Index of Suspicion in the Nursery

A 1-month-old male infant is referred to the neonatal intensive care unit because of persistent fever and bronchopneumonia. He was born at term after an uncomplicated pregnancy with a birthweight of 2.7 kg. The parents are not relatives, and the family history is unremarkable. On the 15th postnatal day, he had a temperature of 102.2°F (39°C) and a cough. Ampicillin and gentamicin were initiated for the treatment of potential sepsis and bronchopneumonia at the secondary medical care hospital. Because no clinical improvement was observed, the patient was referred to the intensive care unit for further investigation. Physical examination reveals a toxic infant whose axillary temperature is 101.8°F (38.8°C), heart rate is 168 beats/min, respiratory rate is 64 breaths/min, blood pressure is 48/26 mm Hg, and pulse oximetry reading is 80% to 85% on room air. His weight is 2.7 kg, equal to his birthweight. Auscultation of the chest reveals bilateral diffuse fine crackles. His abdomen is soft and slightly distended. There is neither mass nor hepatosplenomegaly. A red edematous and warm lesion surrounds the perianal region. Previously he had had oral lesions, such as gingivitis and apthous ulcers. A chest radiograph shows diffuse patchy infiltrates bilaterally. Laboratory results are as follows: hemoglobin, 11 g/dL (110 g/L); hematocrit, 33% (0.33); platelet count, 296×103/mcL (296×109/L); white blood cell count, 7.8×103/mcL (7.8×109/L) with 78% lymphocytes, 10% eosinophils, 12% monocytes, and 0.3% neutrophils (absolute neutrophil count [ANC] of 25/mcL); C-reactive protein, 52 mg/L; sedimentation rate, 100 mm/h; immunoglobulin (Ig)A, 40 mg/dL (4 g/L); IgG, 750 mg/dL (7.5 g/L); IgM, 200 mg/dL (2 g/L); IgE, 18 IU/mL; CD3 lymphocytes, 60% (normal, 50% to 80%); CD4 lymphocytes (T-helper), 32% (normal, 40% to 60%); CD8 lymphocytes (T-supressor), 36% (normal, 20% to 40%); CD19 lymphocytes (B-lymphocyte), 22% (normal, 20% to …