Bile Differentiation Discs

Differentiation of Bacteroides fragilis group


HardyDisk™ Bile Differentiation Disks are used for the differentiation of Bacteroides fragilis group and for identification of other gram-negative anaerobic bacilli.


Anaerobic gram-negative bacilli are the most commonly encountered anaerobes in clinical specimens, with Bacteroides fragilis group isolated more frequently than any other anaerobe. Organisms in the Bacteroides genus have received notoriety due to their frequent involvement in infectious disease and their resistance to antimicrobial agents. Penicillin-resistant strains of the B. fragilis group are common, however, there are recent reports of new resistance to cefotetan and clindamycin and occasional resistance to piperacillin-tazobactam, imipenem and quinolones. HardyDisk™ Bile Differentiation Disks are instrumental in differentiating the B. fragilis group from other Bacteroides and Prevotella species.The HardyDisk™ Bile Differentiation Disk is used to determine an organism's ability to grow in the presence of high concentrations of bile. Other indicators of bile resistance, including significant growth on BBE (Bacteroides Bile Esculin) media and growth in 20% bile broth, require the inoculation of additional media. In 1983, it was demonstrated that comparable results were obtained using a 15mg bile disk and traditional bile tolerance methods. This study confirmed that the bile disk method is capable of clearly distinguishing between bile-resistant and bile-sensitive anaerobic organisms. A bile disk is a rapid and cost effective method for detecting bile resistance. The disk can be conveniently added to a Brucella subculture plate when a gram stain reveals an isolate to be an anaerobic gram-negative rod.HardyDisk™ Bile Differentiation Disks can be used to determine bile sensitivity in a variety of organisms. An anaerobic, gram-negative rod that is bile-tolerant and resistant to vancomycin, kanamycin, and colistin can be identified as a member of the Bacteroides fragilis group. Additionally, Bilophila which are phenotypically similar to B. ureolyticus, can be differentiated by bile tolerance and a strong catalase reaction. Bile resistance is also useful in the presumptive differentiation of Fusobacterium mortiferum and Fusobacterium varium from other Fusobacterium species.


Each HardyDisk™ Bile Differentiation Disk is prepared by impregnating carefully controlled concentrations of bile onto a high quality 6mm diameter filter paper disk. 

Cat No: HDZ7091

Size: 50 discs


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