Frequency of development of early cortical scarring in acute primary pyelonephritis

Fifty-five cases of primary (that is, without urinary tract abnormalities), acute pyelonephritis (PN) were studied by computed tomodensitometry (CT). There were 48 women and 7 men. All were febrile and 16 had positive blood cultures. In 7 cases, (4 diabetics and 3 malnourished alcoholics) PN was painless, diagnosis was delayed and lesions were severe. Two diabetics underwent emergency nephrectomy for sepsis. Conventional radiological techniques (IVP and ultrasonography) were poorly informative. In contrast, initial CT abnormalities were visible in 44 patients. They consisted of triangular or round hypodense images, diffuse hypodensity in a grossly swollen kidney, and/or abscesses. Hypodense images were presumably due to acute focal ischemia. Renal histology was available in five patients. It showed acute interstitial nephritis with leukocyte infiltrates, edema and hemorrhagic streaks. Pyelonephritis was due to E. coli in 48 cases (87.5%). In 27 cases E. coli isolates were studied by genotypic assays which detect the three most frequent (pap, afa and sfa) of the four operons known to encode adhesin. In all cases, at least one of these genotypic markers of uropathogenicity was found. In 27 cases, repeat CT was done shortly after treatment. It showed healing in only 12. Early cortical scar formation was visible in 2. Final evaluation in 27 cases with adequate follow-up showed that (in addition to the 2 patients who had been nephrectomized), in only 17 of 27 (63%) had the kidneys recovered a normal appearance. In two cases one kidney had undergone atrophy; renal biopsy showed subacute-chronic interstitial nephritis.(ABSTRACT TRUNCATED AT 250 WORDS)