Runyon classification

Abstract: Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms found in soil and water. Infections caused by NTM are increasing with conditions ranging from harmless colonization to invasive infections, the latter being more common in immunocompromised hosts. In this report, we present a case of bacteraemia caused by Mycobacterium chelonae , a rapidly growing NTM belonging to Class IV in the Runyon classification, in a 71-year-old male with ocular myasthenia gravis undergoing treatment with oral prednisolone. Gram staining of these organisms from blood culture can be easily overlooked or confused with diptheroids. Detection of Gram-positive bacilli should prompt Ziehl-Neelsen staining to distinguish diphtheroids from rapidly growing mycobacteria in immunosuppressed patients. In addition, speciation and antimicrobial susceptibility testing are of paramount importance in such cases as there is considerable variation in the resistance patterns between different species of NTM. Line probe assay provides a rapid and reliable method for identification of NTM to the species level, which can guide treatment with appropriate antibiotics. This case report highlights the importance of early detection of such cases so as to optimize management and improve patient outcomes.

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

Abstract: This paper reported forty-one patients with pulmonary atypical mycobacteriae infection from Jan. 1988 to Oct. 1990 in our hospital. 25 male and 16 female. The age ranged from 27 to 70 years, average 50.9 years. According to Runyon classification of mycobacterium diseases, there are 4 cases with Mycobacterisos kansasii, 2 with M. scrofulaceum, 14 with M. intracellulare or M. avium, 9 with M. chelonae and 12 with M. fortuitum, respectively. Characteristics of this disease were long history, mild symptom and unsatisfactory therapeutic effect by anti-tuberculosis drugs.

Abstract: Phylogenetic correlations of 17 members of the genus Mycobacterium were analyzed. A phylogenetic tree built using the neighbor-joining method consists of three clades, i.e., fast-growing, thermotolerant fast-growing, and slow-growing Mycobacteria; this indicates the genetic determination of growth-rate features and thermotolerance. Chromogenesis, which serves as a criterion for the Runyon classification of Mycobacteria, does not reflect their phylogenetic correlations.