Entamoeba histolytica autochthonous isolates from mentally retarded Italian patients

A total of 77 mentally retarde male inpatients residing in a psychiatric institution in northern Italy were screened for the presence of stool parasites,Entamoeba histolytica particularly. Parasitological stool examination showedEntamoeba spp. (E. histolytica and/orE. dispar) in 26 cases (33.7%). In vitro culture on Robinson's medium was positive in 16 cases (61.1%); in 11 cases we could stabilize and clone the isolates and proceed to electrophoretic assays. In all cases, patterns of pathogenic zymodemes were found (zymodeme II, 3 isolates; zymodeme XII, 4 isolates; zymodeme XIV, 4 isolates). All isolates were therefore identified asE. histolytica.     

An outbreak of hepatitis A in an institution for the mentally retarded

From December 1977 until April 1978 a hepatitis A outbreak occurred in an institution for the mentally retarded. The institution housed 311 residents and had a staff of 308. The outbreak was studied by enzyme-linked immunosorbent assays for hepatitis A antigen and antibodies, and by liver function tests in serum. When the investigations started, 13 residents and one staff member were ill and already seropositive; 34 of the 182 residents that were seronegative at that time and 12 of the 223 seronegative staff members subsequently developed disease. Out of the 60 cases 32 were asymptomatic; 19 cases with jaundice were seen. Normal human immunoglobulin was administered to a large part of the seronegative group, but the effect is difficult to interpret as the immunoglobulin was often given after the presumed time of infection and failed to protect. Elevated liver enzyme levels were demonstrated in 38 of 60 patients.     

Invasive amebiasis at an institution for the mentally retarded in Hyogo Prefecture]

An outbreak of amebiasis caused by Entamoeba histolytica occurred at an institution for mentally retarded persons in Hyogo Prefecture. Twelve out of a total of 49 admitted persons exhibited E. histolytica cysts in their stool, and 13 including persons in whom no cysts had been detected showed positive serological reactions for E. histolytica infection. However, neither the cyst nor the antibody against the organism was detected in the staff members of the institution. Indirect fluorescence antibody test and sandwich enzyme-linked immunosorbent assay with a monoclonal antibody specific for pathogenic strains of E. histolytica revealed that all trophozoite strains grown from cysts in stool samples from five patients were pathogenic. Epidemiological analysis strongly suggested that a patient in the institution had been infected with an organism from a patient outside the institution, and that infection may have spread among the admitted persons due to abnormal behavior. Administration of metronidazole resulted in effective elimination of the cysts from the stool of the cyst-carriers.     

Prevalence of antibody to the hepatitis A virus in a large institution for the mentally retarded.

The prevalence of antibody to hepatitis A virus (anti-HAV) was determined in 854 people living in a large institution for the mentally retarded in Melbourne. Altogether 638 (74.4%) of the subjects were found to have specific antibody detectable by solid-phase radioimmunoassay (SPRIA). No difference in antibody prevalence was observed between males and females; however, the prevalence was higher among subjects with Down syndrome (84.1%) than those of other forms of mental retardation (72.8%). In both groups there was an increase in prevalence of antibody with increasing age and duration of institutionalization. When compared with the open community, patients in this institution have a higher prevalence of antibody and appear to acquire their infections at an earlier age.     

Comparison of serine-rich protein genes of Entamoeba histolytica isolates obtained from institutions for the mentally retarded in Kanagawa and Shizuoka Prefectures, Japan

In Japan, amebiasis has been observed in homosexual men, in institutionalized persons, and in overseas travelers. We have previously reported an outbreak of amebiasis that occurred from 1986 to 1994 in institutions for the mentally retarded in Kanagawa and Shizuoka Prefectures in Eastern Japan. Entamoeba histolytica but not Entamoeba dispar was identified in Entamoeba cultures obtained from cyst passers in four institutions located in different municipalities in this region. In the present study, serine-rich protein genes of eight isolates from the four institutions were sequenced, and their polymorphism was analyzed. The results showed that all the sequences from the E. histolytica isolates were identical. This retrospective study led us to conclude that the outbreak of amebiasis in different municipalities was derived from a single source of E. histolytica.     

A cytogenetic survey of an institution for the mentally retarded: I. Chromosome abnormalities

A cytogenetic survey of 475 patients in an institution for the mentally retarded is reported. The chromosomes of all patients were studied using both a non-banding and a G-banding technique in order to estimate the relative efficiency of the two technique in detecting structural rearrangements of the chromosomes. A total of 57 patients was found to have a chromosome abnormality, including five with a balanced structural rearrangement. The contribution of chromosome aberrations to the etiology of mental retardation is discussed with special emphasis on the contribution of balanced structural rearrangements.     

Prevalence and genetic diversity of Entamoeba species infecting macaques in southwest China

Many colonies of macaques (Macaca fascicularis and Macaca mulatta) are maintained in China, especially in Guangxi and Guizhou. A total of 803 fresh stool samples infected with Entamoeba were obtained from three big colonies of macaques located in southwest China. The samples were examined for the presence of five Entamoeba species using PCR. Entamoeba nuttalli, Entamoeba dispar, Entamoeba coli, and Entamoeba chattoni infections were detected, but Entamoeba histolytica infection was not. This study is the first to report on the prevalence of E. nuttalli in wild macaques from China. Eighteen E. nuttalli isolates and five E. dispar isolates were obtained by culturing the samples in Tanabe–Chiba medium. The serine-rich protein (SRP), ribosomal RNA (rRNA), hexokinase (HXK), glucose-6-phosphate isomerase (GPI), and phosphoglucomutase (PGM) genes of E. nuttalli isolates were compared with other reported isolates. The results showed clear differences among the Chinese E. nuttalli isolates and other isolates based on the SRP gene sequences. However, HXK, GPI, and PGM genes of these strains were similar to those of other isolates. The rRNA genes of E. coli and E. chattoni were also amplified and analyzed from these samples. The results suggested that host species might be a more important factor than geographic location in amebic genetic diversity.     

A cytogenetic survey of 449 patients in a Japanese institution for the mentally retarded

A cytogenetic survey was carried out on 449 patients (261 males and 188 females) in an institution for the mentally retarded in Japan. A total of 37 patients (8.1 %) were shown to have chromosome abnormalities. There were 33 individuals (7.3 %) with 21 trisomy. In addition, we found one patient with 46,XY/47,XY, + 12p, one with 46, XY, r(22), and one with 45, XY, -13, -14,+t(13q14q). Only one female was found to have an abnormal sex chromosome constitution, 47, XXX. The significant contribution of chromosome abnormalities in the etiology of mental retardation is also shown in the present survey. The most common chromosome abnormality was 21 trisomy, as seen in other similar surveys.     

Geographic diversity among genotypes of Entamoeba histolytica field isolates

It has been known that only 5 to 10% of those infected with Entamoeba histolytica develop symptomatic disease. However, the parasite and the host factors that determine the onset of disease remain undetermined. Molecular typing by using polymorphic genetic loci has been proven to aid in the close examination of the population structure of E. histolytica field isolates in nature. In the present study, we analyzed the genetic polymorphisms of two noncoding loci (locus 1-2 and locus 5-6) and two protein-coding loci (chitinase and serine-rich E. histolytica protein [SREHP]) among 79 isolates obtained from different geographic regions, mainly Japan, Thailand, and Bangladesh. When the genotypes of the four loci were combined for all isolates that we have analyzed so far (overlapping isolates from mass infection events were excluded), a total of 53 different genotypes were observed among 63 isolates. The most remarkable and extensive variations among the four loci was found in the SREHP locus; i.e., 34 different genotypes were observed among 52 isolates. These results demonstrate that E. histolytica has an extremely complex genetic structure independent of geographic location. Our results also show that, despite the proposed transmission of other sexually transmitted diseases, including human immunodeficiency virus infection, from Thailand to Japan, the spectra of the genotypes of the E. histolytica isolates from these two countries are distinct, suggesting that the major E. histolytica strains prevalent in Japan at present were likely introduced from countries other than Thailand. Although the genetic polymorphism of the SREHP locus was previously suggested to be closely associated with the clinical presentation, e.g., colitis or dysentery and liver abscess, no association between the clinical presentation and the SREHP genotype at either the nucleotide or the predicted amino acid level was demonstrated.     

Localization and identification of an Entamoeba histolytica adhesin

The adherence of Entamoeba histolytica trophozoites to target cells was studied by using monoclonal antibodies (MAbs) and adhesion-deficient mutants of the parasite. MAbs Adh-1 and Adh-2 reacted with a surface protein of approximately 112 kDa of the total proteins of trophozoites from the wild type strain, clone A, strain HM1:IMSS. Both MAbs reacted weakly with the adhesion-deficient mutant clones, C-98, C-919 and C-923, all derived from HM1:IMSS. MAbs Adh-1 and Adh-2 incubated with trophozoites from clone A inhibited adherence to red blood cells, erythrophagocytosis and cytopathic effect on cell culture monolayers. Antibodies against a approximately 112 kDa polypeptide were found in the sera from patients with hepatic abscess. These results demonstrate that the adherence of trophozoites to target cells is a necessary event in order for cytopathogenicity to occur.     

Prevalence of the fragile-X syndrome in mentally retarded boys in a Swedish county

In an etiological study of an unselected series of mentally retarded children (IQ less than 70) born 1959-1970 in a northern Swedish county, 12 of 205 boys (5.9%) were found to have a fragile site on the distal end of the C-chromosome (fra (X) (q27]. The incidence of the fra (X) syndrome was calculated to be 1:1500 boys in this county. If this is true for the whole of Sweden, 30-40 new cases of the fra (X) syndrome should be born yearly in Sweden. This must be considered a minimum figure, since a certain proportion of individuals with fra (X) are not observed in groups of mentally retarded patients. Next to trisomy 21, the fragile X syndrome is the most common specific cause of mental retardation among mentally retarded boys in Sweden.     

Chromosome studies of males in an institution for the mentally handicapped.

Karyotypes were examined in 512 (91.9%) of 557 male patients in an institution for the mentally handicapped. A total of 110 (21.5%) had an abnormal karyotype: 65 (12.7%) with Down's syndrome, 30 (5.9%) with the fragile X syndrome, 13 (2.5%) with autosomal anomalies other than Down's syndrome (12 unbalanced, one balanced), and two (0.4%) with sex chromosome anomalies.     

Nucleotide sequence analysis of an Entamoeba histolytica ferredoxin gene

A cDNA clone (subclone B) previously isolated from the human parasite Entamoeba histolytica was characterized. DNA sequence analysis of subclone B identified the DNA as that encoding apoferredoxin. E. histolytica ferredoxin cDNA contains unusually short 5' and 3' noncoding regions of 9 and 25 nucleotides, respectively. A genomic ferredoxin clone was isolated from E. histolytica DNA, and comparison of genomic and cDNA sequences revealed that the ferredoxin gene is unspliced. The deduced amino acid sequence of E. histolytica ferredoxin resembles clostridial type of ferredoxins, and shows an arrangement of cysteines characteristic for the coordination of 2[4Fe-4S] centres. Of interest is the absence of an aromatic amino acid in the N-terminal region of the protein, a feature which is conserved in clostridial ferredoxins. Southern blot analysis of three different E. histolytica strains (200:NIH, Rahman and HM-1:IMSS) demonstrated the presence of a family of at least two ferredoxin genes. One of these genes is marked by restriction length polymorphisms in different strains of E. histolytica.     

Simultaneous differentiation and typing of Entamoeba histolytica and Entamoeba dispar

Sequences corresponding to some of the polymorphic loci previously reported from Entamoeba histolytica have been detected in Entamoeba dispar. Comparison of nucleotide sequences of two loci between E. dispar strain SAW760 and E. histolytica strain HM-1:IMSS revealed significant differences in both repeat and flanking regions. The tandem repeat units varied not only in sequence but also in number and arrangement between the two species at both the loci. Using the sequences obtained, primer pairs aimed at amplifying species-specific products were designed and tested on a variety of E. histolytica and E. dispar samples. Amplification results were in complete agreement with the original species classification in all cases, and the PCR products displayed discernible size and pattern variations among the isolates.     

Evaluation of the intestinal microbial diversity in miniature pig after orally infected with Entamoeba histolytica

The objective of this study was to analyze the difference in intestinal microbial diversity between healthy and (Entamoeba histolytica) orally infected minipig. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to analyze this diversity and dynamic change, including the duodenum, jejunum, ileum, cecum, and rectum from healthy and orally infected minipig at different time points. The results showed that the intestinal microbial community of the control minipigs was stable and the ERIC-PCR band numbers of the control minipigs were the lowest in the rectum and highest in the cecum. ERIC-PCR bands of orally inoculated minipigs showed no obvious change until 24 h after postinoculation (hpi). The numbers of the ERIC-PCR bands gradually decreased from 24 to 72 hpi, then, with the development of disease, the band numbers gradually increased until 6 days postinoculation. The prominent bacteria had changed in the presence of E. histolytica infection and the DNAstar of staple of ERIC-PCR showed that obligate aerobes and facultative aerobes (Escherichia coli, Shigella, Salmonella) became the preponderant bacilli in the intestine of orally infected minipigs with E. histolytica. This study has provided significant data to clarify the intestinal microbial diversity and dynamic change of healthy and E. histolytica orally infected minipigs.