Streptococcus agalactiae
- epidemiology
- classification and characteristics
- virulence factors
- transmission and infection
- clinical manifestations
- diagnosis
- treatment
Streptococcus agalactiae is more commonly known as group B Strep, or GBS.
Epidemiology
Healthy women have a 15-40% vaginal carrier rate.
Classification and Characteristics
Gram positive cocci forming chains.
Virulence Factors
Transmission and Infection
Clinical Manifesations
GBS is not harmful to adults but can be devestating for neonates, leading to neonatal sepsis, meningitis, pneumonia, or UTI.
Risk factors for neonatal disease include:
- GBS bactiuria
- previous infant with invasive infection
- preterm labour (<37 weeks)
- amniotic fluid rupture >18 hours before delivery
- intrapartum maternal temprature >38 C
- positive GBS screen during pregnancy
Diagnosis
Two approaches:
- swab and identify all GBS+ mothers at 36 wks; treat all those mothers in labour
- treat all mothers in labour who are <37 wks gestation, have prolonged rupture of membranes, or have a fever during labour: this strategy misses 25% of cases
Treatment
Risk of sepsis is 1:200 in GBS+ mothers without prophylaxis.
Penicillin G 5 million U IV then 2.5 million U IV q4h until delivery
- cefazolin (2g IV, 1g q8h) or clindamycin (900 mg IV q8h) can be used with penicillin allergy