tannins and Amebiasis

Free-living amoebae belonging to Acanthamoeba genus are widely distributed protozoans which are able to cause infection in humans and other animals such as keratitis and encephalitis. Acanthamoeba keratitis is a vision-threatening corneal infection with currently no available fully effective treatment. Moreover, the available therapeutic options are insufficient and are very toxic to the eye. Therefore, there is an urgent need for the development of more effective anti-amoebic agents. Nanotechnology approaches have been recently reported to be useful for the elucidation antimicrobial, antiviral, antifungal and antiprotozoal activities and thus, they could be a good approach for the development of anti-Acanthamoeba agents. Therefore, this study was aimed to explore the activity and cytotoxicity of tannic acid-modified silver nanoparticles, pure silver nanoparticles and pure gold nanoparticles against clinical strains of Acanthamoeba spp. The obtained results showed a significant anti-amoebic effect of the tannic acid-modified silver nanoparticles which also presented low cytotoxicity. Moreover, tannic acid-modified silver nanoparticles were well absorbed by the trophozoites and did not induce encystation. On the other hand, pure silver nanoparticles were only slightly active against the trophozoite stage and pure gold nanoparticles did not show any activity. In conclusion and based on the observed results, silver nanoparticle conjugation with tannic acid may be considered as potential agent against Acanthamoeba spp.

Topics: Acanthamoeba; Acanthamoeba Keratitis; Amebiasis; Amoeba; Animals; Antiprotozoal Agents; Central Nervous System Protozoal Infections; Gold; Humans; Infectious Encephalitis; Metal Nanoparticles; Silver; Tannins; Trophozoites

Human "O" cells were fixed with pyruvic aldehyde, treated with tannic acid, and fixed with glutaraldehyde. The cells were sensitized with amoeba antigen and stored in a refrigerator. The sensitized cells were used periodically for the indirect hemagglutination test with a battery of sera from patients with intestinal amebiasis and confirmed and unconfirmed amebic liver abscess, and also from negative controls. The same battery was tested with cells sensitized with different batches of antigen and also with fresh sheep cells. None of the cells showed any reaction with negative control sera. The fixed cells remained sensitive and stable throughout the study. Reproducibility of the titers with the fixed cells within each day and from day to day was satisfactory. The titers with fixed human "O" cells were slightly lower than were the titers with fresh sheep cells. The advantages of using stable, sensitized cells are pointed out.

Topics: Aldehydes; Amebiasis; Animals; Blood Group Antigens; Diagnosis, Differential; Entamoeba histolytica; Erythrocytes; Evaluation Studies as Topic; Glutaral; Hemagglutination Tests; Humans; Liver Abscess, Amebic; Methods; Refrigeration; Sheep; Tannins

Optimal conditions for carrying out the indirect haemagglutination test with sheep erythrocytes were studied using the microtitre system. The age of the erythrocytes, concentration of reagents, time and temperature of tanning, sensitization, and incubation are described with reference to replication of titres. Sera from patients with amoebic colitis were used to evaluate the test conditions.

Topics: Amebiasis; Animals; Colitis; Entamoeba histolytica; Erythrocytes; Hemagglutination Tests; Humans; Methods; Sheep; Tannins; Temperature; Time Factors