1517. Multidrug-Resistant Escherichia coli ST131 Late-Onset Neonatal Sepsis in Premature Twins Linked to Contaminated Maternal Frozen Breast Milk

BACKGROUND: Sequence type 131 (EC-ST131) is a prevalent cause of extraintestinal Escherichia coli infection, including in neonates, and accounts for a majority of multidrug-resistant strains. Rare reports of neonatal unit outbreaks have emerged, with one linking the source to freshly expressed breast milk (BM) sharing. We report on premature twin girls whose infection was linked to their mother’s contaminated frozen BM. METHODS: Blood culture isolates were from twin girls born at 24–1/7 weeks’ gestation who developed severe sepsis caused by ampicillin- and gentamicin-resistant E. coli on days 11 (Baby A; died) and 8 (Baby B; survived) of life; both neonates had sterile blood cultures at birth, and received orogastric feeds using frozen BM provided by their mother. Five remaining frozen BM samples predating onset of sepsis were thawed and cultured; E. coli resistant to ampicillin and gentamicin was recovered from 1 collected on day 5 of life. DNA was extracted from cultured isolates using the Zymo Research Quick-DNA™ Fungal/Bacterial Miniprep kit, sequencing libraries prepared (Nextera® XT PE), and sequencing (Illumina MiSeq® with V2 2 X 250 bp chemistry) completed for the 2 blood and 1 BM isolates. Multilocus Sequence Typing (MLST) and core genome MLST (cgMLST) analyses were performed using SeqSphere+, version 5.1.0 (Ridom, Munster, DE) software, with 2513 alleles analyzed for cgMLST. RESULTS: The 2 blood and 1 BM isolates were typed as ST131 by MLST and were indistinguishable by cgMLST. Of the 2513 alleles queried, only 263 (10.5%) differed from the ST131 strain SCB34 (figure). Thus, our EC-ST131 cluster isolates belong to the same clonal complex as, but are genetically divergent from, SCB34. In addition to the E. coli described above isolated from a BM sample, all 5 frozen BM samples grew multiple morphotypes of coagulase-negative staphylococci. The mother had acute chorioamnionitis and was treated with intravenous ampicillin, gentamicin, and metronidazole for 48 hours immediately after delivery. CONCLUSION: Despite frozen BM’s persistent antibacterial activity, it is a potential source of multidrug-resistant bacteria for neonates, as evidenced by this report of EC-ST131 neonatal sepsis in premature twins. [Image: see text] DISCLOSURES: Robin Patel, MD, ASM and IDSA: Other Financial or Material Support, Travel reimbursement, editor’s stipends; CD Diagnostics, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, ContraFect, TenNor Therapeutics Limited, Shionogi: Grant/Research Support; Curetis, Specific Technologies, NextGen Diagnostics, PathoQuest, Qvella: Consultant; NBME, Up-to-Date, the Infectious Diseases Board Review Course: Honorarium recipient, Other Financial or Material Support; Patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued: Other Financial or Material Support, Patents.