ISO 19250 (2013) medium: MKTTn broth

Media control Water quality 

Microorganisms and performance criteria for selective isolation media 'MKTTn broth' used in Water quality  microbiology according to ISO 11133.

  • Qualitative control of Productivity

  • Best Practice MKTTn broth

    Qualitative control of Selectivity of liquid medium, mixed culture

    1. Use a quantitative reference material or test suspension with a known number of Salmonella Typhimurium and Salmonella Enteritidis and Escherichia coli.
    2. Inoculate one tube of test medium with < 100 cells of target microorganisms and with >103 cells of non-target organisms.
    3. Incubate at 36 °C ± 2 °C for 24 h ± 3 h.
    4. Remove 10 µl and streak to a plate of specific medium for the target organism.
    5. Incubate at 36 °C ± 2 °C for 24 h ± 3 h.
    6. Growth of target microorganisms should reach ">10 characteristic colonies on XLD agar or other medium of choice" with a characteristic reaction of: Characteristic colonies according to each medium (see ISO 6579).

    Control strain WDCM number Incubation Criteria Characteristic reaction
    Salmonella Typhimurium 36 °C ± 2 °C for 24 h ± 3 h >10 characteristic colonies on XLD agar or other medium of choice Characteristic colonies according to each medium (see ISO 6579)
    + Salmonella Enteritidis
    + Escherichia coli or
    + Pseudomonas aeruginosa
    The best practice for Qualitative control of Productivity for media control of 'MKTTn broth' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Selectivity

  • Best Practice MKTTn broth

    Qualitative control of Selectivity of liquid medium, single culture

    1. Use a quantitative reference material or test suspension with a known number of Escherichia coli and Enterococcus faecalis.
    2. Inoculate one tube of test medium with >103 cells of non-target organisms.
    3. Incubate at 36 °C ± 2 °C for 24 h ± 3 h.
    4. Remove 10 µl and streak to a plate of reference medium (TSA).
    5. Incubate at 36 °C ± 2 °C for 24 h ± 3 h.
    6. Growth of non-target microorganisms should comply with the criteria: "Partial inhibition ≤100 colonies on TSA".

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Escherichia coli or TSA 36 °C ± 2 °C for 24 h ± 3 h Partial inhibition ≤100 colonies on TSA Partial inhibition ≤100 colonies on TSA
    + Enterococcus faecalis or
    The best practice for Qualitative control of Selectivity for media control of 'MKTTn broth' is based on the data displayed in this table according ISO 11133.