Tazobactam-induced haemolytic anaemia, possibly caused by non-immunological adsorption of IgG onto patient's red cells.

A patient with pneumonia was treated with Tazocin (piperacillin/tazobactam). However, the expected haemoglobin (Hb) increment after transfusion was not achieved. Plasma bilirubin and lactate dehydrogenase were raised. The direct antiglobulin test (DAT) was positive (4+) for immunoglobulin G (IgG) only, but no RBC antibodies were demonstrable in the plasma or an eluate from the patient's RBCs. Drug-induced haemolysis was suspected. After discontinuing Tazocin administration, Hb and bilirubin levels returned to expected values. The patient's plasma gave a positive (3+) indirect antiglobulin reaction only with RBCs pretreated with tazobactam. However, random patient plasmas also gave weak (+/- to 1+) reactions, indicating non-immunological adsorption of IgG onto RBCs rather than specific anti-tazobactam antibodies. Subsequently, plasma samples with varying IgG levels (0.8-89.7 g L(-1)) were tested against RBCs pretreated with tazobactam. The amount of plasma IgG non-immunologically adsorbed onto the drug-coated RBCs was found to correlate directly with the plasma IgG level. The patient had a high plasma IgG level (41.6 g L(-1)) which explains why the antiglobulin test was stronger with the patient's plasma than with random plasma samples. Previous reports (Garratty & Arndt, (1998) British Journal of Haematology, 100, 777-783; Arndt & Garratty (2000) Transfusion, 40, 29S) suggested that non-immunological coating of RBCs with IgG may affect RBC survival; our results would support that suggestion. This is the first reported case of haemolytic anaemia associated with tazobactam.