Treatment with Sulphapyridine (M&B 693) of Guinea-pigs infected with Brucella abortus
BMJ (Clinical Research Edition)
In a previous paper (Wilson and Maier, 1939) evidence was brought to show that the administration of sulphanilamide twice daily in a dosage bordering on the toxic limit to guinea-pigs infected seven weeks previously with a virulent strain of Br. abortus was able to bring about sterilization of the tissues after treatment for three to five weeks. The total daily dosage used corresponded to an average of 0.8 mg. per gramme of body weight. Animals given half this dosage still remained infected
... mained infected after two to four weeks' treatment. These results receive confirmation from the work, in the United States, of Chinn (1939), who, starting treatment one week after inoculation with Br. abortuis, Br. melitensis, or Br. suis, and using twice-daily doses of sulphanilamide amounting in the aggregate to 1 mg. per gramme of body weight, achieved sterilization of the tissues in twenty-one out of twenty-eight guinea-pigs treated for twenty-four days. On the other hand, they are quite incompatible with the findings of Menefee and Poston (1939) , who started treatment five days after a large inoculation with Br. mnelitensis, gave a dosage of sulphanilamide of only 0.06 mg. per gramme of body weight (60 mg. per kilo) for ten days and then 0.03 mg. per gramme for a further ten days, and succeeded in sterilizing the tissues of nineteen out of twenty infected guinea-pigs. Since Chinn found that animals infected with Br. melitensis tended to be more refractory to treatment than those infected with Br. abortus or Br. suis, the most probable explanation of Menefee and Poston's resultsis that they were using a comparatively avirulent strain of Br. melitensis. These results are conflicting, but on the whole it looks as if successful treatment of guinea-pigs infected with Brucella can be achieved by sulphanilamide only after prolonged treatment with large doses. Since sulphapyridine is said to be less toxic than sulphanilamide (Wien, 1938) , it seemed desirable to make observations on this drug in the hope that cure might be obtained without the risk of poisoning the animals. The following experiments were therefore undertaken. Experiment 1 On March 17, 1939, fourteen male and fourteen female guinea-pigs, weighing between 240 and 520 grammes, with an average weight of 340 grammes, were inoculated intramuscularly into the left thigh with 1,000,000 living organisms washed off from a two-day liver-agar culture of a virulent CO2-sensitive strain of Br. abortuis (Lanyon). They were then divided up into five groups, A, B, Ct D, and E, of approximately equal weight. Groups A, B, and D contained each two bucks and two does, Group C contained three bucks and three does, and Group E, representing the control group, contained five bucks and five does. Six weeks later, April 27, treatment of the first four groups was-begun. it was originally intended to give Groups A, B, and C 200-mg. doses of suliphapyridine (2-sulphanilyl-aminopyridinie) by mouth t1ice a day on six days a week for two, four, and six weeks respectively, but owing to the acute toxaemic death of one animal on the fourth day of treatment, and the partial paralysis of some of the others, the dosage was halved for a few days. It was later increased to 150 mg. twice a day, and then, on account of the death of two more animals from presumably chronic toxaemia, it was again reduced to 100 mg. twice a day. The dosage of the individual animals was varied considerably according to their condition, and sometimes had to be stopped for two or three days at a time. The sulphapyridine, which had been dispensed in tablets, was given in powdered form by means of a special glass funnel introduced into the mouth at the back of the tongue. Following the practice of Chinn (1939) it was washed down with two or three drops of 5 per cent. glucose solution. The treatment of Group D had similarly to be altered. It was intended to give these animals subcutaneoLus inoculations, twice daily on six days a week for a fortnight, of 100 mg. of soluble sulphapyridine, made up in a 33,3 per cent. solution, but owing to the acute toxaemic death of one animal on the fourth day of treatment the dosage was halved. Many of the animals in this group developed dry gangrene of the extremities, and when' half of them were killed after a fortnight they were found to be suffering from large axillary abscesses containing necrotic masses of tissue. For this reason the injections were discontinLued and the remaining animals were given two daily doses of 100 mg. of sulphapyridine by the mouth for another fortnight. Half the animals in Groups A, B, and C and all the animals in Group D were killed the day after their last dose the other half were killed a week later. Two to five control animals were killed at the same time as each subgroup of infected animals. In making the bacteriological examination the animal was anaesthetized with ether, the thorax opened, and blood taken for agglutination from the inferior vena cava. The great vessels were then cut and the animal was allowed to bleed to death. The spleen and sublumbar glands were excised, ground Lip separately in Griffith tul3es, and suspended in N/4 Ringer solution; viable bacterial cotunts were then made on the suspensions by the roll-tube method. In addition the macroscopic appearance of the glands, spleen, and liver was carefully noted, particular attention being paid to the degree of enlargement of -the organ as a whole-and to the number and size of any focal lesions that might be present. The results were recorded in a series of index numbers varying from 0 to 4. The summarized results are given in Table 1 . (The figures in both tables represent arithmetic mean values, with the exception of agglutinin titres, for which the geometric mean has been used.) The -macroscopic appearance of the sublumbar glands did not differ greatly in the treated and control animals, but the involvement of the spleen and liver, particularly in Groups A, B, and C, was considerably less than in the corresponding controls. Bacteriologically the sublumbar glands proved sterile in all the treated animals except two belonging to Group A. The spleens of two animals in Groups B and D and of all animals in Grouip C were likewise sterile. The sublumbar glands of three of the control animals proved sterile, but the spleens were all heavily infected. The agglutinin titres varied greatly from animal to animal, but were lowest in Group C. Little difference was observed between the animals killed the day after and those killed a week after the cessation of treatment, suggesting that the-effect of the drug was well maintained. It is worth noting that two animals in Group B and two in Group C showed no macroscopic lesions whatever and yielded no growth of Br. abortus on culture. There is little doubt, from this experiment, that the treatment with sulphapyridine favourably influenced the course of the infection. The treatment with the soluble product, especially when followed by sulphapyridine by mouth, gave much the same results as treatment for the same length of time by oral administration.