Evaluation of several selective media for recovery of Aeromonas hydrophila from polluted waters

Abstract

Eleven media were studied for their suitability in the selective isolation ofAeromonas hydrophila. Preliminary results showed that five of them (inositol-brilliant green-bile salts agar, bile salts-brilliant green agar, Rimler-Shotts agar, xylose-sodium deoxycholate-citrate agar, and dextrin-fuchsin-sulfite agar) allowed the growth of several microorganisms that are usually present in the same samples in which A. hydrophila is found. Six media (mA agar, modified Rimler-Shotts agar, DNase-toluidine blue-ampicillin agar, Pril-xylose-ampicillin agar, MacConkey-trehalose agar, and starch-bile salts agar) were selected for evaluation as recovery selective media on the basis of their efficiency in the isolation of A. hydrophila from natural water samples. mA agar showed the best recovery rate and also an acceptable specificity, but its selectivity was low. Another medium that can be considered is DNase-toluidine blue-ampicillin agar, which showed good accuracy, but its specificity was low.

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

“…Moreover, xylose which was used as a fermentable carbohydrate in this medium gave less differentiability between ,.leromonas isolates and some other bacteria such as pseudomonads. Such results agree with those of other workers in which xylose was used as a differentiating carbohydrate and ampicillin as an inhibitory substance (Havelaar et al 1987;Arcos et al 1988;Holmes and Sartory 1993). The poorest recovery of aeromonads obtained with PXA agar can be explained by the effect of toxic products resulting from xylose (Havelaar et al 1987).…”

“…hydrophila strains examined were sensitive to novobiocin. This effect was also pointed out by other authors who found that media which contained sodium novobiocin suppressed the growth of sensitive .leromonas species from a variety of sources (Palumbo et al 1985;Arcos et al 1988;Cahill and MacRae 1992 lower rate for Aer. sobria strains.…”

“…Some authors (Havelaar et al 1987;Kll.0'c hel 1989) have also repo rted the poor di ffe rentiati on of Aeromonas species fro m backgroun d fl ora on DFS aga r. Indeed, on this medi um the co lour of the coloni es changed upon ex posure to light and air. l• urthermore, Arcos et al (1988) have noted that DFS aga r inhibi ted a hi gher percentage of Aer. hydrophila strai ns, all owin g the growth of mi cro-organisms such as K lehsiella and Enterobacter.…”

“…However, most of them were not considered fully satisfactory (Havelaar et ul. 1987;Arcos et al 1988;Kmchel 1989;Ribas et al 1991;Cahill and MacRae 1992), because they showed poor recovery rates of *.leromunas spp. or the); did not allow better discrimination of presumptive >.leromonus strains.…”

Analysis of the interaction of Aeromonas caviae, A. hydrophila and A. sobria with mucins

“…Other experiments were done with Aeromonas cells grown in minimal salt plus casamino acid broth (M9/ CA) [16], chemically de¢ned broth (CDB) [17], marine broth adjusted to 0.15 M NaCl (2216B) [18], MH broth (MH) [19], minimal medium broth adjusted to 0.15 M NaCl (MMB) [20], CIB-4 broth [19], peptone water (PW), colonization factor antigen broth (CFAB), brain heart infusion broth (BHI), and with cells grown on tryptic soy agar (TSA), Gab-Camp agar base containing 10% v/v fetal calf serum (GC), MacConkey-trehalose agar (McCT) [21], blood agar base containing 5% v/v de¢brillated horse blood (HDBA), brain heart infusion agar (BHIA), colonization factor antigen agar (CFA), Vibrio cholerae selective agar medium (CLED), and nutrient agar containing 1% Tween-20 (T20).…”