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SULPHAMETHYLTHIAZOLE IN EXPERIMENTAL STAPHYLOCOCCAL INFECTIONS
1157 TABLE I-EFFECT OF AEROSOL ON THE BACTERIAL CONTENT OF THE AIR OF THE WARD
carrier to patient seems unlikely. This is the finding that none of the equally susceptible influenza patients in the adjacent ward became affected, although they were being attended by the same medical, nursing, and domestic staff. (3) The infecting streptococcus was abundantly present in the air of the ward in which the outbreak took place and absent from that of the adjacent ward.
spread by
further
supported by
SUMMARY
Hm. st.
=
Heemolytic streptococcus.
Unc.
=
uncountable.
cultures before the aerosol was used, whereas after treatment only one nasal swab was positive, and that came from a man with a pathological lesion of his nose. Two days later this patient’s nasal culture was still positive, and one other patient had scanty haemolytic streptococci in his nose. EPIDEMIOLOGY
The suggested sequence of events in this little outbreak are these. One patient in a ward accommodating six men with clinical influenza has a streptococcal infection of the upper respiratory tract. The infecting streptococcus, Strep. pyogenes type I, which commonly causes scarlet fever, is sprayed into the air by frequent coughing and, when it reaches an effective concentration, sets up secondary streptococcal infection (including a case of scarlet fever) in all but one of the remaining five patients. The spread of infection is facilitated by the susceptible state of the upper respiratory tract of patients recovering from influenza, by overcrowding, and by inadequate natural ventilation. Besides the blackout at night, windows were not kept as open during the day as they might have been, because the outbreak took place during a very cold spell of weather. The secondarily infected patients pollute the air of the ward still more, till most of them become, by inhalation, nasal carriers of the infecting organism. Attempts to disinfect the atmosphere with aerosol reduce the numbers of streptococci in the air and allow the natural sterilising mechanism of the nasal mucosa to get rid of the inhaled
An outbreak of streptococcal infection among a group of men recovering from influenza is believed on bacteriological and epidemiological evidence to have been aerially spread. The use of aerosol to disinfect the air of the ward seemed to help the patients to get rid of the infecting streptococcus from nose and throat. We
are
indebted to Dr. H. Neisser for
serological typing of the streptococci.
help
with the
REFERENCES
Pulvertaft, R. J. V., Lemon, G. C. and Walker, J. W. (1939) Lancet, 1, 443. Straker, E. A., Hill, A. B. and Lovell, R. (1939) Rep. publ. Hlth med. Subj., Lond. No. 90.
SULPHAMETHYLTHIAZOLE IN EXPERIMENTAL STAPHYLOCOCCAL INFECTIONS
BY A.
MACDONALD, M.B. Aberd.
GARDEN RESEARCH FELLOW IN THE UNIVERSITY OF ABERDEEN
THE treatment of Staphylococcus aureus infections in man with sulphanilamide and its derivatives has been disappointing ; therefore reports of compounda efficient in these infections are of interest. The new drugs are provisionally named sulphathiazole and
sulphamethylthiazole ; the formulae parent sulphanilamide.
show their rela-
tion to the
streptococci. TABLE II-RESULTS OF NOSE AND THROAT SWABS TAKEN BEFORE AND AFTER TREATMENT OF THE WARD WITH AEROSOL
+ = Some colonies of heemolytic streptococcus. Numerous colonies of hsemolytio streptococcus. ++ * This patient was convalescing from a staphylococcal infection of the nose. =
That the outbreak was air-borne and not spread by droplet infection or by fomites is suggested by the following facts :(1) The patients became infected almost simultaneously, which indicates a source equally available to all ; in this
respect the air seems to be the natural medium for the carriage of respiratory pathogens, as water or milk is for
intestinal pathogens. (2) The patients were all confined to bed at the time of the secondary outbreak ; hence direct spread from patient to patient was impossible. The patient nearest to the originally infected man was the only one who did not develop a clinical infection, although he became a nasal carrier. None of the attendant nursing staff was proved to be a carrier of the infecting streptococcus ; hence
Some of the properties of these drugs have already been discussed (Long 1940, THE LANCET, 1940). It is known that sulphamethylthiazole disappears more rapidly than sulphapyridine from the blood of mice, and it is said that in mice a dose of 1 g. of sulphamethylthiazole per kg. of body-weight causes a maximal concentration of 15 mg. per 100 c.cm. of blood in four hours. Daily doses of 1-5 g. per kg. of body-weight given by mouth for fifteen days produced no ill effects in mice, and a daily dose. of 5 g. caused toxic symptoms in ten days. Toxic effects, as judged by otherwise unaccountable loss of weight of the mice, were not observed in the present work. The new drugs have been tried on a wide range of organisms by McKee and colleagues (1939), Barlow and Homburger (1939), and others, but the chief interest lies in their therapeutic effect against staphylococcal infections. For this reason it was decided to test the small available supply of sulphamethylthiazole solely against staphylococcal infections in mice. Mice were infected by the intraperitoneal, intravenous, and subcutaneous routes, and the drug The strain of S. aureus used was given by mouth. in all experiments was recovered from the blood-
1158 TABLE I-ACTION OF SULPHAMETHYLTHIAZOLE IN INTRAPERITONEAL STAPHYLOCOCCAL INFECTIONS
stream of a patient who died of pyaemia, and it showed the commonly accepted criteria of a pathogenic strain. Early attempts to kill mice by intraperitoneal injection of this strain were not always successful, but repeated mouse passage increased its virulence. The susceptibility of mice to infection with staphylococci is known to be highly variable and must always be reckoned with in experiments of this kind. The organisms for injection were grown on agar slopes for twelve to eighteen hours at 37° C., washed thrice in nutrient broth to remove toxin, and finally suspended in saline, the suspension containing 1000-1500 million cocci per c.cm. Young mice weighing 18-25 g. were used in all experiments.
form. Sulphamethylthiazole was given in milk by mouth at the same times as before (table 11). S. aureus was recovered in all mice dying before the twenty-first day from abscesses either in the kidney or elsewhere, and no appreciable difference in the number or size of abscesses or evidence of healing was found in the mice treated with sulphamethylthiazole. Autopsies on the mice living for twentytwo days showed that 2 receiving the higher dose and 1 the smaller dose of sulphamethylthiazole had no abscesses, and S. aureus was not recovered on culture. Since sulphamethylthiazole is rapidly excreted from the blood of mice, it was incorporated in their food and milk to secure a more uniform concentration in the blood. A 1 per cent. and a 1-5 per cent. addition of sulphamethylthiazole to the diet of two groups of 10 mice was expected to give a fairly constant intake of the drug, because the mice fed regularly both day and night. At the end of the tenth day 7 of each treated group of 10 mice were alive, and on the twenty-second day 1 control, 5 on the 1 per cent. diet, and 4 on the 1-5 per cent. diet were still alive. TABLE II-ACTION OF SULPHAMETHYLTH7AZOLE IN INTRAVENOUS STAPHYLOCOCCAL INFECTIONS
INTRAPERITONEAL INFECTIONS
In a preliminary test 16 mice were given about 1000 million living washed staphylococci intraperitoneally, and 8 of them were treated with 10 mg. of sulphamethylthiazole in milk by mouth, half an hour and six hours after injection, thereafter twice daily for four days, and then once daily till the fifteenth day. At the end of twenty-one days 4 of the treated mice and 2 control animals were alive. The survivors were killed on the twenty-second day, and at S. aureus was recovered either from abscesses autopsy in the kidneys or other organs or from the bloodstream in both of the surviving controls and in 3 of the treated mice. Similar experimental conditions were repeated with five sets of mice (table I), the dose of sulphamethylthiazole being 0-5 and 1-0 g. per kg. of body-weight, while mice similarly injected but treated with sulphapyridine served as further controls. All the mice received 1000 million staphy-
lococci intraperitoneally. Of the mice surviving twenty-one days 1 control, 3 treated with sulphapyridine, and 3 treated with sulphamethylthiazole showed no evidence of staphylococcal infection at autopsy. The experiments were thought to show that both sulphapyridine and sulphamethylthiazole had some beneficial effect. The large inoculum of organisms required to produce even relatively uniform results and the survival of control animals, though common in experimental work on staphylococcal infections in mice, were disquieting, and the use of an adjuvant to invasion, such as mucin, was considered. Whitby (1938) was able to kill 3 out of 6 mice with only 150 staphylococci, and the advantages of a small infecting dose are many. It was thought best, however, to try another route of infection because of unfamiliarity with the use of mucin, whose action is imperfectly understood. By giving the organisms intravenously (a method employed by many American workers) a smaller dose was required and more constant results were obtained. INTRAVENOUS INFECTIONS S
With the same organism 0-2 c.cm. of a washed saline suspension containing roughly 400 million cocci This dose was injected ’into the tail veins of mice. usually caused pyaemia, abscesses being concentrated mostly in the kidneys and less often in the liver, spleen, and joints. As with other routes of infection, however, a few mice died within twenty-four to forty-eight hours, often before abscesses had time to
A comparison of the different sulphonamides now used in staphylococcal infections is shown in table III. The injections were made intravenously, and the drugs were suspended in milk and given by mouth. In only 1 mouse (treated with sulphamethylthiazole in the diet) was the organism not recovered at autopsy. These experiments suggest that both sulphapyridine and sulphamethylthiazole protect mice from early death by staphylococcal infections, and that in the doses used they have more effect than the other drugs, given in the same doses under similar conditions, in prolonging the life of mice. The relative values of the various compounds cannot, however, be adequately compared in experiments such as these, which have no check on the absorption, optimal dosage, and concentration in the blood of the various
drugs. SKIN LESIONS
The last group of experiments was made to find out whether sulphamethylthiazole would affect experimental staphylococcal lesions of the skin. For this purpose 4 rabbits were given 0-2 c.cm. of a washed staphylococcal suspension containing 200-300 million organisms into the shaved skin of each flank according to the method described by Downie (1937). Sulphamethylthiazole 1 g. in suspension was given by mouth to 2 of the rabbits, the first dose two hours before injection and the second six hours later. The treated rabbits were given 6-0 g. of sulphamethylthiazole in all, treatment being stopped on the fifth day. All the lesions healed in about the same time, the last abscess to heal being in a treated animal. Because of the chronicity of the lesions and for reasons of economy an attempt was made to cause similar lesions on the skin of mice. The original strain of staphylococcus proved satisfactory and was accordingly used. With subcutaneous or intradermal injection thorough washing of the organisms is important, because preformed toxins may induce large areas of necrosis within twenty-four hours with little immediate inflammation and slow separation of sloughs. When the organisms were washed, abscesses were formed, and necrosis developed slowly and was less than with unwashed cultures. Control experiments with washed heat-killed staphylococci caused neither necrosis nor abscesses. On the day before
1159
injection the bellies and flanks of the mice were shaved
phonamide drugs that when they act they do so that accidental abrasions of the skin were avoided, quickly. and for the test lesions 0 -05 c.cm. of a saline suspension Some of the results obtained compare unfavourably containing about 75 million washed staphylococci with those of several experienced workers. Domagk was injected under the skin of the lateral part of the (1937), who infected mice with intraperitoneal injecbelly. The mice were watched daily, care being taken tions of a broth-culture of staphylococci, obtained to ensure that the bedding in all cages was clean and satisfactory results with Uleron when the mice were watched for less than a week, and Whitby’s (1938) dry to prevent secondary infections. results with sulphapyridine are better than those After twelve hours there was usually slight reddening and oedema at the site of injection and after forty- reported here. From the present work, however, it eight hours definite abscess formation. The lesions seems that both sulphapyridine and sulphamethylincreased in size for four or five days, when they were thiazole prevented many of the early deaths in commonly 0-5-0-75 cm. in diameter and the central TABLE IV-ACTION OF SULPHAMETHYLTHIAZOLE ON area of the abscess was beginning to separate, leaving STAPHYLOCOCCAL LESIONS OF THE SKIN shallow The usual time for the lesion to heal ulcer. a untreated in mice was ten to fifteen days. Histological examination of the lesions on the fourth day showed necrosis of the skin and subcutaneous tissues and intense cellular reaction, with clumps of staphylococci mostly in the necrotic areas but invading all the tissues down to the muscle layer, which was the site of oedema and inflammation. Cultures made from the floors of many of the ulcers or from the exudate after scabs had formed gave growths of S. aureus to within four days of healing. Treatment was not begun in this series until two days after inoculation, when well-developed abscesses staphylococcal infections of mice, and it is probable It was continued for ten days, the were present. drugs are less efficient after abscesses have in and milk drugs being suspended given by mouth, that both to form. except when incorporated in the diet, and all lesions begun None of the sulphonamide drugs is particularly were unprotected (table IV). in the presence of pus, and the experiments active cultural methods evidence that there was no the By with skin abscesses may indicate that sulphamethylstaphylococci disappeared more rapidly from any one thiazole does not completely overcome this difficulty. group of lesions. Besides the ordinary controls for Barlow and Homburger (1939) believe that sulphathis experiment a number of mice were infected with methylthiazole prevents the development or allows and them of haemolytic streptococci, many developed the abscesses in a significant of healing staphylococcal localised lesions. Several of these animals, however, number of mice suffering from pyaemia. In one of died from a spreading streptococcal infection within the experiments quoted by these workers all 10 control mice died, while 9 of the mice treated with TABLE III-ACTIONS OF DIFFERENT SULPHONAMIDES IN sulphamethylthiazole survived, and at autopsy the INTRAVENOUS STAPHYLOCOCCAL INFECTIONS abscesses were fewer in the treated group than in the controls. The implication that fewer abscesses indicates efficient therapy may be difficult to maintain when there is great variation in abscess formation in untreated mice. Herrell and Brown (1939) found that better protection could be obtained in staphylococcal infections of mice by sulphamethylthiazole than by sulphapyridine, and this impression may be true ; but there is yet little evidence that sulphamethylthiazole is as specific for staphylococcal infections as other sulphonamide compounds are for pneumococcal or for streptococcal infections. so
SUMMARY
forty-eight hours, while most of those treated with sulphanilamide survived. The lesions in the surviving treated animals healed more quickly than in those not treated ; and, though the number of mice was small, there was some evidence that streptococcal skin lesions in mice could be favourably influenced by sulphanilamide therapy. In contrast, staphylococcal lesions in all treated mice healed within the period which had been found to be normal for untreated animals. The treatment did not seem to affect either the extent, nature or healing of the lesions, or the degree of invasion of the tissues.
About half the numberof mice infected with staphylococci by the intraperitoneal and intravenous routes survived twenty-one days when treated for fifteen days with sulphamethylthiazole. Sulphapyridine under similar conditions was only slightly less effective. Many of the treated mice still harboured S. aureus in the kidneys or other organs after twentyone
days.
Neither sulphamethylthiazole nor sulphapyridine given by mouth affected the course of experimental staphylococcal lesions of the skin of mice. I wish to thank Prof. John Cruickshank for his help and advice ; and the research department of the Maltbie Chemical Co. for the sulphamethylthiazole.
COMMENTS
In these experiments about 200 mice were studied, number inadequate for chemotherapeutic trial, and the results obtained must therefore lead mainly to impressions. Of the mice infected both by the intraperitoneal and intravenous routes and treated with sulphapyridine or with sulphamethylthiazole about half lived for twenty-one days. Many of those surviving this length of time harboured the infecting organism, and some still had abscesses in the kidneys. Treatment for only fifteen daysmay not have been sufficient, but it is fairly characteristic of the sula
REFERENCES
Barlow, O. W. and Homburger, E. (1939) Proc. Soc. exp. Biol., N.Y. 42, 792. Domagk, G. (1937) Klin. W schr. 16, 1412. Downie, A. W. (1937) J. Path. Bact. 44, 573. Herrell, W. E. and Brown, A. E. (1939) Proc. Mayo Clin. 14, 753. Lancet (1940) May 11, p. 883. Long, P. H. (1940) J. Amer. med. Ass. March 9, p. 870. McKee, C. M., Rake, G., Greep, R. O. and van Dyke, H. B. (1939) Proc. Soc. exp. Biol., N.Y. 42, 417. Whitby, L. E. H. (1938) Lancet, 2, 1095.
carrier to patient seems unlikely. This is the finding that none of the equally susceptible influenza patients in the adjacent ward became affected, although they were being attended by the same medical, nursing, and domestic staff. (3) The infecting streptococcus was abundantly present in the air of the ward in which the outbreak took place and absent from that of the adjacent ward.
spread by
further
supported by
SUMMARY
Hm. st.
=
Heemolytic streptococcus.
Unc.
=
uncountable.
cultures before the aerosol was used, whereas after treatment only one nasal swab was positive, and that came from a man with a pathological lesion of his nose. Two days later this patient’s nasal culture was still positive, and one other patient had scanty haemolytic streptococci in his nose. EPIDEMIOLOGY
The suggested sequence of events in this little outbreak are these. One patient in a ward accommodating six men with clinical influenza has a streptococcal infection of the upper respiratory tract. The infecting streptococcus, Strep. pyogenes type I, which commonly causes scarlet fever, is sprayed into the air by frequent coughing and, when it reaches an effective concentration, sets up secondary streptococcal infection (including a case of scarlet fever) in all but one of the remaining five patients. The spread of infection is facilitated by the susceptible state of the upper respiratory tract of patients recovering from influenza, by overcrowding, and by inadequate natural ventilation. Besides the blackout at night, windows were not kept as open during the day as they might have been, because the outbreak took place during a very cold spell of weather. The secondarily infected patients pollute the air of the ward still more, till most of them become, by inhalation, nasal carriers of the infecting organism. Attempts to disinfect the atmosphere with aerosol reduce the numbers of streptococci in the air and allow the natural sterilising mechanism of the nasal mucosa to get rid of the inhaled
An outbreak of streptococcal infection among a group of men recovering from influenza is believed on bacteriological and epidemiological evidence to have been aerially spread. The use of aerosol to disinfect the air of the ward seemed to help the patients to get rid of the infecting streptococcus from nose and throat. We
are
indebted to Dr. H. Neisser for
serological typing of the streptococci.
help
with the
REFERENCES
Pulvertaft, R. J. V., Lemon, G. C. and Walker, J. W. (1939) Lancet, 1, 443. Straker, E. A., Hill, A. B. and Lovell, R. (1939) Rep. publ. Hlth med. Subj., Lond. No. 90.
SULPHAMETHYLTHIAZOLE IN EXPERIMENTAL STAPHYLOCOCCAL INFECTIONS
BY A.
MACDONALD, M.B. Aberd.
GARDEN RESEARCH FELLOW IN THE UNIVERSITY OF ABERDEEN
THE treatment of Staphylococcus aureus infections in man with sulphanilamide and its derivatives has been disappointing ; therefore reports of compounda efficient in these infections are of interest. The new drugs are provisionally named sulphathiazole and
sulphamethylthiazole ; the formulae parent sulphanilamide.
show their rela-
tion to the
streptococci. TABLE II-RESULTS OF NOSE AND THROAT SWABS TAKEN BEFORE AND AFTER TREATMENT OF THE WARD WITH AEROSOL
+ = Some colonies of heemolytic streptococcus. Numerous colonies of hsemolytio streptococcus. ++ * This patient was convalescing from a staphylococcal infection of the nose. =
That the outbreak was air-borne and not spread by droplet infection or by fomites is suggested by the following facts :(1) The patients became infected almost simultaneously, which indicates a source equally available to all ; in this
respect the air seems to be the natural medium for the carriage of respiratory pathogens, as water or milk is for
intestinal pathogens. (2) The patients were all confined to bed at the time of the secondary outbreak ; hence direct spread from patient to patient was impossible. The patient nearest to the originally infected man was the only one who did not develop a clinical infection, although he became a nasal carrier. None of the attendant nursing staff was proved to be a carrier of the infecting streptococcus ; hence
Some of the properties of these drugs have already been discussed (Long 1940, THE LANCET, 1940). It is known that sulphamethylthiazole disappears more rapidly than sulphapyridine from the blood of mice, and it is said that in mice a dose of 1 g. of sulphamethylthiazole per kg. of body-weight causes a maximal concentration of 15 mg. per 100 c.cm. of blood in four hours. Daily doses of 1-5 g. per kg. of body-weight given by mouth for fifteen days produced no ill effects in mice, and a daily dose. of 5 g. caused toxic symptoms in ten days. Toxic effects, as judged by otherwise unaccountable loss of weight of the mice, were not observed in the present work. The new drugs have been tried on a wide range of organisms by McKee and colleagues (1939), Barlow and Homburger (1939), and others, but the chief interest lies in their therapeutic effect against staphylococcal infections. For this reason it was decided to test the small available supply of sulphamethylthiazole solely against staphylococcal infections in mice. Mice were infected by the intraperitoneal, intravenous, and subcutaneous routes, and the drug The strain of S. aureus used was given by mouth. in all experiments was recovered from the blood-
1158 TABLE I-ACTION OF SULPHAMETHYLTHIAZOLE IN INTRAPERITONEAL STAPHYLOCOCCAL INFECTIONS
stream of a patient who died of pyaemia, and it showed the commonly accepted criteria of a pathogenic strain. Early attempts to kill mice by intraperitoneal injection of this strain were not always successful, but repeated mouse passage increased its virulence. The susceptibility of mice to infection with staphylococci is known to be highly variable and must always be reckoned with in experiments of this kind. The organisms for injection were grown on agar slopes for twelve to eighteen hours at 37° C., washed thrice in nutrient broth to remove toxin, and finally suspended in saline, the suspension containing 1000-1500 million cocci per c.cm. Young mice weighing 18-25 g. were used in all experiments.
form. Sulphamethylthiazole was given in milk by mouth at the same times as before (table 11). S. aureus was recovered in all mice dying before the twenty-first day from abscesses either in the kidney or elsewhere, and no appreciable difference in the number or size of abscesses or evidence of healing was found in the mice treated with sulphamethylthiazole. Autopsies on the mice living for twentytwo days showed that 2 receiving the higher dose and 1 the smaller dose of sulphamethylthiazole had no abscesses, and S. aureus was not recovered on culture. Since sulphamethylthiazole is rapidly excreted from the blood of mice, it was incorporated in their food and milk to secure a more uniform concentration in the blood. A 1 per cent. and a 1-5 per cent. addition of sulphamethylthiazole to the diet of two groups of 10 mice was expected to give a fairly constant intake of the drug, because the mice fed regularly both day and night. At the end of the tenth day 7 of each treated group of 10 mice were alive, and on the twenty-second day 1 control, 5 on the 1 per cent. diet, and 4 on the 1-5 per cent. diet were still alive. TABLE II-ACTION OF SULPHAMETHYLTH7AZOLE IN INTRAVENOUS STAPHYLOCOCCAL INFECTIONS
INTRAPERITONEAL INFECTIONS
In a preliminary test 16 mice were given about 1000 million living washed staphylococci intraperitoneally, and 8 of them were treated with 10 mg. of sulphamethylthiazole in milk by mouth, half an hour and six hours after injection, thereafter twice daily for four days, and then once daily till the fifteenth day. At the end of twenty-one days 4 of the treated mice and 2 control animals were alive. The survivors were killed on the twenty-second day, and at S. aureus was recovered either from abscesses autopsy in the kidneys or other organs or from the bloodstream in both of the surviving controls and in 3 of the treated mice. Similar experimental conditions were repeated with five sets of mice (table I), the dose of sulphamethylthiazole being 0-5 and 1-0 g. per kg. of body-weight, while mice similarly injected but treated with sulphapyridine served as further controls. All the mice received 1000 million staphy-
lococci intraperitoneally. Of the mice surviving twenty-one days 1 control, 3 treated with sulphapyridine, and 3 treated with sulphamethylthiazole showed no evidence of staphylococcal infection at autopsy. The experiments were thought to show that both sulphapyridine and sulphamethylthiazole had some beneficial effect. The large inoculum of organisms required to produce even relatively uniform results and the survival of control animals, though common in experimental work on staphylococcal infections in mice, were disquieting, and the use of an adjuvant to invasion, such as mucin, was considered. Whitby (1938) was able to kill 3 out of 6 mice with only 150 staphylococci, and the advantages of a small infecting dose are many. It was thought best, however, to try another route of infection because of unfamiliarity with the use of mucin, whose action is imperfectly understood. By giving the organisms intravenously (a method employed by many American workers) a smaller dose was required and more constant results were obtained. INTRAVENOUS INFECTIONS S
With the same organism 0-2 c.cm. of a washed saline suspension containing roughly 400 million cocci This dose was injected ’into the tail veins of mice. usually caused pyaemia, abscesses being concentrated mostly in the kidneys and less often in the liver, spleen, and joints. As with other routes of infection, however, a few mice died within twenty-four to forty-eight hours, often before abscesses had time to
A comparison of the different sulphonamides now used in staphylococcal infections is shown in table III. The injections were made intravenously, and the drugs were suspended in milk and given by mouth. In only 1 mouse (treated with sulphamethylthiazole in the diet) was the organism not recovered at autopsy. These experiments suggest that both sulphapyridine and sulphamethylthiazole protect mice from early death by staphylococcal infections, and that in the doses used they have more effect than the other drugs, given in the same doses under similar conditions, in prolonging the life of mice. The relative values of the various compounds cannot, however, be adequately compared in experiments such as these, which have no check on the absorption, optimal dosage, and concentration in the blood of the various
drugs. SKIN LESIONS
The last group of experiments was made to find out whether sulphamethylthiazole would affect experimental staphylococcal lesions of the skin. For this purpose 4 rabbits were given 0-2 c.cm. of a washed staphylococcal suspension containing 200-300 million organisms into the shaved skin of each flank according to the method described by Downie (1937). Sulphamethylthiazole 1 g. in suspension was given by mouth to 2 of the rabbits, the first dose two hours before injection and the second six hours later. The treated rabbits were given 6-0 g. of sulphamethylthiazole in all, treatment being stopped on the fifth day. All the lesions healed in about the same time, the last abscess to heal being in a treated animal. Because of the chronicity of the lesions and for reasons of economy an attempt was made to cause similar lesions on the skin of mice. The original strain of staphylococcus proved satisfactory and was accordingly used. With subcutaneous or intradermal injection thorough washing of the organisms is important, because preformed toxins may induce large areas of necrosis within twenty-four hours with little immediate inflammation and slow separation of sloughs. When the organisms were washed, abscesses were formed, and necrosis developed slowly and was less than with unwashed cultures. Control experiments with washed heat-killed staphylococci caused neither necrosis nor abscesses. On the day before
1159
injection the bellies and flanks of the mice were shaved
phonamide drugs that when they act they do so that accidental abrasions of the skin were avoided, quickly. and for the test lesions 0 -05 c.cm. of a saline suspension Some of the results obtained compare unfavourably containing about 75 million washed staphylococci with those of several experienced workers. Domagk was injected under the skin of the lateral part of the (1937), who infected mice with intraperitoneal injecbelly. The mice were watched daily, care being taken tions of a broth-culture of staphylococci, obtained to ensure that the bedding in all cages was clean and satisfactory results with Uleron when the mice were watched for less than a week, and Whitby’s (1938) dry to prevent secondary infections. results with sulphapyridine are better than those After twelve hours there was usually slight reddening and oedema at the site of injection and after forty- reported here. From the present work, however, it eight hours definite abscess formation. The lesions seems that both sulphapyridine and sulphamethylincreased in size for four or five days, when they were thiazole prevented many of the early deaths in commonly 0-5-0-75 cm. in diameter and the central TABLE IV-ACTION OF SULPHAMETHYLTHIAZOLE ON area of the abscess was beginning to separate, leaving STAPHYLOCOCCAL LESIONS OF THE SKIN shallow The usual time for the lesion to heal ulcer. a untreated in mice was ten to fifteen days. Histological examination of the lesions on the fourth day showed necrosis of the skin and subcutaneous tissues and intense cellular reaction, with clumps of staphylococci mostly in the necrotic areas but invading all the tissues down to the muscle layer, which was the site of oedema and inflammation. Cultures made from the floors of many of the ulcers or from the exudate after scabs had formed gave growths of S. aureus to within four days of healing. Treatment was not begun in this series until two days after inoculation, when well-developed abscesses staphylococcal infections of mice, and it is probable It was continued for ten days, the were present. drugs are less efficient after abscesses have in and milk drugs being suspended given by mouth, that both to form. except when incorporated in the diet, and all lesions begun None of the sulphonamide drugs is particularly were unprotected (table IV). in the presence of pus, and the experiments active cultural methods evidence that there was no the By with skin abscesses may indicate that sulphamethylstaphylococci disappeared more rapidly from any one thiazole does not completely overcome this difficulty. group of lesions. Besides the ordinary controls for Barlow and Homburger (1939) believe that sulphathis experiment a number of mice were infected with methylthiazole prevents the development or allows and them of haemolytic streptococci, many developed the abscesses in a significant of healing staphylococcal localised lesions. Several of these animals, however, number of mice suffering from pyaemia. In one of died from a spreading streptococcal infection within the experiments quoted by these workers all 10 control mice died, while 9 of the mice treated with TABLE III-ACTIONS OF DIFFERENT SULPHONAMIDES IN sulphamethylthiazole survived, and at autopsy the INTRAVENOUS STAPHYLOCOCCAL INFECTIONS abscesses were fewer in the treated group than in the controls. The implication that fewer abscesses indicates efficient therapy may be difficult to maintain when there is great variation in abscess formation in untreated mice. Herrell and Brown (1939) found that better protection could be obtained in staphylococcal infections of mice by sulphamethylthiazole than by sulphapyridine, and this impression may be true ; but there is yet little evidence that sulphamethylthiazole is as specific for staphylococcal infections as other sulphonamide compounds are for pneumococcal or for streptococcal infections. so
SUMMARY
forty-eight hours, while most of those treated with sulphanilamide survived. The lesions in the surviving treated animals healed more quickly than in those not treated ; and, though the number of mice was small, there was some evidence that streptococcal skin lesions in mice could be favourably influenced by sulphanilamide therapy. In contrast, staphylococcal lesions in all treated mice healed within the period which had been found to be normal for untreated animals. The treatment did not seem to affect either the extent, nature or healing of the lesions, or the degree of invasion of the tissues.
About half the numberof mice infected with staphylococci by the intraperitoneal and intravenous routes survived twenty-one days when treated for fifteen days with sulphamethylthiazole. Sulphapyridine under similar conditions was only slightly less effective. Many of the treated mice still harboured S. aureus in the kidneys or other organs after twentyone
days.
Neither sulphamethylthiazole nor sulphapyridine given by mouth affected the course of experimental staphylococcal lesions of the skin of mice. I wish to thank Prof. John Cruickshank for his help and advice ; and the research department of the Maltbie Chemical Co. for the sulphamethylthiazole.
COMMENTS
In these experiments about 200 mice were studied, number inadequate for chemotherapeutic trial, and the results obtained must therefore lead mainly to impressions. Of the mice infected both by the intraperitoneal and intravenous routes and treated with sulphapyridine or with sulphamethylthiazole about half lived for twenty-one days. Many of those surviving this length of time harboured the infecting organism, and some still had abscesses in the kidneys. Treatment for only fifteen daysmay not have been sufficient, but it is fairly characteristic of the sula
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