Epidemiology
Several studies were published on prevalence of ASB
in pregnancy. In general, the studies were of poor
quality: small sample size, prevalence of ASB diagnosed
at different gestational ages or the definition
of ASB as not clearly defined.
In a prospective cohort study performed in India,
371 pregnant women were screened for ASB before
20 weeks’ and 274 women between 32 and 34 weeks’
gestation. The prevalence of ASB was 17% in early
pregnancy and 16% in the third trimester. Even
though all pregnant women with ASB received antimicrobial
treatment, an increased incidence of preterm
labour (RR 3.27, 95% CI 1.38–7.72) and
neonatal weight below the 10th percentile (RR
3.79, 95% CI 1.80–7.97) was found in women with
ASB in the third trimester compared with women
without ASB. No differences were found between
women with and women without ASB in early pregnancy
[14&&].
Another study performed in Nigeria showed a
40% prevalence of ASB (50 of 124 women) in pregnant
women between 9 and 24 weeks’ gestation.
Surprisingly, Staphylococcus aureus (72%) and Proteus
spp. (14%) and not E. coli (4%) were the most
common pathogens [15]. In other studies, S. aureus
is only found in around 5% of the cases [16]. These
findings suggest that contamination with skin flora
instead of real bacteriuria was present in the
majority of patients. Unfortunately, the authors
do not provide a definition of ‘significant’ growth
or ‘positive culture’ in the methods [15].
Studies focusing on the occurrence of UTI
during pregnancy published recently used mainly
population-based data. Bruce et al. [17&] analysed
data of 37 741 pregnancies of patients registered at a
health maintenance organization in Georgia and
found UTI to be one of the five most common
conditions during pregnancy (12%). The incidence
of UTI during pregnancy studied in 4501 Jordan
women was even higher (20.2%) [18]. In the Netherlands,
UTI is the most frequent reason for a general
practitioner (GP) visit during pregnancy. UTI diagnosis
was more common in pregnant than in nonpregnant
women (14 vs. 6 per 100 women) [19].
Concluding, both ASB and UTI are common
during pregnancy; however, the found prevalence
and incidence rates were widespread, possibly due to
a combination of differences in diagnostic techniques,
timing of urine collection and/or in cutoff
points for significant bacteriuria.