Rapid presumptive identification of human black pigmented Bacteroides species

A simple and reliable technique is described for the rapid presumptive identification of black pigmented Bacteroides species of human origin. This method involved a microtitration technique that detected the hydrolysis of specific chromogenic enzyme substrates and haemagglutination of sheep erythrocytes. Pure cultures of black pigmented Bacteroides strains, representing the eight human species, were successfully differentiated and identified within 4 h by the identification scheme developed with this method. This is a highly reproducible method and the scheme should be useful in laboratories lacking the sophisticated equipment often needed for the identification of black pigmented Bacteroides.