CHOLERA DFA - AN IMPROVED DIRECT FLUORESCENT MONOCLONAL-ANTIBODY STAINING KIT FOR RAPID DETECTION AND ENUMERATION OF VIBRIO-CHOLERAE O2

An improved fluorescent monoclonal antibody staining kit, Cholera DFA, for direct detection and enumeration of Vibrio cholerae O1 has been d eveloped, employing a highly specific anti-A antigen monoclonal antibo dy, COLTA, labeled with fluorescein isothiocyanate (FITC). An optimize d quantity of anti-photobleaching agent is used in a glycerol mounting medium to retard the rapid fading of immunofluorescent stained cells during fluorescent microscopy, thus enabling prolonged inspection of i ndividual fields, as well as improved photographic recording of result s without loss of fluorescence intensity. When tested for specificity, all 30 strains of V. cholerae O1 reacted with Cholera DFA, whereas 10 0 heterologous species examined did not, yielding 100% specificity for all strains examined in this study. A field trial was conducted in Ba ngladesh, employing Cholera DFA and the results were compared with tho se obtained by conventional culture methods. Of 44 diarrheal stool spe cimens tested, Cholera DFA was positive for V. cholerae O1 in all cult ure-positive stool specimens and negative for all culture-negative sto ol specimens. The procedure is sensitive and highly specific, as well as simple, i.e., less complex than the indirect fluorescent assay, req uiring only one reagent and less than 30 min to complete the staining process, while retarding rapid fading that often occurs with fluoresce nt microscopy.