MEDIA FOR AEROMONAS SPP, PLESIOMONAS-SHIGELLOIDES AND PSEUDOMONAS SPPFROM FOOD AND ENVIRONMENT

Several media are proposed particularly for the detection of Aeromonas spp. but also for Plesiomonas shigelloides and Pseudomonas spp. Some are for general purposes and others specifically for the examination o f clinical, environmental or food samples. All media are selective, du e to antibiotics, bile salts, dyes and other selective agents, as well as differential, primarily based on the ability of the microorganisms to ferment/not ferment carbohydrates. As with all selective media, th e recovery of stressed cells is sometimes prevented and the competing flora is not always completely inhibited so that confirmatory tests ne ed to be made on presumptive positive colonies. The choice of a specif ic medium for isolation of Aeromonas spp. will always depend on the ty pe of sample to be examined and whether the investigator needs qualita tive detection or quantitative recovery. The best medium for quantitat ive estimation of Aeromonas spp. from food and environmental samples s eems to be starch ampicillin agar (SAA), though others might be recomm ended. There is a need for a comparative study including Rippey Cabell i agar (mA), ampicillin bile salts inositol xylose (MIX) agar, ampicil lin dextrin agar (ADA), dextrin fuchsin sulphite agar (DFS) and starch glutamate ampicillin penicillin C-glucose agar (SGAP-10C) in addition to SAA. For routine analysis of environmental and food samples for P. shigelloides, spread plating on inositol brilliant green bile salts ( IBB) and plesiomonas (PL) agars is recommended. For Pseudomonas spp., CFC agar permits quantitative recovery of both pigmented and non-pigme nted strains from food and environmental samples, whilst at the same t ime inhibiting most other organisms.