Blood neutrophil response to bacterial infection in the first month of life.

Serial white blood cell counts were undertaken on 100 babies who required admission to hospital in the first 4 weeks of life. Severe neutropenia was seen in 3 babies who died with overwhelming septicaemia, but a significant and early rise in the absolute polymorphonuclear neutrophil count was detected in 9 of the remaining 11 cases of septicaemia. A similar neutrophil response was seen within 24 hours of the onset of symptoms in 5 babies with meningitis, 10 babies with urinary infection, and 5 babies with pneumonia. Raised neutrophil counts were seen in only 9 of the remaining 66 babies, and all 9 had undergone major surgery. In more than 98% of healthy babies the neutrophil count is within the range 1350 to 8840 cells/mm3 after the first 4 days of life; counts outside this range nearly always occur during serious bacterial infection.