l had a baby who, at 4 days old started having seizures and l took her to the hospital to find out after a week there, that she had meningitis. WHen l was pregnant with her, l was tested for the Group B streptococcusand l guess l tested negative for it because no one ever mentioned anything to me about my results, but her pediatrician said it was most likely something from the vagina that caused her infection. My question is how likely is it that l tested negative for group b but really did have it? Educatedplease!

Group B streptococcus(GBS) is the most common cause of sepsis (blood infection) & meningitis (infection of the fluid & lining around the brain) in newborns.

Approximately 50% of the cases of GBS disease among newborns happen in the first week of life (''early-onset disease''), & most of these cases start a few hours after birth. Sepsis, pneumonia (infection in the lungs), & meningitis r the most common problems.

Premature babies r more at risk of getting a GBS infection, but most babies who become sick from GBS r full-term.GBS disease may also develop in infants one week to several months after birth (''late-onset disease''). Meningitis is more common with late-onset GBS disease.

Only about half of late-onset GBS disease among newborns comes from a mother who is a GBS carrier; the source of infection for others with late-onset GBS disease can be hard to figure out. Late-onset disease is slightly less common than early-onset disease.

As far as ur results, GBS may come & go, but a negative test within 5 weeks of delivery has a ‘negative predictive value’ of about 95%. This implies that only 5% of women r likely to acquire GBS between the time of screening & delivery. Interestingly, if GBS is detected at routine screening, the ‘positive predictive value’ of the bacteria actually being found at delivery is only about 87%.

l have some data that false negatives can be as high as 10 to 20% depending on the quality of the laboratory.