Urinary tract infection in primary health care in northern Sweden. III. Bacteriology in relation to clinical and epidemiological factors.

The spectrum of bacteria causing urinary tract infection (UTI) and their patterns of drug resistance were found to be more associated with the process of selecting the patients and their sex and age than with the symptoms of the patient (lower, upper or asymptomatic UTI). UTI caused by Staphylococcus saprophyticus was seen mainly in female patients in primary health care (PHC), showed a peak in August and was rarely complicated by therapeutic failures or recurrences. The average risk of resistance of the infecting strain to the seven drugs tested increased from eight per cent for the uncomplicated and 17% for the average PHC patient to 36% among PHC patients with indwelling catheter or urinary incontinence, whereas recurrences of UTI were associated with a surprisingly small increase of drug resistance. In all UTI patient groups studied, the lowest incidences of bacterial resistance were recorded for trimethoprim and co-trimoxazole (0-17%). Thus, rational selection of UTI therapy in PHC requires knowledge of the influence of clinical factors on the expected bacteriology including the local pattern of drug resistance.