Nitrofurazone-coated urinary catheter segments inhibited 51 (75%) of 70 urinary bacterial isolates from patients with indwelling catheters. Inhibition zones correlated significantly with the nitrofurazone MIC (r2 = 0.79, P = 0.0001). All strains except the Pseudomonas spp. were inhibited by c64 ig of nitrofurazone per ml.MICs of nitrofurazone and nitrofurantoin correlated significantly (r2 = 0.93, P = 0.0001).

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To clarify the usefulness of histopathology in evaluating invasiveness during acute cystitis and pyelonephritis in a mouse model of urinary tract infection, findings from bladder and kidney sections of mice inoculated transurethrally with Escherichia coli were compared with results of bladder, kidney, spleen, and blood cultures and with changes in peripheral blood leukocyte counts. All of the 14 bladder histopathologic abnormalities evaluated were significantly associated with a positive bladder culture, and 7 were associated with splenic infection. Histopathologic features of cystitis were present in some culture-negative bladders. Eleven of 12 renal histopathologic abnormalities evaluated were significantly associated both with a positive kidney culture and with splenic infection, and two correlated with the development of peripheral leukocytosis. Histopathologic features of pyelitis and nephritis permitted culture-positive kidneys to be categorized as exhibiting colonization only, pyelitis only, or pyelitis plus frank nephritis and demonstrated that some culture-negative kidneys exhibit signs of pyelitis and nephritis. These findings suggest that detailed, semiquantitative histopathologic evaluation can add to quantitative cultures in the assessment of bacterial urovirulence in the mouse model of ascending urinary tract infection.

To determine the usefulness of detailed histopathological evaluation in the assessment of urovirulence of different Escherichia coli strains in a mouse model of ascending, unobstructed urinary tract infection, and to evaluate the relationship between susceptibility to urinary tract infection and renal levels of P fimbrial receptor glycolipids in different mouse strains, female Swiss Webster and Balb/c mice were inoculated transurethrally with one of four different well-characterized wild type E. coli strains or with an E. coli K-12 laboratory strain, and renal glycolipid levels were determined for both mouse strains. In Swiss Webster mice, each of the wild type E. coli strains was more virulent than the laboratory strain by both microbiological and histopathological criteria. Despite the common origin and identical virulence factor profiles of the three urosepsis isolates studied, one was significantly less urovirulent than the other two. Paradoxically, this strain stimulated a greater degree of leukocytosis than did the more urovirulent strains. Balb/c mice were significantly more susceptible to infection with this strain than were Swiss Webster mice, a difference possibly contributed to by the significantly higher renal levels of P fimbrial receptor glycolipids in Balb/c mice. Detailed histopathological analysis revealed significant differences in virulence between bacterial strains, and in susceptibility to infection between different mouse strains, that were inapparent from culture results alone.