[Urinary infection and pyelonephritis]

Actual concepts on urinary tract infection (UTI) and pyelonephritis have changed constantly through the years. A brief historical review has been considered in this paper, with the hope that nowadays concepts may help the clinician towards a better diagnostic and management approach of these still so common clinical disorders. Bacteriological studies were performed in 245 urine samples obtained by three different procedures, in order to evaluate the reability of each technique, which were: different procedures, in order to evaluate the reability of each technique, which were: a) suprapubic puncture; b) single culture obtained by midstream voiding technique, and c) serial cultures in three different samples, also obtained by the latter technique. E. coli was isolated in 91% of the initial diagnosed episode of UTI, and in 87% of the recurrences. Same bacteria, as well as other organisms and mixed flora were isolated from patients with predisposing factors present within the urinary tract (intra UT predisposing factor). Results show that suprapubic tap is the most reliable technique, since bacterial contamination of the sample is avoided. Fifty percent incidence of false positive results was found when a single culture by midstream voiding technique was used. A better correlation between suprapubic puncture and serial cultures obtained by midstream voiding technique was found. Both procedures are recommended. Predisposing factors, mainly within the urinary tract, were found in 68% of the cases with demonstrated UTI. Vesicoureteral reflux was found in 27% from the total number of patients studied, and in 52% of the patients with intra-UT predisposing factors. Suggestions are made in relationship with diagnostic approach and management of patients with UTI, in order to reveal the presence of predisposing factors, since they are the main feature to take into account regarding UTI, location of the site of infection, recurrences, chronic evolution, treatment and prognosis.