False-positive coliform reaction mediated by Aeromonas in the Colilert defined substrate technology system.
The Colilert defined substrate technology system allows specific, one-step detection of both coliforms and Escherichia coli while claiming to suppress the influence of non-coliform heterotrophs. The Colilert assay was examined in order to determine whether organisms from the genus Aeromonas could interfere and cause production of a false-positive coliform result as aquatic Aeromonas are known to constitute a fraction of the heterotrophic population found in drinking water. Results obtained clearly demonstrate that Aeromonas sp. can elicit a positive coliform type reaction at very low densities. Cell suspensions as low as 1 x 10(1) cells 10 ml-1 were observed to yield a positive reaction using Colilert reagent 4 weeks short of shelf-life expiry. Use of aged Colilert for monitoring water quality could lead to overestimation of coliforms as Aeromonas have been identified in many treated drinking water supplies.
Landre
J P
JP
School of Applied Sciences, Robert Gordon University, Aberdeen, UK.
Gavriel
A A
AA
Lamb
A J
AJ
D000333:Aeromonas / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005189:False Positive Reactions; D014871:Water Microbiology; D014881:Water Supply