Laboratory diagnostics of renal function in an experimental model of ascending pyelonephritis with high-virulent...

Urinary tract infections (UTI) are caused in 95% of cases by bacteria--E. coli. UTIs usually are limited to the lower urinary tract, but it may also evolve into pyelonephritis and acute kidney injury.

The aim of this study was the laboratory evaluation of renal function in an experimental model of ascending pyelonephritis caused by intravesical infusion of E. coli.

In female Wistar rats UTI was induced by intravesical administration of E. coli suspension in a dose 10(5) c.f.u./ml (Group 1), and 10(7) c.f.u./ml (Group 2). On the 0,7th, 14th and 21st day of the experiment the animals underwent the procedures of collecting blood and urine samples.

The results shown that in group 2 on the 7th and 14th day of the study the creatinine clearance decreased by 36%, and on 21th by 34%. The increase in serum uric acid concentration (micromol/l) in group 2 was observed on the 7th (229.75 +/- 79.05) and 21st day (98.5 +/- 11.33) with respect to day 0 (77.12 +/- 11.63). In group 2 on the 7th day of the experiment there was observed the increased levels of potassium (mmol/l) in serum (13.5 +/- 1.48) with respect to day 0 (7.74 +/- 0.88). In group 2 in the 7th (1.06 +/- 0.18) and 14th day (1.32 +/- 0.26) there was noted the decreased excretion of potassium in the urine (mmol/24h) with respect to day 0 (3.75 +/- 1.9). The decrease in serum sodium levels (mmol/l) in group 2 was recorded on 14th day (121.5 +/- 8.7) with respect to day 0 (131.62 +/- 4.07). Increased factional sodium excretion--FENa (%) was observed in group 2 on 14th day (0.25 +/- 0.06) with respect to day 0 (0.12 +/- 0.06).

Our main finding is that--independently of the amount bacteria present in urinary bladder--in this inflammatory model there occurs inevitably acute kidney injury, however higher bacteria amount depicts a very clear profile of laboratory parameters that point at the kidney impaired function.