Factors influencing development of metachromatic granules in the diptheria bacillus

E. Megrail
1922 Journal of Infectious Diseases  
A study was made of some of the outside influences which may affect the production of granules in the diphtheria bacillus. Factors were sought that might hasten the appearance of granules and make an earlier diagnosis possible, and also those which might delay the appearance of the granules, thus interfering with the accuracy of routine examinations. Types of granules were studied exclusively as most commonly seen in this locality. It is reasonable to suppose that conditions modifying granule
more » ... modifying granule formation would also modify the formation of bars in that type of organism. The appearance of granules at different ages of the organism has been studied by Denny,' Albert 2 and others, who have found that granules appear in cultures from 4 to 8 hours old, and attain their larg-est average size in cultures from 12 to 15 hours old. The effect of reaction of the medium on granule formation was studied by Layborne 2 and Bunker." Layborne found that blood serum of PH 7 to 7.5 gave the largest percentage of granule forms. As the reaction approached PH 5.5 and 8.5 the organism became smaller and the percentage of granule forms less. Denny 4 says that the transition from the solid to the granular form depends on either the accumulation of bacilli or products of growth of the organism. Denny also studied the effects of various incubation temperatures in reference to granule formation and found that the appearance of granules was delayed at a temperature of 19 to 21 c., and at a temperature of 40. He also found that symbiotic growth with various organisms delayed the granule production. Heineman' and Mellon G varied the morphology of the organism, producing a coccus-like form from a g-ranule form by growing it on veal glucose broth and bringing it hack to the granule form on blood serum or hlood agar. Wherry 7 studied the morphology of one culture in relation to oxygen tension. He found that the barred and gr anulc forms disappeared when grown on Loeffler's blood serum under anaerobic conditions and also that growth with B. subtilis produced the same effect.
doi:10.1093/infdis/31.5.393 fatcat:4iez4hctxzhhbgeybo5u3cyhum