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Fifty women with pyelonephritic renal scarring were prospectively followed for five years and the changes in renal function were related to blood pressure control, plasma renin activity, urinary albumin excretion and the incidence of urinary tract infections (UTI). Five patients (10%) developed end stage renal disease. All these patients had bilateral disease, proteinuria and anti-hypertensive treatment at presentation. The mean +/- SD glomerular filtration rate (GFR) of all patients with renal scarring was 74 +/- 27 ml/min x 1.73 m2 at presentation which was significantly lower than the GFR in 55 patients with a recent episode of acute pyelonephritis (p less than 0.001) and 10 healthy controls (p less than 0.001). GFR and age corrected GFR decreased significantly during follow-up (p less than 0.001) and p less than 0.02 respectively). The decrease in GFR was significantly higher in patients with bilateral scarring, in patients on blood pressure treatment and in patients with an episode of symptomatic UTI during follow-up. Eight patients (16%) had antihypertensive treatment at presentation and another 11 patients (26%), of whom 10 had bilateral scarring, developed hypertension (greater than 140/90 mmHg) during follow-up. Seventy-five per cent of all patients had symptomatic UTI and 40% had an episode of acute pyelonephritis during follow-up. In conclusion, patients with pyelonephritic scarring have a high incidence of UTI and are at high risk of developing renal failure and hypertension. It is essential that recurrent episodes of symptomatic UTI are treated promptly and that blood pressure is monitored carefully in these patients.

The maximal urine concentration capacity was studied in patients with acute pyelonephritis and in patients with clinically diagnosed acute cystitis. In the former group renal concentration ability was reduced in 16 of 22 patients and improved in all but two patients. Among patients with symptoms of acute cystitis 6 of 22 had a concentration capacity below 2 SD of normal values. Several of these patients had raised acute phase proteins and increased their urine osmolality at follow-up indicating that cases of acute pyelonephritis could have been included. It is concluded that the wide overlap between the groups makes the maximal urinary concentration capacity a method of limited value for level diagnosis in acute UTI infection. The test should be reserved for follow-up to reveal permanent renal damage.

The association of bacterial virulence with the host response to bacteriuria was evaluated in 70 pregnant women with acute pyelonephritis or bacteriuria detected at screening. Patients infected with Escherichia coli attaching to Gal alpha 1----4Gal beta-containing receptors, had significantly higher levels of C-reactive protein and lower renal concentrating capacity than patients infected with strains lacking this specificity. The renal concentrating capacity ranged from 419-1151 mOsm/kg in the women with bacteriuria on screening. 5/11 women with a renal concentrating capacity less than or equal to 784 mOsm/kg were infected with Gal alpha 1----4Gal beta-specific bacteria, compared to 0/16 of patients who concentrated the urine greater than 784 mOsm/kg. According to earlier studies the risk for progression to pyelonephritis and recurrences during pregnancy was increased in bacteriuric women with a reduced renal concentrating capacity. The present study demonstrates that this risk group can be identified in part by the properties of the infecting E. coli strains.