ISO 19250 (2013) medium: RVS

Media control Water quality 

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

  • Qualitative control of Productivity

  • Best Practice RVS

    Qualitative control of Selectivity of liquid medium, mixed culture

    1. Use a quantitative reference material or test suspension with a known number of Salmonella Enteritidis and Salmonella Typhimurium 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 (41,5 ± 1) °C for (24 ± 3) h.
    4. Remove 10 µl and streak to a plate of specific medium for the target organism.
    5. Incubate at (41,5 ± 1) °C for (24 ± 3) h.
    6. Growth of target microorganisms should reach "> 10 colonies on XLD or other medium of choice" with a characteristic reaction of: Characteristic colonies according to each medium (see standard).

    Control strain WDCM number Incubation Criteria Characteristic reaction
    Salmonella Enteritidis (41,5 ± 1) °C for (24 ± 3) h > 10 colonies on XLD or other medium of choice Characteristic colonies according to each medium (see standard)
    + Salmonella Typhimurium
    + Escherichia coli or
    + Pseudomonas aeruginosa
    The best practice for Qualitative control of Productivity for media control of 'RVS' is based on the data displayed in this table according ISO 11133.
  • 1 Qualitative control of Selectivity man

  • Best Practice RVS

    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.
    2. Inoculate one tube of test medium with >103 cells of non-target organisms.
    3. Incubate at (41,5 ± 1) °C for (24 ± 3) h.
    4. Remove 10 µl and streak to a plate of reference medium (TSA).
    5. Incubate at (41,5 ± 1) °C for (24 ± 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 (41,5 ± 1) °C for (24 ± 3) h Partial inhibition ≤ 100 colonies on TSA Growth
    The best practice for Qualitative control of Selectivity for media control of 'RVS' is based on the data displayed in this table according ISO 11133.
  • 2 Qualitative control of Selectivity man

  • Best Practice RVS

    Qualitative control of Selectivity of liquid medium, single culture

    1. Use a quantitative reference material or test suspension with a known number of Enterococcus faecalis.
    2. Inoculate one tube of test medium with >103 cells of non-target organisms.
    3. Incubate at (41,5 ± 1) °C for (24 ± 3) h.
    4. Remove 10 µl and streak to a plate of reference medium (TSA).
    5. Incubate at (41,5 ± 1) °C for (24 ± 3) h.
    6. Growth of non-target microorganisms should comply with the criteria: "< 10 colonies on TSA".

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Enterococcus faecalis or TSA (41,5 ± 1) °C for (24 ± 3) h < 10 colonies on TSA < 10 colonies on TSA
    The best practice for Qualitative control of Selectivity for media control of 'RVS' is based on the data displayed in this table according ISO 11133.