Aeromonas Agar

Bile Salt Irgasan Brilliant Green Agar

LAB 167

*The selective nature of the medium may mean occasional strains do not grow, or grow poorly.

Description

Aeromonas Agar is a highly selective medium for the isolation of Aeromonas spp. from food, clinical and environmental samples. Based on the selective agents, brilliant green and irgasan, this medium will not inhibit those strains of Aeromonas sensitive to ampicillin used in other media.

Appearance: Purple, Clear gel pH: 7.0 ± 0.2

Method for reconstitution

Weigh 45.5 grams of powder and disperse in 1 litre of deionised water. Allow to soak for 10 minutes, swirl to mix and sterilise by bringing to the boil. Cool to 47˚C, mix well and dispense into Petri dishes.

Inoculation: Faecal specimens: Inoculate surface of medium directly, spreading for single colonies. Samples requiring enrichment: Inoculate alkaline peptone water and incubate at 37˚C for 18-24 hr. Subculture onto Aeromonas Agar, surface spreading for single colonies.

Incubation: Incubate plates aerobically at 37˚C for 18-24 hr. Examine for typical colonies and confirm as Aeromonas spp.

Storage: Poured plates: 7 days at 2-8˚C in the dark (may be extended if moisture tight packaging used).

Minimum Q.C. organisms: Aeromonas hydrophila NCIMB 9240 E. coli NCIMB 50034 (inhibited)

Confirmation

Typical colonies (translucent pink colonies 0.5-3.0mm diameter) should be confirmed as presumptive Aeromonas spp. by performing an oxidase test and inoculating into Hugh & Leifsons O/F medium. Aeromonas spp. will give a positive oxidase reaction and demonstrate both oxidative and fermentative metabolism. Pseudomonas spp. will also be oxidase positive, but do not possess fermentative metabolism. An alternative method is to inoculate triple sugar iron tubes. Aeromonas will typically produce an acid butt (yellow) and an alkaline or unchanged slant (red) whilst Pseudomonas spp. will remain unchanged in both the butt and slant. To fully identify colonies as Aeromonas spp. the above tests should be supported using a proprietary kit such as API 2ONE or Microbact 24E (other products may be available).