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The in vitro activity of Ro 23-6240 (AM833), 6,8-difluoro-l-(2-fluoroethyl)-1,4-dihydro-4-oxo-7(4-methyl-lpiperazinyl) quinolone-3-carboxylic acid, was compared with those of norfloxacin, enoxacin, ofloxacin, and ciprofloxacin. Ro 23-6240 inhibited the majority of Enterobacteriaceae isolates at a concentration of c0.5 ,ug/ml. It was especially active against Shigella sp., SalmoneUla sp., Escherichia coli, and Yersinia enterocolitica, with an MIC for 90% of the strains of

Enoxacin is a new quinolone carboxylic acid compound. Its activity against 740 bacterial isolates was determined. It inhibited 90% Escherichia coli, Klebsiella sp., Aeromonas sp., Enterobacter spp., Serratia spp., Proteus mirabilis, and Morganella morganii at -0.8 ,ug/ml. The majority of Pseudomonas aeruginosa was inhibited by <3.1 p.g/ml. Haemophilus spp. and Neisseria spp. were inhibited by <0.1 jig/ml. Although most Staphylococcus aureus were inhibited by 3.1 ,ug/ml, some streptococcal species had minimal inhibitory concentrations of 6.3 to 12.5 ,ug/ml and Bacteroides sp. had minimal inhibitory concentrations -25 ,ug/ml. Activity of enoxacin and norfloxacin was similar. Enoxacin inhibited organisms resistant to cefotaxime, moxalactam, gentamicin, and piperacillin. Enoxacin was less active in urine at an acid pH than in broth, but serum did not decrease minimal inhibitory concentrations or minimal bactericidal concentrations. There was no major difference between minimal inhibitory concentrations and minimal bactericidal concentrations. Resistance frequency development was <10-9 for most bacterial species.Quinolone antimicrobial agents such as nalidixic acid and related compounds have been used primarily to treat urinary tract infections. Agents of this class have various ring structures affixed to y-pyridone-p-carboxylic acid which appears to be essential for the activity of these synthetic compounds. Recently, compounds have been synthesized which do not appear to suffer from the defects of nalidixic acid, namely restricted antibacterial activity and poor oral absorption. These agents are active against bacteria resistant to nalidixic acid, and they inhibit gram-positive species and Pseudomonas aeruginosa (4, 7). Enoxacin, formerly called AT-2266 or CI 919, is a 1-ethyl-6-fluro-1,4-dihydro-4-oxa-7-(1-piperazinyl)-

The glycopeptide antibiotic teichomycin had in vitro activity comparable to that of vancomycin against most gram-positive species, and it inhibited methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. It was twofold more active against many S. aureus and S. epidermidis isolates than was vancomycin. Teichomycin had activity comparable to that of vancomycin against Listeria monocytogenes and Streptococcus faecalis. It was generally more active against streptococci than was vancomycin. There were no major differences between minimal inhibitory concentrations and minimal bactericidal concentrations of these drugs. Teichomycin acted synergistically with gentamicin against some bacteria.