Evaluation on effects of chromogenic medium in rapid detection of Coliform and Escherichia coli

Abstract

To evaluate the detective efficacy of Chromogenic Coliform and Escherichia Coli Agar (CCEA). A new chromogenic medium CCEA prepared by Huankai laboratory was used to compare with a classical medium of violet red bile agar (VRBA), and other two Chromogenic media Agar I and Agar II by detecting separately 11 reference strains, thirteen sterile samples with Coliform or E.coli and other four samples, and the accordant rates of detection were observed. CCEA had the good selectivity. To seven kinds of quality strains in the resultant analysis, CCEA with VRBA and Agar I had not shown salience difference (P > 0.05), and CCEA with Agar II had significant difference (P < 0.05). CCEA showed more advantages than the Agar II. To thirteen sterile samples with Coliform or E.coli in resultant analysis, CCEA with Agar I and Agar II had shown no significant difference (P > 0.05), while CCEA with VRBA had significant difference (P < 0.05). CCEA might be more advantageous than the VRBA. In analysis of the four actual samples of Coliform, CCEA with VRBA, Agar I and Agar II showed no significant difference (P > 0.05). The accordant rates were 90%, 71.88%, 86.25% and 81.25% respectively, showing CCEA > Agar I > Agar II > VRBA. To two actual samples of E.coli in the resultant analysis, the CCEA with Agar I and Agar II had not shown significant difference (P > 0.05). The accordant rates were 100% respectively. The CCEA might be more advantageous than the VRBA, having the same efficacy as with Agar I and Agar II.