In vitro activity of florphenicol

Florphenicol was active at a lower concentration than chloramphenicol against over half of 234 recent clinical bacterial isolates. The majority (98 %) of the isolates were inhibited by florphenicol at a concentration of 8 mg/l or less. Florphenicol was particularly effective against chloramphenicol resistant strains ofHaemophilus influenzae, Klebsiella aerogenes andBacteroides spp. Florphenicol was bacteristatic for salmonellae andEscherichia coli but bactericidal forHaemophilus influenzae. Florphenicol was slightly more active than chloramphenicol againstChlamydia trachomatis, Mycoplasma hominis andMycoplasma pneumoniae but less active againstUreaplasma urealyticum.