[In-vivo bacteriostatic and bactericidal activity of pefloxacine]

After oral ingestion of pefloxacin (400 mg every 12 hours for four days), the following characteristics were studied: bacteriostatic and bactericidal activity of urine for controls free of urinary tract infection on 6 "test" strains; kinetics of bacteriostatic and bactericidal activity of urine as compared to serum in patients with urinary tract infection. The urinary bacteriostatic level approximates bactericidal levels in healthy individuals. This level, that varies across bacterial species, remains steady between the third hour and the twenty-fourth hour following initiation of treatment: values found were 1/16 to 1/8192 for enterobacteria, 1/64 to 1/256 for Pseudomonas aeruginosa and 1/256 to 1/512 for Staphylococcus aureus. In patients, urinary killing curves show that bacteriuria decreases by 5 Log10 approximately, starting at the third hour. Urine was sterile by the sixth hour. In most cases, serum bacteriostatic activity was above 1/32 throughout treatment, with maximum levels being recorded on the fourth day (above 1/64). Bactericidal activity is similar to bacteriostatic activity.