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.
School of Applied Sciences, Robert Gordon University, Aberdeen, UK.
J P
JP
Landre
A A
AA
Gavriel
A J
AJ
Lamb
D000333:Aeromonas / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005189:False Positive Reactions; D014871:Water Microbiology; D014881:Water Supply