Mother-to-child transmission of extended-spectrum-beta-lactamase-producing Enterobacteriaceae

Preterm infants are at high risk for extended-spectrum-beta-lactamase-producing Enterobacteriaceae (ESBL-E) sepsis and neonatal intensive care unit (NICU) outbreaks. Maternal colonization with ESBL-E may be precursory to mother-to-child transmission. However, there is no consensus regarding surveillance of pregnant women for ESBL-E colonization.

To identify pairs of mothers and infants harbouring same-strain ESBL-E colonization and to determine whether maternal transmission may play a role in increasing ESBL-E carriage in preterm infants.

This was a one-year analysis from an ongoing, prospective ESBL-E surveillance of mothers of premature infants and their offspring. Mother-infant pairs colonized with the same bacteria underwent strain analysis using pulsed-field gel electrophoresis (PFGE). Clinical parameters were collected from the hospital computerized records.

Between January 2015 and January 2016, 313/409 (76.5%) mothers and all 478 (100%) infants were screened for ESBL-E colonization; carriage rates were 21.5% and 14.8%, respectively. Four (5.6%) colonized infants developed late-onset sepsis and two (2.8%) died. Twenty-five mother-infant pairs colonized with the same bacterial strain were identified; a subgroup of 10 pairs of isolates underwent PFGE, and 70% displayed an identical PFGE fingerprint. No similarities were found between isolates recovered from unrelated neonates and mothers. ESBL-E colonization was found significantly earlier in infants of mothers colonized at birth (P<0.001) compared with infants of non-colonized mothers.

ESBL-E carriage rates in mothers and NICU infants with non-negligible maternal-neonatal ESBL-E transmission in the study region indicate that maternal colonization surveillance and/or further infection control interventions should be considered.