Volume s1-21, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



A strain of with a mixed undetermined flora produced cysts for a period of three months and then ceased to do so. A second strain, growing with three separate species of bacteria, produced cysts in Erlenmeyer flask cultures for an indefinite period of time; a sub-strain developed by micro-isolation and seeded with NIH 563 and failed to produce cysts.

Cysts of underwent marked loss of viability during storage for 19 days in physiologic saline at 10°C.

During the micro-isolation operation, exposure to a 1:5,000 solution of mercuric chloride in physiologic saline lowered the viability of cysts.

Cysts were freed by micro-isolation from bacteria and grown in pure culture with each of the following bacteria: , an actinomyces-like organism, NIH 563, , and . The cultural characteristics of the amoebae changed greatly with each change in the flora.

Ten cysts per tube were selected at random with the micro-isolation apparatus, freed from bacteria, planted into 564 tubes of the medium of Boeck and Drbohlav, and seeded either with or NIH 563. Twenty per cent of tubes seeded with the latter bacterium developed amoebae but none seeded with the former became positive. Changes from the normal in morphological and cultural characteristics of the strain of were demonstrated and may have accounted for the results shown.

Twenty-five cysts per tube were selected by micro-isolation with the aid of the neutral red staining technique from lots of cysts having 75 per cent in the tetra-nucleate stage; the cysts were freed from bacteria and then seeded either with NIH 563 or an actinomyces-like organism. With one series of micro-isolations, the yield of positive amoeba cultures was as high as 80 per cent of the tubes planted.

Cysts of from fresh human stools were selected by micro-isolation technique, freed from bacteria and planted into Boeck and Drbohlav's medium with single species of bacteria. Amoeba cultures developed from these cysts.

The addition to the medium of Boeck and Drbohlav of bacteria killed at 56°C. and 100°C., or sterile filtrates of lyophilized bacteria, or products of the tryptic and pancreatic digestion of coagulated egg failed in each case to support growth of in cultures free from bacteria.


Article metrics loading...

The graphs shown below represent data from March 2017
Loading full text...

Full text loading...

  • Received : 10 Jan 1941

Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error