ANNUAL REPORT, 1938 25 



streptococci and on the ratio between streptococci and coliform bacteria, as well 

 as a study of the streptococci to determine their source. 



The test for coliform bacteria {Bacillus coli group) is used, as with drinking 

 water, to indicate the sanitary quality of the water used to fill swimming pools. 

 When pool water is treated by some purification process, usually chlorination, 

 the presence of coliform bacteria may be interpreted as indicating contamination 

 of the water by those using the pool. 



Authorities are giving attention also to streptococci present in water as evidence 

 of contamination, both in drinking water supplies and in swimming pool water. 

 Streptococci do not survive as long in water as do coliform bacteria. The presence 

 of streptococci, therefore, can be interpreted as evidence of comparatively recent 

 contamination. The streptococci can be differentiated by laboratory methods 

 to give some idea of their source, whether they come from the intestinal tract 

 or from the nose and throat. If they are from the intestinal tract, they have the 

 same significance as the coliform bacteria. If they are from the nose and throat, 

 they may indicate possible danger of nose, throat, or sinus infections among pool 

 users. Both types may be found in pool water at the same time. 



Following are reports of studies made during the year. 



Influence of Bile and Bile Salts on Aerobacter aerogenes. (James E. Fuller.) 

 This study has been published in the Proceedings of the Society for Experimental 

 Biology and Medicine, Vol. 38, pp. 507-510, 1938. 



Salt Tolerance of Fecal Bacteria. (James E. Fuller and R. H. Guiberson.) 

 This is a study of the salt (sodium chloride) tolerance of streptococci isolated 

 from feces as influenced by carbohydrates, bile, and reaction of the medium. The 

 object is to obtain results that may assist in differentiating these streptococci in 

 order to evaluate their sanitary significance. A similar study is being made of 

 the coliform bacteria, for comparison with results of the streptococcus study. 



Studies completed have shown that members of the streptococci isolated from 

 feces are classified as forms from the nose and throat (by accepted physiological 

 reactions). Salt tolerance tests of coliform bacteria showed that Escherichia coli 

 tolerated 9.5 grams of salt per 100 millilitres of nutrient broth; Aerobacter aero- 

 genes tolerated 9.0 grams of salt per 100 millilitres of broth; and certain intermed- 

 iates tolerated no more than 8 grams of salt per 100 millilitres of broth. Tol- 

 erance was indicated by visible growth. It was possible to recover living bacteria 

 from all cultures up to the limit of salt concentration employed, 11 grams of salt 

 in 100 millilitres of broth. This portion of the experiment will parallel that with 

 the streptococci by determining the influence of fermentable carbohydrates, 

 bile salts, and different media reactions. 



A Study of the Eijl<man Test. (Ralph L. France.) This test for the sanitary 

 quality of water is based upon the claim of its originator that only Escherichia coli 

 definitely significant of sewage contamination will produce acid and gas in dex- 

 trose broth at 46° C, and that less significant members of the coliform group 

 will not do so. More than three hundred coliform bacteria cultures were culti- 

 vated in Eijkman's dextrose broth at several temperatures (46°, 45°, 44°, 43°, 

 41°, and 39° C). The bacteria represent Escherichia coli, Aerobacter aerogenes, 

 and intermediates of the group selected on the basis of standard tests (Voges- 

 Proskauer, Methyl red, and sodium citrate). It was anticipated that the use of 

 the several temperatures might aid in grouping these bacteria with reference 

 to their relative sanitary significance. It was found, however, that only Escherichia 

 coli was selected by the procedure. This was in agreement with the usual inter- 

 pretation of the test. There appeared to be no relationship, among other strains, 

 to their differential reactions. 



