Inhibition of Granulopoiesis in Vivo and in Vitro by β-Lactam Antibiotics

P-Lactam antibiotics can induce severe neutropenia by a hitherto unknown mechanism. Fifty cases of p-lactam antibiotic-induced neutropenia ( 15% in patients treated for >10 days with large doses of any 3-lactam antibiotic but 95% of cases recovery occurred between one to seven days after withdrawal of P-lactam antibiotics. Bone marrow aspirates were characterized by a lack of well-differentiated myeloid elements in the presence of numerous immature granulocyte precursors. Nine penicillins and eight cephalosporins inhibited in vitro granulopoiesis in a dose-dependent manner. There was a good correlation between the inhibitory capacity of 3-lactam antibiotics in vitro and the doses inducing neutropenia in vivo. These observations may be relevant for therapy in the granulocytopenic patient.