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After the colonies were identified using 16S rRNA analysis, the population of total coliforms detected by MI agar, Chromocult® coliform agar, and Compass CC agar were classified per genera. Results showed that the population detected was more extended for MI agar and Chromocult® coliform agar (nine and seven different genus, respectively) than Compass CC agar (only four different genus; Table 2). Our results also showed a larger population within the species detected by each method (data not shown). Like the Maheux et al. (2008) study, the results of the present study showed the lack of correlation between test methods based on the same enzymatic principle to recognize a strain as non-E. coli total coliform. Indeed, our results showed that there is a weak correlation between the three methods tested either within the same genera or the same species. Since all colonies of the present study were isolated from the same water sample and treated in the same way (filtration, incubation, etc.), the difference observed in the population of strains detected by each method cannot just be attributed to environmental factors. The composition of each medium is also involved. This result is in accordance with Maheux et al. (2014b), who showed that the E. coli detection is influenced by the composition of the medium.

Table 2

Population of total coliform per genera detected by MI agar, Chromocult® coliform agar, and Compass CC agar from 2 μL of sewage water

MI agar
Chromocult® coliform agar
Compass CC agar
SpeciesNo.%SpeciesNo.%SpeciesNo.%
Escherichia spp. 14 31.1 Klebsiella spp. 11 28.2 Escherichia spp. 14 63.6 
Enterobacter spp. 10 22.2 Enterobacter spp. 10 25.6 Klebsiella spp. 22.7 
Klebsiella spp. 13.3 Escherichia spp. 23.1 Citrobacter spp. 9.1 
Yersinia spp. 11.1 Citrobacter spp. 12.8 Enterobacter sp. 4.5 
Citrobacter spp. 8.9 Yersinia spp. 5.1    
Kluyvera spp. 6.7 Kluyvera sp. 2.6    
Rahnella sp. 2.2 Raoultella sp. 2.6    
Raoultella sp. 2.2       
Serratia sp. 2.2       
Total 45 100.0  39 100.0  22 100.0 
MI agar
Chromocult® coliform agar
Compass CC agar
SpeciesNo.%SpeciesNo.%SpeciesNo.%
Escherichia spp. 14 31.1 Klebsiella spp. 11 28.2 Escherichia spp. 14 63.6 
Enterobacter spp. 10 22.2 Enterobacter spp. 10 25.6 Klebsiella spp. 22.7 
Klebsiella spp. 13.3 Escherichia spp. 23.1 Citrobacter spp. 9.1 
Yersinia spp. 11.1 Citrobacter spp. 12.8 Enterobacter sp. 4.5 
Citrobacter spp. 8.9 Yersinia spp. 5.1    
Kluyvera spp. 6.7 Kluyvera sp. 2.6    
Rahnella sp. 2.2 Raoultella sp. 2.6    
Raoultella sp. 2.2       
Serratia sp. 2.2       
Total 45 100.0  39 100.0  22 100.0 

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