Molecular evidence to support a proposal to reserve the designation Mycobacterium avium subsp. avium for bird-type isolates and 'M. avium subsp. hominissuis' for the human/porcine type of M. avium.

Abstract

In an attempt to clarify the taxonomy of the Mycobacterium avium complex, the relationship between IS1245 RFLP, growth temperature, 16S rDNA signature sequences and the 16S-23S rDNA internally transcribed spacer (ITS) of 160 M. avium-complex isolates from different sources was investigated. All 70 isolates identified as M. avium by INNO-LiPA MYCOBACTERIA (Innogenetics, Belgium), a DNA probe test that targets the ITS, and by 16S rDNA analysis carried multiple copies of IS1245. Three isolates with multiple copies of IS1245 were identified by 16S rDNA analysis as Mycobacterium intracellulare and by LiPA as M. intracellulare (n = 1) and M. avium-intracellulare complex (n = 2). A dichotomy among the M. avium isolates was found on the basis of a C and a G signature nucleotide at position 228 of the 16S-23S rDNA spacer sequence, and this grouping was largely confirmed on the basis of similarities in IS1245 RFLPs. Strains with the characteristic three-band IS1245 'bird-type', as well as M. avium subsp. silvaticum or 'wood-pigeon' strains, invariably contained the C signature. A third characteristic that separated the M. avium bird-type isolates from M. avium isolates from humans and other mammals was growth-temperature tolerance: in contrast to bird isolates, human/porcine isolates grew at 24 and 45 degrees C. Based on differences in IS1245 RFLP, 16S-23S rDNA ITS and growth temperature, M. avium isolates originating from birds should be considered as a separate, evolutionarily conserved taxon. Because all M. avium isolates from birds are invariably of this type, the designation M. avium subsp. avium should be reserved for these bird-type strains. For clarity in the epidemiology of M. avium-related disease, isolates from humans and pigs with multibanded IS1245 RFLPs merit a separate designation. The designation 'M. avium subsp. hominissuis' is suggested for this group of bacteria.

Escherichia coli, Salmonella, and Mycobacterium avium subsp. paratuberculosis in Wild European Starlings at a Kansas Cattle Feedlot

“…If these isolates are Mycobacterium avium subsp. hominisuis, then starlings pose a potential risk for spreading disease to humans (38). In summary, these results suggest that starlings are not a significant threat for spreading E. coli O157:H7, bovine pathogenic E. coli, Salmonella, or Mycobacterium avium subsp.…”

Mycobacterial infection of pigs in Croatia

“…The proposed name for this group is M. a. hominissuis (Mijs et al, 2002). The third group consists of M. intracellulare isolates of the remaining serotypes 7, 12 to 20 and 22 to 28, which do not include any of the above-mentioned IS elements and are practically not virulent for birds (Mijs et al, 2002). M. a. avium of serotypes 1, 2 and 3 is a much more serious pathogen for pigs than M. a. hominissuis and M. intracellulare.…”

“…They are only partially virulent for birds, do not include IS901 but include IS1245 in a number higher than 3 copies (Ritacco et al, 1998). The proposed name for this group is M. a. hominissuis (Mijs et al, 2002). The third group consists of M. intracellulare isolates of the remaining serotypes 7, 12 to 20 and 22 to 28, which do not include any of the above-mentioned IS elements and are practically not virulent for birds (Mijs et al, 2002).…”

“…a.) avium (Mijs et al, 2002). Isolates are entirely virulent for birds and are the cause of generalised avian tuberculosis.…”

Isolation and characterisation of Mycobacterium avium and Rhodococcus equi from granulomatous lesions of swine lymph nodes in Slovenia

“…The first group consists of M. a. avium isolates entirely virulent for birds, which cause generalised avian tuberculosis. These isolates belong mainly to serotypes 1, 2 and 3 of MAC and, if isolated from field samples, more than 95% of them contain IS901 (Pavlik et al, 2000;Mijs et al, 2002). The second group consists of M. a. hominissuis which is only partially virulent for birds (Mijs et al, 2002).…”