The interleukin-1 receptor antagonist can either reduce or enhance the lethality of Klebsiella pneumoniae sepsis in newborn rats.

Klebsiella pneumoniae, a worldwide cause of nosocomial infections, is one of the most common causes of death in newborns in nurseries. In this study, we investigated the role of interleukin-1 (IL-1) in an experimental animal model of neonatal sepsis, using a natural antagonist of IL-1 receptors, the IL-1 receptor antagonist (IL-1Ra), to block IL-19s effects in neonatal Klebsiella sepsis in the absence of antibiotic treatment. Newborn Wistar-Kyoto rats were injected intraperitoneally with a single dose (10 mg/kg) of either IL-1Ra (n = 43) or human serum albumin as a control (n = 40). At the same time, a 50% lethal dose of K. pneumoniae was injected subcutaneously. No antibiotics were given at any time. After 10 days, survival was 60% for the albumin group and 80% for the IL-1Ra group (P