Publication:

Adverse drug reaction to piperacillin-tazobactam mimicking Kounis syndrome in a pregnant lady diagnosed with pyelonephritis: a case report

Piperacillin-tazobactam is commonly used to treat severe infections during pregnancy, but it can also lead to life-threatening hypersensitivity reactions like Kounis syndrome (KS). A 25-year-old primigravida (G1P0) at 20 weeks' gestation presented with intractable vomiting, fever, and abdominal pain. She was admitted to the ICU with a diagnosis of pyelonephritis with septic shock, evidenced by hypotension (70/40 mmHg), tachycardia (114 bpm), leukocytosis (20,300/mm3), and elevated C-reactive protein (338.9 mg/l). She was initiated on IV fluids, noradrenaline, and empirical antibiotics, including piperacillin-tazobactam. Shortly after the first dose of piperacillin-tazobactam, the patient developed an acute, severe reaction characterized by hypertension (180/100 mmHg), tachycardia (130 bpm), hypoxia (89% SpO2), angioedema, wheezing, and chest pain with widespread ST-T abnormalities on ECG, suggesting a possible KS. The drug was immediately discontinued, and the patient was stabilized. A positive re-exposure on the following day with a single challenge dose confirmed the severe hypersensitivity and established causality. The drug was permanently withdrawn, and the patient was successfully managed with meropenem. This case suggests a life-threatening piperacillin–tazobactam hypersensitivity in pregnancy, with clinical features overlapping septic deterioration and possible KS.