Cross-reactivity between Mycobacterium tuberculosis H37Rv and various Actinomycetes and related organisms

Abstract One hundred and forty-one strains of Actinomycetales and related organisms were investigated by immunodiffusion for the presence of antigens which cross-react with the antigens of M. tuberculosis H37Rv. The test strains comprised 86 different species names and 20 different genus names; they were mainly environmental organisms isolated from soil, plants, animals and such like. More than 90% of these strains were shown to have one or more antigens in common with the tubercle bacillus, and 77 % had two or more antigens in common with this organism. Certain strains, of Nocardia and Rhodococcus , demonstrated abundant cross-reactivity with the tubercle bacilli, sharing up to 5 and 6 precipitinogens respectively.