Piperacillin/tazobactam-induced reversible pancytopenia in a pregnant patient: A case report.

Hematologic responses (< 1%) to piperacillin/tazobactam were uncommon, and mostly reported in non-pregnant adults. The use of piperacillin/tazobactam during pregnancy is considered to be moderately safe for the human embryo-fetus (pregnancy grade B). However, changes in pharmacokinetics during pregnancy (such as an increase in plasma volume and an increase in renal clearance rate) may alter the toxicity threshold of the drug. This is a case of a pregnant woman (26 weeks of gestation) treated with piperacillin/tazobactam for psoas abscess (Proteus mirabilis). After 22 days, the patient developed low-grade fever, leukopenia, neutropenia, and thrombocytopenia. Three days after discontinuation of piperacillin/tazobactam, the above adverse reactions were all reversed. The Naranjo scale yielded a score of 7, which indicates a definite result for this adverse drug reaction. This was the first report of piperacillin-tazobactam-induced pancytopenia in pregnancy.