ABSTRACT
Two different procedures were employed for detecting Salmonella spp. in environmental water samples: a rapid method (enrichment in Salmosyst Broth and plating in Rambach Agar-Merck) and a longer assay (pre-enrichment in Buffered Peptone Water, enrichment in Selenite-Cistyne Broth and plating in Brilliant Green Agar-Difco). The efficiency of microbiological tests was measured by the following criteria: recovery, sensitivity and specificity. The results analysed by the Kendall concordance coefficients demonstrated that the rapid method appeared more effective even if poorly specific.
Subject(s)
Bacteriological Techniques , Salmonella/isolation & purification , Water Microbiology , Colony Count, Microbial , Fresh Water , Humans , Italy , Sensitivity and SpecificityABSTRACT
Tests were carried out to evaluate the efficiency of various combinations of selective enrichment and plating techniques using pure cultures of Listeria monocytogenes, Listeria seeligeri and Listeria innocua in suspension and samples of surface water. The best yields for the various Listeria spp. were obtained after a single passage in LEB (Oxoid) or LEB Buffered (Oxoid) and after using Palcam and Oxford agar (Oxoid). Palcam agar was, however, shown to be the most efficient means of detecting the Listeria spp. in the natural water samples.
Subject(s)
Bacteriological Techniques , Listeria/isolation & purification , Water Microbiology , Agar , Culture Media , Listeria/classification , Listeria/growth & development , Listeria monocytogenes/classification , Listeria monocytogenes/growth & development , Listeria monocytogenes/isolation & purification , SerotypingABSTRACT
The quantity of Listeria species was determined in 49 samples of various types of water (river, brackish water, urban wastewater). Twenty nine strains of Listeria were isolated. These were mainly identified as Listeria monocytogenes (72,4%), but Listeria innocua, Listeria grayi, Listeria ivanohovii and Listeria welshimeri were also present. With the exception of water taken from the estuary, 74.4% of samples contained Listeria in mean concentrations of between 2 MPN/100 ml and 1320 MPN/100 ml in fresh surface water and untreated sewage respectively.
Subject(s)
Listeria/isolation & purification , Water Microbiology , Animals , Enterobacteriaceae/isolation & purification , Feces/microbiology , Fresh Water , Humans , Italy , Listeria monocytogenes/isolation & purification , SewageABSTRACT
A comparison was made of three different growing media already proposed by some authors for the recovery of Aeromonas hydrophila in environmental water samples of various origins. The media tested were Rippey and Cabelli m Aeromonas agar, Rimler-Shotts agar and the Ryan Aeromonas Base Medium with the addition of ampicillin. The efficiency of the three media was evaluated on the basis of the following reference criteria: accuracy, selectivity and specificity. The results obtained, analyzed by calculating the Kendall concordance coefficients, demonstrated that m Aeromonas agar is the most suitable media for quantitative recovery of Aeromonas hydrophila from surface water samples even if a reduction in the total heterotrophic load of 3-logs was never obtained with this medium.
