β-lactam-associated neutropenia

Background

• Adverse reaction to β-lactam antibiotics occurring in about 10% of courses longer than 2 weeks
• Higher risk with penicillin G, nafcillin, oxacillin, piperacillin-tazobactam, ceftriaxone, and ceftaroline
• Risk increases with cumulative exposure
• Mechanism is unclear; may be some combination of a direct toxic effect or an immune-mediated hypersensitivity reaction

Clinical Manifestations

• Neutropenia
• Usually presents after 2 to 3 weeks of parenteral antibiotics
• Rash in 25-50% of cases
• May have associated eosinophilia or thrombocytopenia
• Can progress to agranulocytosis

Management

• Consider stopping the offending antibiotic if ANC falls below 1
• Other β-lactam antibiotics are probably still safe to use

Further Reading

• A Review of β-Lactam-Associated Neutropenia and Implications for Cross-reactivity. Ann Pharmacother. 2021;55(8):1037-1049. doi: 10.1177/1060028020975646