Phagocytosis of monocytes and platelets in a neutropenic infant with septicemia.

The case is described of a low birth weight infant who developed severe neutropenia, thrombocytopenia and monocytosis in the course of staphylococcal septicemia. Light microscopy examination of the blood revealed bacteria inside the monocytes. On electron microscopy, the monocytes were degranulated and distorted by the presence of large vacuoles containing bacteria. While most of the bacteria were intact, some showed capsular dissolution suggesting the effect of lysosomes. Rarely, the bacteria were also noted within the polymorphonuclear leukocytes and platelets. Based on the finding of electron microscopy in this case, the phagocytic function of the monocytes, neutrophils and possibly the platelets was intact. In view of the fatal outcome, despite the previous findings, it is suggested that granulocyte transfusion be considered in low birth weight infants with persistent sepsis.