VANCOMYCIN-INDUCED NEUTROPENIA DURING TREATMENT OF ENDOCARDITIS IN A PEDIATRIC-PATIENT

OBJECTIVE: To report a case of reversible vancomycin-associated neutro penia occurring during long-term therapy with vancomycin using weight and,age-adjusted dosing. CASE SUMMARY: A 2-year-old boy was started on vancomycin therapy for presumed endocarditis resulting from his ventr iculoseptal defect. After 18 days of treatment, neutropenia with an ab solute neutrophil count (ANC) of 990 x 10(6) cells/L was noted. The ne utropenia progressed over the next 3 days and reached a nadir concentr ation of 459 x 10(6) cells/L. Vancomycin therapy was discontinued afte r 17 days (antibiotic day 20). A rise in the ANC occurred within 2 day s of discontinuation. An improved ANC of 1672 x 10(6) cells/L occurred within 5 days. Vancomycin serum concentrations remained within an acc eptable range: a peak of 30 mug/mL and a trough of 9 mug/mL. DISCUSSIO N: Case reports in the literature of vancomycin-associated neutropenia in adults were briefly reviewed and compared. The onset and resolutio n and mechanism of vancomycin-induced neutropenia were studied. The po tential relationship between vancomycin, weight-, and age-adjusted dos ing and the occurrence of rieutropenia in our pediatric patient was po stulated. CONCLUSIONS: Vancomycin is identified as a possible cause of drug-induced neutropenia. More data are needed that clearly indicate vancomycin as the offending agent in children. The vancomycin-induced neutropenia is believed to be immunologically based and independent of drug concentrations.