SOME ATYPICAL COLON-AEROGENES FORMS 

 ISOLATED FROM NATURAL WATERS 



MARGARET C. PERRY and W. F. MONFORT 

 Received for publication July 6, 1920 



Attempts to bring cultures isolated from routine water samples 

 in the laboratory of the Illinois State Water Survey within the 

 tentative classification of the committee of the American Public 

 Health Association (1917) reveal certain inadequacies of the 

 scheme, some of which have been previously noted in the litera- 

 ture without emphasis. 



ANOMALOUS METHYL RED-VOGES-PROSKAUER REACTIONS 



Correlation of the methyl red reaction with the Voges-Pros- 

 kauer reaction has been adjudged almost complete for low ratio 

 organisms; but for high ratio types, a very considerable number 

 of exceptions have been noted. 



Berrier, McCrady and Lafreniere (1916), applying these tests 

 to 450 organisms isolated from feces, city sewage and grains, 

 found the Voges-Proskauer and methyl red tests to agree com- 

 pletely with the generally accepted standard tests for Bad. coli 

 organisms when applied to 197 strains from human feces, except 

 in one instance. Applied to grain and sewage cultures the cor- 

 relation was found in 80 per cent of the cases. 



Levine (1916) cites a small group of organisms isolated from 

 soil, resembling Bad. aerogenes with respect to gas formation 

 from various carbohydrates, etc., which did not give the Voges- 

 Proskauer reaction and were neutral to methyl red after three 

 days' incubation at body temperature. Some did not give the 

 Voges-Proskauer reaction and were not alkaline to methyl red 

 until the fifth or seventh day of incubation. These resemble 

 closely a form described by MacConkey, who records the Voges- 

 Proskauer reaction as positive or negative. 



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