IQ4 ADDENDUM 



various varieties of B. mesenteriais. Occasionally bread has 

 been coloured red by B. prodigiosus. Upon stale bread moulds 

 such as Mucor mucedo and A spergillu s glaucus may develop. 



The bacteria in bread are for the most part killed in the 

 process of baking but several investigators (i.e. Roussel,Marchand) 

 have inoculated dough with B. tuberculosis and recovered this 

 organism in a pathogenic state after baking. In experiments 

 conducted by Auche on the other hand this organism was 

 destroyed, or was incapable of producing tuberculosis in inocu- 

 lated animals, after the bread was baked. 



Of more importance is the question of the extent to which 

 bread is bacterially contaminated after baking either in the 

 bakery or during its distribution. The writer is unaware of 

 investigations in this country but the following undertaken in 

 America and Germany illustrate the extent of bacterial con- 

 tamination which may occur. K. Howell 1 examined 100 loaves 

 from various districts of Chicago, some wrapped, some un- 

 wrapped, and from shops of all degress of cleanliness. The 

 method of examination used was to swab the entire loaf with 

 wet sterile cotton the cotton then being thoroughly rinsed in 

 loc.c. of sterile water. From this suitable dilutions were made. 

 The platings were done upon gelatine and lactose litmus agar, 

 the former being counted after 72 hours at 20 C. and the latter 

 after 24 hours at 37 C. All acid colonies were picked off and 

 examined for B. coli and streptococci. In addition I c.c. of 

 the original emulsion from each loaf was added to each of five 

 fermentation tubes containing lactose broth, for gas production 

 and B. coli. 



B. coli was isolated from three loaves and streptococci from 

 30 samples. As regards the number of bacteria the following 

 results were obtained : 



Percentage of samples with Unwrapped Bread Wrapped Bread 

 More than 10,000 bacteria* 17 o 



Tooo-10,000 45 15 



Less than 1000 38 85 



*Agar at 3 7C. 

 1 American Journ. of Public Health^ 1912, n, p. 321. 



