Neutropenia During Meropenem and Vancomycin Therapy for Clinically Presumed Brain Abscess

Neutropenia is a recognized adverse event associated with antimicrobial therapy, particularly β-lactams and glycopeptides. Although carbapenems, including meropenem, can also cause neutropenia, the number of reported cases is limited. We report a case of clinically presumed brain abscess in a 74-year-old man who developed neutropenia during treatment with high-dose meropenem and short-term concomitant vancomycin. After the antimicrobial regimen was changed to levofloxacin, the neutrophil count gradually normalized ∼2 months later. A review of previously published cases identified 10 cases of neutropenia developing during meropenem therapy, with central nervous system infection and renal dysfunction being common clinical contexts; however, detailed information on pharmacokinetic exposure, concomitant medications, and mechanistic evaluation was often limited. Although causality could not be definitively established and the relative contribution of vancomycin could not be excluded, the clinical course raised the possibility of antibiotic-associated neutropenia during combination therapy. This case highlights the difficulty of causality assessment in neutropenia occurring during prolonged antimicrobial therapy and underscores the importance of regular complete blood count monitoring during prolonged, high-dose antimicrobial treatment.