Why hasn't this tender nodule responded to an antibiotic?

November 5, 2009

A 63-year-old woman presents with a tender nodule of 10 days’ duration on the dorsum of her right hand. She does not remember any specific injury, but she does do her own housework. Another physician prescribed doxycycline, 100 mg bid; however, the nodule has persisted. You order a bacterial culture.

Case 2:
A 63-year-old woman presents with a tender nodule of 10 days’ duration on the dorsum of her right hand. She does not remember any specific injury, but she does do her own housework. Another physician prescribed doxycycline, 100 mg bid; however, the nodule has persisted. You order a bacterial culture.

Pending the culture results, what action would you take?

A. Continue the doxycycline.
B. Change to minocycline.
C. Change to ciprofloxacin.
D. Change to cephalexin.
E. Change to trimethoprim/sulfamethoxazole.
F. Start intravenous antibiotics.
G. Perform a skin biopsy.

Continued on Next Page

The results of the culture revealed methicillin-resistant Staphylococcus aureus. The patient was given trimethoprim/sulfamethoxazole (double strength), E, and topical retapamulin, which successfully treated the infection. Doxycycline could probably have been continued, because the organism was sensitive to it, but since there had been no clinical improvement, the switch to the sulfa antibiotic was made.