following diseases:

• Angina;
• Scarlet fever;
• Face;
• Impetigo (skin disease);
• Endocarditis is infectious;
• Abscesses (abdominal cavity, brain);
• Meningitis, sepsis of newborns;
• Sepsis sepsis;
• Various infections of the genitourinary system.

There is also alpha-hemolytic streptococcus. What it is? This is the same hemolytic streptococcus (green), only it destroys the red blood cells in part. It may seem that this species is less dangerous. In fact, it causes such dangerous diseases as:

• Abscesses of the peritoneum and brain;
• Periodontitis;
• Endocarditis is infectious;
• pneumonia;
• meningitis.

These streptococci, as already mentioned above, are able to change the color of the environment from red to green.

There is also gamma-hemolytic streptococcus. What it is? So called bacteria that do not completely destroy the red blood cells and do not change the environment around the agar (the so-called non-hemolytic). But they can cause a number of diseases:

• Endocarditis is infectious;
• sinusitis;
• Infection in the wounds.

Streptococcal angina

In general, angina is a broad concept, meaning any inflammation of the throat. It can be caused not only by streptococci, but also by other viral and bacterial pathogens. Let's discuss what to do if a streptococcus is found in the throat, what it is and how not to go wrong with the diagnosis, because the way of treatment depends on it. The exact verdict can be made only by the doctor according to the results of microbiological analysis (smear). It is taken with a sterile swab from the throat. In addition, there are two rapid tests, but the smear is the most accurate. Infect streptococcal angina is possible only when in contact with the patient, if not observed precautions. The main symptoms are:

• Pain in the throat, especially during swallowing;
• temperature;
• General weakness, chills;
• Soreness of cervical nodes;
• Edema of the mucous membranes;
• White or purulent deposits on the tonsils and in the throat;
• In rare cases, pain in the abdomen.

The disease with proper treatment lasts up to 5 days. Medicines should be selected in such a way that the kidneys and joints do not suffer.

Most often, patients are prescribed antibiotics orally, and in special cases, subcutaneously. To reduce pain in the throat, use sprays or rinses with antiseptics, chamomile broths, a solution of soda food.

Approximately the same symptoms as angina, characterized by scarlet fever, only with this disease is added a small-dot red rash all over the body, caused by streptococcal toxins. With scarlet fever there is also a symptom of "strawberry tongue" (with white coating and red papillae). Treatment is similar to the above.

Streptococcal skin diseases

In some patients, doctors are sent to pass an analysis for streptococcus SPP. What it is? Yes, all the same bacteria are cocci. It is more correct to call this group Streptococcus SPP. It includes already known to us pyogenic streptococci, which are the cause of many diseases, as well as Streptococcus pneumoniae, which causes pneumonia, meningitis, bronchitis, blood infection, and Streptococcus mutans, responsible for the occurrence of caries and endocarditis.

Streptococcal diseases of the skin include impetigo and erysipelas.

The first disease is caused by pyogenic streptococci A-groups. As a rule, it is more often observed in children, if sanitary norms are not observed. Streptococci in everyday life are constantly on the skin of people. Where they "are friendly with cleanliness" (washing their hands, doing regular wet cleaning), they are removed from the skin. And where the hygiene is not all right, streptococci occupy the skin constantly and with the slightest trauma, including light scratches and insect bites, penetrate into the subcutaneous layer. Symptoms of impetigo are painless rashes near the nose, lips and very rarely on other parts of the body. At the first stage these rashes have the appearance of red nodules (papules), which later turn into purulent vesicles (pustules), burst and dry up with the formation of yellowish crusts. Treat impetigo with antibiotics.

The pimples are also caused by pyogenic streptococci. The disease occurs due to the penetration of bacteria into the subcutaneous tissue. Causes - various violations of the integrity of the skin, from cuts to insect bites. Symptoms:

• Redness, tenderness, swelling of the affected area of the skin;
• chills;
• fever.

One of the most unpleasant properties of the pathology is the possibility of relapses many years after the apparent cure.

Pneumonia

This disease has several varieties, depending on the pathogen. Streptococcal pneumonia is one of the most dangerous. It is caused by penetration into the lungs of Streptococcus pneumoniae. You can catch the infection by inhaling air, which contains pathogenic bacteria. Pneumonia begins suddenly, but there are cases of its gradual development. Symptoms:

• heat;
• cough;
• Pain in the chest;
• dyspnea;
• fever;
• Purulent effusion (accumulation of pus in the lungs) - this process has a persistent tendency to increase, and if urgent measures are not taken, spikes form in the lungs.

Diagnose pneumonia by radiography, as well as testing of excreted sputum. Antibiotics and corticosteroids are treated, as a rule, an integrated approach is required. The scheme of therapy is developed only by a qualified specialist! Without proper treatment, pneumonia often leads to death.

Streptococcus agalactia: what is it?

With group A streptococci, we sorted out more or less. Let's talk now about the parasites of group B. They were first identified by studying mastitis in cows. Later it was found that these bacteria cause meningitis and sepsis in newly born babies, and their mothers have postpartum sepsis. They called parasites Streptococcus agalactiae (in Russian - "streptococcus agalactia"). What it is? We answer: these are very dangerous bacteria, leading either to death or to serious complications. Their body (cell walls) contains capsular polysaccharides, the latter - 9 variations. Accordingly, there are 9 serotypes of streptococcus agalactia. To determine exactly which of them caused the disease, conduct a CAMP test. Abbreviation - this is just the capital letters of the names of scientists who deal with this problem.

Due to some confusion in the classifications there are certain difficulties. So, take, for example, group B Streptococcus. What is it? Yes, the same as streptococcus agalactia. These are two names of the same bacteria. Group B streptococci are either oval or round. Their main "place of residence" is the human urogenital system. Newborn bacteria are transmitted in the process of birth. Sepsis develops in only 2% of children, but 50% of them die, and survivors often suffer from brain disorders. Septicemia can occur immediately (during the first day) or with time (from a week to 3 months). Symptoms:

• drowsiness;
• Sluggish sucking;
• Respiratory insufficiency;
• Hypotension of the arteries;
• Bacteremia (in the presence of bacteria);
• Pneumonia or meningitis.

In childbirth, streptococcal sepsis is manifested in soreness and swelling of the abdomen, bacteremia. Sometimes meningitis begins and / or infective endocarditis.

In all categories of citizens, Group B streptococci cause such diseases:

• meningitis;
• bronchopneumonia;
• Arthritis purulent;
• Inflammation of the urogenital system;
• osteomyelitis;
• Abscesses of the pelvis, peritoneum and others.

Streptococcus groups C and D

In a small number of people, streptococci in other groups are found. Bacteria belonging to group C are beta-hemolytic and cause the same diseases as pathogens of the A-group. Group D includes both streptococci and enterococci. They cause diseases mainly in the elderly, people weakened by diseases and those who, due to the uncontrolled intake of antibiotics, have violated the balance of microflora in the body.

It is often asked what is the norm of streptococci, because they do not always cause illness. As such, there is no norm. These bacteria remain harmless, as long as the immunity is able to "keep them in check." Therefore, the main task of all of us is to enhance and strengthen our immunity in all ways that are available. If he suddenly weakens, the streptococci go out of control and attack. To destroy bacteria is unthinkable, since the place of those who left in a few hours will take on new ones, because they are full in the environment around us. In the oral cavity, streptococci accounts for up to 60% of all microorganisms. As for streptococci in the B-group, found on the mucous genitalia, they should not be normal.