No abstract
Several problems have been encountered with the application of published methods for the study of bacterial adherence to isolated uroepithelial cells. Of particular importance is the observation that urinary mucus traps some organisms but not others. Established techniques have been modified to overcome these difficulties and so allow a distinction to be made between adherence of bacteria to uromucoid and adherence to uroepithelial cells per se. The modified method was used to assess the ability of 34 urinary isolates of Escherichia coli to adhere to uroepithelial cells, uromucoid, or both after serial subculture in nutrient broth. The ability of the organisms to produce mannose-sensitive (MS) agglutination of guinea pig erythrocytes and mannose-resistant (MR) agglutination of human erythrocytes was tested simultaneously and taken to indicate possession of MS type 1 fimbriae andated MR fimbriae, respectively. Results revealed that only MS-positive organisms adhered to uromucoid (P < 0.001), whereas MR-positive strains showed significantly greater attachment to uroepithelial cells than did MR-negative strains (P < 0.05). These observations demand that published data derived from the use of a methodology in which no differentiation can be made between adherence to uromucoid and adherence to cells should be interpreted with caution.
IN adults urinary tract infection rarely leads to progressive kidney damage in the absence of obstructive uropathy. (Freedman and Andriole, 1969;Asscher, 1970). In contrast, the late sequel= of urinary tract infection in childhood may be more serious. Smellie and Normand (1968) showed that uncontrolled infection in children may lead to impairment of kidney growth and kidney scarring particularly when the infection is associated with vesico-ureteric reflux.These observations suggest that the growing kidneys of children may be more susceptible to the effects of ascending infection than the fully grown kidneys of adults. This hypothesis has been tested in the experimental animal by comparing the incidence of renal infection and scars following ascending Escherichia coliinfection in animals with both kidneys in situ with that observed amongst animals in whom unilateral nephrectomy was performed immediately after the establishment of infection so as to produce rapid growth due to compensatory hypertrophy in the remaining kidney.Material and Methods.-All experiments were carried out on female rats of the Wistar strain approximately 3 months old and weighing between 165 and 258 grams. The animals were fed on Oxoid diet 41B and allowed tap water ad libitum. In preliminary experiments (Asscher et al., 1971) it was shown that vesico-ureteric reflux can be produced in the rat by squeezing the bladder filled with 0.25 ml. of contrast medium (" Urovision " Schering, Berlin) whilst the external urethral orifice is temporarily occluded with forceps. This procedure was, therefore, used to produce ascending urinary tract infection. A strain of E. coli (sero-type 0 78) which had originally been isolated from a patient with urinary tract infection was used to produce infection. The organisms were grown overnight at 37°C in Difco brain-heart infusion broth. 0.25 nil. of an N saline suspension of the organism containing approximately 106 bacteria was injected into the bladder which had been exposed under light ether anmthesia through a small suprapubic incision. The bladder was then squeezed empty whilst the external urethral orifice was occluded. Sixty animals were infected in this manner. Table I summarises the experimental protocol. In half of these animals (Group 1) 1 kidney, the right or left alternatively, was excised and weighed. In the remaining 30 animals (Group 2) a sham unilateral neplirectomy was performed. The experiment was terminated 3 weeks later when total body weights and the weights of the remaining kidneys were recorded. The kidneys were removed aseptically, they were inspected, a small piece was saved for histological examination and the remainder was homogenised in a sterile all-glass tissue grinder and cultured. Urine cultures were performed weekly on all animals; the urine being obtained by suprapubic bladder aspiration.The controls consisted of 60 animals. In 20 of these (Group 3) 0.25 ml. of N saline was injected into the bladder, the bladder was squeezed as above and a unilateral nephrectomy was performed i...
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