Streptococcus agalactiae bacteria

Streptococcus agalactiae

Streptococcus agalactiae picture streptococcus agalactiae rotating

Streptococcus agalactiae on Columbia agar with 5% sheep blood (Bio-Rad™). Colonies of group B streptococci tend to be larger and often have less pronounced zones of beta-hemolysis than do other beta-hemolytic streptococci; some group B strains are nonhemolytic. The majority of group B streptococci produce a diffusable extracellular protein (CAMP factor) that acts synergistically with staphylococcal beta lysin to lyse erythrocytes.

Streptococcus agalactiae (also known as Group B streptococcus or GBS) is a beta-hemolytic gram-positive streptococcus. S. agalactiae is a species of the normal flora of the female urogenital tract and rectum. Its chief clinical importance is that it can be transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection. In the western world, S. agalactiae is one of the major causes of bacterial septicemia of the newborn, which can lead to death or long-term sequelae. S. agalactiae can also cause neonatal meningitis, which does not present with the hallmark sign of adult meningitis, a stiff neck; rather, it presents with nonspecific symptoms such as fever, vomiting and irritability and can consequently go undiagnosed until it is too late. Hearing loss can be a long-term sequelae of GBS-meningitis. Somewhat more rarely, S. agalactiae can also cause invasive group B streptococcal disease of the adult in the pregnant, elderly, or immunosuppressed. S. agalactiae is present in up to one-third of women of childbearing age, and one in every thousand live births will be affected by group B streptococcal infection. In the elderly or persons with compromised immune systems septicemia or other serious infections are seen. This occurs also rarely during pregnancy or maternity.

Abbreviated from Wikipedia.

Streptococcus agalactiae basic characteristics


Identification of Streptococcus agalactiae

  • The catalase test (negative)
  • The CAMP test (positive)
  • The hippurate test (positive)
  • The PYR test ( negative unlike S.pyogenes )
  • Lancefield's group B antigen presence(latex agglutination)

Antibiotic treatment of Streptococcus agalactiae infections

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

  • penicillin

  • ampicillin
  • amoxicillin

  • cephalosporins I, II, III

  • macrolides

  • clindamycin

  • vancomycin

Streptococcus agalactiae colonies on agar cultivation media

streptococcus agalactiae on blood agar plate group B beta-hemolytic Streptococcus, GBS group B streptococcus(GBS), S.agalactiae and beta-hemolytic, group C streptococcus colonies of GBS (Streptococcus agalactiae) on blood agar streptococcus agalactiae colonies with beta-hemolysis Streptococcus agalactiae, an incomplete beta-hemolysis

Streptococcus agalactiae beta-hemolysis

S.agalactiae colonies, morphology and hemolysis on agar streptococcus agalactiae in a mixed culture with nonhemolytic colonies streptococcus agalactiae photograph, colonies with hemolysis colonies of Streptococcus agalactiae, streptococcus group B in detail GBS colonies, streptococcus agalactiae on blood agar Group B streptococcus beta-hemolytic streptococcus of Group B growing on blood agar streptococcus agalactiae colony morphology streptococcus agalactiae and Staphylococcus aureus comparison streptococcus agalactiae and Enterococcus faecalis comparison streptococcus agalactiae growth on CAP blood agar

Streptococcus agalactiae; the CAMP test & other tests for identification

CAMP test with Streptococcus agalactiae, CAMP factor CAMP test, reverse CAMP test CAMP test and reverse CAMP test, results CAMP test, zone of enhanced lysis of erythrocytes CAMP test biochemical identification of streptococcus agalactiae s.agalactiae latex agglutination, streptococcal group antigen B

Streptococcus agalactiae Gram stain

streptococcus agalactiae micrograph, Gram stain

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