Streptococcus pyogenes bacteria

Streptococcus pyogenes (Group A streptococci)

streptococcus pyogenes, group A streptococcus streptococcus pyogenes rotating

Streptococcus pyogenes on Columbia agar with 5% sheep blood. Cultivation 24 hours, in an aerobic atmosphere enriched with 5% carbon dioxide. Colonies are surroundend by a wide zone of beta-hemolysis. Positive PYR test is useful for preliminary identification of isolated strains (together with the negative catalase test). Identification can be confirmed by the latex agglutination test.

S. pyogenes is the cause of many important human diseases, ranging from mild superficial skin infections to life-threatening systemic diseases. Infections typically begin in the throat or skin. Examples of mild S. pyogenes infections include pharyngitis ("strep throat") and localized skin infection (impetigo). Erysipelas and cellulitis are characterized by multiplication and lateral spread of S. pyogenes in deep layers of the skin. S. pyogenes invasion and multiplication in the fascia can lead to necrotizing fasciitis, a potentially life-threatening condition requiring surgical treatment. Infections due to certain strains of S. pyogenes can be associated with the release of bacterial toxins. Throat infections associated with release of certain toxins lead to scarlet fever. Other toxigenic S. pyogenes infections may lead to streptococcal toxic shock syndrome, which can be life-threatening.

Streptococcus pyogenes can also cause disease in the form of postinfectious "nonpyogenic" (not associated with local bacterial multiplication and pus formation) syndromes. These autoimmune-mediated complications follow a small percentage of infections and include rheumatic fever and acute postinfectious glomerulonephritis. Both conditions appear several weeks following the initial streptococcal infection. Rheumatic fever is characterised by inflammation of the joints and/or heart following an episode of streptococcal pharyngitis. Acute glomerulonephritis, inflammation of the renal glomerulus, can follow streptococcal pharyngitis or skin infection.

Abbreviated from Wikipedia

Streptococcus pyogenes basic characteristics

  • GRAM-POSITIVE COCCI
  • NONMOTILE
  • NON-SPORE-FORMING
  • CATALASE: NEGATIVE
  • OXIDASE: NEGATIVE
  • FACULTATIVELY ANAEROBIC

Identification of Streptococcus pyogenes

  • The catalase test (negative)
  • The PYR test (positive)
  • Lancefield's group A antigen presence(e.g., latex agglutination)



Antibiotic treatment of Streptococcus pyogenes infections

Should be always guided by in vitro susceptibility tests!!
Selection of appropriate antibiotics depends on diagnosis!!

Treatment:
Other beta-lactam antibiotics, e.g.:
ALTERNATIVES:


Streptococcus pyogenes colonies on agar cultivation media

agar plate with Streptococcus pyogenes colonies, S.pyogenes in Petri dish S.pyogenes growing on blood agar, penicillin susceptible Petri dish with beta-hemolytic colonies of Streptococcus pyogenes large mucoid beta-hemolytic colonies of S.pyogenes Streptococcus pyogenes surrounded by a wide zone of beta-hemolysis colonies of beta-hemolytic and nonhemolytic bacteria in Petri dish bacterial colonies surrounded by complete hemolysis (beta-hemolysis) and colonies without hemolysis S.pyogenes on BAP (blood agar plate) s.pyogenes culture in Petri dish, blood agar morphology of Streptococcus pyogenes colonies Group A beta-hemolytic streptococcus colonies; Streptococcus pyogenes and hemolysis on agar S.pyogenes colonies with hemolysis type of hemolysis in group A streptococcus (S.pyogenes), colony appearance S.pyogenes growth on blood agar colony morphology of Streptococcus pyogenes (group A streptococcus) on blood agar wide zone of complete hemolysis around Streptococcus pyogenes colonies streptococcus pyogenes streptococcus pyogenes streptococcus pyogenes streptococcus pyogenes Strep A colonies surrounded by a zone of beta-hemolysis

Streptococcus pyogenes identification

streptococcus pyogenes and PYR test result positive PYR test with streptococcus pyogenes latex agglutination agglutination of streptococcus pyogenes (group A strep, GAS) latex agglutination with streptococcus pyogenes

Streptococcus pyogenes Gram stain

streptococcus pyogenes under the microscope streptococcus pyogenes micrograph s.pyogenes computer generated image

Strep throat

strep throat caused by streptococcus pyogenes

Useful Links

WIKIPEDIA
CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC)
MEDSCAPE