AJTMH ASTMH MEMBERSHIP INFORMATION: astmh@astmh.org
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am. J. Trop. Med., s1-21(1), 1941, pp. 63-73
Copyright © 1941 by American Journal of Tropical Medicine

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Snyder, T. L.
Right arrow Articles by Meleney, H. E.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Snyder, T. L.
Right arrow Articles by Meleney, H. E.

The Excystation of Endamoeba Histolytica in Bacteriologically Sterile Media1

Thomas L. Snyder AND Henry E. Meleney
From the Department of Preventive Medicine and Public Health, Vanderbilt University School of Medicine, Nashville, Tennessee

1. A method for obtaining cysts of E. histolytica free of living bacteria is described.
2. These bacteria-free cysts usually excyst when suspended in various media with living bacteria. Excystation of the bacteria-free cysts in the absence of bacteria was observed only in the presence of the reducing agents, cysteine or neutralized thioglycollic acid, or under conditions of reduced oxygen tension produced by aeration with nitrogen gas or by alkaline pyrogallol. With all of these methods, excystation was correlated with a decrease of the oxygen tension of the medium as indicated by the reduction of methylene blue.
3. Excystation of bacteria-free cysts of E. histolytica was observed in a medium containing only inorganic salts (modified Locke's solution).
4. Anaerobic cultures of motile forms of E. histolytica with bacteria showed a greater sensitivity to oxygen than did aerobic cultures.
5. Continued cultivation of the bacteria-free excysted forms has not yet been effected without the addition of living bacteria.
6. On the basis of these observations it was concluded that:
(a) In addition to water and certain salts, a factor usually supplied by living bacteria is required for excystation of bacteria-free E. histolytica cysts. This factor is probably any agent that reduces the oxygen tension of the medium.
(b) Other factors in addition to the above are required for continued cultivation and "normal multiplication" of bacteria-free excysted forms of E. histolytica. These factors are not furnished by heat-killed bacteria. They have not yet been discovered, although a number of nutrient media have been tested.

Received December 9, 1940.
1 Read before the American Society of Tropical Medicine, Louisville, Kentucky, November 13, 1940.

This work was aided by a grant-in-aid from the John and Mary R. Markle Foundation.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1941 by the American Society of Tropical Medicine and Hygiene.