Abstract
A simple screening test is described for separating Bacteroides fragilis from other anaerobic gram-negative bacilli. The test utilizes filter paper disks impregnated with 25 mg of oxgall (Difco), tested in conjunction with antibiotic identification disks. The bile disks and antibiotic disks are placed on a supplemented brucella blood agar plate which has been inoculated by swabbing with a standardized cell suspension. After 24 h at 35 degrees C in a GasPak jar, resistance to kanamycin and bile is taken as a presumptive identification of B. fragilis. Susceptibility to one or both disks indicates the need for further identification and additional biochemical tests are required. Those strains that produce insufficient growth within 24 h are not likely to be B. fragilis. The reliability of the bile disk method was tested by comparing results with 100 clinical isolates versus results with bile in thioglycolate broth, peptone-yeast extract-glucose broth, and tryptic soy agar. All four bile test methods gave equilvalent results, but the broth media required much longer periods of incubation.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Blazevic D. J. Antibiotic susceptibility of the subspecies of Bacteroides fragilis. Antimicrob Agents Chemother. 1976 Mar;9(3):481–484. doi: 10.1128/aac.9.3.481. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Finegold S. M., Harada N. E., Miller L. G. Antibiotic susceptibility patterns as aids in classification and characterization of gram-negative anaerobic bacilli. J Bacteriol. 1967 Nov;94(5):1443–1450. doi: 10.1128/jb.94.5.1443-1450.1967. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jones R. N., Fuchs P. C. Identification and antimicrobial susceptibility of 250 Bacteriodes fragilis subspecies tested by broth microdilution methods. Antimicrob Agents Chemother. 1976 Apr;9(4):719–721. doi: 10.1128/aac.9.4.719. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Martin W. J., Gardner M., Washington J. A., 2nd In vitro antimicrobial susceptibility of anaerobic bacteria isolated from clinical specimens. Antimicrob Agents Chemother. 1972 Feb;1(2):148–158. doi: 10.1128/aac.1.2.148. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimada K., Sutter V. L., Finegold S. M. Effect of bile and desoxycholate on gram-negative anaerobic bacteria. Appl Microbiol. 1970 Nov;20(5):737–741. doi: 10.1128/am.20.5.737-741.1970. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sutter V. L., Finegold S. M. Antibiotic disc susceptibility tests for rapid presumptive identification of Gram-negative anaerobic bacilli. Appl Microbiol. 1971 Jan;21(1):13–20. doi: 10.1128/am.21.1.13-20.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sutter V. L., Finegold S. M. Susceptibility of anaerobic bacteria to 23 antimicrobial agents. Antimicrob Agents Chemother. 1976 Oct;10(4):736–752. doi: 10.1128/aac.10.4.736. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vargo V., Korzeniowski M., Spaulding E. H. Tryptic soy bile-kanamycin test for the indentification of Bacteroides fragilis. Appl Microbiol. 1974 Mar;27(3):480–483. doi: 10.1128/am.27.3.480-483.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zabransky R. J., Johnston J. A., Hauser K. J. Bacteriostatic and bactericidal activities of various antibiotics against Bacteroides fragilis. Antimicrob Agents Chemother. 1973 Feb;3(2):152–156. doi: 10.1128/aac.3.2.152. [DOI] [PMC free article] [PubMed] [Google Scholar]