Detection of bifidobacterium species by enzymatic methods and antimicrobial susceptibility testing

Twenty four strains of bifidobacteria and 16 strains of lactobacilli were examined for activities of fructose-6-phosphate phosphoketolase, alpha-galactosidase, and alpha-glucosidase and the resistance to metronidazole and mupirocin over 24 h. The detection of alpha-galactosidase, alpha-glucosidase, and metronidazole susceptibility gave unclear results. The mupirocin susceptibility using disc diffusion method (200 mu g mupirocin per disc) had the same validity as the detection of fructose-6-phosphate phosphoketolase - the key enzyme of the bifidobacteria carbohydrate metabolism. While 24 bifidobacteria strains tested were mupirocin-resistant, 16 lactobacilli strains were susceptible. Hence, the resistance to mupirocin may serve as a simple criterion distinquishing Bifidobacterium spp. from Lactobacillus spp.