Abstract
Rats deficient in riboflayin or pantothenic acid are as resistant to experimentally induced pneumococcal lobar pneumonia as rats receiving the same basal diet supplemented with adequate quantities of riboflavin or pantothenic acid. Thiamin deficiency and possibly pyridoxin deficiency appeared to lower the resistance of rats to this infection somewhat if compared to the group receiving the same basal diet plus all the B vitamins. With the exception of thiamin deficiency, all deficient groups, including those on a complete synthetic diet deficient in unknown factors, showed a greater resistance to infection than rats fed the normal stock diet ad libitum. Inanition had no apparent influence on the resistance of rats. There was essentially no difference in the rate or degree of growth of pneumococci added to the blood of deficient or healthy rats.