DEVELOPMENT OF CRYSTAL VIOLET CO AGGLUTINATION FOR DETECTION OF ESCHERICHIA COLI O157:H7 IN GROUND BEEFS.G. NINGRUM, W. ARNAFIA, R.S. ADJI, H. LATIF, R.D. SOEJOEDONO AND I.W.T. WIBAWAN
Highly sensitive and specific co agglutination using crystal violet staining for detection of Escherichia coli O157 H7 was introduced. In this method, crystal violet was used to stain the Staphylococcus aureus cells that have much of protein A. This staining acts as a detector reagent in this assay. The antibody immobilized with stained S. aureus protein A using combination of formaldehyde and heating method. The antigen (test bacteria) was detected visually by development of purple color (due to specific reaction between antigen and matrix) on slide. This assay was specific to E. coli O157 H7 when compared with other Enterobactericeae. In addition, crystal violet co agglutination was able to detect E. coli O157 H7 from ground beef samples inoculated with 1 cell/g. Furthermore, the efficacy of this crystal violet co agglutination was evaluated by comparing this test to other serological tests such as dipstick immunoassay (Rapidcheck E. coli O157) in detecting E. coli O157 H7 in ground beef. The ground beef samples were spiked with STEC O157:H7 ATCC 35150 with spike levels were 1, 10 and 100 cell/g. Both methods gave same results; crystal violet co agglutination 15 (100%) and dipstick immunoassay 15 (100%). The sensitivity and specificity of this assay are determined by comparing test results with PCR. This research is expected to promising kit for a rapid and specific diagnostic detection of E. coli O157:H7 in food.
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