Background
: In order to make accurate diagnosis and to avoid unnecessary use of medications in UTI, family physicians require sensitive & rapid diagnostic methods. In this study we analyzed the relationship between symptoms and the results of microscopic examination of urine with the results of urine cultures in order to identify predictors of cultures result in the diagnosis of UTI.

Methods : Usual symptoms, signs, and urinalysis (including microscopy of urinary sediment) as predictors of UTPs in patients were evaluated in 65 primary care visits in two community based hospitals, using a positive urine culture as gold standard (which was defined by colony count≥10).

Results : 1) The overall culture positivity rate was 26.2%(17 out of 65 cases). The 17 isolated was 26.2%(17 out of 65 cases). The 17 isolated bacteria were E.coli (11), Serratia species(4), G(+) Bacilli(1), Acinetobacter species(1), in order of decreasing frequency. 2) A difference was not found between sexes(p=,206), but was among age groups(p=.046). 3) The presenting features with the higher efficacy were dysuria, frequency, generalized symptoms, and no history of previous antibiotic use. A positive nitrite test, albuminuria, and ketonuria had relatively high specificities, but relatively low sensitivities. 4) The sensitivity and specificity of microscopic bacteriuria were 41.2% and 85.4%, respectively. At the maximal cutoff point for microscopic leukocytes(10/HPF) and erythrocyte(2/HPF), the sensitivity and specificity were 94.1% and 64.6%, 70.6% and 54.2%, respectively. 5) In cases of symptoms and signs consisting of dysuria, urgency, abdominal pain, or costovertebral angle tenderness, and microscopic findings of WBC≥(10/HPF), the sensitivity and the specificity were 94.1% and 64.6%, and the positive and negative predictive values were 48.5% and 96.9%, respectively. 6) In cases of any symptoms and signs consisting of dysuria, urgency, abdominal pain, or costovertebral angle tenderness, and urine tests consisting of a positive nitrite test, microscopic bacteriuria, microscopic WBC≥20/HPF, the sensitivity, specificity, positive and negative predictive values were 88.2%, 70.8%, 51.4%, and 91.4%, respectively, and were the most predictive values in our study.

Conclusion : Among some diagnostic methods, the finding of at least 10 WBC/HPF was found to have the highest correlation with positive urine culture. Specificity of WBC result is increased by symptoms & signs of patients and microscopic examinations of organism & RBC. This is further enhanced by addition of a nitrite test. The combination of these diagnostic methods yield the highest validity in the prediction of urine culture result.