00:00
Lastly we will consider pneumocystosis caused
by pneumocystis jiroveci. This used to be
called pneumocystis carinii and it was one
of the first indications that the AIDS epidemic
was starting. In the early 1980s, there was
a cluster of cases of what's called PCP pneumonia,
pneumocystis pneumonia in gay men in California
and this was never seen in such numbers. It
was a very rare disease, only seen in severely
immunocompromised people. The presence of
this infection, of PCP in these men was an
early clue that something was going on and
that led to the discovery of the virus causing
AIDS. So PCP pneumonia was one of the first
measures used to say, is there AIDS in this
community? This fungus is inhaled from the
environment, but we actually do not know the
precise source, so we know that Aspergillus
for example is everywhere, we know that Candida
is part of your normal flora, we really do
not know where pneumocystis comes from. We
do think that we acquire infection at a young
age, perhaps as children we inhale these,
the organism simply remain in the lung for
a long time, our immune system takes care
of them and it's only when our immune function
decreases, is it a problem. So for example,
if you develop AIDS, then pneumocystis starts
to replicate and causes pneumonia. So it's
probably already there at the onset, you don't
acquire it when you get AIDS. These organisms
are rarely found outside the lung, so this
is a lung disease and that is indicated by
the name pneumocystis pneumonia.
01:53
How do we diagnose it? You can take samples,
clinical specimens, sputum samples from the
lung and then you can stain them with silver,
you can stain them with antibodies, directed against
the antigen of the fungus, or you can do polymerase
chain reaction on bronchoalveolar lavage,
or a biopsy that you have taken to discover
the nucleic acid of the organism. And once
confirmed you can treat it with trimethoprim
sulfamethoxazole. A different drug than we've
used for all of the other fungal infections.
02:29
So let's take a look at the summary of some
of these drugs that are used to treat these
opportunistic fungal infections. Let's zoom
in on the top part of this chart. You can
see that Candida, Cryptococcus and Aspergillus
can all be treated with amphotericin B. Candida
can also be treated with nystatin, that's
a topical form of treatment for candid intertriginous
Candida, whereas the amphotericin B is an
intravenous application for systemic infection
and then we can go lower down into this chart
and see the treatments for Aspergillus, itraconazole.
03:08
Candida and Cryptococcus we can use fluconazole
and Candida and Aspergillus; voriconazole.
03:15
In the class of Echinocandins, we can use
caspofungin, intravenously to treat systemic
Candida infections. And a pyrimadine inhibitor
flucytosine is an oral drug to treat both
Cryptococcus and Candida.