Therapeutic effects of cefpirome (HR 810) on experimental mixed infections with Enterococcus faecalis and Escherichia coli in mice.

The therapeutic effects of cefpirome (HR 810), a new cephalosporin, on mixed infections induced in mice with Enterococcus faecalis HL1147 and Escherichia coli HL34 were compared with those of ampicillin (AMP), cefuzonam (CZON), and ceftazidime (CAZ). Cefpirome was more effective in protecting mice with systemic mixed infection (median effective dose, 52 mg/kg) than the other antibiotics (all more than 320 mg/kg). With increasing doses of cefpirome, the percentages of the animals having E. faecalis and E. coli bacteremia were decreased. CZON and CAZ reduced only E. coli, and AMP failed to reduce both strains. In the mice with urinary tract mixed infection, cefpirome and CZON (40 mg/kg x 5, s.c.) significantly decreased the cfu/g kidney (p less than 0.01 vs. nontreated control), while AMP and CAZ were active only against E. faecalis (p less than 0.05) and E. coli (p less than 0.01), respectively.