VOL. XI

INFECTIONS OF THE KIDNEY*

HUGH CABOT, M.D., Boston, Massachusetts Professor in Surgery, Medical School of Harvard University

Mr. Chairman, Members of the Society-I want to call your attention this afternoon to the general subject of infection of the kidney. It is quite extraordinary, I think, how much that subject has been confused, and it almost seems as if there had been a conspiracy to render confusions

worse.

One of the gravest difficulties is one which is not peculiar to this condition. That is, that our eminent brethren belonging to the pathological department have a curious inability to remember that the patients upon whom they perform have the misfortune to have died. It is common that after death these people will show the lesions which caused the death, and from that has arisen, for instance, the extraordinary dictum which long held sway that tuberculosis of the kidney was habitually bilateral. As a matter of fact, we now know it was almost universally unilateral, but that was forced down the throats of the pathologists by the clinics.

One can see at once how simple the doctrine is. One type of kidney infection, that of the colon

bacillus, is more marked in the female than in the

male. You can see what follows. Obviously, for anatomical reasons, infection of the bladder in the female is conceivably more possible than in the male, and upon that alone, apparently, was erected the theory of the ascending infection, the view being that the bladder having become infected the organism then ascended to the kidney, all of which is in total disregard of practically

all facts.

It is well known that it is practically impossible to infect the normal bladder, that no amount of introduction of infectious material into the bladder without injury will produce infection. That is true not only experimentally but clinically. Experimentally, it was shown more than a genera

Read before the Tri-State District Medical Society, Rockford,

Illinois, September 1, 2, 3, 4, 1919.

No. 1

tion ago that infection of the bladder could not be produced except by injury to the bladder or by the production of artificial retention of the urine. It was then shown, at the same time, that these artificial infections of the bladder having been produced, there was no observable tendency of that infection to proceed upward to the kidney. The business of proceding upward is far simpler anatomically than physiologically.

Anatomically, we conceive of these organisms as being endowed with legs, something like centipedes, and having obtained a foothold in the bladder they proceed to crawl upward in utter disregard of the descending current of urine which tends to make the ascent difficult. It was then pointed out, that the ascension might take place on the ground, so to speak, that the ascension might take place by direct tracks along-in or beneath the mucous membrane, and the poor lymphatics were dragged in to help out again in utter disregard of the fact that there is no lymphatic stream which proceeds up the urine. It is common knowledge that lymphatics follow the course of blood-vessels, that there are no blood-vessels following the course of the urine, that the blood supply and the lymphatic supply of the urine is segmental in character, that these organisms which would proceed in the lymphatics must pass through a series of lymph-nodes and fight their way through.

It was forgotten that in the lower third of the urine the lymphatics drain not upward but downward into the lymphatic glands of the pelvis, so that instead of getting toward their alleged goal of the kidneys, these poor bugs would be going down into the pelvis to get lost forever in the

It is not my intention to ask you to believe that ascension from bladder to kidney does not occur. It does occur, but only under highly and unusually special cases and conditions in which all of us would expect it. We know that in obstruction of a hollow viscus, reversed peristalsis is the rule. In obstruction of the urine at its lower end, whether by stone, tumor or scar, reversed peristalsis has been assumed to occur and has been demonstrated to occur. Under these conditions infections of the bladder with extension by continuity, as does in fact occur to the lower segment of the urine, brings the organisms directly in contact with a stream, a column of urine in which reversed persistalsis has taken place and infection of the kidney in those cases undoubtedly may occur. I have no reason to doubt that it does in fact occur, but after all, a very small group of cases are found. In people with incontinence of the valvular arrangement at the lower end, and in cases of urinary obstruction in the lower tract the ureter has practically become a part of the bladder, the whole muscular contractual structure from the renal pelvis to the urethra having become part and parcel of the same mechanism.

Contractions of the bladder will force urine back and forth by back-wash to the renal pelvis, and under these circumstances, of course, infection of the kidneys follows infection of the bladder as night follows day, but this again, is a small group of cases, and it is one with which we are not importantly concerned.

I want to invite your attention to what I be lieve does, in fact, occur. What is the natural history of kidney infections? For simplicity's sake, let us take only the normal kidney. Let us not complicate the picture by dragging in the anomalies of the kidney, the horseshoe-kidney, the misplaced kidney, the dilated kidney. They only complicate the picture without essentially helping it.

The infections of the kidney take place through the blood stream. They hemoglobinous. Long ago everybody was entirely willing to admit that infections with staphylococcus and other somewhat similar pus producing organisms were called hematogenous, blood-born, in other words. Nobody doubted it.

The rather early and excellent work of Brewer, now almost a century old and which met with immediate assent, states that staphylococcus infections of the kidney were commonly associated with staphylococcus infections elsewhere-boils, carbuncles and the like. It never occurred to any

thereby committed themselves to the general proposition that all infections of the kidney were on substantially the same basis. Now the field has been enormously confused, largely through our fault by failure of the pathologist and the clinician to work in any reasonable contact. They have each shut themselves in and made faces at each other through the door without being willing to discuss the situation, and neither one has ever had any real knowledge of what the other was talking about.

The pathologist has taken the late results of kidney infection and of necessity become entangled in the result of multiple lesions, and he has, as a consequence, described different stages in the same infection as three entirely separate pathological entities.

An analysis which we made in 1888 of suppurative infections of the kidney showed a large group of cases in which you could show three different kinds of infection with different organisms at different periods of time, some of them extending back for more than a generation, and yet the poor pathologist, having no knowledge of the clinical history, was asked to make a diagnosis upon these kidneys, and naturally he picked out the most prominent lesion.

Organisms affecting the kidney do not, from the mere fact that they reach the kidney, discard all their peculiar properties there. In fact they retain them. The groups of organisms which prowill produce a circumscribed abscess in the kidney. The group of organisms which does not produce a circumscribed abscess elsewhere will not produce a circumscribed abscess in the kidney. The organisms which rapidly tend to destroy tissue will do so in the kidney. You can, in fact, divide the infectious lesions of the kidney very nicely by the properties of the organisms which infect it.

Let us deal first with the group of suppurative organisms which we are but too familiar with, containing the staphylococcus, the streptococcus piogenes and various bacilli, although the staphylococcus and streptococcus piogenes are the most common. These organisms have always been admitted to reach the kidney through the blood stream, and it saves our arguing the point, so there is no world need of doing so. They produce lesions close to the cortex of the kidney because they early stop in the cortical portion, not passing through the kidney freely, and produce circumscribed areas of suppuration. They have very little tendency to extend broadcast through the kidney, but they have a very marked tendency

to form subcortical abscesses to cause perinephritis and perinephritic abscess.

For years we have always been running into cases of very obscure subdiaphragmatic abscess. They are obscure not only in their origin but in their existence. Many of you here will doubtless recall patients whom you have watched for weeks with unexplained fever; finally one morning your find fullness below one costal margin or the other in the back and you find an abscess there containing perhaps a quart or more of pus and which at once you recognize must have been there for weeks and was, in fact, the cause of the ill-defined fever. Those cases were not tied on to the kidneys because the urine, as ordinarily examined, was normal and remained practically normal throughout the course of the disease. There is nothing to attract attention to the kidneys as the source of this lesion, and in many cases the amount of evident damage to the kidney is so small that the pretty rough exploration which one can make of the kidney in the face of the massive abscess does not reveal it to be abnormal. It lies in the wall of the cavity, behind the abscess, and appears grossly normal, and yet it is beyond doubt, in the vast majority of cases if not in all cases, a fact that the subdiaphragmatic abscess is of urinary origin.

The attempt at excretion of these organisms by the kidney having failed, subcortical abscesses having occurred with extension into the fat capsule and through the fat capsule into the perirenal portion, these cases, if seen early, can almost always be demonstrated. This leads me to say what I might have said before in a more general part of the discussion: That all organisms which circulate in the blood are excreted by the kidneys, and many of them may be found in the urine. It has been possible, for instance, for one of my colleagues to determine the organism concerned in a pneumonia case more suddenly and far earlier by examination of the urine than by any other method. They occur early with certainty and they are the organisms which are loose. in the blood. Undoubtedly, in the vast majority of cases, the kidney succeeds in excreting these without its undergoing any damage whatever. It is undoubtedly in only the minority of cases that this does not occur. Upon what that susceptibility of the kidney depends I do not pretend to know, but undoubtedly there are people who have put out organisms through the kidney for years. without any damage whatever to the kidney.

It follows that this coccus infection of the kidney in its early stages, in other words during the stage when the organism is circulating, will show

the organism in the urine. It is short-lived. It may not extend beyond twenty-four hours. It rarely does, in our comparatively small experience, extend beyond two or three or four days. During that time, the evidence of damage to the kidney is of the very slightest. There may be a little blood; there may be a little albumin.

Those organisms which produce circumscribed abscess in the kidney do not produce pus in the urine, and the urine is microscopically normal, abnormal only when treated with special care.

It is perhaps worth while to point out to you the method by which one may get these organisms separated and distinguished. The method was worked out by an associate of mine, E. G. Crabtree. It consists principally in dealing with specimens of urine taken with scrupulous care and then subjected to very high power centrifuge. You will then get in the bottom of your tube a thin scum of pure organism, and you will readily distinguish the accidental contamination from the predominant organism. So far as I know, it is impossible to draw urine from the blood without the incident of contamination, but the number of organisms is small and will never compare importantly with the organisms which are, in fact, being excreted by the kidney and which, to be regarded as of etiological importance, must be present in large numbers, large numbers being considered only, however, when you subject the urine to prolonged high power treatment through the centrifuge. The ordinary examination of urinary sediment will cast no light on the subject at all. If you deal with the matter in this way, you will be able to select with great certainty organisms which are of etiological importance as against those which are accidental contamination, and you will recognize the large undescribed bacilli which so commonly occur in the urethra as obvious contamination.

The condition just described is the mildest type of the coccus infection of the kidney. The severest type is that most importantly drawn to our attention by Brewer of New York as I have already referred to, which is an overwhelming infection of one kidney, somewhat more commonly the right, but the difference is not great. It is a kidney which he described as acute focal necrosis which shows some tendency to present lesions in pyramidal form. Any suppuration of the kidney may tend to take a pure apical type if the infection starts at the apex of the pyramid. Pyramidal lesions of the kidney by no means prove embolic origin. In the worst cases, the infection is overwhelming. It is generally mistaken for an acute abdominal trouble. I do not remember to

have seen or heard of a case in which the correct diagnosis was made. They are generally regarded as gastric ulcer and acute appendicitis. The diagnosis is generally made at the operation. The kidney may, within twenty-four hours after the onset, be so changed that it is literally a pulp and will come out in your hands. The milder cases are comparatively common, the acute cases fortunately rare, but the milder grades, or what is commonly referred to as the staphylococcus kid ney, are not so rare.

You may see a kidney the cortex of which is studded with small, yellowish areas, typical abscesses, and often more roughly meshed by the swelling which takes place around these abscesses. It has been the habit to divide this group of cases into acute and subacute, but there is no hard and fast rule, and I know of no more difficult decision in surgery than as to whether or not the kidney of this kind should be removed. My own experience has been that whichever course I took I was sorry for it. On several occasions I have not removed these kidneys, only to find the temperature persists, and in a week or ten days or two weeks or even three weeks afterwards I have to go in and remove them under obviously more difficult conditions. These attacks are always accompanied by fever which commonly is the socalled septic type. There is always definite enlargement of the kidney which in the vast majority of cases, is perfectly obvious; it is the only type of infection of the kidney in which you commonly get, within a day or two days after the onset, a definite kidney tumor or which can be palpated and which is tender. Accompanied by fever with a microscopically clear urine, it is almost diagnostic, the final touch being made by the recovery of the organism from the urine. That picture is, of course, occasionally mixed with a mixed infection, but it will retain the dominant qualities of the pus producing organism and the other organisms which contaminate the infections, although producing lesions which confound the pathologist are much less likely to be confusing to the surgeon. The picture throughout is dominantly that of the coccus kidney. Precisely opposed to that is the infection of the kidney with the group of bacilli which for convenient practice we are in the habit of referring to as the colon typhoid group.

There are doctors here who could tell you how many thousands of different kinds of those organisms there are, but they do not even fall into respectable groups, as far as I am concerned, and the isolation of the particular type of colon bacillus involved in these infections is a pretty thank

less task, but they are essentially different from the coccus infections, from the suppurative infections, and enormously more complicated. It is, in fact, this colon typhoid group which produces the vast majority of all kidney infections. Unfortunately, the name pyelitis has been pinned on to this group because there is the predominating symptom of the picture, but is is none the less true that they are excretory in their origin, the kidney primarily, the pelvis secondarily.

It is possible to watch this whole picture experimentally, although it is probably not true that the organism behaves in precisely the same way in animals as it does in men, but we have been able to watch a few cases in men, and the picture is of a diffuse low grade infection of the kidney involving chiefly the condition of tumor producing what pathologists describe as a cloudy swelling, a condition which very rapidly clears up, in many cases, within forty-eight hours, in most cases within a few days.

For some reason quite unknown to me, the organism having passed through the kidney, finds a satisfactory resting place in the mucosa of the kidney pelvis, and the colon bacillus, on the whole, seems to prefer the mucosa of the kidney pelvis to any other portion of the urinary tract. Here they will remain over long periods of time, and, unfortunately, in this position they have introduced complicated factors which have confounded not only the clinician but the pathologist.

The effect of this organism upon the function of the kidney is a very striking one and quite the opposite of that produced by the coccus infection, the reason being clear that the coccus infection involves chiefly the cortical area, not the secreting portion of the kidney, and the coccus infection will affect kidney function only in so far as it destroys kidney tissue.

On the other hand, the colon bacillus produces a diffuse process throughout the secreting portion of the kidney and produces an immediate and very great effect upon the kidney function.

I have seen these patients drop, for instance, from a 40 per cent grade to an immeasurable grade in twenty-four hours after the onset of the disease. Two or three days later, these patients commonly show constitutional symptoms or evidence of retention of products which they should have excreted-the so-called uremic symptoms. By that time, the actual function of the kidney has begun to recover, and by the time the constitutional symptoms are at their height, the kidney functions have often returned more than half way to normal.

Unless you are in position to watch these, you