Ureteric catheterization in the diagnosis of pyelonephritis--an experimental evaluation.

Experimental models of renal infections have been used to determine the accuracy with which the cellular and microbiologic components of ureteric and voided urine reflected the pathologic status of the kidney in pyelonephritis. In acute pyelonephritis, the composition of the ureteric urine reflected the pathologic status of the kidney, although in a few cases ureteric samples were either sterile or cell free. Animals with chronic pyelonephritis in which the lesions were either infected or sterile commonly had sterile ureteric urine. Pyuria, however, was demonstrable in both these situations. In subclinical pyelonephritis, ureteric samples from infected kidneys were variably culture positive, although pyuria was a common observation. Discriminate function analysis based on actual renal status and ureteric data gave an overall correct classification rate of 67% and demonstrated at least 80% agreement in four of the five classification groups.

Antimicrobial agents in the management of urinary tract infection: an experimental evaluation.

Persistent and recurrent infections of the urinary tract are a formidable clinical problem, but several recently developed antibiotics have properties that suggest an increased ability to eradicate such infections. Three of the new-generation antibiotics were compared with established agents by using animal models of urinary tract infection. Of the antibiotics tested, gentamicin and ceftriaxone alone were capable of eradicating infection from acute and chronically infected kidney tissue. Chronic lower urinary tract infection was best managed by using norfloxacin or ceftriaxone. Gentamicin, aztreonam, cotrimoxazole and ampicillin were much less effective. In subacute pyelonephritis, gentamicin, aztreonam, norfloxacin and ceftriaxone successfully eliminated microorganisms from most of the infected kidneys, whereas ampicillin and cotrimoxazole had little effect on bacterial numbers. The data have provided an experimental basis for the selection of antibiotics in the management of persistent urinary tract infection.

Host defence mechanisms in the bladder. II. Disruption of the layer of mucus.

The urinary bladder wall is lined by a layer of mucus which is believed to provide an important barrier to bacterial invasion of the urinary tract. Abnormal function of this protective layer could therefore be a factor predisposing the host to urinary tract infection (UTI). This study investigated the contribution of the bladder mucus to host defence in both acute and chronic lower UTI, using a non-obstructive animal model of infection which reproduces many features of the disease in man. The ultrastructural appearance of the infected bladder mucosa was assessed in tissue in which both the layer of mucus and bacterial glycocalyces were stabilized prior to examination by scanning and transmission electron microscopy. The protective role of the mucus layer was determined by disrupting the layer immediately prior to bacterial challenge. Both ultrastructural and bacteriological analyses have shown that infection was increased in those animals where the mucus barrier was disrupted.

An animal model for chronic infection of the unobstructed urinary tract.

Chronic cystitis due to Escherichia coli is frequently associated with anatomical or functional abnormalities of the lower urinary tract, but there is no satisfactory animal model available to help resolve biological and management problems. We have induced chronic infection of the unobstructed urinary tract in the rat by implanting a small polyurethane sponge into the dome of the bladder, 14 days before bacterial challenge. This manipulation provides a focus of infected urine and leads to the establishment of a chronic cystitis. Both the predisposing factor and the pathological details mimic important features of the disease in man.