Clonally related <i>Escherichia coli</i> ST69 causing neonatal sepsis in preterm siblings born 1 year apart

ABSTRACT Background Recurrent neonatal infection caused by the same bacterial lineage across pregnancies is rarely documented. We describe two preterm siblings born one year apart who developed Escherichia coli sepsis caused by clonally related strains. Case Summary Two female infants were born preterm, 1 year apart, at 26 weeks and 4 days and 30 weeks and 3 days of gestation, respectively, following prolonged premature rupture of membranes. Both infants were evaluated for early-onset sepsis at birth with blood cultures and administered empiric ampicillin and gentamicin; initial blood cultures were sterile, and antibiotics were discontinued after 24 h. At 7 days of age, each infant developed new clinical signs of infection, and both were diagnosed with E. coli bacteremia. Both infants recovered after treatment with intravenous antibiotics. Whole-genome sequencing identified the isolates as O15:K52:H18, sequence type 69 (ST69), differing by only a few single nucleotide polymorphisms. Conclusion These cases suggest recurrent vertical transmission of a pathogenic E. coli lineage leading to neonatal infection arising just beyond the immediate newborn period.