Host-Parasite Relationship Between Amazonian Anurans and Atypical Mycobacteria (Mycobacterium chelonei and M. fortuitum)

Abstract

In a study of 450 Amazonian anurans, we isolated Mycobacterium chelonei abscessus, Mycobacterium fortuitum fortuitum, and Mycobacteriumfortuitum peregrinum from the viscera of 21 animals (Bufo marinus, Bufo granulosus, Hyla geographica, Hyla lanciformes, Hyla sp., Leptodactylus pentadactylus, and Leptodactylus sp.). We also detected M. chelonei abscessus, Mycobacterium chelonei chelonei, and M. fortuitum peregrinum in the soil and water samples of the anuran breeding ground. Adult toads (B. marinus) that had been force-fed a mycobacterial suspension retained and later excreted the microorganisms into their environment. Tadpoles of tree frogs (H. geographica) also ingested and retained mycobacteria that had been experimentally introduced into their milieu. Our findings indicated that the Amazonian anurans could play the role of a facultative intermediate host and dispersal agent for M. chelonei and M. fortuitum in nature. ATYPICAL MYCOBACTERIA ARE ACID-FAST BACILLI exclusive of the virulent mammalian tubercle bacilli Mycobacterium tuberculosis and Mycobacterium bovis. They are widespread in nature as saprophytes and parasites throughout the animal kingdom. According to the Runyon classification based on growth rate and pigment production, the group IV atypical mycobacteria are a rapid-growing species. Among the rapid growers, M. chelonei abscessus, M. chelonei chelonei, M. fortuitum fortuitum, and M. fortuitum peregrinum are known opportunistic pathogens for man and animals. They occur naturally as saprophytes in water, soil, and dust (Chapman 1971, Paull 1973, Romanelli et al. 1980). Although M. chelonei was originally isolated from diseased turtles (Friedmann 1903), the known animal hosts for M. chelonei and M. fortuitum are only the domestic hog and the armadillo, Chaetophractus villosus (Garcia-Rodriguez et al. 1975, Kantor 1978, S'aenz and