Researchers at the Oceanographic Observatory ("Observatoire océanologique
biologique"*) in Banyuls-sur-Mer, working in
collaboration with industry partners Chemunex**,
EDF, and Indicia Diagnostic have developed a technique to detect pathogenic
amoebae in waters. This method will subsequently be applied to the
real time monitoring of toxic algae in seawater. It should soon replace
traditional diagnosis methods, which are based on microbial cultures.
and sensitive detection of toxic algae is a major health concern due
to food poisoning caused by contaminated shellfish. Currently, two
to three days are required to diagnose the presence of pathogenic
micro-organisms in the water. Direct detection methods such as epifluorescence
microscopy or flow cytometry are faster, but sensitivity is too low.
new protocol for detecting the amoeba Naegleria fowleri based
on immunofluorescence, which is capable of detecting one amoeba in
10 milliliters of water, has been used to monitor the cooling water
of the Civaux nuclear power station and revealed the absence of amoeba
in these waters during summer 2000. An improved method exploiting
magnetic separation is under development to analyze larger volumes
toxic algae such as Alexandrium minutum, Pseudo-nitzschia
multiseries, and Dinophysis spp. are routinely monitored in coastal
waters, but are detected only with difficulty at low sensitivity.
A European program for their detection by solid-phase cytometry is
work has shown that it is possible to diagnose the viability of bacteria
in minutes based on their metabolic activity and membrane integrity
using fluorescent probes. The combination of this viability test and
the specific detection of micro-organisms such as amoebae, algae and
bacteria should enable the identity and viability of pathogenic microbes
to be determined rapidly.
CNRS-University Paris 6.