Group strep B is a bacteria that a vast majority of the population carry around in their bodies without actually developing any form of illness. Usually in their gut, but women also carry it around in their uterus and their vagina so that during labour they can transfer that bacteria to their child.
Strep B is the cause of meningitis and sepsis (blood poisoning)..
People with lowered immune systems are more susptable to this illness mainly because the bacteria can easily grow in their bodies in spread where in a normal person our immune systems would keep it under control. Its why meningitis and MRSA are so prevalent in hospitals where healthy people carrying the bacteria are visiting people with lowered immune systems.
The problem is that the testing doesn't guarantee to catch all the mothers who are carrying the strep b bacteria...which is why I think some NHS trust do not test for it.. Plus not every mother who is a carrier and doesn't receive treatment will go on and infect their child making their child ill... infact that proportion is quite minute considering. Also stating that not every mother identified as a carrier and who has treatment is guaranteed not to pass the disease on to their newborn child, and their child get's ill regardless..
As we know meningitis is a nasty unpredictable disease. Tia developed it at 9 months (Good Friday 2000 to be exact...the easter bunny came round as she went for her second lp) It would have been caused by the Strep b bacteria but it was unlikely to have come from me. But I know that after she was diagnosed with meningitis I got pumped full of antibiotics that made me pee red...
If you are really worried, speak to your midwife... apparently you can have the test done privately in the UK for around 30 quid I think. In which case if its positive all you will need is a course of iv antibiotics during your labour....