Thymidine-dependent strain of Salmonella oslo selected by trimethoprim-sulfamethoxazole therapy.

A case report describing the isolation of a multiple-drug-resistant strain of Salmonella oslo from urine and stool specimens is presented. After ten days of trimethoprim-sulfamethoxazole therapy, a second strain of Salmonella oslo was isolated from another stool specimen. The second strain was determined to be a thymidine-requiring organism. The significance of this thymidine-requiring strain is described.