The in vitro activities of several 14-, 15-and 16-membered macrolides were compared with that of erythromycin. In general, 14-membered macrolides such as erythromycln, clarithromycin, and flurithromycin were more active against streptococci and Bordetelk pertussis than was the 15-membered mnacroZlde azithromycin, which was more active than 16-membered macrolides such as niocamycin and rokitamycin. Clarithromycin was the most active compound against Streptococcus pyogenes, pneumococti, Listeria monocytogenes, and Corynebactenium species. LegioneUla pneumophila was most susceptible to m pycin, clarithromycin, and rokitamycin. BranhameUa catarrhais, Neisseria gonorrhoeae, and Haemophillus iqluenzae were most susceptible to azithromycin. Azithromycin and dirithromycin were the most active compounds against Campylobacterjejuni. MICs of 16-membered macrolides for strais expressing inducible-type resisace to erythromycin were cl >&/ml, whereas none of the compounds had activity apinst strins expressing constitutive-type resistance. The MICs of roxlthromycin, miocamycin, rokitamycin, and josamycin increased in the presence of human serum, whereas MICs of the other compounds either were unchanged or decreased.
The in vitro and in vivo properties of a new 1-difluorophenyl-6-fluoroquinolone, temafloxacin hydrochloride (A-62254), were compared with those of difloxacin and ciprofloxacin. Temafloxacin hydrochloride was as active as ciprofloxacin and difloxacin against staphylococci and as active as ciprofloxacin and 2 twofold dilutions more active than difloxacin against streptococci. Against gram-negative enteric bacteria and Pseudomonas aeruginosa, temafloxacin hydrochloride was 2 twofold dilutions more active than difloxacin but 2 to 4 twofold dilutions less active than ciprofloxacin. The MICs of temafloxacin hydrochloride and difloxacin were increased by 2 to 5 twofold dilutions in urine at pH 6.5 compared with 4 to 5 twofold-dilution increases in the MICs of ciprofloxacin. The MICs of temafloxacin hydrochloride, difloxacin, and ciprofloxacin were increased by 1 to 3 twofold dilutions in serum. The MICs of temafloxacin hydrochloride, difloxacin, and ciprofloxacin were the same or within 1 to 2 twofold dilutions at pHs 6.5, 7.2, and 8.0. When administered orally in mouse protection tests, temafloxacin hydrochloride was as active as difloxacin and 5 to 10 times more active than ciprofloxacin against infections with Staphylococcus aureus and streptococci. Against infections with gram-negative enteric bacteria and P. aeruginosa, temafloxacin hydrochloride was as active as difloxacin and ciprofloxacin. Temafloxacin hydrochloride was three times less active than difloxacin but was five times more active than ciprofloxacin against infections with Salmonella typhimurium. Temafloxacin hydrochloride was as active as difloxacin and ciprofloxacin against P. aeruginosa and Proteus mirabilis pyelonephritis in mice. The peak serum concentration and serum half-life of temafloxacin hydrochloride in mice were approximately one-half and one-sixth, respectively, that of difloxacin after oral administration. The peak serum concentration of temafloxacin hydrochloride in mice after oral administration was six times higher than that of ciprofloxacin, and the serum half-life was equal to that of ciprofloxacin.As a class, the aryl-fluoroquinolones exhibit broadspectrum in vitro potency, as well as excellent in vivo activity (2). We have previously described the activity of two of these new quinolones, difloxacin and A-56620 (5, 14). Difloxacin is four-to eightfold less active in vitro than is ciprofloxacin against members of the family Enterobacteriaceae and Pseudomonas spp.; its similar in vivo efficacy in experimental infections, however, is probably due to its higher serum concentration and longer half-life. The mean terminal elimination serum half-life of difloxacin in humans after oral administration is 26 h (7). Temafloxacin hydrochloride (A-62254) was discovered while searching for a new quinolone with improved activity against gram-negative bacteria, higher solubility in water, and a serum half-life shorter than that of difloxacin but longer than that of ciprofloxacin. The structure of this compound, 1-o,p-difluorophenyl-6-fluoro-1 ,4-d...
The in-vitro activities of several 14-, 15- and 16-membered macrolides and fluoroquinolones against Campylobacter pylori were determined. In general, 14-membered macrolides, such as clarithromycin and flurithromycin, were more active than the 15-membered macrolide, azithromycin, which was more active than 16-membered macrolides, such as miocamycin and rokitamycin. Fluoroquinolones, except ciprofloxacin and A-61827, were less active than macrolides. Clarithromycin was the most active of the new compounds against C. pylori and was as active as ampicillin. MICs of all compounds at pH 5.5 were increased when compared to MICs determined at pH 7.3. All compounds had MBCs which were the same as or within one two-fold dilution of their MICs. Frequencies of spontaneous resistance development by C. pylori NCTC 11637 at four and eight times the MIC of the compounds were low and ranged from less than 1 x 10(-9) to 1 x 10(-7).
ABT-719 (A-86719.1) is the first compound of a new class of novel DNA gyrase inhibitors, the 2-pyridones, with potent antibacterial activity against gram-positive, gram-negative, and anaerobic organisms. ABT-719 was more active than ciprofloxacin, sparfloxacin, and clinafloxacin against gram-positive bacteria. ABT-719 was particularly active against Staphylococcus aureus (MIC at which 90% of the isolates were inhibited [MIC90] = 0.015 micrograms/ml) and Streptococcus pneumoniae (MIC90 = 0.03 micrograms/ml). ABT-719 was also the most active of the compounds tested against ciprofloxacin-resistant S. aureus isolates, with an MIC90 of 0.25 micrograms/ml, compared with 64 micrograms/ml for ciprofloxacin. Against gram-negative organisms, ABT-719 was as active as or slightly more active than ciprofloxacin and was the most active compound against ciprofloxacin-resistant Pseudomonas aeruginosa (MIC90 = 2.0 micrograms/ml). ABT-719 was also the most active compound against both gram-positive and gram-negative anaerobes, with MIC90s ranging from 0.12 to 0.25 micrograms/ml.
Tirandalydigin is a new tetramic acid antibiotic which was discovered in a screen designed to find compounds with activity against pathogenic anaerobic bacteria. It was named tirandalydigin because it possesses structural features that are commonto both tirandamycin and streptolydigin. The producing culture, strain AB1006A-9, is a Streptomyces and was compared to the streptomycetes that synthesize tirandamycin and streptolydigin. It is closely related to the former culture and was named Streptomyces tirandis subsp. umidus. Tirandalydigin has MICs in the range of 0.5 to 32 /^g/ml against manypathogenic anaerobes, streptococci, enterococci and legionellae.
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