A bug in the gut

A bug in the gut

In the absence of routine screening for GBS in pregnant women, identifying those at high risk can help reduce GBS-associated perinatal morbidity and mortality, recommend Dr Rajiv Aggarwal & Dr Prabha Ramakrishna.

Group B Streptococcus (GBS), a common colonist in the reproductive tract and gut of women, can cause serious infection in neonates. GBS is a bacteria, which is commonly present in human bodies, often without causing any symptoms or harm. 

However, when a pregnant woman has a colony of the bacteria in her, she carries high risk of transmitting it to her newborn. Epidemiological surveys in India have revealed that the vertical transmission rate (from mother to child) of GBS is between 53-56 percent. The bacteria may penetrate the baby’s body either through the mother’s genitourinary tract into the amniotic fluid at the time of rupturing of the amniotic membrane or when the baby passes through the birth canal. Once the baby aspirates the contaminated amniotic fluid, GBS enters the lungs causing pneumonia and respiratory distress. It is extremely crucial to give the neonate intravenous antibiotic therapy at this time to control the infection. Failure to do so results in sepsis and meningitis as the bacterial invasion spreads to the blood and brain, often leading to death of the neonate.  Although the bacteria transmission rate among the newborns is quite high, the reported cases of neonatal GBS disease are low in India. However, taking into account that most of the reported incidences of GBS infection represent the cases occurring in tertiary care hospitals and the fact that 60 percent of women in India give birth at home, it can be said that the real burden of GBS remains vague. Majority of the GBS cases occur within a few hours after the childbirth, when the baby is still in the hospital. In late onset GBS, the symptoms appear within a week or few months. It has been seen that babies whose mother are GBS positive require more frequent NICU (Neonatal Intensive Care Unit) admissions than those with GBS negative mothers.

Symptoms which indicate that a woman is at a higher risk, of delivering a baby with GBS, include labour or rupture of membrane before 37 weeks, rupture of membrane for 18 hours or longer, fever during labour, GBS urinary tract infection and history of delivering previous baby with GBS disease. A woman with any of these symptoms qualifies for intravenous antibiotic treatment, against GBS, during delivery.  

Since GBS is present as natural flora in the gut, it may develop again after taking the antibiotic treatment. Therefore, it is important that the antibiotic therapy is taken at the time of delivery, and not before labour, in order to provide complete protection to the neonate against GBS. Also, antibiotics should be administered only to those at risk, as irrational use may lead to bacterial resistance.  In India, the incidence of severe GBS infection in neonates is not high enough to include GBS screening in routine testing of pregnant women. But the consequences of GBS infection in newborns are very severe; it often results in lifelong handicaps and even death. Therefore, it is prudent to introduce national guidelines regarding GBS screening and antibiotic use. 

Meanwhile, in the absence of routine screening for GBS in pregnant women, identifying those at high risk and providing antibiotic therapy to them at the time of delivery can help in substantially reducing GBS associated perinatal morbidity and mortality. 
(Dr Rajiv is head, paediatrics , and Dr Prabha is head, obstetrics and gynaecology,  Sakra World Hospital, Bangalore)