Pril-ampicillin-dextrin-ethanol agar for the isolation and quantification of Aeromonas spp. from polluted environmental waters

Abstract

Several selective media were evaluated for their suitability for the isolation and quantification of mesophilic Aeromonas species from naturally polluted samples. Satisfactory recoveries were obtained with most of them but only when densities of background microflora were low. When analysed samples were from highly polluted waters, results were inconsistent because they did not give quantitative recovery of mesophilic aeromonads or they did not permit ready differentiation of Aeromonas species from the competitive bacteria. A new medium was developed on the basis of the combination of some positive aspects of several published media, pril-ampicillin-dextrin-ethanol (PADE) agar. The medium employs dextrin (Merck 3006) as a fermentable carbohydrate and pril, ampicillin and ethanol as inhibitory substances. Recovery on PADE agar from suspensions of 15 tested strains of Aeromonas prepared from pure cultures was excellent. The confirmation rate of typical colonies designated Aeromonas spp. isolated from polluted samples exceeded 90%. Recoveries of stressed aeromonad strains on both PADE agar and a non-selective medium (TSA) did not show any significant difference (P > 0.05). PADE agar was more reliable for quantitative recovery of mesophilic aeromonads than the other selective media because of its characteristics: (i) inhibition of the swarming of Proteus, (ii) good reduction of the background, (iii) inhibition of the over growth of Klebsiella spp., (iv) absence of NaCl makes it unfavourable for the growth of halophilic vibrios, (v) combination of two pH indicators permitted a very easy differentiation between Aeromonas colonies and the competitive microflora. The medium can also be used for isolation of aeromonads from various sources by membrane filtration.

Population dynamics ofAeromonasspp. in an urban river watershed

“…Several investigators have shown that the degree of faecal pollution may play an important role in determining the species composition and population dynamics of Aeromonas (Schubert 1991; Araujo et al . 1991; Stecchini & Domenis 1994; Imziln et al . 1997).…”

Occurrence of Antimicrobial Resistance in Fish-Pathogenic and Environmental Bacteria Associated with Four Danish Rainbow Trout Farms

“…Moreover, all samples from fish and sediment from the pond were routinely plated on selective media designed for the recovery of Y. ruckeri (ribose-ornithindextrin agar [ROD] [13]), A. salmonicida (Coomassie brilliant blue [10]), and Aeromonas hydrophila (Pril-ampicillin-dextrin-ethanol [PADE] agar [21]). Coomassie brilliant blue and PADE agar plates were incubated at 20°C for 2 days, and ROD agar plates were incubated at 20°C for 4 days.…”

Characterisation of potential virulence markers in Aeromonas caviae isolated from polluted and unpolluted aquatic environments in Morocco

“…Some investigators have demonstrated A. caviae to be associated with paediatric gastroenteritis as it has been mostly isolated from diarrhoeal stool specimens especially from children [7^9]. In a previous study, we have observed a variation in Aeromonas concentration and di¡erences in biotypes isolated from aquatic environments of Marrakech, Morocco [10,11]. In Morocco, drinking water is generally sourced from fresh waters (river waters, lakes, etc.).…”

“…The methods used for determination of water chemistry, total viable counts, coliforms and streptococci are described elsewhere [10^12]. The method of isolation and identi¢-cation of Aeromonas strains has been described earlier [11]. Brie£y, 0.1 ml of suitable sample dilutions were spread onto pril-ampicillin-dextrin-ethanol (PADE) agar [11].…”

“…The method of isolation and identi¢-cation of Aeromonas strains has been described earlier [11]. Brie£y, 0.1 ml of suitable sample dilutions were spread onto pril-ampicillin-dextrin-ethanol (PADE) agar [11]. After 24 h of incubation at 37³C, typical Aeromonas colonies were puri¢ed and identi¢ed to phenospecies level [13] and only the strains which did satisfy the biochemical pro¢le of A. caviae were used in this study.…”