Streptococcal infections are a group of diseases, including infections caused by streptococcal flora of different types and manifested in the form of lesions of the respiratory tract and skin. Streptococcal infections include streptococcal impetigo, streptoderma, streptococcal vasculitis, rheumatism, glomerulonephritis, erysipelas, sore throat, scarlet fever and other diseases. Streptococcal infections are dangerous due to the tendency to develop post-infectious complications from various organs and systems. Therefore, diagnostics includes not only the identification of the pathogen, but also an instrumental examination of the cardiovascular, respiratory and urinary systems.
General information
Streptococcus is a genus of facultatively anaerobic gram–positive globular microorganisms resistant in the environment. Streptococci are resistant to drying, they persist in dried biological materials (sputum, pus) for several months. At a temperature of 60 ° C. they die in 30 minutes, under the influence of chemical disinfectants – in 15 minutes.
The reservoir and source of streptococcal infection is a carrier of streptococcal bacteria or a person suffering from one of the forms of infection. The transmission mechanism is aerosol. The pathogen is released to patients when coughing, sneezing, during a conversation. Infection occurs by airborne droplets, so the main sources of infection are people with a predominant lesion of the upper respiratory tract (sore throat, scarlet fever). At the same time, it is no longer possible to get infected at a distance of more than three meters. In some cases, it is possible to implement alimentary and contact transmission routes (through dirty hands, contaminated food). Group A streptococci, when exposed to a favorable nutrient medium of certain foods (milk, eggs, shellfish, ham, etc.), are characterized by reproduction and long-term preservation of virulent properties.
The probability of purulent complications during infection with streptococci is high in people with burns, wounds, pregnant women, newborns, patients after surgery. Group B streptococci usually cause infections of the genitourinary sphere and can be transmitted during sexual intercourse. Newborns often get an infection as a result of infection of the amniotic fluid and during the passage of the birth canal. The natural susceptibility of a person to streptococcal bacteria is high, type-specific immunity and does not prevent infection with streptococci of another species.
Symptoms
The symptoms of streptococcal infections are extremely diverse due to the large number of possible localizations of the focus of infection, types of pathogen. In addition, the intensity of clinical manifestations depends on the general condition of the infected person. Group A streptococci are prone to damage to the upper respiratory tract, hearing aid, skin (streptoderma), this group includes pathogens of scarlet fever and erysipelas.
Diseases that have developed as a result of the defeat of these microorganisms can be divided into primary and secondary forms. Primary forms are inflammatory infectious diseases of the organs that have become the gates of infection (pharyngitis, laryngitis, angina, otitis, impetigo, etc.). Secondary forms develop as a result of the inclusion of autoimmune and toxic-septic mechanisms of inflammation in various organs and systems. Secondary forms of streptococcal infections with an autoimmune mechanism of development include rheumatism, glomerulonephritis and streptococcal vasculitis. Necrotic lesions of soft tissues, meta- and peritonsillar abscesses, streptococcal sepsis are of a toxin-infectious nature.
Rare clinical forms of streptococcal infections: necrotic inflammation of muscles and fascia, enteritis, toxic shock syndrome, focal infectious lesions of organs and tissues (for example, soft tissue abscess). Group B streptococci overwhelmingly cause infections in newborns, although they occur at any age. This is due to the predominant lesion of this pathogen of the genitourinary tract and infection of newborns intranatally.
Streptococcal infections of newborns are manifested in the form of bacteremia (30% of cases), pneumonia (32-35%) and meningitis. In half of the cases, the infection manifests itself clinically in the first day of life. At the same time, streptococcal infections of newborns are extremely difficult, the mortality rate among the sick is about 37%. Meningitis and bacteremia may occur later. In this case, about 10-20% of patients die, and half of the survivors have developmental disorders.
Group B streptococcal infections are often the cause of postpartum endometritis, cystitis, adnexitis in maternity patients and complications in the postoperative period during cesarean section. Streptococcal bacteremia can also be observed in persons with a pronounced weakening of the immune properties of the body (elderly people, patients with diabetes mellitus, immunodeficiency syndrome, malignant neoplasms). Streptococcal pneumonia often develops against the background of a flowing ARI. Greening streptococcus can cause the development of endocarditis and subsequent valvular defects. Mutans group streptococci cause caries.
Complications of streptococcal infections are autoimmune and toxicoseptic secondary lesions of organs and systems (rheumatism, glomerulonephritis, necrotic myositis and fasciitis, sepsis, etc.).
Diagnostics
Etiological diagnosis of streptococcal infection of the mucous membrane of the pharynx and skin requires bacteriological examination with the isolation and identification of the pathogen. Scarlet fever can be considered an exception. Since currently many types of streptococcal bacteria have acquired a certain resistance to antibiotics of some groups, a thorough microbiological study and the implementation of an antibiotic sensitivity test are necessary. Diagnosis, made in sufficient volume, contributes to the choice of effective treatment tactics.
Rapid diagnostics of group A streptococci allow you to identify the pathogen within 15-20 minutes from the moment of taking the analysis without isolating a pure culture. However, the detection of the presence of streptococci does not always mean that they are the etiological factor of the pathological process, this fact can also speak about the usual carrier. Rheumatism and glomerulonephritis are almost always characterized by an increase in the titer of antibodies to streptococci already from the first days of exacerbation. The titer of antibodies to extracellular antigens is determined by a neutralization reaction. If necessary, examination of organs affected by streptococcal infection is carried out: examination by an otolaryngologist, lung x-ray, ultrasound of the bladder, ECG, etc.
Treatment
Depending on the form of streptococcal infection, treatment is carried out by a gynecologist, urologist, dermatologist, pulmonologist or other specialists. Etiological treatment of primary clinical forms of streptococcal infections consists in prescribing a course of penicillin antibiotics, to which streptococci have a fairly high sensitivity. If the ineffectiveness of the antibiotic is detected when using it for more than five days, the drug is changed. It is advisable to test the culture of the pathogen for sensitivity to drugs of different (erythromycin, azithromycin, clarithromycin, oxacillin, etc.) groups in order to choose an antibiotic more reliably. Practice shows that tetracycline drugs, gentamicin and kanamycin are ineffective.
Pathogenetic and symptomatic treatment depends on the clinical form of the disease. If it is necessary to prescribe long courses of antibiotic therapy (for secondary forms of streptococcal infection), prolonged-acting drugs are often prescribed. Recently, the positive effect of the use of human immunoglobulin and immunostimulating agents on the course of the disease has been noted.
Prevention
Prevention of infection with streptococcal infection implies measures of personal hygiene and individual prevention during contacts in a narrow team with persons with respiratory diseases: wearing a mask, processing dishes and surfaces on which microorganisms could get, washing hands with soap. General prevention consists in the implementation of systematic control over the state of health of collectives: preventive examinations in schools and kindergartens, isolation of identified patients, adequate therapeutic measures, identification of hidden forms of streptococcal infection and their treatment. To free the body from the pathogen and complete cure, WHO recommends the use of penicillins for at least 10 days.
Particular attention should be paid to the prevention of nosocomial infection with streptococcal infection, since infection in the hospital of a patient in a weakened state is several times more likely, and the course of infection in such patients is noticeably more severe. Prevention of infection of women in labor and newborns consists in careful observance of sanitary and hygienic standards and the regime developed for gynecology departments and maternity hospitals.