Trimethoprim resistance in urinary tract pathogens in two Nigerian hospitals.

One hundred and twenty eight (63.3%) of 202 isolates of Gram-negative bacilli from urinary infections in patients in two Nigerian hospitals were found to be resistant to trimethoprim. Of the trimethoprim-resistant organisms, 111 (86.7%) showed MICs of trimethoprim in excess of 1000 mg/l. Trimethoprim resistance was found to be transferable from 65 (50.8%) of these highly resistant organisms into Escherichia coli EC1005. The trimethoprim-resistant strains obtained in the study were also resistant to at least one other antibiotic of the nine tested.