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Streptococcus agalactiae
Group B streptococcus, GBS

streptococcus agalactiae on agar plate

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 strains; 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 the major cause 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.

description image
GRAM-POSITIVE COCCI
NONMOTILE
NONSPOREFORMING
CATALASE: NEGATIVE
OXIDASE: NEGATIVE
FACULTATIVELY   ANAEROBIC

BASIC TESTS
FOR IDENTIFICATION

catalase test: -
CAMP test: +
PYR test: -
Lancefield's group B antigen presence(latex agglutination)

ANTIBIOTIC
TREATMENT

Should be guided by in vitro susceptibility tests!!

Selection of appropriate antibiotics depends on diagnosis!!


IF SUSCEPTIBLE:
penicillin G

ALTERNATIVES:
macrolides
ampicillin
amoxicillin
clindamycin
cephalosporins I,II,III
vancomycin
list of anntibiotics Gram-positive cocci drawing

COLONY MORPHOLOGY

streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae
streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae
streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae
streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae
streptococcus agalactiae streptococcus agalactiae streptococcus agalactiae  
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