ELECTROCHEMILUMINESCENCE-BASED DETECTION OF BETA-LACTAM ANTIBIOTICS AND BETA-LACTAMASES

Bacterial resistance to clinically administered beta-lactam antibiotic s is usually caused by beta-lactamases, enzymes that hydrolytically in activate the antibiotics, This paper describes the use of electrogener ated chemiluminescence (ECL) to detect beta-lactam antibiotics and the ir hydrolysis by beta-lactamases. All 10 tested antibiotics were detec ted on the basis of their ability to participate in an ECL reaction wi th ruthenium(II) tris(bipyridine). In every case, antibiotic-promoted ECL changed when the antibiotic was hydrolyzed by beta-lactamases or N aOH. Standard curves of antibiotic concentration versus ECL intensity showed that antibiotics could be quantitated to low micromolar concent rations. Substrate profiles were generated for four beta-lactamases us ing six structurally diverse: beta-lactam antibiotics. ECL-based antib iotic detection was accomplished in untreated whole milk, and beta-lac tamases were detected in crude bacterial broth culture. Because severa l structurally diverse antibiotics were detectable by ECL, this method may become valuable for the detection of many or all beta-lactam anti biotics and their inactivation by beta-lactamases.