Bacteria in Daily Life

It was not, perhaps, unnatural that rash assumptions as to the efficacy of sunshine should have been readily accepted when such remarkable feats performed on microbes by sunshine were being continually put forward.

Thus it has been found that insolation, even when it does not destroy, may effect profound changes in the physiological character of certain micro-organisms.

Dr. Lohmann, of Rostock, discovered that some hours' exposure to bright sunshine entirely destroys yeast cells, whilst even feeble and intermittent sunshine is capable of paralysing them, and that they only recover their vitality when removed from this obnoxious influence. This recuperative power is not, however, shared equally by all varieties of yeast, some possessing it in a far greater degree than others. Dr. Lohmann also found that yeast cells, after being exposed to sunshine, assumed a shrunken and distorted appearance, showing that insolation had produced a striking physiological effect upon the structure of these cells.

Professor Hansen published some years ago a most interesting memoir on some of the characteristic features of the moulds which are to be found on manure heaps, in which he records how light exerts a very important influence on the manner in which the spore or fruit of these lowly vegetables is set free or distributed. All the various phases in the fructification process of some of these moulds were carefully watched by Dr. Hansen. He kept his caged specimens near a window with an eastern aspect, and he states that in the first instance the stalks inclined towards the light, but that afterwards they assumed an upright position. Darkness was nearly always chosen for the liberation of the spores, but in a few instances a small number were released during the daytime, and it was noticed that when this did occur they were invariably discharged on the side away from the source of light. In various other ways he confirmed this interesting observation, and found that the fruit of the mould was invariably discharged in the opposite direction to that in which the stalk had previously inclined under the influence of light. The force with which the spores were discharged varied very considerably, sometimes being cast to a distance of four inches or more from the stalk, and sometimes being found close to and even on the stalk.

The manner in which sunshine may also modify the pigment-producing powers of micro-organisms is remarkable.

Many microbes are able to elaborate when grown on various culture media, such as gelatine or slices of potato, most brilliant and beautiful pigments ranging from intense blood-red to the most delicate shades of pink, and embracing every gradation of yellow, as well as browns, greens, and violets. Now it has been found that some of these pigment-producing bacteria, when exposed to sunshine on these nutritive materials, fail to exhibit their characteristic colour, although the duration of insolation may not have sufficed to destroy their actual vitality. One of these organisms originally obtained from water has been specially studied in this respect by M. Laurent. If slices of potato are streaked with a small number of this particular bacillus (bacille rouge de Kiel) a magnificent patch of blood-red colour makes its appearance in the course of a day or two, but if, on the other hand, similar slices of potato are exposed to three hours' sunshine, a colourless growth subsequently develops, except where here and there a few isolated spots of pale pink are visible. When the insolation is prolonged for five hours nothing whatever appears on the potato, the bacilli having been entirely destroyed. But this is not all. M. Laurent found that if he took some of the colourless growth and inoculated it on to potatoes he obtained again, but without insolation, a colourless vegetation – in fact, three hours' insolation had so modified the physiological character of the bacillus that a new race had been generated, a race deprived of its power of producing this red pigment. In what numerous directions the character of microbes may be and are being modified, even by simple exposure to sunshine, opens up a wide field for speculation and research, whilst the tractability of these minute and most primitive forms of life, if we only approach their education with sufficient insight and patience, may enable us to make them serve where they now are masters.

The remarkable discoveries on the modification of the disease-producing properties of certain bacteria by sunshine may perhaps encourage the idea that we are making some progress towards the attainment of this desirable millennium. That diminution of the virulence or disease-producing power of such deadly microbes as those of cholera, anthrax, and tuberculosis can be brought about through simple exposure to the sun's rays seems almost inconceivable, yet it has been discovered that by placing the cholera bacillus, for example, in the sunshine its virulent character undergoes such a profound modification that it is actually reduced to the condition of a vaccine, and may be employed to protect animals from infection with its still virulent brethren. Yet this is what has been undoubtedly shown by Dr. Palermo in very carefully conducted investigations. He was, moreover, able to indicate, within a very narrow margin, the precise amount of insolation necessary to bring about this result: for if the cholera cultures were only exposed for three hours, their toxic properties were not reduced to the condition of vaccine; but if the insolation was continued for three and a half hours up to four and a half hours, they became endowed with the requisite immunising properties, and animals treated first with the so-called sunshine-cholera-vaccine were able subsequently to withstand otherwise fatal doses of virulent cholera cultures. Dr. Palermo also found that, besides producing this subtle modification in the character of cholera bacilli, sunshine exerted a remarkable physiological change in these organisms, for when examined under the microscope they no longer exhibited their typical activity, having been deprived of all powers of movement, whilst those kept during the same length of time in the dark had not abated one jot of their customary mobility.

But sunshine not only controls in this wonderful manner the action of the living bacillus, but it also operates upon the products elaborated by disease organisms. Thus the microbe producing lock-jaw or tetanus may be grown in broth, and the latter may be subsequently passed through a porcelain or a Berkefeld filter, so that the resulting liquid is entirely deprived of all germ life. This tetanus-filtrate, as it is called, is endowed with very powerful toxic properties, and it will retain its lethal action even when kept for upwards of three hundred days, providing it is screened from all light; but place such filtrates in diffused light, and they lose their poisonous properties, requiring, however, upwards of ten weeks to become entirely harmless; if, on the other hand, they be exposed to sunshine, they are completely deprived of their toxic character in from fifteen to eighteen hours. Again, as little as five hours' sunshine is sufficient to greatly modify the toxic action of diphtheria cultures. It is of interest also to note that even the venom of the rattlesnake, that most potent of all poisons, cannot emerge unscathed from an exposure to sunshine maintained during a fortnight.

Interesting as all these isolated observations are, they indicate what an immense amount yet remains to be done before we can hope to have any connected conception of the mechanism, so to speak, of insolation. At present there is too large an allowance, which we are compelled to make, for the unknown to permit of our adequately manipulating this marvellous agency in relation to bacteriological problems. But who shall say what part has been, and is being still, played by sunshine in determining the individual character of microbes, operating as it has done from time immemorial upon countless generations of these minute germs of life?

The problem of insolation has been attacked from an entirely novel point of view by Dr. Masella, who has endeavoured to find out whether sunshine plays any part in the predisposition of animal life to infection.

Now sunshine has long been credited with possessing therapeutic powers, and, indeed, traditions of cures effected by the ancients by means of insolation have been treasured up and handed down to the present day. Even as late as the beginning of the present century we may read of a French physician seriously recording his claim to have cured a dropsical patient within two weeks by placing him daily for several hours in the sunshine, and many medical journals of recent years contain communications on the beneficial results derived from the use of sunshine in the treatment of various diseases. It seems curious, therefore, that whilst so much has been done to test the action of light on disease microbes in artificial surroundings, such as are to be found in laboratory experiments, hardly any investigations have been made to try and define more precisely how sunshine may affect their pathogenic action within the animal system. Dr. Masella's researches, undertaken with the express object of, if possible, elucidating this question, are therefore of special interest and importance.

The first series of experiments was carried out to ascertain whether exposure to sunshine increases or reduces an animal's susceptibility to particular diseases, those selected for investigation being typhoid fever and cholera. For this purpose guinea-pigs were exposed to the full rays of the sun during a period of from nine to fifteen hours for two days, whilst other guinea-pigs, for the sake of comparison, were not permitted to have more light than that obtainable in a stable where only diffused light was admitted. Both these sets of animals were subsequently infected with virulent cultures of cholera and typhoid germs respectively, and were in neither case exposed to sunshine. The results which Dr. Masella obtained were remarkable, for he found that those animals which previous to infection had been placed in the sunshine died more rapidly than those which had been kept in the stable, and that the exposure to the sun's rays had so increased their susceptibility to these diseases that they succumbed to smaller doses, and doses, moreover, which did not prove fatal to the other guinea-pigs. Still more striking was the part played by insolation in the course of these diseases in animals exposed to sunshine after inoculation, for instead of dying in from fifteen to twenty-four hours, they succumbed in from three to five hours.

Here, then, we find sunshine, in some mysterious manner not yet understood, far from benefiting the animal and assisting it in combating these diseases, actually contributing to the lethal action of these bacteria. It has been asserted on the authority of some medical men that in cases of small-pox recovery is rendered more easy and rapid when light is excluded from the patient's room; whether Dr. Masella's experiments will permit of any such interpretation being placed upon them remains to be seen; they are, at any rate, extremely suggestive.

That it is possible for temperature to have some determining influence upon the course of certain diseases has been shown by O. Voges, who, experimenting with a minute bacillus which he isolated from tumours characteristic of a cattle disease very prevalent in South America, found that although this bacillus was the undoubted fons et origo of the disease, he could not produce fatal results in animals if he kept them in cold surroundings; only when the temperature was raised to from 35-45 degrees Centigrade did the infected animals succumb. The dependence of the activity and virulence of this micro-organism upon temperature is also borne out in actual experience, the disease being the more prevalent and the more fatal the hotter the climate of the country.

It may be mentioned in passing that this bacillus has the distinction of being the smallest yet discovered; the influenza bacillus hitherto held the palm in this respect, but it must yield its position to its more successful rival, for Voges states that when magnified about fifteen hundred times it is only just discernible in the microscopic field.

Even the smoke-laden atmosphere of our great cities, our leaden skies and dreary fogs and mists, may after all, then, if we can only learn to look at them from Dr. Masella's point of view, become a source of benefit and a subject for congratulation; yet our inherent love of light and sunshine would cause us willingly to hand over our murky climate had we but the chance of obtaining in exchange that of any of the sunny cities of the south. Moreover, in the case of tubercular disease experience is daily impressing upon us the wisdom, and indeed necessity, of absorbing as much sunshine as possible, and hence the pilgrimage which is now recommended to Davos and other resorts where invalids can get the maximum amount of bright sunshine. And not only is this the outcome of practical experience, but De Renzi has shown by actual experiment that sunshine acts beneficially in cases of tuberculosis in animals. Thus, guinea-pigs were infected with tuberculous material and exposed in glass boxes to the sun for five or six hours daily, others being similarly infected but protected from sunshine. The animals which had received the sunshine died in 24, 39, 52, and 89 days respectively, whilst those which had not been sunned succumbed in from 29, 25, 26, and 41 days; or, in other words, De Renzi found that insolation had very materially increased the infected animals' power of coping with tuberculosis.

The part which sunshine plays, or may be made to play, in disease is very obscure, but it would appear at least justifiable to assume that it is an agent which further investigation may show we cannot afford to disregard, contributing as it may to the production of a healthy tone in the system, and thereby materially assisting the body to defy the insidious attacks made upon it from without.

The so-called open-air treatment of consumption which has made such giant strides in the last few years is an example of how, by contributing to the general health of an individual, the powers for resisting a localised disease may be so increased that the latter can, in many cases, be thrown off altogether. In no country has more progress been made in the establishment of institutions for the cure of consumption on these lines than in Germany. At the end of the year 1899 there were forty-nine such institutions in Germany, with four thousand beds; in a little more than twelve months later there were no less than sixty such, with accommodation for altogether five thousand patients. It is of interest to note that amongst the earliest of these institutions to be founded was that erected and endowed by the famous Badischen Anilin and Soda Fabrik Company, for the exclusive benefit of those of their workpeople who were suffering from tuberculous disease.

We have learnt that sunshine is endowed with distinctly lethal action as regards particular bacteria, that it can modify the subtle properties of toxic solutions, and we are asked to believe that it may exercise an important influence on the animal system in determining the power of the latter to deal with the agents of disease; but, as we have seen, the mechanism of it all is shrouded in mystery, and we are at a loss to divine how it works. Might not some fresh light be thrown upon this problem if we could ascertain the effect of sunshine on some of these natural fluids of the body, which recent brilliant research has shown to be endowed with such wonderful protective or immunising properties? So far as I am aware, the action of sunshine on these anti-toxins or protective fluids has not yet been investigated. Can sunshine interfere with the therapeutic effect of diphtheria-serum, for example? If simple insolation can so profoundly modify the character of toxic fluids, it is not unreasonable to anticipate some action on these anti-toxins, and their study in this connection would appear to offer an important step in the direction of unravelling the mystery attending the action of light on life.

BACTERIOLOGY AND WATER

Whilst the Hamburg cholera disaster of 1892 will certainly rank in the annals of epidemiology as one of the great catastrophes of recent times, it will also be memorable as one of the most instructive which has ever taken place.

It is perhaps not unnatural that this should be the case, for since the last European epidemic of importance our study of the principles of sanitation has received a new impetus, and this impetus must be in great part ascribed to the science of bacteriology, which has sprung into existence within the past two decades. We have now no longer to confront mysterious and unknown morbific material, but have been brought face to face with some of the most dreaded foes of the human race. We are no longer groping, as it were, in the dark, but have a definite object, in the shape of well-recognised micro-organisms associated with specific zymotic diseases, for our common crusade.

But it is the light which has been thrown for the first time upon numerous intricate problems connected with the sanitary aspects of public water-supplies which constitutes not the least important of the many services rendered by bacteriology to the public. Perhaps one of the most striking of these may be considered the insight which it has afforded into the value of various processes of water-purification, furnishing us with the most subtle and searching tests, surpassing in delicacy those of the most refined chemical methods.

Thus for years the processes of sand-filtration, as practised at waterworks in dealing with river and other surface waters, were regarded by chemical experts as of but little or no value, because, on chemical analysis, but little or no difference was found to exist between the filtered and unfiltered samples respectively. Water engineers started this method of water treatment in London as far back as the year 1839, with no other object than the distribution of a water bright and clear on delivery, but, unknown to themselves, they were carrying out a system of water-purification the nature and extent of which has been left to the infant science of bacteriology to unravel and reveal.

It was in the year 1885 that Dr. Koch's new bacteriological water-tests were introduced, and systematically applied for the first time to the London water-supply by Professor Percy Frankland, and the entirely unexpected result obtained, that whereas the River Thames water at Hampton contained as many as 1,644 micro-organisms in about twenty drops, this water, after passing through the sand-filters, possessed as few as thirteen in the same number of drops. The remarkable purification effected in the treatment of the water was thus very clearly shown, and an entirely new aspect was given to the processes of sand-filtration.

The importance of these results was quickly appreciated by the official water-examiner, the late Sir Francis Bolton, and at the request of the Local Government Board regular monthly bacteriological examinations of the London water-supply were conducted.

It is amusing to recall that, at the time when these results were first published, the public, instead of being reassured by these facts, were greatly alarmed, and it is a matter of history that the mere demonstration of the presence of micro-organisms in drinking-water caused a fall in the price of several of the water companies' stocks!

These investigations, which have since been confirmed by others both in this country and on the Continent, have clearly shown, then, that sand-filtration, when carefully carried out, offers a most remarkable and obstinate barrier to the passage of microbes, and there was every justification in presuming that if disease organisms should at any time be present in the raw untreated water, they would also undergo a similar fate, as there was no reasonable ground for supposing that they would behave any differently from the ordinary harmless water bacteria.

But this was a hypothesis only, and, however satisfactory experiments in this direction made in the laboratory might prove, there was always the uncertainty attaching to a fact which had not passed through the ordeal of practical experience.

The answer to this searching and all-important question has been furnished in the most conclusive manner by the history of the cholera epidemic in Hamburg and Altona respectively in the year 1892.

These two cities are both dependent upon the River Elbe for their water-supply, but whereas in the case of Hamburg the intake is situated above the city, the supply for Altona is abstracted below Hamburg after it has received the sewage of a population of close upon 800,000 persons. The Hamburg water was, therefore, to start with, relatively pure when compared with that destined for the use of Altona. But what was the fate of these two towns as regards cholera? Situated side by side, absolutely contiguous, in fact, with nothing in their surroundings or in the nature of their population to especially distinguish them, in the one cholera swept away thousands, whilst in the other the scourge was scarcely felt; in Hamburg the deaths from cholera amounted to 1,250 per 100,000, and in Altona to but 221 per 100,000 of the population. So clearly defined, moreover, was the path pursued by the cholera, that although it pushed from the Hamburg side right up to the boundary line between the two cities, it there stopped, this being so striking that in one street, which for some distance marks the division between these cities, the Hamburg side was stricken down with cholera, whilst that belonging to Altona remained free. The remarkable fact was brought to light that in those houses supplied with the Hamburg water cholera was rampant, whilst in those on the Altona side and furnished with the Altona water not one case occurred.

We have seen that the Hamburg water, to start with, was comparatively pure when compared with the foul liquid abstracted from the Elbe by Altona, but whereas in the one case the water was submitted to exhaustive and careful filtration through sand before delivery, in Hamburg the Elbe water was distributed in its raw condition as drawn from the river.

But further testimony was afforded later to the truth of these results, for during the winter, whilst the cases of cholera had almost completely died out in Hamburg, suddenly a most unexpected and unaccountable recrudescence of the epidemic occurred, and this time in Altona. This outbreak could not be traced to any direct infection from Hamburg, but must have arisen in Altona itself. In all about forty-seven cases were recorded between December 23rd, 1892, and February 12th, 1893. A searching inquiry was instituted, and it was ascertained that the number of bacteria found in the filtered water, usually about fifty, had during these months risen to as many as 1,000 and more in about twenty drops of water, clearly indicating that the filtration of the water was not being efficiently carried out. That this was actually the case was proved by the fact that one of the sand-filters which had been cleaned during the frost had become frozen over, and was not able to retain the bacteria. That the outbreak did not become more serious Koch ascribes to the fact that this, to all intents and purposes raw untreated water, was largely diluted with efficiently filtered water before delivery. Dr. Koch, who personally superintended this inquiry in Altona, traced another local outbreak of cholera in the city to the use of a well-water obviously open to pollution, which was used by about 270 persons. In one of the houses employing this water, and in the immediate vicinity of the well, a boy died of cholera on January 23rd, and during the week following a number of cases occurred amongst persons using this source. On discovering the cholera bacilli in this polluted water, its contamination was placed beyond doubt, and five days after the well was closed all cases ceased in the locality.

There cannot be any longer a doubt as to the value of sand-filtration as a means of water-purification, but the responsibility which we have seen attaches to this treatment of water cannot be exaggerated, for whilst when efficiently pursued it forms a most important barrier to the dissemination of disease germs, the slightest imperfection in its manipulation is a constant menace during any epidemic.