BBL™ CHROMagar™ Orientation medium is a nonselective differentiated medium for the isolation, differentiation and enumeration of urinary tract pathogens. BBL CHROMagar Orientation medium allows for the differentiation and identification of Escherichia coli and Enterococcus without confirmatory testing.

Escherichia coli, enterococci, the Klebsiella-Enterobacter-Serratia (KES) and the Proteus-Morganella-Providencia (PMP) groups are frequently encountered organisms in urinary tract infections (UTI). Most UTIs are caused by E. coli alone, or in combination with enterococci. Staphylococcus saprophyticus and Streptococcus agalactiae may be isolated from females, although less frequently.

Due to the different antimicrobial susceptibility patterns of the microorganisms involved, identificaton to the species level is necessary for effective antimicrobial therapy. The most frequently isolated species or organism groups produce characteristic enzymes. Thus, it is possible to identify these organisms to the species level with a limited number of substrate fermentation or utilization tests.¹

Some of the organisms encountered in UTIs produce enzymes either for the metabolism of lactose or glucosides or both. Other organisms produce none of these enzymes. For example, E. coli contains enzymes for lactose metabolism but is ß-glucosidase negative. Some members of the family Enterobacteriaceae are ß-glucosidase positive but do not contain enzymes necessary for lactose fermentation; others may contain both types of enzymes or none of them. ß-glucosidases are also found in gram-positive cocci, such as S. agalactiae and the enterococci. Tryptophan deaminase (TDA) is an enzyme characteristically found in the Proteus-Morganella-Providencia group.

CHROMagar Orientation medium was developed by A. Rambach and is sold by BD under a licensing agreement with CHROMagar, Paris, France.