Infections cause by A group Streptococci

Streptococcal infections are among the most common bacterial infections. Streptococci are obligately pathogenic, facultatively pathogenic and saprophytic microorganisms. We classify them according to the degree of hemolysis - α-hemolytic (incomplete, partial hemolysis on agar) and β-hemolytic (complete, complete hemolysis), according to serological differentiation of capsule antigen C into groups A and B.

The most common infections caused by group A streptococci include:

• sore throat
• Scarlet fever
• erysipelas
• contagious impetigo

A group Streptococci

• Group A streptococci are the cause of 90% of streptococcal infections,
• toxins: erythrogenic toxin, streptolysin O and streptolysin S (hemolysis, toxic to myocardial fibers and hepatocytes), streptokinase (fibrinolysis), hyaluronidase (invasive factor of streptococci), etc.
• against some streptococci, Ig is formed useful in diagnosis - ASLO (antistreptolysin O) - they decline in the few weeks after infection.
• cause a variety of diseases: - damage to the skin and mucous membranes, prolonged seropurulent rhinitis in young children, scarlet fever, impetigo, tonsillitis and pharyngitis

Complications of sore throat and scarlet fever

• Submandibular node covation, retrotonsillar or paratonsillar abscess, otitis, mastoitis, sinusitis,
• more rarely - bacteremia, metastatic foci - purulent arthritis, endocarditis, meningitis, brain abscess, osteomyelitis and mediastinitis. Transmission of infection to the mediastinum is a rare but very dangerous complication with a high mortality rate.
• without therapy - risk of late complications - rheumatic fever or glomerulonephritis.

Rheumatic fever

• Most often after group A streptococci, 1-4 weeks after infection (about 3% infected),
• the course of the original infection may be inapparent (without obvious symptoms),
• acute immunological multisystemic inflammation,
• often affects the heart - chronic changes in the valves,
• main manifestations: migrating polyarthritis, pancarditis, subcutaneous nodules, erythema marginatum and Sydenham's chorea - dance of St. Vita, chorea minor (neurological disorder - unconscious untargeted rapid movements),
• side effects: non-specific - fever, joint pain, increased CRP…,
• diagnosis: Jones criteria - history of streptococcal infection, presence of at least two manifest symptoms (major or minor)
• pathogenesis: hypersensitivity reactions, Ig against M protein of streptococci cross-react with glycoproteins of heart muscle, joints, etc.,
• relapses.

Complications of skin infections with streptococcus

• Rare septic complications, possibly also glomerulonephritis,
• rheumatic fever is rare
• acute glomerulonephritis.

Links

Similar articles

• Streptococci: Streptococcus pyogenes • Streptococcus agalactiae • Streptococcus pneumoniae • Streptococcus mutans • Orální streptokoky

Literature

• HRODEK, Otto a Jan VAVŘINEC, et al. Pediatrie. 1. vydání. Praha : Galén, 2002. ISBN 80-7262-178-5.

• ŠAŠINKA, Miroslav, Tibor ŠAGÁT a László KOVÁCS, et al. Pediatria. 2. vydání. Bratislava : Herba, 2007. ISBN 978-80-89171-49-1.

Source

• ws:Infekce streptokoky skupiny A
• BENEŠ, Jiří. Studijní materiály [online]. ©2007. [cit. 2009]. <http://www.jirben.wz.cz/>.