Abstract
The Auto Microbic system Anaerobes Identification Card (Vitek Systems, McDonnell Douglas, Inc., U.S.A.), a fully automated and computer-assisted method for identifying anaerobic bacteria based on 29 biochemical reactions, was compared with the conventional method, using 112 strains of anaerobic bacteria (8 genera and 21 species) isolated from human feces. In addition to comparison with conventional method, the following parameters were tested using selected isolates: (i) the effect of composition of media for growth of strains tested, (ii) the effect of variation in inoculum size, and (iii) reproducibility of the identification of anaerobic bacteria. In the present study, the inoculum was prepared with some colonies on the surface of Brucella HK agar and the inoculum size was more than McFarland No.4. The reproducibility of identification of anaerobic bacteria by ANI Card was feasible and accurate. There was a 34.8% correlation and a 30.4% incorrelation between the ANI Card and conventional methods. Of 37 strains of the Bacteroides fragilis group, 33 strains were identified (89.2%). Each species of Eubacterium aerofaciens, Lactobacillus gasseri, L.reuteri, Clostridium innocuum, and C.clostridiiforme was not identified by ANI Card. The reactions of genus Bifidobacterium and anaerobic gram-positive cocci by this system were firstly determined. These findings suggested that VITEK Systems was feasible and accurate for the identification of the B.fragilis group as predominant anaerobes of human intestine, but not Eubacterium, Lactobacillus, and Clostridium.
