It sounds like it might be a different type of infection with a similar name? Or maybe just a different cause. I think even if you're a carrier you don't have the bacteria present all of the time or something like that.
I don't know much about it to be honest. I just remember reading it's something like a 1 in 2000 chance your baby can get infected with it when they are born (in general) and it can cause some really nasty outcomes, but if you're positive for it at the time of birth, then it's more like 1 in 200. So if they know you're positive then they can give you precautionary antibiotics just in case the baby picks up an infection.
I didn't get tested for it in my first pregnancy and I don't regret that decision, it was the right decision at the time. There can be a high false positive rate, and then you're having unnecessary antibiotics, which isn't great for the baby plus it restricts you more in labour. Also if you have it too early your negative result might not actually be accurate by the time you give birth.
But in the second one because we had the issues with the genetic testing I just wanted to know anything and take any precaution possible - this was probably more DH's attitude coming over on me, but I didn't disagree in principle. So I had the test assuming it would be negative and it wasn't!
I didn't actually find the antibiotics in labour to be as annoying/restrictive as I thought they'd be, it was perfectly fine. But I do wonder if the GBS+ test caused the hospital staff to panic and read things into DS2 struggling to breathe a bit when he was born. He never had a temperature and I don't think he ever had an infection. I think the breathing problems were caused by the cord being compressed during the final stages of labour, or it might have been that he ingested too much amniotic fluid in the womb (that's what they said they thought if it wasn't an infection). So he was on antibiotics for 5 days for possibly no reason, whereas perhaps it would have been better to hold off and see whether he developed a temperature before giving them. It doesn't seem to have done him any harm, and since infections in newborns can be incredibly dangerous on balance I think I'd rather that he had them than not, but still. I don't really know whether he actually needed to be whisked away to special care and because I wasn't there I couldn't ask these questions. I just trusted them to do what was best.
The ideal scenario would be for all women to be offered a rapid test in labour because then the information is absolutely up to date and accurate, but unfortunately that isn't really feasible due to cost and lack of availability of the lab staff to do the tests. Currently it takes a few days to get the results through which is obviously too late to be doing it when you go into labour. Possibly this will be offered in the future though.