Tobramycin-induced hypersensitivity reaction

To report a case of a hypersensitivity reaction associated with the use of intravenous tobramycin in a patient with cystic fibrosis.

An 18-year-old man was hospitalized for exacerbation of his cystic fibrosis. Tobramycin 125 mg iv q6h and ceftazidime 2 g iv q8h were administered through the patient's implantable access system in the left chest. Within seconds of receiving the third dose of tobramycin, the patient experienced shaking, his left arm turned white, and urticaria and pruritus were noted on the left side of the patient's chest. The patient had experienced a similar incident, accompanied by breathing difficulty, with intravenous tobramycin 4 years prior to this incident. The patient had been skin-tested for tobramycin allergy and had been desensitized and was receiving tobramycin since that time without incident. The patient's desensitization was maintained with tobramycin 160 mg/d hs by nebulization, but the drug had been discontinued by the patient 6 months prior to the latest event.

Hypersensitivity reactions to aminoglycosides are unusual. Hypersensitivity to 1 aminoglycoside antibiotic frequently is associated with hypersensitivity to at least 1 other amino-glycoside. In patients who develop hypersensitivity to an amino-glycoside antibiotic, desensitization may be an effective alternative to changing therapy.

Tobramycin is very important in the drug regimen for Pseudomonas aeruginosa infections in patients with cystic fibrosis. Effective desensitization can be maintained by daily administration of nebulized tobramycin.