In many neonates, septicemia involves signs of serious illness that usually develop within 6 to 12 hours of birth. These include respiratory distress, apnea, and hypotension. At the outset, therefore, neonatal infection must be diferentiated from respiratory distress syndrome caused by insuicient surfactant production (Chap. 34, p. 636). he mortality rate with early-onset disease has declined to approximately 4 percent, and preterm newborns are disparately afected.
Late-onset disease caused by GBS is noted in 0.32 per 1000 live births and usually manifests as meningitis 1 week to 3 months after birth (Centers for Disease Control and Prevention, 2015). he mortality rate, although appreciable, is less for late-onset meningitis than for early-onset sepsis. Unfortunately, it is not uncommon for surviving infants of both early-and late-onset disease to exhibit devastating neurological sequelae.
As GBS neonatal infections evolved beginning in the 1970s and before widespread intrapartum chemoprophylaxis, rates of early-onset sepsis ranged from 2 to 3 per 1000 live births. By 2010, these outcomes led to a policy of universal rectovaginal culture screening for GBS at 35 to 37 weeks' gestation followed by intrapartum antibiotic prophylaxis for women identified to be carriers. hese outcomes stimulated development of expanded laboratory identiication criteria for GBS; updated algorithms for screening and intrapartum chemoprophylaxis for women with preterm prematurely ruptured membranes, preterm labor, or penicillin allergy; and described new dosing for penicillin G chemoprophylaxis. Following these changes, the incidence of early-onset G BS neonatal sepsis decreased to 0.21 cases per 1000 live births by 2015 (Centers for Disease Control and Prevention, 2015).
hus, during the past three decades, several strategies have been proposed to prevent perinatal acquisition of GBS infections. These strategies have not been compared in randomized trials and are either culture-based or risk-based guidelines (Ohlsson, 2014). hese methods have been adopted in the United States, but not all European countries have guidelines (Di Renzo, 2015).
Culture-Based Prevention. he CDC (2010) GBS guidelines recommend a culture-based approach, which was also adopted by the American College of Obstetricians and Gynecologists (20 16e). Shown in Figure 64-6, this strategy is designed to identiy women who should be given intrapartum antimicrobial prophylaxis. Women are screened for GBS colonization at 35 to 37 weeks' gestation, and intrapartum antimicrobials are given to women with rectovaginal GBS-positive cultures. Selective enrichment broth followed by subculture improves detection. In addition, more rapid techniques such as DNA probes and NAATs are being developed (Helali, 2012). A previous sibling with GBS invasive disease and identiication of GBS
Vaginal and rectal GBS screening cultures at 35-37 weeks' gestation for ALL pregnant women (unless patient had GBS bacteriuria during the current pregnancy or a previous infant with invasive GBS disease)
Previous infant with invasive GBS disease
Positive GBS screening culture during current pregnancy (unless a planned cesarean delivery, in the absence of labor or amniotic membrane rupture, is performed)
Unknown GBS status (culture not done, incomplete, or results unknown) and any of the following:
Previous pregnancy with a positive GBS screening culture (unless a culture was also positive during the current pregnancy)
Planned cesarean delivery performed in the absence of labor or membrane rupture (regardless of maternal GBS culture status)