Clinical Tetanus Despite a 'Protective' Level of Toxin-Neutralizing Antibody

TETANUS is a preventable disease. Although immunization guidelines¹are generally very effective, tetanus has occurred in patients with prior immunization.²In most cases it was presumed that levels of toxin-neutralizing antibody were low. Although data on the protective level of neutralizing antibody in humans are extremely limited, animal data have been used to support the belief that 0.01 antitoxin unit/mL is protective.³,⁴This report describes a patient with a wound, followed by severe generalized tetanus, who was found at the onset of symptoms to have a neutralizing antibody level 16 times that considered protective. Report of a Case A 35-year-old man sustained a puncture wound in the plantar surface of his left foot. He was seen at a community hospital 35 hours later for increasing foot pain. There was no evidence of infection, and he was treated with tetanus toxoid, dicloxacillin, and acetaminophen. Approximately 38 hours after the