Germ Theory and Its Applications to Medicine and Surgery, 1878
Translation: H.C.Ernst,
Germ Theory And Its Applications To Medicine And
Surgery1
[Footnote 1: Read before the French Academy of Sciences, April 29th, 1878.
Published in Comptes rendus de l'Academie des Sciences, lxxxvi., pp. 1037-43.]
The Sciences gain by mutual support. When, as the result of my first communications on
the fermentations in 1857-1858, it appeared that the ferments, properly so-called, are
living beings, that the germs of microscopic organisms abound in the surface of all
objects, in the air and in water; that the theory of spontaneous generation is chimerical;
that wines, beer, vinegar, the blood, urine and all the fluids of the body undergo none of
their usual changes in pure air, both Medicine and Surgery received fresh stimulation. A
French physician, Dr. Davaine, was fortunate in making the first application of these
principles to Medicine, in 1863.
----Louis Pasteur: Louis Pasteur in his laboratory. From the painting by Albert
Edelfelt.]
Our researches of last year, left the etiology of the putrid disease, or septicemia, in
a much less advanced condition than that of anthrax. We had demonstrated the probability
that septicemia depends upon the presence and growth of a microscopic body, but the
absolute proof of this important conclusion was not reached. To demonstrate experimentally
that a microscopic organism actually is the cause of a disease and the agent of contagion,
I know no other way, in the present state of Science, than to subject the microbe (the new
and happy term introduced by M. Sedillot) to the method of cultivation out of the body. It
may be noted that in twelve successive cultures, each one of only ten cubic centimeters
volume, the original drop will be diluted as if placed in a volume of fluid equal to the
total volume of the earth. It is just this form of test to which M. Joubert and I
subjected the anthrax bacteridium.2 Having cultivated it a great number of
times in a sterile fluid, each culture being started with a minute drop from the
preceding, we then demonstrated that the product of the last culture was capable of
further development and of acting in the animal tissues by producing anthrax with all its
symptoms. Such is - as we believe - the indisputable proof that anthrax is a bacterial
disease.
[Footnote 2: In making the translation, it seems wiser to adhere to Pasteur's
nomenclature. Bacillus anthracis would be the term employed to-day. Translator.]
Our researches concerning the septic vibrio had not so far been convincing, and it was
to fill up this gap that we resumed our experiments. To this end, we attempted the
cultivation of the septic vibrio from an animal dead of septicemia. It is worth noting
that all of our first experiments failed, despite the variety of culture media we employed
- urine, beer yeast water, meat water, etc. Our culture media were not sterile, but we
found most commonly - a microscopic organism showing no relationship to the septic vibrio,
and presenting the form, common enough elsewhere, of chains of extremely minute spherical
granules possessed of no virulence whatever.3 This was an impurity, introduced,
unknown to us, at the same time as the septic vibrio; and the germ undoubtedly passed from
the intestines - always inflamed and distended in septicemic animals - into the abdominal
fluids from which we took our original cultures of the septic vibrio. If this explanation
of the contamination of our cultures was correct, we ought to find a pure culture of the
septic vibrio in the heart's blood of an animal recently dead of septicemia. This was what
happened, but a new difficulty presented itself; all our cultures remained sterile.
Furthermore this sterility was accompanied by loss in the culture media of (the original)
virulence.
[Footnote 3: It is quite possible that Pasteur was here dealing with certain septicemic
streptococci that are now known to lose their virulence with extreme rapidity under
artificial cultivation. - Translator.]
It occurred to us that the septic vibrio might be an obligatory anaerobe and that the
sterility of our inoculated culture fluids might be due to the destruction of the septic
vibrio by the atmospheric oxygen dissolved in the fluids. The Academy may remember that I
have previously demonstrated facts of this nature in regard to the vibrio of butyric
fermentation, which not only lives without air but is killed by the air.
It was necessary therefore to attempt to cultivate the septic vibrio either in a vacuum
or in the presence of inert gases-such as carbonic acid.
Results justified our attempt; the septic vibrio grew easily in a complete vacuum, and
no less easily in the presence of pure carbonic acid.
These results have a necessary corollary. If a fluid containing septic vibrios be
exposed to pure air, the vibrios should be killed and all virulence should disappear. This
is actually the case. If some drops of septic serum be spread horizontally in a tube and
in a very thin layer, the fluid will become absolutely harmless in less than half a day,
even if at first it was so virulent as to produce death upon the inoculation of the
smallest portion of a drop.
Furthermore all the vibrios, which crowded the liquid as motile threads, are destroyed
and disappear. After the action of the air, only fine amorphous granules can be found,
unfit for culture as well as for the transmission of any disease whatever. It might be
said that the air burned the vibrios.
If it is a terrifying thought that life is at the mercy of the multiplication of these
minute bodies, it is a consoling hope that Science will not always remain powerless before
such enemies, since for example at the very beginning of the study we find that simple
exposure to air is sufficient at times to destroy them.
But, if oxygen destroys the vibrios, how can septicemia exist, since atmospheric air is
present everywhere? How can such facts be brought in accord with the germ theory? How can
blood, exposed to air, become septic through the dust the air contains?
All things are hidden, obscure and debatable if the cause of the phenomena be unknown,
but everything is clear if this cause be known. What we have just said is true only of a
septic fluid containing adult vibrios, in active development by fission: conditions are
different when the vibrios are transformed into their germs,4 that is into the
glistening corpuscles first described and figured in my studies on silk-worm disease, in
dealing with worms dead of the disease called "flacherie." Only the adult
vibrios disappear, burn up, and lose their virulence in contact with air: the germ
corpuscles, under these conditions, remain always ready for new cultures, and for new
inoculations.
[Footnote 4: By the terms "germ" and "germ corpuscles," Pasteur
undoubtedly means "spores," but the change is not made, in accordance with note
2, p. 364 - Translator.]
All this however does not do away with the difficulty of understanding how septic germs
can exist on the surface of objects, floating in the air and in water.
Where can these corpuscles originate? Nothing is easier than the production of these
germs, in spite of the presence of air in contact with septic fluids.
If abdominal serous exudate containing septic vibrios actively growing by fission be
exposed to the air, as we suggested above, but with the precaution of giving a substantial
thickness to the layer, even if only one centimeter be used, this curious phenomenon will
appear in a few hours. The oxygen is absorbed in the upper layers of the fluid - as is
indicated by the change of color. Here the vibrios are dead and disappear. In the deeper
layers, on the other hand, towards the bottom of this centimeter of septic fluid we
suppose to be under observation, the vibrios continue to multiply by fission-protected
from the action of oxygen by those that have perished above them: little by little they
pass over to the condition of germ corpuscles with the gradual disappearance of the thread
forms. So that instead of moving threads of varying length, sometimes greater than the
field of the microscope, there is to be seen only a number of glittering points, lying
free or surrounded by a scarcely perceptible amorphous mass.5 Thus is formed,
containing the latent germ life, no longer in danger from the destructive action of
oxygen, thus, I repeat, is formed the septic dust, and we are able to understand what has
before seemed so obscure; we can see how putrescible fluids can be inoculated by the dust
of the air, and how it is that putrid diseases are permanent in the world.
[Footnote 5: In our note of July 16th, 1877, it is stated that the septic vibrio is not
destroyed by the oxygen of the air nor by oxygen at high tension, but that under these
conditions it is transformed into germ corpuscles. This is, however, an incorrect
interpretation of facts. The vibrio is destroyed by oxygen, and it is only where it is in
a thick layer that it is transformed to germ-corpuscles in the presence of oxygen and that
its virulence is preserved.]
The Academy will permit me, before leaving these interesting results, to refer to one
of their main theoretical consequences. At the very beginning of these researches, for
they reveal an entirely new field, what must be insistently demanded? The absolute proof
that there actually exist transmissible, contagious, infectious diseases of which the
cause lies essentially and solely in the presence of microscopic organisms. The proof that
for at least some diseases, the conception of spontaneous virulence must be forever
abandoned - as well as the idea of contagion and an infectious element suddenly
originating in the bodies of men or animals and able to originate diseases which propagate
themselves under identical forms: and all of those opinions fatal to medical progress,
which have given rise to the gratuitous hypotheses of spontaneous generation, of
albuminoid ferments, of hemiorganisms, of archebiosis, and many other conceptions without
the least basis in observation. What is to be sought for in this instance is the proof
that along with our vibrio there does not exist an independent virulence belonging to the
surrounding fluids or solids, in short that the vibrio is not merely an epiphenomenon of
the disease of which it is the obligatory accompaniment. What then do we see, in the
results that I have just brought out? A septic fluid, taken at the moment that the vibrios
are not yet changed into germs, loses its virulence completely upon simple exposure to the
air, but preserves this virulence, although exposed to air on the simple condition of
being in a thick layer for some hours. In the first case, the virulence once lost by
exposure to air, the liquid is incapable of taking it on again upon cultivation: but, in
the second case, it preserves its virulence and can propagate, even after exposure to air.
It is impossible, then, to assert that there is a separate virulent substance, either
fluid or solid, existing, apart from the adult vibrio or its germ. Nor can it be supposed
that there is a virus which loses its virulence at the moment that the adult vibrio dies;
for such a substance should also lose its virulence when the vibrios, changed to germs,
are exposed to the air. Since the virulence persists under these conditions it can only be
due to the germ corpuscles - the only thing present. There is only one possible hypothesis
as to the existence of a virus in solution, and that is that such a substance, which was
present in our experiment in non-fatal amounts, should be continuously furnished by the
vibrio itself, during its growth in the body of the living animal. But it is of little
importance since the hypothesis supposes the forming and necessary existence of the
vibrio.6
[Footnote 6: The regular limits oblige me to omit a portion of my speech.]
I hasten to touch upon another series of observations which are even more deserving the
attention of the surgeon than the preceding: I desire to speak of the effects of our
microbe of pus when associated with the septic vibrio. There is nothing more easy to
superpose - as it were - two distinct diseases and to produce what might be called a
septicemic purulent infection, or a purulent septicemia. Whilst the microbe-producing pus,
when acting alone, gives rise to a thick pus, white, or sometimes with a yellow or bluish
tint, not putrid, diffused or enclosed by the so-called pyogenic membrane, not dangerous,
especially if localized in cellular tissue, ready, if the expression may be used for rapid
resorption; on the other hand the smallest abscess produced by this organism when
associated with the septic vibrio takes on a thick gangrenous appearance, putrid, greenish
and infiltrating the softened tissues. In this case the microbe of pus carried so to speak
by the septic vibrio, accompanies it throughout the body: the highly-inflamed muscular
tissues, full of serous fluid, showing also globules of pus here and there, are like a
kneading of the two organisms.
By a similar procedure the effects of the anthrax bacteridium and the microbe of pus
may be combined and the two diseases may be superposed, so as to obtain a purulent anthrax
or an anthracoid purulent infection. Care must be taken not to exaggerate the predominance
of the new microbe over the bacteridium. If the microbe be associated with the latter in
sufficient amount it may crowd it out completely-prevent it from growing in the body at
all. Anthrax does not appear, and the infection, entirely local, becomes merely an abscess
whose cure is easy. The microbe-producing pus and the septic vibrio (not)7 being both anaerobes, as we have demonstrated, it is evident that the latter will not much
disturb its neighbor. Nutrient substances, fluid or solid, can scarcely be deficient in
the tissues from such minute organisms. But the anthrax bacteridium is exclusively
aerobic, and the proportion of oxygen is far from being equally distributed throughout the
tissues: innumerable conditions can diminish or exhaust the supply here and there, and
since the microbe-producing pus is also aerobic, it can be understood how, by using a
quantity slightly greater than that of the bacteridium it might easily deprive the latter
of the oxygen necessary for it. But the explanation of the fact is of little importance:
it is certain that under some conditions the microbe we are speaking of entirely prevents
the development of the bacteridium.
[Footnote 7: There is undoubtedly a mistake in the original. Pasteur could not have
meant to say that both bacteria are anaerobes. The word "not" is introduced to
correct the error. - Translator.]
Summarizing - it appears from the preceding facts that it is possible to produce at
will, purulent infections with no elements of putrescence, putrescent purulent infections,
anthracoid purulent infections, and finally combinations of these types of lesions varying
according to the proportions of the mixtures of the specific organisms made to act on the
living tissues.
These are the principal facts I have to communicate to the Academy in my name and in
the names of my collaborators, Messrs. Joubert and Chamberland. Some weeks ago (Session of
the 11th of March last) a member of the Section of Medicine and Surgery, M. Sedillot,
after long meditation on the lessons of a brilliant career, did not hesitate to assert
that the successes as well as the failures of Surgery find a rational explanation in the
principles upon which the germ theory is based, and that this theory would found a new
Surgery - already begun by a celebrated English surgeon, Dr. Lister,8 who was
among the first to understand its fertility. With no professional authority, but with the
conviction of a trained experimenter, I venture here to repeat the words of an eminent
confrere.
[Footnote 8: See Lord Lister's paper in the present volume. - Ed.]
Source:
Scientific papers; physiology, medicine, surgery, geology, with introductions,
notes and illustrations. New York, P. F. Collier & son [c1910] The Harvard
classics v. 38.
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