Rapid diagnosis of infections caused by β-lactamase-producing bacteria by means of an enzyme radioisotopic assay

We developed a sensitive enzyme radioisotopic assay for the measurement of β-lactamase, an enzyme produced by a number of pathogenic bacteria. This ERIA was 100-fold more sensitive than the commonly used iodometric or spectrophotometric assays for the measurement of β-lactamase and, unlike these other assays, the ERIA was not significantly influenced by serum proteins or unlabeled penicillin. Clinical specimens consisting of blood, peritoneal, pleural, and cerebrospinal fluids from patients infected with β-lactamase-producing organisms yielded positive ERIA tests; fluids from uninfected patients were negative. The ERIA takes approximately 90 minutes to perform, and offers great potential for the rapid diagnosis of serious bacterial infections caused by bacteria which produce β-lactamase.