effects of betamethasone and gentamicin on renal scarring induced by mannose-sensitive e coli pyelonephritis in rat

background: pyelonephritis can lead to renal scar.   objective : to evaluate the effects of betamethasone in preventing renal scarring in rat model of pyelonephritis.   methods : sixty three female sprague-dawley rats were divided into seven groups. group a was the control. mannose-sensitive e coli was directly inoculated into the left kidney exposed under general anesthesia in groups c–g. group b received normal saline. two days after bacterial inoculation, groups c, e and f received gentamicin for 10 days. betamethasone was injected for three days to animals in groups of d, e (2 days after bacterial inoculation) and f (5 days after bacterial inoculation). group g received no treatment. eight weeks after bacterial inoculation, animals were sacrificed and the volume (amount) of renal scar was determined using the stereological techniques.   results: changes in the weight and volume of the kidneys were not statistically significant. no scar was detected in group a, but all other groups including group b with intrarenal injections showed scarring. the volume density and absolute volume of the scar in groups c–g were significantly more than group b (p<0.001), whereas they did not differ significantly from each other.   conclusion : betamethasone and/or gentamicin, when used two days after induction of pyelonephritis were not effective in preventing renal scar.