The effect of pH and culture system on the attachment of plasmid-bearing and plasmid-cured Yersinia enterocolitica to a polycarbonate membrane in a surface adhesion immunofluorescent technique

A rapid surface adhesion based immunofluorescence technique was used to iso late and detect Yersinia enterocolitica from inoculated enriched culture sy stems. The pathogen was isolated by surface adhesion to a polycarbonate mem brane which was mounted on a glass slide and immersed in the enriched cultu re for 15 min. The pathogen was detected using a fluorescent labelled (FITC ) monoclonal antibody which was specific for Y. enterocolitica serotype O:3 and then viewed using fluorescent microscopy. The effect of culture type ( broth, meat homogenate and minced meat) and pH (5.00, 7.00, 9.00 and 11.00) on the adhesion of plasmid-bearing and plasmid-cured Y. enterocolitica to the polycarbonate membrane in this technique was determined. The pH had a s ignificant effect (P < 0.05) in broth and meat homogenate cultures, with en hanced attachment of Y. enterocolitica (P+ and P-) at pH 9.00 than at pH 5, 7 or 11. Culture type was also important, with differences observed in the numbers of Yersinia adhering to membranes immersed in broth, meat homogena te and minced beef: Differences in attachment were noted between plasmid-be aring and plasmid-cured Y. enterocolitica isolated from similar cultural en vironments. The reasons for these observed differences, and their implicati ons for the surface adhesion immunofluorescent rapid method, are discussed.