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IV./2.4.: Common causes of childbed fever: Streptococci
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Streptococci are Gram-positive, round or oval-shaped bacteria, with the size of 0.6-1 microns and with a link-like arrangement. They are widely distributed in the nature. Some subtypes can be found in the mouth, respiratory tract, in the gastrointestinal tract as a part of the normal flora. Other subtypes care expressedly pathogenic. Their categorization has been previously based on their haemolysing ability; alpha and beta haemolysing and non-haemolysing forms were differentiated.
Pathogenic Streptococci can be classified into 4 groups:
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1. alpha-haemolysing Streptococci,
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2. beta-haemolysing Streptococci
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3. Streptococcus faecalis (Enterococcus),
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4. anaerob Streptococci.
Beta-haemolysing Streptococci and Streptococcus faecalis are subtypes of higher importance. The most important member of beta-haemolysing Streptococci is the
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Streptococcus pyogenes. The bacteria are cultured on media containing native proteins. Mainly blood agar is used, but vitamin B and amino-acids also have to be provided, since the bacteria are very selective. The developing bacterial colonies are 0.5-1 millimetres in diameter; they are convex, colourless, and circled by a beta-haemolytic zone. According to their appearance they can be mucoid, matt or smooth. Virulent strains form mucoid or matt colonies because of their M protein content. Streptococci usually contain more antigens according to their strains, which makes their classification into different serological groups (A-D) and types possible.
Relevant antigens:
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- C carbohydrate,
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- M protein,
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- T and R antigens.
The M protein is a cellular wall protein, the main defining characteristic and main factor of the virulence of A-type Streptococci.
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The members of this group produce more than twenty extracellular metabolites, which include streptokinase, hyaluronidase, streptodornase, eritrogenic toxin and haemolysins. Streptococcus pyogenes causes the most diverse symptoms. The most frequent symptoms include symptoms of the throat and airway system, pharyngitis, pharyngeal angina, tonsillitis, otitis as a complication, retropharyngeal abscess, sinusitis, tracheitis, bronchitis and pneumonia. If the pathogens enter the body through the skin, then erysipelas, phlegmone, lymphadenitis can develop, while the disorder developing through female genitals is the childbed fever . 2-3 weeks after the primary infection allergic late or secondary disorders can develop. The most important one is rheumatic fever with its temporary (migrating polyarthritis, chorea minor, erythema nodosum) and permanent (chronic rheumatic valvular endocarditis) complications.
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