Abstract
The importance of vitamin A as an anti-infective factor in diet has been comparatively well established. Green and Mellanby 1 have shown that rats fed on a diet deficient in vitamin A are very susceptible to pyogenic infection. The addition of carotene raised the resistance of the animals to this infection. While several workers have suspected that vitamin A deficiency plays an important role in the resistance of animals to B. tuberculosis infection, the exact relationship of this deficiency has not been well established experimentally, although the work of Smith 2 would appear to indicate that it may play some part in lowering resistance to the infection.
The author investigated the effect of addition of carotene to a vitamin A deficient diet used as food for animals infected with B. tuberculosis. Mice were selected as experimental animals. Browning 3 showed that histologically, tuberculous lesions in mice closely resemble those found in man and that the disease runs a subacute or chronic course in these animals.
Eighty adult mice from the same stock were fed on a modified Drummond-Watson diet which, with cod liver oil as a source of fat-soluble vitamins, maintained normal growth. The modified Drummond-Watson diet was constituted as follows:
Extracted Casein 1000
Rice Starch 2750
Marmite 250
McCollum's Salt Mixture 250
Cotton Seed Oil 500
Each animal received in addition a daily dose of 0.2 gm. ether extracted wheat germ.
Forty animals were inoculated intraperitoneally with 0.75 mg. of moist 21 days' culture of B. tuberculosis (bovine) and on the day of inoculation the animals were divided into 4 groups:
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