In vitro activity of cefoperazone against nonfermenters and Aeromonas hydrophila.

The in vitro activity of cefoperazone against 380 strains (33 species and unnamed groups) of nonferenters and 20 strains of Aeromonas hydrophila was studied by a microdilution method of determining minimal inhibitory concentrations. For comparison, the activities of ampicillin, ticarcillin, and cefamandole were simultaneously studied. Cefoperazone was the most active drug against Pseudomonas sp., Achromobacter xylosoxidans, Flavobacterium meningosepticum. Flavobacterium sp. (group IIb), Group IVc biotype 2, Group Ve, and Aeromonas hydrophila. Against other organisms it was equivalent in activity to or less active than comparative antibiotics. The only organisms which were usually resistant to 128 microgram of cefoperazone per ml were strains of Flavobacterium odoratum and Group IIk biotype 1.