streptokok

Streptococcus, in some contexts referred to as streptokok, is a genus of Gram-positive cocci that typically form chains. They are facultative anaerobes and commonly inhabit the human mouth, throat, skin, and gut as part of the normal microbiota. Several species cause human disease, ranging from mild to life-threatening infections.

Classification relies on hemolysis patterns on blood agar and Lancefield grouping. The most clinically important are beta-hemolytic streptococci, including Streptococcus pyogenes (Group A) and Streptococcus agalactiae (Group B). Other groups (C, G) and alpha-hemolytic streptococci, such as Streptococcus pneumoniae and the viridans group, cause different diseases.

Common illnesses include strep throat, impetigo, cellulitis, erysipelas, otitis media, pneumonia, meningitis, and endocarditis. Invasive infections caused by Group A streptococcus can progress to necrotizing fasciitis or streptococcal toxic shock syndrome. Group B streptococcus is a major cause of neonatal sepsis and meningitis; prenatal screening and intrapartum antibiotic prophylaxis reduce risk.

Diagnosis is based on clinical signs supported by laboratory tests; rapid antigen detection tests or throat culture for pharyngitis; blood cultures for suspected invasive disease; cerebrospinal fluid analysis as indicated. Penicillin or amoxicillin is first-line for GAS infections; alternatives include cephalosporins or macrolides for penicillin allergy. Severe cases require hospitalization and intravenous antibiotics.

Prevention focuses on hygiene to reduce transmission. For GBS, prenatal screening and intrapartum antibiotic prophylaxis help prevent neonatal infection; vaccines against GAS are not yet available, while pneumococcal vaccines reduce disease caused by S. pneumoniae.