Pure red cell precursor toxicity by linezolid in a pediatric case.

Linezolid (LZD)-induced myelosuppression has been reported in adults; however, LZD-induced pure red cell precursor toxicity rarely occurs. A 2-year-old boy diagnosed with infective endocarditis by Streptococcus mitis received LZD after developing resistance to multiple antibiotics. Although his infective symptoms were improved by LZD, progressive anemia was noticed 2 weeks after LZD therapy. Four weeks after LZD administration, his hemoglobin level was 6.5 g/dL and reticulocytes less than 0.1%. Bone marrow examination revealed markedly decreased erythropoiesis with cytoplasmic vacuolation of erythroblasts. Anemia recovered 19 days after cessation of LZD. Elevated protoporphyrin and a high LZD level in the blood suggested that mitochondrial disturbance by high-dose and long-term treatment with LZD may have been responsible for LZD-induced pure red cell precursor toxicity.