Bstreptokocker

Bstreptokocker, commonly known as group B Streptococcus (GBS), refers to a group of Gram-positive cocci in chains within the genus Streptococcus. They are beta-hemolytic on blood agar and classified by Lancefield grouping as group B. GBS are facultative anaerobes and are part of the normal human microbiota, colonizing the gastrointestinal and genitourinary tracts.

Carriage and transmission are central to GBS epidemiology. Many adults carry GBS without symptoms, and carriage is most relevant in pregnancy, where vaginal-rectal colonization occurs in an estimated 10–30% of women. Neonates can acquire GBS vertically during labor or delivery, which can lead to invasive disease in newborns.

Clinical significance varies by age. In newborns, GBS can cause early-onset disease (within the first week of life), presenting as sepsis, pneumonia, or meningitis, and late-onset disease (up to several months of age). In adults, GBS can cause urinary tract infections, skin and soft tissue infections, bacteremia, and occasionally meningitis, with higher risk in older adults or those with chronic illnesses or immune compromise.

Diagnosis is based on culture or molecular methods from sterile sites in suspected invasive disease, or on maternal colonization screening in pregnancy. In many healthcare settings, pregnant women are screened for GBS colonization at around 35–37 weeks’ gestation to guide intrapartum prophylaxis.

Prevention and treatment rely on antibiotics. Penicillin G remains the first-line therapy for both prophylaxis and treatment; alternatives include ampicillin or certain cephalosporins for penicillin-allergic individuals without anaphylaxis. For those with anaphylaxis to penicillin, vancomycin or other agents may be used. In neonatal suspected disease, empiric therapy often includes a beta-lactam antibiotic plus an aminoglycoside, tailored to culture results and local guidelines. Resistance to penicillin is rare, but macrolide and clindamycin resistance has been reported in some strains. Vaccines against GBS are under development.