Fluorogenic probes with substitutions at the 2 and 7 positions of cephalosporin are highly BlaC-specific for rapid mycobacterium tuberculosis detection

Current methods for the detection of Mycobacterium tuberculosis (Mtb) are either time consuming or require expensive instruments and are thus are not suitable for point-of-care diagnosis. The design, synthesis, and evaluation of fluorogenic probes with high specificity for BlaC, a biomarker expressed by Mtb, are described. The fluorogenic probe CDG-3 is based on cephalosporin with substitutions at the 2 and 7positions and it demonstrates over 120 000-fold selectivity for BlaC over TEM-1 Bla, the most common β-lactamase. CDG-3 can detect 10 colony-forming units of the attenuated Mycobacterium bovis strain BCG in human sputum in the presence of high levels of contaminating β-lactamases expressed by other clinically prevalent bacterial strains. In a trial with 50 clinical samples, CDG-3 detected tuberculosis with 90 sensitivity and 73 specificity relative to Mtb culture within one hour, thus demonstrating its potential as a low-cost point-of-care test for use in resource-limited areas. TB or not TB? A fluorogenic probe (CDG-3) was developed for BlaC, a biomarker expressed by Mycobacterium tuberculosis (Mtb). CDG-3 is based on cephalosporin with substitutions at both the 2 and 7positions and it demonstrates over 120 000-fold selectivity for BlaC over the common β-lactamase TEM-1 Bla. This rapid, low cost, sensitive, and selective method shows great potential for point-of-care tuberculosis (TB) testing in resource-limited settings.