Fifty-four algal species were tested for cross-reaction in the American Society for Testing and Materials Giardia/Cryptosporidium indirect immunofluorescence assay, and 24 showed some degree of fluorescence. Two species, Navicula minima and Synechococcus elongatus, exhibited a bright apple green fluorescence. The addition of goat serum to the assay mixture blocked the fluorescence of most nontarget organisms tested and also decreased the background fluorescence. Goat serum did not interfere with the fluorescence of Giardia cysts or Cryptosporidium oocysts or the identification of cyst and oocyst internal structures.

The use of propidium iodide, whose uptake indicates cell death or damage, was investigated to assess the viability of heat-inactivated and chemically inactivated Giardia muris cysts. This was done by comparing propidium iodide staining with excystation. We first determined that propidium iodide could be used with an immunofluorescence detection procedure by showing that the percentages of Giardia lamblia cysts stained with this dye before and after subjecting them to a fluorescence detection method were similar. G. muris cysts were then exposed to heat (56 degrees C), 0.5 to 4 mg of chlorine per liter (pH 7.0, 5 degrees C), 0.1 to 10 mg of a quaternary ammonium compound per liter, or 2 mg of preformed and forming monochloramine per liter (pH 7.2, 18 to 20 degrees C). A good positive correlation between percent propidium iodide-stained cysts and lack of excystation was demonstrated for G. muris cysts exposed either to heat or to the quaternary ammonium compound. However, no significant correlation between absence of excystation and propidium iodide staining was found for cysts exposed to chlorine or monochloramines. These results demonstrate that the propidium iodide staining procedure is not satisfactory for determining the viability of G. muris cysts exposed to these two commonly used drinking water disinfectants.

The inability to detect the presence of viable Helicobacter pylori bacteria in environmental waters has hindered the public health community in assessing the role water may play in the transmission of this pathogen. This work describes a cultural enrichment method coupled with an H. pylori-specific PCR to identify these bacteria in water. While far from perfected at the present time, this represents an exciting new approach to studying the significance of water as a transmission mechanism for H. pylori. Evidence is presented that indicates culturable H. pylori bacteria were found using this enrichment/PCR method in a local groundwater source. Methode zum Nachweis lebensfähiger Helicobacter pylori in GrundwasserDa man bisher nicht in der Lage war, die Anwesenheit lebensfähiger Helicobacter pyloriBakterien in Proben aus der aquatischen Umwelt nachzuweisen, konnte die Rolle des Wassers bei der Übertragung dieses Krankheitserregers nicht eingeschätzt werden. In der vorliegenden Arbeit wird eine Methode zur Anreicherungskultivierung mit anschließender Identifizierung mittels H. pylori-spezifischer PCR (Polymerase-Kettenreaktion) beschrieben. Obwohl die Methode zum jetzigen Zeitpunkt noch nicht ausgereift ist, eröffnet sie doch vielversprechende Möglichkeiten, die Bedeutung des Wassers als Übertragungspfad für H. pylori zu bewerten. So fanden sich Hinweise auf kultivierbare H. pylori-Bakterien in einer örtlichen Grundwasserprobe.

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