Selective Intrapartum Chemoprophylaxis of Neonatal Group B Streptococcal Early-Onset Disease. I. Epidemiologic Rationale

Abstract

Between 1973 and 1981, 61 cases of neonatal group B streptococcal early-onset disease occurred among 32,384 infants born at Michael Reese Hospital and Medical Center, Chicago. Forty-one (67%) of the 61 affected infants were bacteremic at birth, implying intrapartum acquisition of infection. No significant deviations from the overall attack rate of 1.9 per 1,000 live births were associated with maternal demographic factors, but increased attack rates were associated with birth weights of less than or equal to 2.5 kg (7.9 per 1,000), rupture of amniotic membranes greater than 18 hr before birth (7.6 per 1,000), and intrapartum fever (6.5 per 1,000). Forty-five (74%) of the 61 affected infants and 15 (94%) of the 16 with fatal outcome had one or more of these three perinatal risk factors. Based on an intrapartum vaginal carriage rate of 16.7% among parturients with perinatal risk factors, an attack rate of 45.5 per 1,000 was estimated for infants born to colonized "high-risk" parturients, a subgroup comprising approximately 3% of our obstetric population. These findings provide a compelling epidemiologic rationale for trials of selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease.

Duration of Intrapartum Prophylaxis and Concentration of Penicillin G in Fetal Serum at Delivery

“…Penicillin G levels were examined for each time interval; those who failed to receive the scheduled second dose and those who received more than 8 hours of prophylaxis were examined separately. All groups achieved penicillin G levels significantly above the MIC for GBS (0.1 micrograms/mL),10,11 P<.002. Furthermore, penicillin G levels observed in each individual cord blood sample were 10–179-fold above the MIC (Table 2).…”

Listeriosis in human pregnancy: a systematic review

“…Though vaginal colonization is rare, nearly half of asymptomatic mothers of infants born with neonatal listeriosis will have a positive vaginal culture for L. monocytogenes [85]. This observation is consistent with other perinatal infections like group B Streptococcus (GBS)., Similar to GBS, Listeria is likely to result from spread to the vagina from the lower GI tract [5,15,28]. Furthermore, ascending vaginal colonization is supported by the finding of listerial colonization solely in the firstborn of a set of twins [56] However, haematogenous spread may be more likely, and documented maternal bacteriuria and in utero fetal infection with positive amniotic fluid cultures prior to labor have been recorded [94].…”

Adherence of group B streptococci to buccal epithelial cells in neonates with different gestational ages

“…This may explain, in part, the increased susceptibility of premature infants to GBS infection [2], The ability of GBS to attach and invade chorioamniotic membranes in vitro in 8 hours [7], their Brought to you by | University of Alberta Library Authenticated Download Date | 6/28/15 5:35 PM rapid growth in amniotic fluid [9] and their increased adherence to the premature neonate may partly explain the high incidence of early-onset GBS sepsis in the first 12 hours of life [2]. Adherence of the various types of oral streptococci to oral epithelial cells is a selective process that allows certain organisms to colonize specific sites within the mouth.…”

“…Strains of GBS from term infants with invasive disease also adhere better to cells from infected infants than those from healthy control infants [3]. However, there have been no studies of GBS adherence in premature neonates who have the highest incidence of GBS disease [2]. The present study was performed to determine GBS adherence in neonates of different gestational ages.…”