Immunological distinction of mycobacterial beta-lactamases

Beta-lactamase-containing fractions have been isolated from Myobacterium tuberculosis strain R(1)R(v) and M. smegmatis strains NCTC 8158 and T-64. Antisera raised in rabbits to these fractions demonstrated no cross-reactivity with a commercial Bacillus cereus beta-lactamase. Antiserum to either strain of M. smegmatis revealed no cross-reactivity with M. tuberculosis R(1)R(v), one specificity in common with the other M. smegmatis strain, and two specificities unique to the immunizing fractions. Further characterization of the common specificity was not possible, but beta-lactamase activity was related to the strain-specific precipitin lines in each case. These studies demonstrate the feasibility of isolating beta-lactamase enzyme fractions that may prove useful in the classification and diagnosis of mycobacteria.