Affiliation:
1. Kuzell Institute of Infectious Disease, California Pacific Medical Center Research Institute, San Francisco, California 94115
Abstract
ABSTRACT
Mycobacterium avium
and
Mycobacterium intracellulare
are closely related organisms and comprise the
Mycobacterium avium
complex. These organisms share many common characteristics, including the ability to cause life-threatening respiratory infections in people with underlying lung pathology or immunological defects and occasionally in those with no known predisposing conditions. However, the ability to invade the mucosa of the gastrointestinal tract and cause disseminated disease in AIDS patients has not been epidemiologically linked to
M. intracellulare
and appears to be unique to
M. avium
. We compared the abilities of
M. avium
and
M. intracellulare
to tolerate the acidic conditions of the stomach, to resist the membrane-disrupting activity of cationic peptides, and to invade intestinal epithelial cells in vitro and in vivo. We observed that
M. avium
and
M. intracellulare
were both tolerant to the acidic conditions encountered in the stomach and resistant to cationic peptides. However, when strains of
M. avium
and
M. intracellulare
were examined for their ability to enter cultured human intestinal cells or mouse intestinal mucosa, we observed that
M. avium
could invade more efficiently than
M. intracellulare
. To elucidate the basis of this pathogenic difference and identify genes involved in the invasion of the intestinal mucosa, we performed chromosomal DNA subtractive hybridization using
M. avium
and
M. intracellulare
chromosomal DNAs. In all, 21 genes that were present in
M. avium
but absent in
M. intracellulare
were identified, including some that may be associated with the ability of
M. avium
to invade the intestinal mucosa.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
27 articles.
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