Objectives: The association between piperacillin/tazobactam and the positivity of the galactomannan (GM) detection ELISA test is well described. Little information is available about the kinetics of GM in patients treated with piperacillin/tazobactam. The present study aimed at clarifying the baseline interaction between piperacillin/tazobactam and GM in patients receiving this drug.
Patients and methods: Seven patients undergoing abdominal surgery received perioperative prophylaxis with piperacillin/tazobactam. Each patient received three doses of 4.5 g of the drug, administered at 8 h intervals (one before and two after surgery). Three patients received antibiotic batches with 'medium' (GM-index = 1.782) and four patients received antibiotic batches with 'high' (GM-index = 6.665) GM content. Serum samples for GM evaluation were collected before drug infusion and at times +1, +3, +6 and +8 h after the first and third infusions.
Results: GM levels increased after infusion, in particular when batches with 'high' GM content were used. Moreover, a non-statistically significant increase between the first dose and the third dose was observed. All samples taken >6 h after administration were negative (GM-index < 0.2), both with the 'medium' and the 'high' GM content batches.
Conclusions: The low content of GM 8 h after piperacillin/tazobactam infusion suggests that in non-neutropenic cancer patients with solid tumours receiving up to three doses of piperacillin/tazobactam, serum sampling for GM detection should be performed immediately before the next piperacillin/tazobactam administration.