Group B Streptococcus

GBS and Pregnancy

WHAT IS GBS?
Group B streptococcus (GBS) is a common type of the streptococcus bacterium. Approximately a third of men and women “carry” GBS in their intestines and a quarter of women carry it in their vagina.
Most of us are unaware it’s there, as GBS carried in this way can be difficult to detect and doesn’t cause problems or symptoms. GBS is one of a number of different bacteria that normally live in our bodies and carrying it is perfectly normal. Once GBS has ‘colonised’ the intestines, no antibiotics tested so far can reliably eradicate it.

CAN I FIND OUT IF I CARRY GBS?
If you do carry GBS, that's you and a third of the population, normally without any ill effects. But you may not be able to find out for sure, as no really reliable test is routinely available in the UK. And if you get a positive result, it tells you that you carried GBS at the time the culture was taken. But the tests used miss up to 50% of GBS carriers - so, if your test result was negative, would you believe it?

For the above reasons of false positives and false negatives the RCOG does not recommend routine antenatal screening. 

Useful Link - Preventing GBS infection in Newborn babies - RCOG information

WHAT SHOULD I KNOW ABOUT GBS?
Although GBS is the most common cause of bactenal infection in newborn babies in the UK, this happens relatively rarely. Around one in 1,000 babies in the UK develops a GBS infection, which is about 700 babies a year.
Babies are usually exposed to GBS shortly before or during birth. This happens to thousands of babies with no ill effects: just why some babies are susceptible to the bacteria and develop infection while others don’t is not clear. What is clear is that most GBS infections in newborn babies can be prevented by giving women in high-risk situations antibiotics intravenously (through a vein) from the onset of labour or waters breaking until the baby is born.
Caesareans are not recommended to prevent GBS infections in babies as they do not eliminate the risk of GBS to the baby.
Very occasionally GBS causes infection of the ‘waters’, womb or urinary tract in mothers of newborn babies.

WHO IS MOSTAT RISK OF GBS INFECTION?
There are 7 situations where a baby is more likely to be exposed to GBS and, if susceptible, to develop GBS infection:
Clinical factors: each increases the risk at least 3 times:
• where labour is preterm (prior to 37 completed weeks of pregnancy);
• where there is preterm premature rupture of membranes (prior to 37 completed weeks of pregnancy) with or without other signs of labour;
• where there is prolonged rupture of membranes (more than 18 to 24 hours before delivery) with or without other signs of labour; and
• where the pregnant woman has a raised temperature (37.8 degrees C or higher) during labour.
Mothers who have previously had a baby infected with GBS: multiplies the risk about 10 times:
• where the pregnant woman has had a baby who developed a GBS infection.
Mothers who carry GBS during the present pregnancy:
multiplies the risk at least 4 times:
• where the pregnant woman has been found to carry GBS during the present pregnancy; and
• where the pregnant woman has GBS bacteria in her urine at any time during the present pregnancy (this should be treated at the time of diagnosis).

In higher-risk situations, giving pregnant women intravenous antibiotics at regular intervals from the start of labour or waters breaking through until delivery has been proven to be effective in stopping most GBS infections in newborn babies.
There are small but serious risks associated with taking antibiotics, so the decision must be considered carefully.

RECOMMENDATIONS:
Our medical advisory panel’s 6 key recommendations for preventing GBS infection in newborn babies are:
1. Women at increased risk should be offered antibiotics immediately at the onset of labour through until delivery (this includes women known to carry the GBS bacteria where no other risk factor is present and women not known to carry GBS but who have another risk factor present).
2. Women at particularly high risk should be strongly advised to accept intravenous antibiotics immediately at the onset of labour until delivery (this includes women known to carry the GBS bacteria and who have one or more risk factors, and women who have previously had a baby infected with GBS regardless of other risk factors. It also includes women not known to carry GBS who have multiple risk factors).

3. For women in labour, the recommended doses of penicillin G are 3 g (or 5 MU) intravenously initially and then 1.5 g (or 2.5 MU) at 4-hourly intervals until delivery (for women allergic to penicillin, it is recommended that clindamycin 900 mg intravenously every 8 hours until delivery be used).
4. Intravenous antibiotics should be given for at least 4 hours prior to delivery where possible.

5. Babies born in situations where there is increased risk and the mother has received at least 4 hours of intravenous antibiotics prior to delivery should be assessed carefully by a paediatrician and, if completely healthy, intravenous antibiotics should not be given to them.
6. Babies born in situations where there is increased risk and the mother has not received at least 4 hours of intravenous antibiotics prior to delivery should be investigated fully and initially commenced on antibiotics until it is established the baby is not infected.

SIGNS OF GBS INFECTION IN A BABY
Approximately 60% of GBS infection in babies is apparent at birth and 90% is apparent within the baby’s first 2 days, so these infections should be detected and treated in hospital.
Fortunately, aggressive intravenous antibiotic therapy successfully treats most babies who develop GBS infection but, even with the best medical care, sadly 10-20% of these babies die (typically from septicaemia, pneumonia or meningitis) and some suffer long-term problems.
In the unlikely event you need this information, typical signs of GBS infection in a new baby include:
• grunting;
• poor feeding;
• lethargy;
• low blood pressure;
• irritability; and/or
• high/low temperature, heart rates and/or breathing rates.
Around 10% of GBS infection develops after the baby is 2 days old (“late-onset” GBS infection), usually as meningitis with septicaemia. About 5-10% of babies who develop late-onset GBS die and approximately a third suffer long-term problems.
The warning signs of late-onset GBS infection may include:
• fever;
• poor feeding and/or vomiting; and/or
• impaired consciousness.
The warning signs of meningitis in babies may include, as well as any of those listed above, one or more of:
• shrill or moaning cry or whimpering;
• dislike of being handled, fretful;
• tense or bulging fontanelle (soft spot on head);
• involuntary body stiffening/jerking movements;
• floppy body;
• blank, staring or trance-like expression;
• altered breathing patterns; turns away from bright lights; and/or
• pale and/or blotchy skin.
If your baby shows signs consistent with late-onset GBS infection or meningitis, call your GP immediately. If your GP isn’t available, go straight to your nearest Casualty Department.
If your baby has late-onset GBS infection or meningitis, early diagnosis and treatment are vital: delay could be fatal.
The risk to a baby of developing GBS infection decreases with age - GBS infection in babies is rare after one month of age and virtually unknown after three months.
The GBS bacteria may be passed from the hands so everyone (including the parents), whether they carry GBS or not, should wash their hands and carefully dry them before handling a baby for its first three months of life.

WHAT SHOULD I DO NEXT?
You should discuss GBS with your midwife and obstetrician and agree a pregnancy and birth plan which includes what should happen about GBS.
Proven methods exist which stop most GBS infections from developing in newborn babies. In the vast majority of cases, pregnancy can be managed so the babies of women who carry GBS are protected - and are born healthy and free from GBS.

©2003 - 2011 Dr Paul Fogarty