Section IV., 1915 [121] Trans. R.S.C. 



On the Heat Resistance of Bacterial Spores, With a Consideration of the 



Nature of the Spore-like Bodies Seen in B. Tuberculosis 



and Allied Forms. 



By Eleanor Shanly. 



Presented by Dr. J. G. Adami, F.R.S.C. 

 Read May Meeting, 1914. 



Every bacteriologist will agree that the proof of the spore lies in 

 its resistance. There is abundant evidence on every hand that its 

 resistance to heat and disinfectants is markedly superior to that of the 

 vegetative non-spore bearing stage of the bacillus from which it is 

 developed, or of non-spore bearing bacteria in general. The B. 

 Anthrax spore, commonly but mistakenly regarded as "the most re- 

 sistant known," is employed as the test par excellence of efficiency of 

 disinfectants. Koch found that the bacillus of B. Anthracis is killed 

 by an exposure to one per cent phenol for two minutes but that the 

 spores, subjected to solutions of this strength, survive from one to 

 fifteen days.^ The spore's greater capacity to withstand heat, par- 

 ticularly moist heat, is attested by general statements in all the 

 text-books. "The temperature necessary to kill bacteria is not far 

 above 60°C. for ten minutes, in a moist condition, where spores are 

 present 90°-100°C. is required and this must sometimes be applied by 

 the intermittent method." In using the Arnold steam sterilizer we 

 have always assumed that the average spore would stand twenty 

 minutes insteamat 100°. McFarland^ states that some spore-bearers are 

 able to withstand boiling for an hour. Sternberg notes that while the 

 spore of B. Anthracis requires four minutes boiling to kill it, the 

 spores of B. Alvei, Wurtzel bacillus, and B. butyricus withstand a similar 

 treatment, as also that Globig worked with soil bacteria which resisted 

 streaming steam for five to six hours. Madzsar^ did not destroy the 

 spores of B. gangraena pulpae of Agkovia by the action of steam at 100° 

 for twenty-three minutes, and according to WieH B. mesentericus 



^ Frost and McCampbell: "General Bacteriology," p. 49. I purposely quote 

 here from the ordinary text-book rather than from special and advanced work on the 

 subject, in order to emphasize the general trend of opinion upon the matter of resist- 

 ing qualities of spores. 



2 McFarland: "Text-book upon the Pathogenic Bacteria." 



^Ctbl. f. Bakt. 29: 1901, p. 745. 



«Ctbl. f. Bakt. Abt. I, 30, 1911, 500-526. 



