GBS Flashcards
Ref: EB MFM, ACOG GBS Practice bulletin
What is GBS?
Streptococcus agalactiae
An encapsulated gram-positive coccus that colonizes the vaginal & GI tract
Manifestations of GBS in the mother
Urinary tract infection Chorioamnionitis Endometritis Bacteremia Stillbirth
What are the 2 types of newborn GBS infection?
Early-onset - usually within first 24 hrs of life, up to 6 days after birth
Late-onset - Usually at 3-4 weeks of age, can occur any time from 7 days - 3 months
Symptoms of neonatal GBS
Early-onset: Respiratory distress Shock Pneumonia Meningitis (occasionally)
Late-onset: Bacteremia (common) Meningitis (common) Poor feeding Irritability Extreme drowsiness Listlessness Localized infection: middle ear, sinuses, bones, joints, skin
Prevalence of asymptomatic GBS anovaginal colonization in pregnant women
20%, can be transient or persistent
A substantial portion of women colonized in one pregnancy will not have colonization during a subsequent pregnancy
Percentage of neonates born to mothers colonized with GBS that are colonized themselves
40-75%
Risk factors for early-onset GBS disease
Prolonged ROM (>/= 18 hrs) Preterm birth (but >80% GBS are term) Termp >/= 38 deg C Maternal GBS colonization btw 35-37w Previous infant with invasive GBS disease Maternal choio Black or Hispanic GBS bacteriuria during pregnancy
DM or GBS colonization in a previous pregnancy are not risk factors
Neonatal mortality due to GBS disease
5%
25% if < 33w GA
Is there a vaccine for GBS?
accination against GBS is potentially the most effective method of preventing the morbidity and mortality caused by infection. GBS vaccines have been investigated as a tool to reduce maternal colonization and prevent transmission to the neonate; however, a licensed vaccine is not yet available.
What percentage of neonates with early-onset GBS sepsis are born to women without risk factors?
20%
How effective is a screening-based strategy compared to a risk factor-based strategy for GBS?
> 50% more effective for early-onset GBS, but does not affect the incidence of late-onset GBS sepsis
For whom is intrapartum GBS prophylaxis indicated?
Previous infant with invasive GBS disease
GBS bacteriuria during current pregnancy
+GBS screening culture during current pregnancy (unless C/S prior to ROM)
Unknown GBS status and:
/= 18 hrs
Intrapartum temp >38 deg C
Intrapartum NAAT GBS+
For whom is intrapartum GBS prophylaxis NOT indicated?
Previous pregnancy with a positive GBS screening culture (unless indication present during current pregnancy)
C/S in absence of labor or ROM (regardless of culture status)
Negative vaginal & rectal GBS screening culture 35-37w, regardless of intrapartum risk factors
What is the NPV of GBS cultures at 35-37w
95-98%, if prevalence 20%
Recommended regimen for GBS prophylaxis
Penicillin G, 5 million units IV x 1, then 2.5-3 million units IV q 4 hrs until delivery
Alternative GBS regimen
Amp 2 g IV x 1, then 1 g IV q 4 hrs until delivery
GBS prophylaxis - PCN allergic, but not at high risk for anaphylaxis
Cefazolin 2 g IV x 1, then 1 g IV q 8 hrs until delivery
GBS prophylaxis - PCN allergic, at high risk for anaphylaxis, susceptible to clinda & erythro
Clinda 900 mg IV q 8 hrs until delivery
GBS prophylaxis - PCN allergic, but not at high risk for anaphylaxis - resistant to clinda or erythro or susceptibility unknown
Vancomycin 1 g IV q 12 hrs until delivery
How is susceptibility testing for GBS performed?
Resistance to erythromycin is often, but not always, associated with clindamycin resistance. If a strain is resistant to erythromycin, but appears susceptible to clindamycin, it may still have inducible resistance to clindamycin. Treatment with erythromycin is not recommended.
Have current prevention strategies decreased the incidence of late-onset GBS disease.
Nope.
How long is a GBS screening culture valid for?
5 weeks
