Very low birth weight (VLBW) infants are highly susceptible to late-onset sepsis (LOS). Compared to Gram-positive bacteria, Gram-negative bacteria are less common to cause LOS, but are associated with a more severe clinical manifestation, higher mortality, and increased risk of neonatal morbidity. So far, the clinical picture of late-onset Gram-negative sepsis (LOGNS) in VLBW infants has not been elucidated. An up-to-date and thorough understanding of the clinical picture of LOGNS in VLBW infants is important to optimize current anti-sepsis protocols. Areas covered: Literature published in the last three decades was searched for data on the epidemiology, pathogen profile, risk factors, clinical manifestations, laboratory parameters, mortality, and short-term and long-term morbidity of LOGNS in VLBW infants. Expert opinion: Gram-negative bacteria are major contributors of neonatal morbidity and mortality in VLBW infants with LOS, potentially posing a significant disease burden. Unravelling the pathogen-specific clinical picture of LOGNS and the underlying mechanisms is of particular interest. VLBW infants may differ from more mature neonates in terms of disease burden and clinical course of LOGNS. Epidemiologic studies aided by advanced molecular techniques may help to develop anti-sepsis protocols specialized for VLBW infants, with strategies targeting Gram-negative bacteria.
Keywords: Gram-negative bacteria; late-onset sepsis; neonatal morbidity; neonatal mortality; very low birth weight.