Late-onset sepsis in preemies starts in the gut

Preterm babies’ guts harbor bacteria that can cause late-onset sepsis, according to a new study.

Unlike early-onset sepsis, which is usually caused by pathogens acquired from the mother in the amniotic sac or birth canal, researchers from the Washington University School of Medicine in St. Louis and colleagues from Michigan State University and the University of Minnesota found that the late-onset form of this life-threatening bloodstream infection usually arises from 1 of 3 infectious microbes commonly harbored in preterm babies’ lower intestines.

The researchers studied 217 premature infants from whom they collected stool samples beginning as soon as possible after birth. All were patients in the neonatal intensive care unit at St. Louis Children’s Hospital. Of the 217 infants, 11 of the preemies developed sepsis at or after 3 days of age.

In 7 of the 11 babies, bacteria in the stool samples taken days to weeks before the onset of sepsis genetically matched bacteria in blood samples taken after the sepsis occurred, suggesting that the bacteria were from the gut, rather than from anywhere else. The microbes identified in the bloodstreams of the 7 babies who developed late-onset sepsis were Escherichia coli, group B Streptococcus, or Serratia marcescens.

The researchers explain that knowing the source is the gut, and not the skin, will aid in the detection and prevention of these life-threatening infections. The findings demonstrate that infection through such mechanisms as insertion of intravenous apparatus, catheters, and other tubes is not the cause in many of these cases and that we may need to refocus on other practices to prevent dissemination of gut bacteria. The findings also have the potential to benefit other patient populations who are susceptible to bloodstream infections, such as those in intensive care units, people with chronic illnesses, and anyone with a suppressed immune system. 

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