The rapid rise of multi-drug resistant Enterobacteriaceae (MDR-E) is severely threatening
the way we treat common infectious diseases. A particularly vulnerable population are
neonates where a delay in the treatment of MDR-E sepsis can be fatal. Additionally,
highly drug resistant bacteria such as the pandemic E. coli ST131 strain are persistent
gut and vaginal colonizers (1). In animal models of gut colonization, these strains
out-compete drug-sensitive, commensal Escherichia coli. Early life exposure to MDR-E
could, therefore, have long-lasting effects on the developing microbiome and overall
child health (2).
Among extra-intestinal pathogenic Enterobacteriaceae, resistance against a number of
antibiotics, especially the beta-lactams, has rapidly risen in the last decade. Since the
gut is a major reservoir of these pathogens even in otherwise healthy individuals it is
likely that there is a concomitant increase in gut colonization with extended spectrum
beta-lactamase producing Enterobacteriaceae (ESBL-E) among the general population (3, 4).
Even in regions with a low prevalence of community acquired ESBL-E infections, perinatal
transmission occurs in 35% of infants born to mothers colonized with these strains (5).
It has recently been shown that healthy infants in South Asia, a region with a high use
of antibiotics per capita, are carriers of ESBL-E (6). In vitro studies suggest that ESBL
E. coli isolated from these infants have a higher growth potential than commensal E.
coli. Using a murine model of perinatal transmission of E. coli, it was shown that some
of the ESBL E. coli strains adept in human infant gut colonization can also readily
colonize pregnant dams and be perinatally transmitted. The burden of ESBL-E colonization
among pregnant women and their neonates in the US and the genetic determinants of
perinatal transmission are unknown.
The investigators aim to conduct a prospective surveillance study of mothers and their
infants born vaginally and who are admitted to Northwestern Medicine Prentice Women's
Hospital to determine the prevalence of ESBL-E carriage in healthy post-partum women and
the transmission rate of these strains to their infants. Using whole genome sequencing
and a comparative genomics approach they will determine the relatedness of strains among
mother-infant dyads as well as identify genetic regions common to transmitted strains. It
is hypothesized that; 1) given the diverse population of Chicago there will be a
significant rate of gut colonization with ESBL-E among mothers admitted to Prentice, 2)
ESBL-E strains isolated from neonates will be identical to those from their mothers and
3) genetic determinants of transmission are conserved across ESBL E. coli strains that
are perinatally transmitted. These hypotheses will be tested using the following Aims:
Aim 1: Determine the prevalence of ESBL-E gut colonization and rate of perinatal
transmission among mother-infant dyads Aim 2: Identify genetic determinants of
transmission common to ESBL E. coli that are perinatally transmitted.
The long-term goal is to understand the unique features of persistent gut and vaginal
ESBL-E colonizers and identify genetic and molecular elements that could be attractive
therapeutic targets to decrease the burden of ESBL-E colonization and perinatal
transmission.