Antibodies to streptococcus A, B, C, D, F, G in the blood

Infections caused by streptococci A, B, C, D, F, G. Antibodies to streptococcus A, B, C, D, F, G in serum

The titer of antibodies to streptococcus is normal in serum of 12-166 ED.

Streptococci is considered to be the most common pathogens of bacterial infections in humans. On the basis of antigenic differences, most of the streptococci isolated from humans are assigned to groups A, B, C, D, F, G.

Group A streptococci are extremely important because they often cause infectious diseases in humans and play a significant role in the development of rheumatism and glomerulonephritis.

Group B streptococci frequently colonize female genital tract and mucous membranes of the pharynx and rectum.

Streptococcus groups C and G are referred to commensals, but in some cases they are able to cause pharyngitis.

Group D streptococci often cause urinary tract infections in patients with structural abnormalities and in more than 10% of cases - the etiological factor of bacterial endocarditis.

The main method of diagnosing streptococcal infection is bacteriological. Recently, slides express tests have been developed (the answer can be obtained within 10 minutes) on the basis of the immunochromatography method (sensitivity - 97%, specificity - 95%), which allows to detect the antigen of β-hemolytic streptococcus group A in swabs from the nasopharynx and β-hemolytic group B streptococcus in the vaginal discharge. Serological diagnosis is based on the detection of antibodies titer to group A streptococcus polysaccharide by the ELISA method, as well as ASO in the serum of the patient.

Antibodies to the group-specific polysaccharide polysaccharide (anti-A-CHO) appear in the first week of infection, their titer rapidly increases, reaching a peak at week 3-4 of the disease. The increase in the titer of antibodies in 10-14 days is considered to be diagnostic by no less than 4 times when studying paired sera. It should be borne in mind that even active streptococcal infection causes a 4-fold increase in antibody titer in only 70-80% of patients. The test for antibodies to polysaccharide of group A streptococcus is usually used as a supplement to the detection of ASO and antibodies to deoxyribonuclease B in patients with rheumatic fever. There is a highly specific correlation between the constant content of anti-A-CHO in the serum and the activity of rheumatic carditis. With effective treatment, the anti-A-CHO content decreases several months after the other markers of streptococcal infection.

To diagnose streptococcal infection caused by other groups of streptococci, the ELISA method is used to detect specific antibodies to the carbohydrates of the bacterial wall, mainly groups C and G. However, these studies have not been widely used.

Titer antibodies to streptococci in various diseases

Diseases	Titer AT, ED
Active rheumatic fever	500-5000
Inactive rheumatic fever	12-250
Rheumatoid arthritis	12-250
Acute glomerulonephritis	500-5000
Streptococcal infection of the upper respiratory tract	100-333
Collagenoses	12-250

The definition of antibodies to streptococci is used to diagnose streptococcal infection in the following diseases:

• catarrhal, lacunar, follicular angina;
• erysipelas, scarlet fever, glomerulonephritis, rheumatism;
• septic conditions;
• chronic inflammatory diseases of the lungs.

[1], [2], [3], [4], [5], [6]