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Introduction
Infections of the urinary tract are extremely common, and the numbers of patients presenting to general practice with this condition represent considerable morbidity and workload. 1 Because the symptoms of dysuria and frequency are unpleasant, doctors are under pressure from patients to provide relief. 2 3 However, not all such symptoms are associated with growth of bacteria in a standard midstream urine specimen. More detailed microbiological investigation of women with apparently negative urine cultures on standard testing indicate that a proportion of them have low count bacteriuria. 4 Urine testing with dipsticks that detect the presence of leucocytes and nitrites is commonly used in primary care to predict the subsequent diagnosis of urinary tract infection as determined by standard midstream urine culture and to guide the use of antibiotics. In one general practice study, the presence of leucocytes or nitrites in turbid urine had a positive predictive value of finding a pure growth on subsequent culture of around 66%. 3 Conversely, a negative dipstick test for both leucocytes and nitrites has a negative predictive value of finding a pure growth on subsequent culture of 80-98.5%. 2 3 In 2000 we carried out an epidemiological study to determine the prevalence of antibiotic resistance in bacteria causing uncomplicated urinary tract infections in the community and confirm the negative predictive value of the dipstick. 5
Of 374 specimens collected, 96 (26%) were negative for both leucocytes and nitrites. 5 Eight of these (8%) contained pure growth cultures above the standard conservative cut-off point of 100x106 colony forming units per litre. 6 The negative predictive value of the dipstick test was 92%.
The approach to women with symptoms of uncomplicated urinary tract infection and positive urine dipstick results is to give empirical antibiotic treatment. 7 â[euro]" 9 Recommendations for the treatment of women with symptoms and negative dipstick results vary. Some suggest empirical treatment, 1 10 but others do not. 7 8 11 We carried out a pragmatic trial of antibiotic compared with placebo in women with symptoms of uncomplicated urinary tract infection and negative dipstick results.
Methods
We designed the study as a double blind randomised placebo controlled trial. The intervention was treatment with trimethoprim 300 mg daily for three days.
Participants
We invited women to...