Legionella BCYE-cys supplement ISO

Technique

Collect and prepare diluted samples and volumes as needed according to the specifications, guidelines, standard government regulations and/or results.

Reconstitute the vial with the attached sterile diluent and aseptically add to 500 mL of basal medium (Legionella BCYE Agar Base), previously melted and cooled to 50 °C. Mix gently and pour into Petri dishes.

The inoculated plates are allowed to stand until the inoculum is absorbed and then incubated, inverted, at 36 ± 2 °C for 4-10 days. To ensure that the atmosphere is moist enough, it is not recommended to put a pan of water in the incubator and fill it, if necessary, each time the plates are examined. Incubation in an air atmosphere with 2.5% (v/v) of CO₂ can be very beneficial for the growth of some legionella, but not critical.

The plates are examined with an adequate magnifier at least three times at intervals of 2, 3, 5 days during the incubation period, as legionella are slow growing and may be masked by the growth of other microorganisms.

Legionella colonies cannot grow in this medium, due to the lack of cysteine.

Necessary amount for 500 mL of complete medium:

Reconstitute the original freeze-dried vial by adding 1 vial with 9 mL of sterile solvent.

Physical/chemical control

Microbiological control

Add 1 vial to 500 mL of medium base. DO NOT HEAT once supplemented.

Inoculate 30-300 CFU (productivity), 1000-10,000 CFU (selectivity).

Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.

Aerobiosis. Incubation at 36 ± 2 °C. Reading 2-5 days.

Sterility control

Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.

Check at 7 days after incubation in same conditions.

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