A case of fixed drug eruption due to doxycycline and erythromycin present in food

Abstract

A fixed drug eruption (FDE) is not difficult to diagnose, given its clinical characteristics. However, the causative agent can be difficult to identify, particularly when the patient denies ingestion of any drugs. To the best of our knowledge, we present herein the first reported case of an FDE caused by antibiotics taken in food; doxycycline and erythromycin contained in pork and fish. A 57-year-old female experienced repeated episodes of well-demarcated erythematous patches covering her entire body. She denied taking any medications, but she thought that the lesions appeared after consuming pork and/or fish. An oral provocation test showed positive results for doxycycline and erythromycin, commonly used antibiotics in live-stock farming and in the fishing industry. Because of the antibiotics' thermostability, cooking does not guarantee the elimination of residual drugs. From the patient's history, we concluded that doxycycline and erythromycin contained in the pork and fish that she ate were the cause of the FDE.

Keywords: Fixed drug eruption; doxycycline; erythromycin; food; residual antibiotics.

Fig. 1

(A) On the oral doxycycline provocation test, an erythematous change is observed in a hyperpigmented area of skin. (B) On the oral erythromycin provocation test, an erythema is observed at the site of the previous lesion.

Fig. 2

The disk-diffusion method for doxycycline and erythromycin. There are no significant differences in the zones of inhibition at various temperatures or with the concentrations of doxycycline and erythromycin.