Preventive effect of pentoxifylline on renal scarring in rat model of pyelonephritis

To evaluate the efficiency of pentoxifylline (PTX), a methyl xanthine derivative, in preventing renal scar formation after the induction of pyelonephritis in an experimental rat model with delayed antimicrobial therapy.

An inoculum of 1 x 10(9) colony-forming units/0.1 mL of the K-12 strain of Escherichia coli, which has both type 1 and P pili, was injected directly into both renal parenchyma of Wistar rats (n = 40). Group 1 (control) received isotonic saline instead of bacterial solution (n = 10). Four equal groups were then formed: group 2 was not treated and group 3 was treated only with ciprofloxacin for 5 days, starting 3 days after bacterial inoculation; in group 4, 50 mg/kg of PTX, and in group 5, PTX (50 mg/kg) and ciprofloxacin (15 mg/kg) together were administered intraperitoneally for 5 days, starting 3 days after bacterial inoculation. Six weeks after bacterial inoculation, all the rats were killed, and both kidneys were examined histopathologically for renal scarring.

Delayed treatment with antibiotics had no effect on scarring compared with the untreated controls. However, the addition of PTX to the delayed antibiotic therapy significantly inhibited renal scarring compared with the untreated or antibiotic-only groups (P <0.05).

These results suggest that PTX is effective in preventing renal scar formation in pyelonephritis when the initiation of antimicrobial treatment is delayed in this rat model of pyelonephritis.