Abstract
Agar dilution methodology (with added Oxyrase in the case of the macrolide group to allow incubation without added CO2) was used to compare the activity of RU 64004, a new ketolide, with the activities of erythromycin, azithromycin, clarithromycin, roxithromycin, clindamycin, amoxicillin with and without clavulanate, piperacillin with and without tazobactam, metronidazole, and imipenem against 379 anaerobes. Overall, RU 64004 yielded an MIC at which 50% of the isolates are inhibited (MIC50) of 1.0 microg/ml and an MIC90 of 16.0 microg/ml. In comparison, MIC50s and MIC90s of erythromycin, azithromycin, clarithromycin, and roxithromycin were 2.0 to 8.0 and >64.0 microg/ml, respectively. MICs of macrolides, including RU 64004, were higher for Bacteroides ovatus, Fusobacterium varium, Fusobacterium mortiferum, and Clostridium difficile than for the other species. RU 64004 was more active against gram-positive rods and cocci, Prevotella and Porphyromonas spp., and fusobacteria other than F. mortiferum and F. varium than against the Bacteroides fragilis group. Overall MIC50s and MIC90s (in micrograms per milliliter), respectively, of other compounds were as follows: clindamycin, 1.0 and 16.0; amoxicillin, 4.0 and 64.0; amoxicillin-clavulanate, 0.5 and 4.0; piperacillin, 8.0 and >64.0; piperacillin-tazobactam, 1.0 and 16.0; metronidazole, 1.0 and 4.0; and imipenem, 0.25 and 1.0.
Full Text
The Full Text of this article is available as a PDF (247.6 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Barry A. L., Fuchs P. C. In-vitro potency of azithromycin against gram-negative bacilli is method-dependent. J Antimicrob Chemother. 1991 Oct;28(4):607–610. doi: 10.1093/jac/28.4.607. [DOI] [PubMed] [Google Scholar]
- Barry A. L., Fuchs P. C. Influence of the test medium on azithromycin and erythromycin regression statistics. Eur J Clin Microbiol Infect Dis. 1991 Oct;10(10):846–849. doi: 10.1007/BF01975838. [DOI] [PubMed] [Google Scholar]
- Dubreuil L. In-vitro comparison of roxithromycin and erythromycin against 900 anaerobic bacterial strains. J Antimicrob Chemother. 1987 Nov;20 (Suppl B):13–19. doi: 10.1093/jac/20.suppl_b.13. [DOI] [PubMed] [Google Scholar]
- George W. L., Kirby B. D., Sutter V. L., Citron D. M., Finegold S. M. Gram-negative anaerobic bacilli: Their role in infection and patterns of susceptibility to antimicrobial agents. II. Little-known Fusobacterium species and miscellaneous genera. Rev Infect Dis. 1981 May-Jun;3(3):599–626. doi: 10.1093/clinids/3.3.599. [DOI] [PubMed] [Google Scholar]
- Hansen S. L., Swomley P., Drusano G. Effect of carbon dioxide and pH on susceptibility of Bacteroides fragilis group to erythromycin. Antimicrob Agents Chemother. 1981 Feb;19(2):335–336. doi: 10.1128/aac.19.2.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Retsema J. A., Brennan L. A., Girard A. E. Effects of environmental factors on the in vitro potency of azithromycin. Eur J Clin Microbiol Infect Dis. 1991 Oct;10(10):834–842. doi: 10.1007/BF01975836. [DOI] [PubMed] [Google Scholar]
- Spangler S. K., Appelbaum P. C. Oxyrase, a method which avoids CO2 in the incubation atmosphere for anaerobic susceptibility testing of antibiotics affected by CO2. J Clin Microbiol. 1993 Feb;31(2):460–462. doi: 10.1128/jcm.31.2.460-462.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spangler S. K., Jacobs M. R., Appelbaum P. C. Effect of CO2 on susceptibilities of anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin. Antimicrob Agents Chemother. 1994 Feb;38(2):211–216. doi: 10.1128/aac.38.2.211. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spangler S. K., Jacobs M. R., Appelbaum P. C. Susceptibilities of 201 anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin by oxyrase agar dilution and E test methodologies. J Clin Microbiol. 1995 May;33(5):1366–1367. doi: 10.1128/jcm.33.5.1366-1367.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]