A rare case of streptomycin-induced toxic epidermal necrolysis in a patient with tuberculosis: a therapeutic dilemma.

Objective: To report a case of streptomycin-induced toxic epidermal necrolysis (TEN).

Case Summary: A 55-year-old woman was admitted for treatment of active pulmonary tuberculosis (TB). She was given standard oral anti-TB chemotherapy including isoniazid, rifampin, pyrazinamide, and streptomycin. On the fourth day of therapy, she experienced high fever at 39 degrees C, chills, vomiting, pruritus, and diffuse erythema, followed by extensive bullae formation and skin denudation. Diagnosis of TEN was considered, and all anti-TB drugs were discontinued. Skin biopsy disclosed complete epidermal necrosis with dermal-epidermal cleavage and absence of inflammatory infiltrate, highly suggestive of TEN. The patient was transferred to the intensive care unit. Her general condition and skin lesions improved. A staged-fashion exposure test to the 4 anti-TB drugs allowed the incrimination of streptomycin as the offending agent.

Discussion: Anti-TB drugs, mainly rifampin, ethambutol, and isoniazid, have been incriminated in TEN. Streptomycin-induced TEN remains an extremely rare event. However, minor allergic skin reactions (rash, urticaria) have been described with this drug. Our patient presents a rare case of streptomycin-related TEN. Even though dangerous, a step-wise exposure test was necessary to allow safe treatment of active pulmonary TB. It also provided a strong argument of a cause-effect relationship between TEN and streptomycin. An objective causality assessment using the Naranjo rating scale revealed that the adverse drug event was highly probable.

Conclusions: Streptomycin should be added to the list of drugs that induce TEN.