Trimethoprim resistance in urinary bacteria isolated from patients attending general practitioners.

The incidence of trimethoprim resistance amongst enterobacterial strains responsible for significant bacteriuria in patients attending general practitioners in Edinburgh was 11.4%. Two-thirds of these resistant strains were highly resistant to trimethoprim. Trimethoprim resistance was more prevalent in bacteria isolated from men and from elderly patients. Less than half of the highly resistant strians possessed trimethoprim resistance plasmids; however, amongst those that did, one plasmid predominated. This plasmid was identical with the most successful trimethoprim resistance plasmid in hospital enterobacterial isolates at that time.