Summary
Experimental infections of the hamster liver were carried out with five strains from patients with clinical amoebiasis and ten strains from asymptomatic carriers. Inocula of comparatively small size (12000–36000 amoebae) were injected under the liver capsule.
1. The virulence of the patient strains varied from 21–96% (hamsters with necrotic abscess/hamsters inoculated) and declined sharply within 7–15 weeks after elimination of the associatedb acterial flora. The virulence of the carrier strains varied from 0–100%, probably fluctuating with changes in the concomitant bacterial flora (Table 1).
2. The interrelation between size of inoculum, period of bacteria-free growth, and virulence was demonstrated with a Crithidia-associated patient strains (Table 2).
3. A patient strain showed a faster decrease of virulence during axenic than in Crithidia-associated cultivation (Table 3).
4. Two successive passages through hamster liver resulted in a marked increase of virulence of two bacteria-free strains, lasting for several months (Table 4).
5. A significant enhancement of virulence of Crithidia-associated and axenic amoebae by reassociation with a mixed bacterial flora during two weeks, followed by elimination of the bacteria, was demonstrated with two strains. The restored virulence was lost again within a few weeks (Table 5).
6. The virulence of an attenuated patient strain did not become manifest by adding large numbers of dead amoebae to the inoculum (Table 6).
7. The pathology of the different lesions caused in the hamster liver by the amoebae is described, including one of a granulomatous type, frequently found after inoculation with bacteria-free amoebae.
8. In an atempt to explain the occurrence of strains differing in pathogenicity an hypothesis is put forward based on the idea of selection of virulence and avirulent amoebae.
Similar content being viewed by others
References
Aguirre-Garcia, J., Calderón, P., Tanimoto-Weki, M.: Examen histopatologico de las lesiones hepáticas en hamsters inoculadas con cultivo axenico de Entamoeba histolytica. Arch. Inv. Med. (Mex.) 3, Suppl. 2, 341–348 (1972)
Bos, H. J.: The problem of pathogenicity in parasitic Entamoeba. Acta Leidensia 40, 1–112 (1973)
Bos, H. J.: Monoxenic and axenic cultivation of carrier and patient strains of Entamoeba histolytica (in press)
Diamond, L. S.: Improved method for the monoxenic cultivation of Entamoeba histolytica, Schaudinn 1903, and Entamoeba histolytica-like amoebae with trypanosomatids. J. Parasit. 54, 715–719 (1968a)
Diamond, L. S.: Techniques of axenic cultivation of Entamoeba histolytica, Schaudinn 1903, and Entamoeba hystolytica-like amoebae. J. Parasit. 54, 1047–1056 (1968b)
Diamond, L. S., Bartgis, I. L.: Axenic cultures for in vitro testing of drugs against Entamoeba histolytica. Arch. Inv. Med. (Mex.) 2, Suppl. 1, 339–348 (1971)
Diamond, L. S., Phillips, B. P., Bartgis, I. L.: Virulence of axenically cultivated Entamoeba histolytica. Arch. Inv. Med. (Mex.) 4, Suppl. 1, 99–104 (1973)
Gögler, H., Knight, R.: The effect of hepatic injury upon the development of amoebic liver abscess in hamsters. Ann. trop. Med. Parasit. 68, 177–185 (1974)
Gopal Rao, V., Padma, M. C.: Some observations on the pathogenicity of strains of Entamoeba histolytica. Trans. roy. Soc. Trop. Med. Hyg. 65, 606–616 (1971)
Honigberg, B. M.: Mechanisms of pathogenicity among parasitic protozoa. Progress in Protozool. (Proc. 4th Int. Congr. Protozool., Clermont-Fd.), VIII–XXXIX (1973)
Jones, W. R.: Experimental attempts to induce drug-resistance in Entamoeba histolytica. Exp. Parasit. 1, 118–128 (1952)
Kasprzak, W.: Biological characteristics of the strains of Entamoeba histolytica from the carriers in Poznán Palatinate. Acta parasit. pol. 9, 211–229 (1961)
Krupp, I. M., Faust, E. C.: Parasitologic surveys in Cali, dep. del Valle, Colombia. IV. Experimental studies in guinea pigs of the pathogenic capacity of Entamoeba histolytica from infected persons in Ward Siloé Cali. J. Parasit. 45, 449 (1959)
Lupasco, G., Silard, R., Soresco, A.: Experimental investigations concerning reacquirement of pathogenicity by a strain of Entamoeba dysenteriae. Arch. roum. Path. exp. 27, 269–274 (1968)
Michel, R., Westphal, A.: Extraintestinale Infektionsversuche beim Goldhamster mit Entamoeba histolytica aus bakteriefreien Kulturen. Z. Tropenmed. Parasit. 21, 230–239 (1970)
Neal, R. A.: The pathogenicity of Entamoeba histolytica. Proc. 6th Int. Congr. Trop. Med. Mal. 3, 350–360 (1958)
Neal, R. A.: Pathogenesis of amebiasis. Bull. N.Y. Acad. Med. 47, 462–468 (1971)
Neal, R. A., Vincent, P.: Strain variation in Entamoeba histolytica. II. The effect of serial liver passage on the virulence. Parasitology 46, 173–183 (1956)
Phillips, B. P.: Entamoeba histolytica: Concurrent irreversible loss of infectivity/pathogenicity and encystment potential after prolonged maintenance in axenic culture in vitro. Exp. Parasit. 34, 163–167 (1973)
Phillips, B. P., Bartgis, I. L.: Effects of growth in vitro with selected microbial associates and of encystation on the virulence of Entamoeba histolytica for guinea pigs. Amer. J. Trop. Med. Hyg. 3, 621–627 (1954)
Phillips, B. P., Diamond, L. S., Bartgis, I. L., Stuppler, A.: Results of intracecal inoculation of germfree and conventional guinea pigs and germfree rats with axenically cultivated Entamoeba histolytica. J. Protozool. 19, 498–499 (1972)
Raether, W.: Intrahepatikale Infektionsversuche am Goldhamster mit Entamoeba histolytica-Crithidia Kulturen mit oder ohne Beteiligung von Bakterien. Z. Parasitenk. 36, 335–345 (1971)
Reinertson, J. W., Thompson, P. E.: Experimental amebic hepatitis in hamsters. Proc. Soc. exp. Biol. (N.Y.) 76, 518–521 (1951)
Schensnovich, V. B., Soloviev, M. M.: Pathogenicity of strains in Entamoeba histolytica from patients and carriers. Progr. in Protozool. (Proc. 1st Int. Conf. Protozool., Prague), 590–591 (1961)
Tanimoto, M., Sepúlveda, B., Vázquez-Saavedra, J. A., Landa, L.: Lesiones producidas en el higado del hamster por inoculacion de Entamoeba histolytica cultivada en medio axenico. Arch. Inv. Med. (Mex.) 2, Suppl. 1, 275–284 (1971)
Villarejos, V. M.: Studies on the pathogenicity of Entamoeba histolytica and other ameba species. Thesis. Summary in: Trop. Dis. Bull. 59, 780 (1961)
Wittner, M., Rosenbaum, R. M.: Role of bacteria in modifying virulence of Entamoeba histolytica. Studies of amebae from axenic culture. Amer. J. Trop. Med. Hyg. 19, 755–761 (1970)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bos, H.J., Hage, A.J. Virulence of bacteria-associated, Crithidia-associated, and axenic Entamoeba histolytica: Experimental hamster liver infections with strains from patients and carriers. Z. F. Parasitenkunde 47, 79–89 (1975). https://doi.org/10.1007/BF00382631
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00382631