136 DIFGO MANUAL 



protozoa by Felsenfeld^o showed that generally specimens were promptly plated. 

 Glycerol-saline was the most frequently used preservative. S S Agar was the most 

 popular plating medium. It was used especially frequently for direct plating. 

 There was a decrease in the use of Endo Agar. Desoxycholate Agars were found 

 to be more frequently used than the Endo Agar. There were more laboratories 

 using the poured plate of Bismuth Sulfite Agar, MacConkey Agar and Brilliant 

 Green Agar in 1949 than in 1944. The use of streaked plates of Bismuth Sulfite 

 Agar showed a decrease during this period if occasional users were not considered. 

 All but three laboratories were using dehydrated Bismuth Sulfite Agar. He stated 

 that these changes point toward evaluation of experience and economy in public 

 health laboratories. 



Neter and Brody-^ added saccharose and also saccharose and salicin to Bacto-S 

 S Agar in studies on the bacteriological diagnosis and epidemiological aspects 

 of Salmonellosis. The modified media were especially valuable in the follow-up 

 of proven Salmonella cases and in epidemiological studies, but were not suggested 

 in routine work since pathogenic paracolons would be discarded by the modified 

 media. These media would also discard Proteus. 



Schaub22.23 jji jigj. study of the differentiation of paracolon bacilli reported 

 Bacto-S S Agar to give more satisfactory results than the other selective media 

 tried, in that on S S Agar growth of the paracolon bacilli, regarded as aberrant 

 coliforms, is inhibited, as is that of the typical coliform bacillus. Certain other 

 paracolon bacilli grew well. Correlating growth on Bacto-S S Agar with bio- 

 chemical characteristics, the paracolon bacilli were divided into four large 

 groups : 



Group I — aberrant coliform bacilli, consisting of paracolon Escherichia, para- 

 colon Aerobacter and paracolon intermediates; growth inhibited on 

 S S Agar. 

 Group II — hydrogen-sulfide-producing paracolon bacilli, growth not inhibited 

 on S S Agar. This group may be divided culturally into three sub- 

 groups, II-A, II-B and II-C. 

 Group III — anaerogenic paracolon bacilli; growth not inhibited on S S Agar. 

 Group IV — malonate-positive paracolon bacilli; growth not inhibited on S S 

 Agar. 



Schaub also used S S Agar as slants in tubes and found that this was a satisfactory 

 method of demonstrating hydrogen sulfide production. The medium at the base 

 of the slant became markedly blackened when the surface of the slant was 

 streaked with a hydrogen suljfide producing organism. 



Newman,^* in a study of the detection of food poisoning attributable to dairy 

 products, used direct streaking on S S Agar as well as enrichment in Tetra- 

 thionate Broth followed by streaking on S S Agar and Bismuth Sulfite Agar for 

 the isolation of Salmonellae. In a study of methods to be used as a standard for 

 (the bacterial examination of puilorum reactors Jungherr, Hall and Pomeroy,^^ in 

 a committee report showed that in a comparative study of media and enrich- 

 ments from October, 1946 to February, 1950, Bismuth Sulfite Agar and S S Agar 

 permitted the highest number of specific isolations of S. puilorum and S. gal- 

 linarum. These favored selective media suppressed the growth of coliform or- 

 ganisms. Following enrichment of the specimens in Selenite Broth streaking 

 on Bismuth Sulfite Agar gave the largest number of positive isolations, followed 

 t)y S S Agar and then MacConkey Agar. Selenite Broth yielded a higher number 

 of successful isolations on follow-up media than did Tetrathionate Broth. The 

 highest percentage of organisms were isolated from the ovary, followed by gall 

 jbladder, peritoneum, oviduct, intestines and pericardial sac in the order listed. 



The outstanding selectivity of Bacto-S S Agar permits the use of heavy inoculaj 



