When doing bacteriological sampling for diagnostic purposes, it is important that the sample contains disease related bacteria and not just environmental bacteria. Preferably, take samples from moribund or secondarily recently dead fish.
Various bacteria will have different growth preferences. In general, we recommend blood agar for freshwater kept fish and blood agar with salt for seawater kept fish. Please, contact the laboratory to discuss which type of cultivation media is most suitable.
To ensure the identification of the correct dominating disease related agent, samples should be collected from 5-6 fish.
Recommended equipment:
• Scalpel
• Scissors
• Tweezers
• Plastic inoculation loop (can be ordered from Blue Analytics)
If a metal inoculation loop is used a gas burner should be used to sterilise the inoculation loop.
• Agar plates (can be ordered from Blue Analytics)
• Waterproof marker for marking the agar plates.
• Packaging for submission
• Cooling element
Sampling procedure:
When sampling for a systemic bacterial agent, the head kidney is the primary sampling tissue. Open the fish and gently move the intestines to the side, thereby exposing the swim bladder. With the tweezer pull the swim bladder to the side and thereby exposing the kidney without touching it. Push the inoculation loop through the kidney capsule and streak out the sample on a suitable agar plate.
When sampling from wounds the inoculation loop should be moved in beneath the edge of the lesion without touching the area of the lesion directly exposed to the water environment.
Streaking out on agar plates should be performed as shown on figure 1 to achieve a diluting effect. This is to make it easier to pick single colonies for further typing.
Storage and submission:
• The agar plates are labelled and secured (e.g with a rubber band, or parafilm).
• The agar plates must be shipped refrigerated and in a protective packaging.
• The tracking number for the shipment is to be sent to: mottak@blueanalytics.no.
• By agreement, samples can also be delivered at Blue Analytics.
• The completed sample submission form should be placed in a plastic bag and must always be included in the package. Sample submission form histopatology and bacteriology or Sample submission form MLVA Moritella viscosa
Delivery address:
Blue Analytics AS
Kong Christian Frederiks plass 3, entrance A, 1st floor
5006 Bergen
Norway
Figure 1 Streak out the sample on 1/3 of the plates shown (1). Thereafter perform a 90-degree streak out as shown for 2 and 3 this to achieve a diluting effect.