In the recent decade, Group B Streptococcus
(GBS) has been one of the common causes of the
early onset of sepsis among the newborns, which
leads to high rate of morbidity and mortality (
Most women infected by GBS are asymptomatic,
and the organism can be found from their throat,
vagina and rectum (
GBS colonization of the maternal genital tract is
related to early onset neonatal sepsis, as a result of
vertical transmission before or during labor (
The rate of GBS infection in the newborn of
colonized mother who has not received antibiotic
during delivery is one out of 200, and in cases of
receiving antibiotic, it is one out of 4000. In the
presence of other predisposing factors like prematurity,
maternal fever, premature rupture of membranes
(PROM) more than 18 hours, low birth
weight and multi parity, the infection rate increases
The Centers for Diseases Control (CDC) recommended
GBS screening for all pregnant women between
35 and 37 weeks of pregnancy, as well as taking
intrapartum antibiotic prophylaxis (
The mortality rate of early onset sepsis has estimated
about 50% (
This is a cross-sectional descriptive and analytic study performed at Prenatal Care Clinic of the Sarem Hospital in Tehran, Iran in 2011. Vaginal cultures were performed for 980 pregnant women with gestational age of 35-37 weeks. Briefly, two sterile swabs from vagina were taken by a gynecologist and were sent for smear test and culture to the lab. The first swab was used for preparing direct smear and gram staining to detect bacteria, epithelial cells and the number of white blood cells (WBCs). The second swab was cultured for GBS on blood agar, Neisseria on chocolate agar, Gram-negative organism on eosin-methylene blue (EMB) agar and Candida on dextrose agar.
Smear was obtained from β hemolytic colonies on the blood agar. The catalase test was performed on Gram-positive cocci and positive cyclic adenosine mono phosphate (CAMP) colonies.
According to our neonatal intensive care unit (NICU) protocol, complete blood count (CBC), Creactive protein (CRP) and blood count /blood culture (B/C) tests were done for all infants born from mothers with positive history of GBS vaginal colonization (by caesarian section or normal vaginal delivery). If there was any predisposing factor, like premature rupture of membranes (PROM) >18 hours, chorioamnionitis, maternal fever, taking antibiotic during labor, symptomatic newborn, ANC >15000 as a para-clinical infectious predictor, CRP >10 or positive B/C, complete sepsis workup and antibiotics therapy for infants were started.
Newborn with Apgar score <7, meconium aspiration, major anomalies, low birth weight (LBW, <2500 gr), or born from mother with preeclampsia or vaginal bleeding were excluded from our study (4 out of 48). The results were analyzed via SPSS by Chi square, and Fisher’s exact test. Significance level was set at 0.05. The study was approved by The Review Board of Tehran University of Medical Sciences (TUMS) Prenatal Department and all participants gave written informed consent.
Among 980 pregnant women (aged 19-50 years)
with gestational age of 35-37 weeks, 784 (80%) were
25-35 years old. 784 (80%) were prime par and 32
(3.2%) experienced cesarean section. In addition, 48
out of 980 pregnant women had positive vaginal GBS
The frequency of vaginal culture in pregnant women
Mothers with positive vaginal culture for GBS gave birth to babies who were characterized as 28 neonates (63.6%) with Absolute Neutrophil Count (ANC) more than normal, and 22 neonates (50%) with significant sepsis symptom, including poor feeding, lethargy, hypo-hyperthermia, poor muscle tone, and irritability, while in mothers with negative vaginal culture, only 1% of their babies were symptomatic (p<0.0001, χ2=2.27, OR=74.13, CI90: 28.21-194.80, Table 2).
Correlation between GBS positive vaginal culture and symptomatic neonatal sepsis
|VC [n (%)]||Total [n (%)]|
|22 (50)||8 (1)||30 (0.3)|
|22 (50)||928 (99)||950 (98.7)|
VC: vaginal culture, SS: sepsis symptom
Also, we found a significant correlation between positive urine culture and positive vaginal culture in our cases. About 17% of mothers with positive vaginal culture had also positive urine culture [p<0.0001, OR=24.3, CI (95): 17.54-32.91].
The gestational age of newborns was between 37 and 39 weeks (38.1 + 1), and their weight ranged between 2500 and 4200 g (3130 + 500).
The overall prevalence for GBS colonization in different
countries is reported 5-40% depending on the
different regions of the world (
Although none of mothers in our study had predisposing factor such as PROM, and all of them received antibiotics according to anti-biogram during labor,a newborn in our study had positive B/C. According to the Center for Disease Control (CDC), among 400 newborns in danger of GBS whose mothers has received antibiotic, one newborn showed GBS infection, but in our study, about 50% of the newborns had clinical symptoms which might be due to the severity of maternal colonization and the type of GBS species.
The overall vertical transmission rates of GBS colonization
in newborns were reported between 6.4%
and 28.4%, while the most studies have indicated
colonization rates between 8 and 34.5% (
Early bacterial infections develop neutropenia (
Just like other countries, the maternal colonization with GBS is a common problem in Iran. The rate of GBS infection in Iranian newborns is also like the other countries. In order to obtain more information, we recommend screening for GBS in all pregnant women and a close observation for all their newborns.
It would be efficient to perform screening studies by repeating culture in pregnant women according to microorganism specific enriched media for detecting the GBS species. Early detection results to early treatment by proper antibiotic for newborn infected by GBS. We found that neonates born from women with positive vaginal cultures were more symptomatic than others, so our results suggest that early therapeutic intervention during labor and after birth would be beneficial. However, a sensible long-term plan in order to develop an effective vaccine and its routine usage in healthcare centers would be a real triumph.