Colony picture: group B beta-hemolytic streptococci

group B betahemolytic streptococci on blood agar. The betahemolytic zone is less klear, colonies are bigger en less dry compared to group A.

Streptococcus agalactiae or GBS (group B streptococci) were discovered in relation to puerperal sepsis. In addition, GBS cause sepsis and meningitis in newborn infants younger than 3 months. GBS related disease is most frequent in patient older than 60 years.

GBS infections:

• bacteremia
• female genital tract infections especially endometritis
• pneumonia (DM, neurological disease)
• endocarditis (large vegetations, dd. myxomas)
• osteomyelitis
• arthritis – monoarticular
• skin and soft tissue infections
• meningitis

GBS grows hemolytical on blood agars, but have a relative small zone of hemolysis around the small, slightly mucoid colonies. 1-2% are non-hemolytic and may go undetected in cultures. 98-100% of GBS produce CAMP-factor which can be tested in combination with S. aureus which produces beta-hemolysin and resutls in synergistic hemolysis. Ohter features helpful in determination are the that GBS are bacitracin and trimethoprim-sulfamethoxazole resistant. 90% is also tetracyclin resistant. GBS are up to a 10-fold less sensitive to penicillin but are uniformely susceptible.

Treatment for GBS meningitis (SWAB):

• penicillin 2000000 U q6h iv

or local guideline:

• amoxicillin 2000 mg q6h iv

Treatment of endocarditis may require the addition of an aminoglycoside for syndergistic effect.

Duration of treatment should be:

• bacteremia 10 days
• pyelonephritis 10 days
• pneumonia 10 days
• soft tissue infection 14 days
• meningitis 14 days
• osteomyelitis 4 weeks
• endocarditis 4 weeks

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Related posts:

1. Group A beta-hemolytic streptococci
2. Streptococci
3. Betalactams and streptococci
4. Proteus-Providencia group
5. Streptococcus pneumoniae
6. Sepsis, focus in skin/soft tissue, treatment
7. Streptococcus suis
8. Leuconostoc spp
9. Capnocytophaga
10. Necrotizing fasciitis

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