Comparison of a slow-release trimethoprim with co-trimoxazole: efficacy and selection of resistance in the Enterobacteriaceae.

One hundred and fifty one patients with symptoms of urinary tract infection were treated randomly in a double blind study with a slow release form of trimethoprim or with co-trimoxazole. Similar cure rates were seen. There was no difference between the proportions of patients in the two groups who acquired trimethoprim-resistant Enterobacteriaceae. Further clinical trials with slow release trimethoprim should be performed.