Association of bacteria with metacercarial cysts of Echinostoma caproni.

Echinostoma caproni metacercarial cysts often need to be stored for several months to a year to meet laboratory requirements. This study examined the bacteria associated with encysted metacercariae stored at 4 degrees C. Bacterial assemblages from the kidney-pericardial region of uninfected snails and assemblages from the site of metacercarial infection in Biomphalaria glabrata were determined. Four species of Gram-negative rods were isolated and identified from the stored cysts to species or genus as Pseudomonas sp., Alcaligenes sp., Enterobacter cloacae, and Aeromonas hydrophila. Gram-positive rods were also isolated and included small slender rods (alpha hemolytic), small coccobacilli (gamma hemolytic), and small rods that exhibited gamma hemolysis. Accumulation of these bacteria on the surface of encysted metacercariae probably contributed to a decreased cyst viability of E. caproni.