Now let’s turn to the last category, the atypical or the
the classic one of which is Mycobacterium
avium-intracellulare or MAI
or as I said before Mycobacterium Avium-Complex, MAC - same
organism, several different descriptives.
This is a very common opportunistic pathogen which you’ll
see on patients with compromised immunity
especially those with HIV-AIDS but it can occur in others as
However, note to those of you who are budding pediatricians,
children also can acquire disease with MAI simply by
ingesting the outside world
or as we’d like to call it, sensory evaluation of the dirt
on which they walk,
because this organism and many other non-tuberculous
mycobacteria exist in the soil
and the water, it is very possible to inhale, aspirate,
any form of acquisition you can think of this organism.
Children are very good at putting soil and pebbles and other
things in their mouths
and sampling them. In that process, they may ingest, MAI,
and precipitate a localized immune reaction causing a
a chronic cervical lymph node, that is something which is
somewhat common in infectious disease offices.
It is not the sort of thing you’ll see that commonly however
in human medicine.
What you will see is the onset of MAI disease in those who
are at risk for opportunistic pathogens.
Healty patients may develop pulmonary disease
if they have a healthy intact immune system, they may be
meaning exposed to the organism but no disease will display
For those who have an immunocompromised state such as those
with a low CD4 lymphocyte count,
they may develop nonspecific symptoms such as fevers, night
sweats, weight loss, and focal lymphadenitis.
If they then have chest CT scan as you see demonstrated on
one can see multiple areas or nodules of disease spread
throughout the lung fields.
If one had an intact immune system, number one, one would
not develop such disease,
the nodules would not be present, but even if they had a few
nodules, number two, they would be asymptomatic.
Transmission of the non-tuberculous or atypical mycobacteria
as mentioned before,
is the ingested of contaminated anything - food, water,
soil, etc. and so forth.
Treatment for the non-tuberculous atypical mycobacterium is
not the "RIPE" drugs, right?
Really only used for treatment of MTB, instead,
we treat it with one of the macrolide antibiotics
clarithromycin or azithromycin,
and at least one or two others including ethambutol and
These three together are typically used for at least six
in the case of the non-tuberculous lymphadenitis for the
and sometimes even longer than that in patients with
HIV-AIDS, and chemotherapy induced immunosuppression
There is no vaccine for the non-tubercolous mycobacteria but
it’s very important to maintain a high effective lymphocyte
count because patients with HIV
are especially susceptible to MAI disease and those patients
who have a low CD4 count,
they’ll be placed empirically or prophylactically on
as a way to prevent further proliferation of the organism
once they inhale it or ingest it or anything else.
So, there you go, mycobacterium, one whole genus,
a whole lot of diseases associated with that but the ones to
remember are tuberculosis,
leprosy, and non-tuberculous mycobacterial disease.