[Bactericidal speed of ceftriaxone and cefotaxime on 18 strains of Haemophilus influenzae].

The bactericidal effect of ceftriaxone and cefotaxime was studied by killing curves on 18 Haemophilus influenzae at 2, 4, 6 and 24 h. The MIC of ceftriaxone are between 0.0012 and 0.015 mg/l. The MIC of cefotaxime are between 0.006 and 0.03 mg/l. The MBC of ceftriaxone are between 0.0012 and 0.03 mg/l. The MBC of cefotaxime are between 0.006 and 0.03 mg/l. The bactericidal effect was studied at the concentration of 0.06 mg/l; at this concentration we obtained a reduction of 4 log 10 for 3 strains in 6 hours by both drugs. In 24 h, 16 stains give a 99.99% of killing for ceftriaxone and 18 strains for cefotaxime. Our results do not show a significant difference in the bactericidal effect of the two drugs on Haemophilus.