Bacterial
Cheomotherapy
Bacterial
Cheomotherapy -
Antimicrobial
agents
have
been
used
in
folk
remedies
from
early
times.
The
indians
of
Peru
used
cinchona,
bark
for
treating
malaria.
The
active
principle
of
cinchona
bark,
quinine,
was
isolated
in
1920.
The
ipecacuanha
root
was
used
in
Brazil
and
Asia
for
treating
amoebic
dysentery.
Its
active
constituent.
emetin,
was
isolated
in
1817,
and was
shown
to
have
a
specific
action
against
amoebic
dysentery
in
1891.
The
work
of
Pasteur
and
Koch
established
that
microorganisms
were
the
cause
of
infectious
disease,
Paul
Ehrlich
was
the
first
to
propose
that
infectious
diseases
might
be
curab1e
by
using
chemicals
that
inhibit
or
kin
the
infectious
agents,
but
do
not
harm
the
host
at
the
concentration
employed.
His
studies
with
the
vital
dye
methylene blue
showed
that
this
slain
concentrated
in
nervous
tissue,
and
was
readily
taken
up
by
malarial
parasites
in
the
blood.
This
specificity
of
staining
led
to
the
search
for
compounds
with
selective
action
against'
microbial
cells
After
testing
hundreds
of
dyes
he
found
(in
1904)
Trypan
red
as
effective
against
trypanosomiasis
in
horses.
Later
Koch
found
that
arsenical
atoxl
cured
sleeping
sickness
in
humans.
In
1910
Ehrlich
discovered
the
famous
organoarsenical
compound
salvarsan.
which
was
active
against
the
causative
organisms
of
syphilis.
It
was
he
who
first
used
the
term
Chemotherapy,
According
to
his
theory
of
drug
action,
cells
possess
chemical
receptors
to
which
the
drugs
bind.
He
recognized
the
importance
of
quantitative
measurements
to
determine
the
drug
dose
that
would
be
effective
against
the
causative
agent
and
not
have
toxic
effects
on
the
host
He
also
pioneered
method
for
screening
a
large
number
of
compounds
for
biological
activity
in
relation
to
chemical
structure.
Chemical
variants
of
effective
compounds
were
then
synthesized
and
tested
to
see
whether
they
had
improved
antimicrobial
activity
and
reduced
toxicity.
It
was
Ehrlich
who
thus
established
the
principles
of
modern
chemotherapy.
Compounds
that
inhibit
the
proliferation
of
infective
organisms
are
called
chemotherapeutic
agents.
When
there
is
reversible
inhibition
of,
growth
the
compounds
are
said
to
be
bacteriostatic.
Bacteriostats
do
not
kill
bacteria,
but
only
prevent
their
multiplication.
Bacteriostatic
action
usually
offers
sufficient
protection,
because
the
relatively
small
number
of
bacteria
can
be
removed
by
the
antibody
and
phagocytic
defences
of
the
body.
Compounds
with
irreversibe
lethal
action
are
said
to
be
bactericidal.
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