Vancomycin-induced neutropenia during treatment of endocarditis in a pediatric patient.

OBJECTIVE

To report a case of reversible vancomycin-associated neutropenia 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 ventriculoseptal defect. After 18 days of treatment, neutropenia with an absolute neutrophil count (ANC) of 990 x 10(6) cells/L was noted. The neutropenia progressed over the next 3 days and reached a nadir concentration of 459 x 10(6) cells/L. Vancomycin therapy was discontinued after 17 days (antibiotic day 20). A rise in the ANC occurred within 2 days of discontinuation. An improved ANC of 1672 x 10(6) cells/L occurred within 5 days. Vancomycin serum concentrations remained within an acceptable range: a peak of 30 micrograms/mL and a trough of 9 micrograms/mL.

DISCUSSION

Case reports in the literature of vancomycin-associated neutropenia in adults were briefly reviewed and compared. The onset and resolution and mechanism of vancomycin-induced neutropenia were studied. The potential relationship between vancomycin, weight-, and age-adjusted dosing and the occurrence of neutropenia in our pediatric patient was postulated.

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.