Researchers studying intestinal bacteria in newborns have characterized the gut bacteria of premature infants who go on to develop sepsis, a serious and potentially life-threatening condition caused by bacteria in the bloodstream. Their findings suggest new strategies for the early detection and prevention of severe bloodstream infections. The research was funded by several components of the National Institutes of Health (NIH)—the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the National Human Genome Research Institute (NHGRI), the National Institute of Allergy and Infectious Diseases (NIAID), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the NIH Common Fund—and other organizations.
Led by Phillip I. Tarr, M.D., and Barbara Warner, M.D., of Washington University in St. Louis, the investigators collected stool samples from 217 premature newborns who had been admitted to the neonatal intensive care unit (NICU) at St. Louis Children's Hospital soon after birth. Eleven of these infants developed sepsis between 13 and 82 days of age. Using the same blood samples that were used to diagnose the infection, the researchers genetically compared bacteria found in the affected infants' bloodstream to those found in their earlier stool samples. They also assessed whether sepsis-causing infections spread between infants by studying bacteria found in the stools of two comparison groups without the condition: 96 infants whose stays in the NICU overlapped with the sepsis cases, and 60 infants who stayed in the NICU at different times.
In seven of the 11 infants who developed sepsis, the researchers found genetic matches between bacteria in the initial stool samples and those in later blood samples, suggesting that bacteria from the gut—rather than other parts of the body—are responsible for these infections. From the comparison groups, genetic matches were found in four infants who were located near those who developed sepsis, suggesting that such bacteria can be transmitted between infants, though they do not always cause illness. These results pave the way for the evaluation of new sepsis prevention strategies, such as closer surveillance of premature infants to find strains of gut bacteria associated with sepsis, the study authors write.