Higher Risk of Neutropenia Associated With Piperacillin-Tazobactam Compared With Ticarcillin-Clavulanate in Children

BACKGROUND: A series of cases of piperacillin-tazobactam (P/T)-associated neutropenia has been observed recently in children in our center. Because neutropenia was seldom observed in children treated with ticarcillin-clavulanic acid (T/C), we conducted a study to determine if there is an increased risk of neutropenia in children exposed to P/T in comparison with T/C. METHODS: Medical records of subjects aged <18 years who received at least 1 dose of P/T or T/C between 1 January 2008 and 30 June 2011 were reviewed. RESULTS: Two hundred ninety-nine episodes of treatment (65 P/T, 234 T/C) met inclusion criteria. Among those episodes, 213 had data allowing complete white blood cell count analysis and were included in the final analysis. Thirteen cases of neutropenia were observed during the study period. The average time to onset was 17.6 days and all patients were aged <13 years. Seven cases (10.8%) occurred in the P/T group and 6 (2.6%) in the T/C group (unadjusted odds ratio, 4.59; 95% confidence interval, 1.48-14.17). Although a statistically significant correlation was observed between age, treatment duration, and total dose and the development of neutropenia (r = -0.121, P = .037; r = 0.267, P < .001; r = 0.260, P < .001, respectively), this was not the case for sex, indications, neutrophil count at initiation, and concomitant drug treatments. CONCLUSIONS: Although our results need to be confirmed, they suggest that children receiving long courses of therapy (>2 weeks) with P/T may be at increased risk of neutropenia, compared with T/C.