Lecture 14 Flashcards
How can Enterococci/Faecal Streptococci be enumerated from a water sample?
To enumerate Enterococci from a water sample, Membrane Enterococcus Agar (MEA) is used. It contains TTC, which Enterococci reduce to the insoluble red compound formazan. E. faecalis reduces TTC quickly and will appear dark red.
What confirmation agar and other tests are used to detect and confirm Enterococci/Faecal Streptococci as indicator organisms in water and food?
Bile Aesculin Agar (BAA) is used to confirm the presence of Enterococci. Additional tests include Gram staining and the catalase test. Enterococci are Gram-positive cocci that occur in pairs or short chains and are catalase-negative.
What are the limitations of using Enterococci/Faecal Streptococci as indicators
Enterococci/Faecal Streptococci have high resistance to environmental conditions, making them somewhat unreliable as indicators of faecal pollution. They may survive adverse conditions longer than pathogens. Therefore, they should be used in conjunction with total viable counts or coliform/E. coli counts.
