Characterization of clinical isolates of Mycobacterium paratuberculosis by DNA-DNA hybridization and cellular fatty acid analysis.

The DNA-DNA homologies obtained were more than 90 per cent for all strains examined, including the reference strains of Mycobacterium paratuberculosis and Mycobacterium avium. Consequently, in a genetic sense, M. paratuberculosis with its variants belong to a single species which should be considered a subspecies of M. avium. The same reference strains of M. paratuberculosis and M. avium showed small but distinct differences in the cellular fatty acid patterns. The Norwegian goat isolate proved to be M. paratuberculosis, while the three sheep isolates from Iceland and the Faroe Islands showed a typical M. avium pattern.

Relationship between Mycobacterium avium, Mycobacterium paratuberculosis and "wood pigeon mycobacteria". Determinations by DNA-DNA hybridization.

The DNA-DNA homology percentages obtained in this study indicate that M. avium and M. paratuberculosis belong to one species. Consequently, M. paratuberculosis ought to be considered a variant of M. avium, and the following designations are proposed: Mycobacterium avium, subsp. avium. Mycobacterium avium, subsp. paratuberculosis. Identification and classification of "wood pigeon mycobacteria" occurring in wild animals have been problematic due to their dysgonic and mycobactin-dependent growth. DNA-DNA homology percentages indicate that these bacteria are closely related to reference strains both of M. avium and of M. paratuberculosis. "Wood pigeon mycobacteria" should therefore be classified as atypical strains of M. avium, and the following designation is proposed: Mycobacterium avium subsp. columbae.

A cooperative taxonomic study of mycobacteria isolated from armadillos infected with Mycobacterium leprae.

Seventeen strains of mycobacteria, recovered from six armadillos experimentally infected with Mycobacterium leprae, were examined in ten different laboratories. This collaborative study included use of conventional bacteriological tests, lipid analyses, determination of mycobactins and peptidoglycans, characterization by Py-MS, and immunological, metabolic, pathological and DNA studies. These armadillo-derived mycobacteria (ADM) formed five homogeneous groups (numbered ADM 1 to 5) on the basis of phenetic analyses. However, DNA studies revealed only four homogeneous groups since group ADM 1 and one of the two strains in group ADM 3 showed a high level of DNA relatedness. The phenetic and DNA studies confirmed that the ADM strains differed from all other known mycobacteria. Cultural, biochemical, metabolic and pathogenic properties as well as DNA-DNA hybridizations clearly differentiated these ADM from M. leprae.

Determination and re-examination of genome sizes and base ratios on deoxyribonucleic acid from mycobacteria.

Genome sizes of 22 species of mycobacteria have been calculated. Thirteen of these genome sizes are based on results from re-examinations. Base ratios of some of the strains have been determined.

Deoxyribonucleic acid relationships between different serovars of Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium scrofulaceum.

M. avium and M. intracellulare are difficult to distinguish by means of biochemical tests and by means of numerical taxonomy. DNA-DNA hybridization confirms that these species are different but indicates that some serovars of M. intracellulare actually belong to the species M.avium, viz.: serovars 4, 5, 6 and 8. This corresponds to results obtained with sensitin tests on guinea-pigs. The status of strains belonging to serovar 9 is uncertain. The two strains investigated in this study were closely related to, but not identical with M. scrofulaceum serovar 41.

Deoxyribonucleic acid relatedness among species of rapidly growing mycobacteria.

The DNA-DNA homology percentages obtained in this study indicate M. smegmatis, M. phlei, M. fortuitum, M. peregrinum, M. senegalense, M. farcinogenes, M. chelonei, M. parafortuitum, M. vaccae, M. diernhoferi and M. aurum are separate species. Taxonomically there is no justification for the designation M. fortuitum complex, and M. peregrinum should be revived as an independent species. The type strains of M. parafortuitum, M. vaccae, M. aurum and the non-valid M. diernhoferi are so distinct from each other that they should not be combined.

Classification of Mycobacterium simiae by means of comparative reciprocal intradermal sensitin testing on guinea-pigs and deoxyribonucleic acid hybridization.

This study is a contribution to the elucidation of the taxonomic relationships among Mycobacterium simiae serovars 1 and 2, other photochromogenic, mycobacterial species and the non-photochromogenic species M. avium and M. intracellulare. DNA-DNA homology percentages and comparative reciprocal intradermal sensitin reactions in guinea-pigs have confirmed that M. habana is a subjective synonym of M. simiae serovar 1 and that M. asiaticum is a separate species. The two strains of M. simiae serovar 2 studied were distinct from each other and both were distinct from M. simiae serovar 1. M. simiae was so different from M. avium and even from M. intracellulare serovars 12, 14, 16 and 19, that there is no basis for including M. simiae in the so-called M. avium-intracellulare complex. Neither did M. simiae bear any close relation to the photochromogenic species M. kansasii and M. marinum. A fairly close negative correlation was observed between the DNA-DNA homology percentages and the specificity differences of the sensitins from the same pairs of strains. This is per se a proof of the veracity of the two taxonomic methods used in the study.

Reclassification of Mycobacterium phlei PN-bb as Rhodococcus bronchialis PN-bb.

Mycobacterium phlei PN-bb, induced in the parental strain PN by gamma-radiation and ethyl methanesulfonate, should be reclassified as Rhodococcus bronchialis PN-bb. The reclassification is based on the results of lipid analysis, DNA-DNA hybridization and several biochemical tests, performed in comparison with the parental strain PN, earlier reclassified as R. bronchialis, and R, bronchialis (N654).

Comparative studies of the strains PA and PN of Mycobacterium phlei leading to their reclassification: examination of lipids and DNA, biochemical tests and phage typing.

Study of lipid and DNA, biochemical tests and phage typing performed on the strain PA previously labelled Mycobacterium phlei, lead to the conclusion that this strain belongs to the species M. smegmatis. Parallel studies performed on strain PN, isolated from a culture of strain PA, as well as DNA homology percentage of the two strains, do not support the assumption that strain PN could have resulted from a mutation of strain PA Strain PN produces mycolic acids similar to those found in Rhodococcus bronchialis; the few biological tests applied quite agree with such a classification.

Deoxyribonucleic acid relatedness among species of slowly-growing mycobacteria.

DNA-DNA hybridization is a reliable method for determining the phylogenetic relationship between bacterial strains The hybridization kinetics for DNA from different slowly-growing mycobacteria were measured optically in a spectrophotometer. The results indicate that M. tuberculosis and M. bovis belong to one species. M. avium and M. intracellulare are two species, but some serotypes, now designated M. intracellulare, actually belong to M. avium.

Deoxyribonucleic acid hybridization between different species of mycobacteria.

The homology percentages between DNA from M. smegmatis ATCC 607 and DNA from nine various species of mycobacteria have been determined. DNA-DNA hybridization was measured in a spectrophotometer. The technique, calculation of results and the uncertainty of the method are described.

WHO cooperative studies on the phage-typing of mycobacteria. 1. Phage lysis of Czechoslovak and Italian strains of Mycobacterium tuberculosis.

Although phage-typing of some pathogenic microbes-e.g., Escherichia coli and the genera Salmonella, Staphylococcus, and Streptomyces-is in routine use, little progress has yet been made in the phage-typing of mycobacteria, chiefly because mycobacteriophages possess a polyvalence that prevents the reliable identification of individual species of mycobacterium. Furthermore, laboratories cannot compare their results because they employ different methods and culture media and also because the phages used cannot be accurately identified. It has been shown that internationally reproducible results can be obtained for M. tuberculosis by selecting suitable mycobacteriophages and sensitive culture media, and by using a standardized technique of phage-typing. Under these conditions, phage lysis may be utilized to classify strains of M. tuberculosis.