[Detection of cross-reacting protein antigen from urinary tract pathogens by using reversed passive gelatin...

The basic studies on detection and titration of the 60-kDa cross-reacting protein antigen (CRPA), which is common to gram-negative rods, by reversed passive gelatin agglutination test with monoclonal and polyclonal antibodies were performed. The gelatin particles sensitized with 500 micrograms/ml of the monoclonal antibody had an ability to react with 200 ng/ml of the purified CRPA for 1.5 h. In contrast, the particles sensitized with 200 micrograms/ml of the polyclonal antibody had an ability to react with 25 ng/ml of the purified CRPA for 1.5 h. In addition, the detection of the 60-kDa CRPA in urinary tract pathogens, which consisted of 60 bacterial strains representing 14 species, was carried out by using the gelatin particles sensitized with 200 micrograms/ml of the polyclonal antibody. The CRPA was detected in all gram-negative rods of urinary tract pathogens, but not in gram-positive cocci. These results suggested that the detection of the 60-kDa CRPA by reversed passive gelatin agglutination test was a rapid and simple method for screening gram-negative bacteriuria.