Trimethoprim resistance in hospitals.

During November 1980 to April 1981, 1561 urinary tract pathogens were collected from Turku City Hospital, Turku University Central Hospital, and Kuopio University Central Hospital. Resistance of the strains was tested by agar-plate dilution against trimethoprim, sulphamethoxazole-trimethoprim, sulphamethoxazole, ampicillin, and nitrofurantoin. Resistance to trimethoprim (greater than 8 mg/l) occurred in 8.6-12.2% of strains from the university hospitals (Pseudomonas excluded) and 38.3% of strains from Turku City Hospital. Resistance of Escherichia coli occurred in 4.1-6.2% of strains from the university hospitals and 21% of strains from Turku City Hospital. Proteus mirabilis was the most resistant of the clinically important bacterial species with resistance to trimethoprim in 29-78%. Attention is called for in defining the type of hospital used for a particular study: bacterial resistance in different hospitals cannot be compared direct and one hospital is not necessarily representative for a whole country. After seven years' use of plain trimethoprim the prevalence of resistance in the two university hospitals in Finland was similar to that in a London hospital just before plain trimethoprim was registered for use in Britain.