Bacterial Sepsis in the Newborn Infant: Developmental Deficiencies in Neutrophils and the Role of Neutrophil Transfusion

Abstract

Bacterial sepsis is an important cause of morbidity and mortality in newborns. Group B streptococci and Es cherichia coli are the primary causative organisms. New and theoretically more effective antibiotics have not im proved survival. Because the neonate has defects in the immune response, new forms of therapy may be able to improve outcome by correcting or circumventing those deficiencies. The neutrophil has a substantial role in antibacterial defense, yet neonatal neutrophil function is limited by impaired chemotaxis, phagocytosis, and in tracellular killing. The supply of neonatal neutrophils is restricted by a small neutrophil reserve, a delay in mobilization of neutrophils from the bone marrow re serve after bacterial invasion, a small granulocytopoietic progenitor cell reserve, and a limited ability to acceler ate proliferation of progenitor cells during bacterial in fection. Recent studies of neutrophil transfusions in in fected neonates suggest a beneficial effect at least in certain situations. Exchange transfusion with fresh whole blood may be an alternative to transfusion with neutro phils obtained by apheresis. The ultimate role of neutro phil transfusions as an adjunct therapy for neonatal sep sis remains to be determined.