In vitro activity of chloramphenicol and thiamphenicol analogs.

The in vitro activity of three fluorine analogs of chloramphenicol in which the hydroxyl group at position 3 had been replaced with a fluorine was compared with that of chloramphenicol and thiamphenicol. Compound SCH 24893 was the most active agent against staphylococci and Bacteroides strains, and compound SCH 25298 was the most active against Haemophilus, Neisseria, enterococcus, and Klebsiella strains. Serratia marcescens and Pseudomonas aeruginosa strains resistant to chloramphenicol were resistant to the compounds. The agents inhibited all of the Shigella, Salmonella, Staphylococcus aureus, and enterococcus strains resistant to chloramphenicol. They inhibited most (82%) of Escherichia coli and half of the Klebsiella pneumoniae strains which were resistant to chloramphenicol. Isolates in which resistance to chloramphenicol was shown to be plasmic mediated and due to chloramphenicol transacetylase were inhibited by all three agents.