Influence of water diuresis on antimicrobial treatment of enterococcal pyelonephritis

In the present studies, the effect of ampicillin (40 mg intramuscularly twice a day) in combination with water diuresis, produced by the ingestion of 5% dextrose in water, was determined on renal titers of enterococci after intravenous inoculation of 4 x 10(8)-2 x 10(9) enterococci into rats. Ampicillin injections with or without diuresis were started 4 or 21 days after initiation of infection and continued for 7 or 14 days. In comparison to controls (saline injections in rats drinking tap water), diuresis plus saline injections did not lower renal titers of enterococci. Injection of ampicillin in nondiuresing rats had little effect on renal titers of enterococci after 7 days of treatment started 4 or 21 days after initiation of infection. However, 2 wk of ampicillin therapy resulted in a significant decrease in renal titers. The addition of water diuresis to ampicillin treatment markedly potentiated the effect of ampicillin alone in decreasing renal titers of enterococci after 1 or 2 wk of therapy.These studies demonstrate that diuresis resulting from administration of dextrose in water plus ampicillin starting 4 or 21 days after intravenous injection of enterococci reduces renal titers more than ampicillin or diuresis alone.