Mycobacterium avium subspecies paratuberculosis (MAP) is a member of the M avium complex (MAC). It differs genetically from other MAC in having 14 to 18 copies of IS900 and a single cassette of DNA involved in the biosynthesis of surface carbohydrate. Unlike other MAC, MAP is a specific cause of chronic inflammation of the intestine in many animal species, including primates. The disease ranges from pluribacillary to paucimicrobial, with chronic granulomatous inflammation like leprosy in humans. MAP infection can persist for years without causing clinical disease. The herd prevalence of MAP infection in Western Europe and North America is reported in the range 21% to 54%. These subclinically infected animals shed MAP in their milk and onto pastures. MAP is more robust than tuberculosis, and the risk that is conveyed to human populations in retail milk and in domestic water supplies is high. MAP is harboured in the ileocolonic mucosa of a proportion of normal people and can be detected in a high proportion of full thickness samples of inflamed Crohn's disease gut by improved culture systems and IS900 polymerase chain reaction if the correct methods are used. MAP in Crohn's disease is present in a protease-resistant nonbacillary form, can evade immune recognition and probably causes an immune dysregulation. As with other MAC, MAP is resistant to most standard antituberculous drugs. Treatment of Crohn's disease with combinations of drugs more active against MAC such as rifabutin and clarithromycin can bring about a profound improvement and, in a few cases, apparent disease eradication. New drugs as well as effective MAP vaccines for animals and humans are needed. The problems caused by MAP constitute a public health issue of tragic proportions for which a range of remedial measures are urgently needed.

Strains of a new species of rapidly growing, nonphotochromogenic mycobacteria, Mycobacterium mageritense, were isolated from human sputum. The growth characteristics, acid fastness, and mycolic acids of the isolates were consistent with those of Mycobacterium species. The isolates were identified as members of a new species by performing a biochemical analysis and DNA-DNA hybridization experiments, and by comparing the sequences of several conserved genes, such as the 16s rRNA, hsp65, and sod4 genes. A phylogenetic analysis in which 16s rRNA and sod4 sequences were used identified M. mageritense as a novel distinct species and placed M. mageritense between members of the Mycobacteriumfortuitm complex and the thermotolerant rapidly growing group. Our results demonstrate that the taxonomic value of sod4 sequence analysis in the genus Mycobacterium is similar to the well-established value of 16s rRNA sequence analysis.Mycobacteria are aerobic, nonmotile bacteria that are widespread in nature and range from soil-dwelling saprophytes to pathogens of humans and animals (10,36). In taxonomic studies of members of the Mycobacteriaceae workers have traditionally relied on biochemical and cultural characteristics (33, 34) together with analyses of fatty acid composition (8) to determine the identity of a new organism. The systematics of these organisms has been refined by techniques such as highperformance liquid chromatography (7), multilocus enzyme electrophoresis (21), DNA-DNA hybridization, and phylogenetic classification based on the evolutionary sequence diversity of one or more universally present genes (26). The most commonly used gene for phylogenetic studies has been the 16s rRNA gene; however, the inability of 16s rRNA gene data to distinguish some closely related species (1) has suggested that other conserved genes, such as hsp65 (31) and sodA (5, 38), should be used. The current general recommendations for descriptions of new mycobacterial species include the need for at least DNA-DNA hybridization, biochemical, and cultural studies to show significant differences from previously described clusters of organisms (15).Mycobacterial strains that could not be identified by conventional identification procedures were isolated from human sputum specimens. Colonization of the respiratory tract was not associated with disease in all cases. In this paper we describe the results of a taxonomic study of these strains and propose a new species, Mycobacterium mageritense. MATERIALS AND METHODSBacterial strains. Five new strains were studied. Two of these strains (strains 93gT [T = type strain] and 1336) were received in 1987 from the Hospital Cantoblanco in Madrid, Spain; two (strains 1635 and 1636) were received from the same hospital in 1989: and one (strain 1470) was received in 1987 from the Hospital Santa Marina in Pais Vasco, Spain. All of the strains were recovered from sputum specimens from different patients. In addition, we studied the Characterization of strains. Standard methods were used to isolate mycobacte...

We describe a new group (type 3) of the recently proposed species Mycobucteriurn celaturn isolated from eight patients with AIDS in London, England. Sequences of genes coding for 16s rRNA (EMBL accession no. 246664) showed a divergence of 17 bases from M. celuturn type 2 reference isolates and a divergence of 7 bases from M. celaturn type 1 reference isolates. A reference strain is available (NCTC 12882).