Water bacteriology analytical laboratories need to use control organisms (negative - and positive+), to get ISO 17025 accreditation. For this purpose, E coli can be used as total coliform (+) as well as E Coli (+) . As most of the E coli strains are non-pathogenic and can be used safely.
Pseudomonas aeruginosa is used as total coliform (-) and E. coli (-) while, Klebsiella pneumoniae is used for total coliform (+) and E.coli (-)
As Pseudomonas aeruginosa and Klebsiella pneumonia are pathogens, to avoid risk of infections in water analysis laboratories, to use as control organisms, can any expert Microbiologist recommend non-pathogenic strains of these organism or any other alternative non-pathogenic organisms suitable as control bacteria?
Pseudomonas aerugiunosa is a very poor control for a non-coliform, because it is not even a member of the same family any more (of course, it non-coliform then, but is also very far apart in all other properties form coliforms!). Therefore, you should look for non-pathogenic species within the Enterobacteriaceae, A possible choice may be Shimwellia blattae (formerly Escherichia blattae), which should be non-coliform (no lactose degradation according to Bergey's Manual). For positive controls, there are many non-pathogenic strains of E. coli available (e.g. the original strain K12).
Dear Johann Heider, Thank you very much for your valuable comments and contribution.
Hemachandra
On ATCC website you can choose a lot of non-pathogenic E. coli strains. Search for biosafety level 1 (BSL1). Under the link below, you shall find such query. You can also choose from standards from different countries and organisations, and the search engine will show you which one should be suitable. You should also read product information to see the recommended application of selected strain.
https://www.lgcstandards-atcc.org/search#q=escherichia%20coli&sort=relevancy&f:biosafetyLevelFacet=[1]
Good luck!
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