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 of Haemophilus influenzae. Klebsiella aerogenes and Bacteroides spp. Florphenicol was bacteristatic for salmonellae and Escherichia coli but bactericidal for Haemophilus influenzae. Florphenicol was slightly more active than chloramphenicol against Chlamydia trachomatis, Mycoplasma hominis and Mycoplasma pneumoniae but less active against Ureaplasma urealyticum.