[Serodiagnosis of entamoebiasis].
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In most cases the ano-cutaneous clinical symptoms correlated to diseases of the gastro-intestinal tract are not specific (erythema, itching, wounds or scarring). However in the following diseases occasional dermatological lesions may directly contribute to their diagnosis: in Crohn's disease, tuberculosis of bowel, chronic entamoebiasis and bilharziosis, the skin lesions of the anal area have the same histological structure as the gut lesions. Perianal fistulas and ulcers are frequent in Crohn's disease especially if there is a colonic and rectal spreading; they respond badly to steroid therapy and are often correlated with a worse prognosis. Perianal specific lesions occur often in oxyuriasis in children, in candidiasis of the digestive tract, in systemic aphthosis and in some malignancies. In other gastro-intestinal disturbances, the dermatological and features are less specific and can only be suggestive: iatrogenic and microbial diarrheas, side-effects of laxatives, proctological diseases. It has to be emphasized that pruritus ani is only induced by deeper lesions when they spread to the perianal skin. In proctological practice, contact dermatitis by sensitivity to anaesthetics or suppository balsams (Peruvian balsam), itching or burning atrophy by topical steroid abuse, non-diagnosed fungal (candidiasis), bacterial (erythrasma) or psoriatic intertrigos (flexural psoriasis) may sometimes explain the failure of therapy.
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We present two successfully treated cases of amebic peritonitis. Acute peritonitis secondary to intra-abdominal rupture of an amebic liver abscess is an infrequent but serious complication of invasive amebiasis. Its diagnosis should be considered in anyone with a suspected liver abscess, jaundice, or diarrhea in whom peritonitis develops. This diagnosis should be further suggested in the United States if the patient is a male and is of Mexican origin in areas where this racial group constitutes the majority of cases of amebic disease. Use of radioisotope liver scans and the demonstration of serum precipitins to Endamoeba histolytica may provide rapid evidence of invasive disease, although surgical intervention is often necessary to make a specific diagnosis. Emetine hydrochloride alone or followed by metronidazole combined with surgical drainage is the current treatment for amebic peritonitis.
During a five-year period at The New York Hospital, Entamoeba histolytica was identified in the stools of 20 men who had not traveled outside the New York area. All of the patients were found subsequently to homosexual. During this same period amebiasis was diagnosed in 30 men who had traveled; only two were homosexual. Of ten patients with E histolytica infection seen during the first year of this study, none were homosexual whereas eight of 11 patients in the fifth year were homosexual, suggesting a gradual increase during this period of this disease in the homosexual community.
This review focuses on the parasitic diseases which occur frequently in the tropics and which affect pregnant women. Clinical disease of the mother during pregnancy, vertical transmission of parasites and transplacental passage of soluble parasitic antigens are discussed in relation to their immunopathological significance for the fetus. The incidences of congenital malaria, African trypanosomiasis and Chagas' disease are reviewed, together with vertical transmission of filarial infection, involvement of the female genital tract in schistosomiasis, and fulminant colitis due to Entamoeba histolytica infection during pregnancy.
A retrospective and comparative study of 127 case reports of Meleney's postoperative progressive synergistic gangrene and of 62 examples of postoperative amoebic skin gangrene, showed that these two entities were clinically indistinguishable and that therefore a purely clinical diagnosis of Meleney's gangrene could not be made. Furthermore, a critical appraisal of the bacteriological data indicated that a certain diagnosis of Meleney's gangrene cannot be provided by the clinical bacteriologist. Finally, the histological features were entirely non-specific thus precluding a definitive diagnosis by the histopathologist. If Meleney's entity cannot be diagnosed its existence becomes debatable. The alternative diagnosis of cutaneous amoebiasis is advanced for consideration. Several of the outstanding features of Meleney's progressive gangrene, hitherto unexplained, are better understood if Entamoeba histolytica is accepted as the prime cause rather than bacteria.
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The clinical utility of an ELISA test with monoclonal antibodies to detect antigen of Entamoeba histolytica in feces was evaluated in 150 patients with gastrointestinal symptoms. Each subject was examined by rectosigmoidoscopy with rectal smear and/or a triple stool search for ova-bacteria-parasite (OBP); in addition, one stool sample was collected for the ELISA test. All the tests were independent and double blind. E. histolytica was detected by OBP and/or rectosigmoidoscopy in 66 patients; 61 patients had other parasites; and in 23, no parasites were identified. Of all patients, 116 were positive for the ELISA test. Of these, E. histolytica was identified in 52. In 47, other parasites were identified and in 17, no parasites were found. The ELISA test with a monoclonal antibody against E. histolytica antigen showed higher sensitivity than the standard diagnostic methods: the ability to detect the presence of E. histolytica antigen regardless of the destruction of the parasite or of the error due to misidentification of the parasite resulting from faulty preparation of the samples.
Two cases are reported of unexpected and unclarified death caused by an infection with Entamoeba histolytica. The first case concerned a German whose disease was not diagnosed during the asymptomatic phase (2 years' duration) or in the acute phase during the last 3 weeks before death. This is typical of the disease. In the final phase, he developed a hepatic abscess. Death occurred as a consequence of bilateral apoplexia in the adrenal glands. In the second case a Turk fell ill with gastralgia and diarrhea. Developing hepatic insufficiency with comsumptive coagulopathy, he died after 6 days. Intoxication and/or intolerance of fructose were assumed as tentative diagnoses. These two cases show clearly that even outside an endemic area, one has to reckon with the possibility of amebiasis.
417 patients suffering from intestinal amoebiasis were randomly allocated to 6 different treatment groups in a controlled study in 3 District Hospitals in Kenya. The patients received either aminosidine (A), etophamide (E), nimorazole (N), or the combinations NA, NE, EA. Treatment in all cases was given twice daily for 5 days. Before and after treatment, rectosigmoidoscopy was done in each patient, and stool examination with characterization of invasive (IF) and non invasive (NIF) forms of amoeba was done daily throughout treatment, and on Days 15, 30 and 60 of follow-up. Clinical cure was good after all the treatments, varying from 90 to 100%; parasitological cure at the end of treatment was 100% in the NA and EA treatments groups, and 98% in A group. The incidence of relapses was nil in the EA group, followed by 3% in NA and 6% in A groups. Anatomical cure (healing of ulcers) was 97.8% in the NA group, 95.5% in the N group and 88.5% in the A group. Drug tolerance was excellent or good after all the treatments, except that the EA combination produced diarrhoea in 76.5% of patients. Overall analysis of the findings, including tolerance of the various treatments, showed that aminosidine either alone or in combination with nimorazole gave the best results. Ulcers seen on rectosigmoidoscopy were more common in patients excreting invasive forms of amoebae in their stools.
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% (see article) and declined sharply within 7-15 weeks after elimination of the associated bacterial 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 attempt 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.
All of five strains of Entamoeba histolytica, isolated from symptomatic cases of amoebiasis, could be adapted to axenic growth on the TP-S-1 medium of Diamond (1968). Four axenic strains were started from amoeba-Crithidia cultures; one could be axenized directly after isolation from a case of cutaneous amoebiasis. Attempts to monoxenize, resp. axenize strains, isolated from Dutch, asymptomatic carriers, were less successful. Only three out of ten strains could be submitted to bacteria-free growth. These three strains, however, originated probably from a recent case of intestinal amoebiasis. The results, suggesting that highly virulent strains can be easier cultivated bacteria-free than those with low or no virulence, are further discussed. The yield of axenic amoebae per tube fluctuates largely depending on many factors such as the strain, the number of transfers (i.e. degree of establishment), the quality of Panmede liver digest and serum in the TP-S-1 medium, and the care of manipulating the cultures. For optimal growth, a more acid medium was required in an amoeba-Crithidia culture than in an axenic culture. Multinucleated, giant amoebae were frequently observed in axenic cultures.
Trophozoites of Entamoeba histolytica maintained in vitro in Pavlova's medium were inoculated by deep intramuscular injection into the proximal left hindleg of hamsters. Thioglycollate medium was utilized as a successful vehicle to induce the infection. The invasion of the muscular tissue by the vegetative forms caused the formation of abscesses with great destruction of muscular fibers. The lesions were limited to the muscular tissue of the femoral area. The number of trophozoites, the medium of thioglycollate as a vehicle, the volume of the inoculum and the trauma caused by the needle were important elements in the evolution of the muscular amebic abscesses. A limited trial of the amebicidal activity of metronidazole utilizing the amebic intramuscular infection was also performed.
To investigate the role of amebic proteinases and host leukocytes, we studied amebiasis experimentally in the rat testis. The degree of inflammation and necrosis produced by different strains was correlated with proteinase activity and with zymograms. Intratesticular injection of axenically grown trophozoites of a pathogenic strain (HM-1 of Entamoeba histolytica) produced indistinguishable lesions in normal animals and leukopenic rats (less than 1000 leukocytes/mm3), suggesting that granulocytes do not contribute to the formation of lesions in this model. Testicular lesions produced by five different strains of E. histolytica ranging from highly virulent to almost nonpathogenic were proportional to the proteinase activity of each amebic strain. Inhibition of amebic proteinases in vitro and subsequent injection into the rat testis markedly reduced the inflammatory lesions resulting from highly virulent E. histolytica. The pathogenicity of three other amebae (E. laredo, E. moshkovskii, and E. invadens) was generally proportional to their proteinase activity; however, E. laredo showed high proteinase activity and caused minimal tissue damage. These results suggest that the pathogenic potential of Entamoeba spp. in the rat testis may be related to the type as well as the level of their proteinase activity.
Delayed-type hypersensitivity (DTH) to live or fixed Entamoeba histolytica was induced and compared in mice and hamsters. Peak reactions were obtained 24 h post-challenge. In mice, challenge with 10(5) amoebae produced maximal, specific footpad swelling; in hamsters, 5 x 10(4) were required. Elicitation of DTH in mice was strongest 1 week after induction and remained comparatively high for 8 weeks. In hamsters, elicitability declined after 1-2 weeks. Cyclophosphamide increased footpad reactions in mice and hamsters when given 1 day prior to induction but not prior to challenge. Reactions were usually somewhat (but not significantly) stronger in mice than in hamsters, which was also evident from adoptive transfer experiments. Thus, differences in cell-mediated immunity as expressed by DTH in mice and hamsters do not explain the differential susceptibility of these animals to infection with this parasite. In hamsters, multiple footpad injections of live or fixed amoebae lowered the percentage of subsequent liver infections after i.p. injection of virulent amoebae.
The pathogenicity of 47 strains of Entamoeba histolytica isolated in Pernambuco, Brazil, was examined using the polymerase chain reaction (PCR) followed by restriction-endonuclease digestion. Electrophoretic patterns of PCR products digested with HinfI revealed that all strains were nonpathogenic. The results were entirely in accord with phenotypic properties such as isoenzyme patterns and the failure to bind a pathogenic-isolate-specific monoclonal antibody. When the sensitivity of PCR was examined, amplified products could be detected from template DNA equivalent to five trophozoites. These observations indicate that PCR amplification of genomic DNA and subsequent restriction-enzyme digestion is a useful strategy for obtaining a sensitive and accurate diagnosis. The present study also demonstrates that nonpathogenic strains of E. histolytica predominate in northeastern Brazil.