Interpretation
New β-lactamases have emerged rapidly with the development of new
β-lactam antibiotics over the past 20 years, and the prevalence of
ESBL-producing bacteria is increasing worldwide.1,3-5The prevalence of community-acquired ESBL-E infections among
hospitalized patients has also increased in Korea.17In our study, the rate of maternal ESBL-E vaginal colonization increased
to 6.2% in the recent period. In a Norwegian study, the prevalence of
ESBL-E rectal colonization was 2.9% among pregnant women at 36 weeks of
gestation.18 In another study conducted in Sri Lanka,
the pre-delivery ESBL-E lower vaginal colonization rate was
1.6%.19
Our data are in line with previously reported findings that prior use of
antibiotics, particularly fluoroquinolone and cephalosporin, is a risk
factor for ESBL-E infection in hospitalized
patients.1,2 It is well recognized that an increase in
the rate of ESBL-E infection is associated with the widespread use of
antibiotics.1,2,20-22 In our study, the multivariate
analysis confirmed that prior antibiotic treatment and cerclage were the
independent risk factors for ESBL-E vaginal colonization in high-risk
pregnant patients. In fact, previous studies have suggested that
antibiotic administration during pregnancy may alter the vaginal
microbiological ecology.23,24 For example, lessLactobacillus species colonization than expected was reported in
pregnant women using antibiotics, and an increased vaginal colonization
rate by E. coli was reported after antibiotic use during
pregnancy.24 Similar to the general population,
prolonged antibiotic use in pregnant women is also a known risk factor
for ESBL-producing bacterial infection.12,13Similarly, our study also showed that the duration of antibiotic
administration was significantly longer in the ESBL-E-positive group.
Clinically, the proper use of antibiotics during pregnancy is very
important for the health of both the mother and
fetus.25 Considering our study results, antibiotic
treatment during pregnancy could be a risk factor for ESBL-E vaginal
colonization infection and thus should be used only when needed.
Therefore, our study also indirectly supports the limited exposure to
antibiotics during pregnancy with narrow-spectrum antibiotics, if
possible.
Cerclage is an effective treatment option for preventing PTB in women
with cervical incompetency.26,27 In several studies,
dilated cervix and short CL were associated with a paucity ofLactobacillus species in the vagina.28,29 A
reduced abundance of normal vaginal flora could make it vulnerable to
colonization by abnormal vaginal flora. Previous studies have suggested
that cerclage increases the risk of maternal infection requiring medical
intervention and puerperal pyrexia27,30; the
possibility of vaginal dysbiosis owing to the effects of suture
materials has also been suggested.31 Our study found
that cerclage was associated with the risk of ESBL-E vaginal
colonization. However, it is unclear whether cerclage is the cause or
result of ESBL-E vaginal colonization. Similarly, one study confirmed
that when postoperative vaginal culture was performed in patients
undergoing cerclage, more than 75% of the samples were positive forE. coli. 32 Based on the results of these
studies, it is necessary to consider the risks and benefits when
deciding whether to perform cerclage.
Abnormal vaginal colonization by E. coli or K. pneumoniaeduring pregnancy is clinically important with respect to neonatal
infection and PTB.33-36 Especially, ESBL-E is very
important because it has been reported to be the major cause of neonatal
infection, which increases neonatal mortality owing to limitations in
therapeutic options.10,37,38 In light of this
importance, it is considerably regrettable that there are only a few
studies on the screening or treatment of ESBL-E colonization in pregnant
women.
The organisms known to cause EONS are generally colonized in the
maternal genito-urinary tract.39 Among them, maternalE. coli vaginal colonization has been widely studied as an
independent risk factor for neonatal E. colisepsis.40,41 In addition, a previous study has shown
that EONS with E. coli was associated with worse perinatal
outcomes compared with EONS with group BStreptococcus. 42 For this reason, neonatalE. coli sepsis, especially ESBL-E sepsis, which is difficult to
treat, is emerging as an important condition. A recent study on ESBL-E
infection during pregnancy identified that maternal ESBL-E colonization
is an important risk factor for vertical transmission. The authors
explained that the rate of ESBL-E-positive postnatal swabs was
significantly higher in neonates born to mothers who were positive for
ESBL-E colonization at delivery.43 Among the total
neonatal sepsis cases in the ESBL-E-positive group in our study, ESBL-E
was identified in five cases. Consequently, the mother-to-neonate
transmission rate of ESBL-E infection was estimated to be 7.6% (5/66).
According to a Sri Lankan study, the mother-to-neonate transmission rate
of Enterobacteriaceae was 6.9%, of which ESBL producers had a
transmission rate of 0.6%.19 Another study reported a
mother-to-neonate ESBL-E transmission rate of
34.3%.44 Our study also confirmed that the rate of
proven EONS was significantly higher in the ESBL-E-colonized mothers.
This finding supports the results of previous studies and highlights the
importance of evaluating the need for screening and treatment for ESBL-E
colonization in high-risk pregnancies.