Karem Akhbar, 28, left Iraq over a decade ago, but that
doesn't mean she's not worried about 'neo-colonialist'
American policies and the effect they'll have on her unborn
son. Her doctor, on the other hand, is more worried about
whether the pregnant woman, who is in her ninth month,
has been colonized by group B Streptococcus (GBS).
Currently, GBS detection depends on examining cultures,
which means results can take days to develop. This is
a serious drawback if an infection is suspected when a
woman is in labour, as every moment counts in zapping
the potentially transferable infection. A paper in the
October 15 issue of Clinical Infectious Diseases
describes how a speedy 'real-time' polymerase chain reaction
(PCR)-based test accurately detects GBS infections in
pregnant women.
SAVE
THE CHILDREN
The research may provide "an opportunity during labour
to quickly identify women who are carrying strep B and
thus whose children are at risk of serious GBS infection,"
commented the study's lead author Dr H Dele Davies.
Formerly of the Alberta Children's Hospital at the University
of Calgary, Dr Davies is now at Michigan State University
in East Lansing.
The researchers screened 803 pregnant
women for GBS before and after labour began. The antenatal
cultures were taken and analysed. During labour, two
vaginal and two anal swab samples were taken. These
were tested using both the usual culture-based technique
and the new IDI-Strep B PCR-based assay.
The culture-based test detected
the presence of GBS in 149 women, when it was performed
on samples taken during labour. When compared to these
gold-standard results, the PCR test correctly pinpointed
94% of these women as being infected with GBS. Culture
tests performed on antenatal samples, on the other hand,
were right a mere 54% of the time.
KEEP
IT REAL
Another point in favour of the molecular test was that
it produced significantly fewer false negatives and
positives than antenatal culture tests for GBS. Further,
when the two techniques were considered in terms of
the presence of risk factors in the women that predisposed
them to a GBS infection, the molecular assay was leaps
and bounds better than the culture assay in predicting
the "intrapartum status" � the presence or absence of
GBS during labour and delivery. The molecular test was
correct in 94% of all cases while the culture test only
got it right 42% of the time.
"It's our conclusion that this
test is highly sensitive and specific. The results can
be available in under two hours instead of the usual
48 hours for a culture," says Dr Davies. "This means
that in many clinics it can be used in labour in specific
situations." Indeed, the researchers conclude that,
once antibiotic-resistant Strep can be similarly
detected, the method may become "the routine means of
identifying women who carry GBS."
And there's more. The test may
enable not only the detection of GBS in those about-to-become
mums, but may help stop GBS infections in their microbial
tracks. While urging caution in assessing the study's
long-term significance, "it will be interesting to assess
the ability of this test for GBS disease prevention,"
writes Dr Stephanie Schrag of the US Centers for Disease
Control and Prevention, in an accompanying editorial.
About half of pregnant women who carry strep B pass
the bug along to their baby during delivery if antibiotics
are not used. The newborn may subsequently come down
with potentially fatal meningitis or pneumonia. Given
this, a fast, accurate test for GBS in pregnant women
is definitely a blessing.
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