Ask a pediatric trainee which organisms should be targeted in empiric therapy for febrile infants <1 month of age, and we will bet you a carton of raw milk that the answer will include Listeria. Traditional teaching is that the 3 most common pathogens in neonatal sepsis are group B Streptococcus (GBS), Escherichia coli, and Listeria, and current textbooks continue to promote these organisms as the leading pathogens.1,2  However, recent evidence suggests that the modern epidemiology for bacteremia has shifted.3,4 E. coli has now surpassed GBS, and in multiple reports Listeria has gone from rare to exceedingly rare or nonexistent (a decrease that may be explained by enhanced regulation around food safety or a “collateral benefit” of GBS screening and prophylaxis). Nonetheless, ampicillin is still included in most current empiric regimens, presumably to cover for Listeria or Enterococcus. Between 2011...

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