No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
The laboratory diagnosis of human parasite amoebae
Abstract
A method for culturing amoebae, suitable for a clinical laboratory, is given and assessed by recording the results of combined
microscopical and cultural diagnosis on 4,236 specimens from tropical patients of the Dreadnought Seamen's Hospital, London.
Of the total specimens examined 17·7% were positive microscopically for one or more species, and 2/9 of these (4·1% of total
specimens) were missed culturally, while 26·2% were positive culturally for one or more species, and 1/3 of these (8·5%) were
missed microscopically. The figures for Entamoeba histolytica alone are 2·8% missed microscopically but none missed culturally, out of 7·3%. High rates for Nigerian amoebic carriers and
Goan amoebic abscesses are recorded.
... In the present study, culture isolates of Retortamonas spp. were established and maintained for over 3 years in Robinson's medium (Robinson, 1968) supplemented with Desulfovibrio desulfuricans (Yoshida et al., 2019). However, a continuous culture system for C. mesnili using motile flagellates excysted from cysts in stool samples of Japanese macaques could not be established using established culture media [Robinson's medium (Robinson, 1968), Balamuth's medium (Balamuth, 1946), TYSGM-9 (Diamond, 1982), and modified TYI-S-33 medium (Keister, 1983)]. ...
... isolated from swine, and Nyctotherus teleacus isolated from a radiated tortoise. They could be subcultured using the same Robinson's medium for over a year (Robinson, 1968;Yoshida et al., 2019;Suzuki et al., 2020). Under these culture conditions, the four Retortamonas spp. ...
... Phylogenetic analyses of Retortamonadidae strains Culture media Robinson's medium supplemented with 10% heat-inactivated adult bovine serum, Escherichia coli (DH5α), D. desulfuricans, and starch (rice powder) (Robinson, 1968;Yoshida et al., 2019) was used to culture Retortamonas spp. isolates and as excystation medium (step 3) for Chilomastix sp. and Retortamonas spp. ...
In vitro excystation of cysts of microscopically identified Chilomastix mesnili and Retortamonas sp. isolated from Japanese macaques and Retortamonas sp. isolated from small Indian mongooses could be induced using an established protocol for Giardia intestinalis and subsequently by culturing with H2S-rich Robinson’s medium supplemented with Desulfovibrio desulfuricans. Excystation usually began 2 h after incubation in Robinson’s medium. DNA was isolated from excysted flagellates after 4 h of incubation or from cultured excysted flagellates. Phylogenetic analysis based on their 18S rRNA genes revealed that two isolates of C. mesnili from Japanese macaques belonged to the same cluster as a C. mesnili isolate from humans, whereas a mammalian Retortamonas sp. isolate from a small Indian mongoose belonged to the same cluster as that of an amphibian Retortamonas spp. isolate from a ‘poison arrow frog’ [sequence identity to AF439347 (94.9%)]. These results suggest that the sequence homology of the 18S rRNA gene of the two C. mesnili isolates from Japanese macaques was similar to that of humans, in addition to the morphological similarity, and Retortamonas sp. infection of the amphibian type in the small Indian mongoose highlighted the possibility of the effect of host feeding habitats.
... The finding of a nonpathogenic zymodeme in conjunction with a pathogenic one in any single host has never been reported (99,103). Furthermore, no evidence of alteration of isoenzyme patterns, i.e., shifts from nonpathogenic to pathogenic or vice versa, was ever demonstrated in longitudinal culture studies (99,103) which were conducted in the presence of viable bacteria in Robinson's medium (96). Moreover, short-term interaction (for 1 h) of axenically grown ameba with bacteria, which markedly enhanced their virulence (see above) (14), did not cause any changes in their pathogenic zymodeme (60). ...
... At the moment we do not have a rational explanation for the many types of E. histolytica zymodemes that have been characterized to date or for the mechanism of conversion seen in our present experiments. One of the reasons why such a conversion may not have been observed until today in any of the longitudinal studies done by Sargeaunt and colleagues (99,103) may be due to the way the cultures were grown in Robinson's monoxenic media (96). In this system, stool samples are inoculated together with erythromycin to suppress the growth of the original fecal bacterial flora, while separately grown Escherichia coli B cells are added to the cultures. ...
... World-wide morbidity and mortality due to amoebiasis is difficult to estimate. An estimate suggests that approximately 500 million people are infected worldwide with this parasite and causing about 110,000 deaths per year (Walsh 1986, Neal 1983, Robinson 1968, Bhopale et al. 1995. ...
... The trophozoites and the cysts were detected under direct microscopic stool examinations. After the detection, the stool samples were inoculated into Robinson's medium (Robinson 1968) for the cultivation and isolation of E. histolytica. Then, ELISA technique (Haque et al. 1995) was used to detect amoebic antigen in the culture sediments of the stool samples. ...
A total of 72 mice were used for an experimental model of intestinal amoebiasis developed in the Swiss albino mice dividing into three groups, experimental immunocompetent mice group (Group-A), experimental immunodepressed mice group (Group-B) and control group (Group-C). The inoculum (106 cells of Entamoeba histolytica/0.2 ml of medium) was used to inoculate into the caecum of the experimental groups of mice in the ICDDR,B laboratory, Dhaka. The mice were sacrificed at 5, 10, 15, 20, 25 and 30th days after inoculation for observation of caecal lesions and gross pathologic changes and histopathological analysis. The animals in the experimental two groups and control did not develop any caecal amoebiasis. The culture results of the stool of the mice which were inoculated with the inoculum of E. histolytica were found to be positive on the first 10 days after post caecal inoculation. After 10 days, the culture results were negative and the antiamoebic antibody levels of all animals were also found negative. DOI: http://dx.doi.org/10.3329/jbas.v38i2.21341 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 2, 167-175, 2014
... The histological identification of amoeba may be challenging considering their resemblance with exfoliated cells or other cell debris, especially in less-affected gills (Frasca et al., 2018) or in the late stage of the disease (Dyková et al., 2010). Hence, wet mounts (Frasca et al., 2018), culture (Robinson, 1968) as well as PCR (Frasca et al., 2018) are essential complementary diagnostic tools. ...
Nodular gill disease (NGD) is an infectious condition characterized by proliferative gill lesions leading to respiratory problems, oxygen deficiency and mortality in fish. Globally, NGD primarily impacts freshwater salmonids in intensive aquaculture systems. In recent years, numerous outbreaks of severe gill disease have affected more than half of the larger rainbow trout (Oncorhynchus mykiss) farms in Switzerland, mainly during spring and early summer. Mortality has reached up to 50% in cases where no treatment was administered. Freshwater amoeba are the presumed aetiologic agent of NGD. The gross gill score (GS) categorising severity of gill pathology is a valuable first-line diagnostic tool aiding fish farmers in identifying and quantifying amoebic gill disease (AGD) in farmed marine salmonids. In this study, the GS was adapted to the NGD outbreak in farmed trout in Switzerland. In addition to scoring disease severity, gill swabs from NGD-affected rainbow trout were sampled and amoeba were cultured from these swabs. Morphologic and molecular methods identified six amoeba strains: Cochliopodium sp., Naegleria sp., Vannella sp., Ripella sp., Saccamoeba sp. and Mycamoeba sp. However, the importance of the different amoeba species for the onset and progression of NGD still has to be evaluated. This paper presents the first description of NGD with associated amoeba infection in farmed rainbow trout in Switzerland.
... After collecting clinical samples, we immediately initiated the isolation steps of xenic culture using the specific cultivation media for E. histolytica, as previously reported [11,32]. Briefly, the clinical samples revealing trophozoite forms were directly cultured in Robinson's R (defined medium for Escherichia coli) and BR (R medium precultured with E. coli) media [33]. In the case of stool samples revealing cyst forms, the samples were treated with 0.1 N HCl for 10 minutes, then washed with fresh water to kill other bacteria and fungi that may affect the cultivation of E. histolytica before the xenic culture step. ...
The severity of Entamoeba histolytica infection is determined by host immunology, pathogen virulence, and the intestinal environment. Conventional research for assessing pathogen virulence has been mainly performed using laboratory strains, such as a virulent HM-1: IMSS (HM-1) and an avirulent Rahman, under various artificial environmental conditions because of the difficulties of axenic isolation of the clinical strains. However, it is still unclear whether scientific knowledge based on laboratory strains are universally applicable to the true pathogenesis. Hereby, we performed transcriptomic analysis of clinical strains from patients with different degrees of disease severity, as well as HM-1 under different conditions. Even after several months of axenization, Clinical strains show the distinct profile in gene expression during in vitro passage, moreover, difference between any 2 of these strains was much greater than the changes on the liver challenge. Interestingly, 26 DEGs, which were closely related to the biological functions, were oppositely up- or down regulated between virulent Ax 19 (liver abscess) and avirulent Ax 11 (asymptomatic carrier). Additionally, RNAseq using laboratory strain (HM1) showed more than half of genes were differently expressed between continuously in vitro passaged HM1 (in vitro HM1) and periodically liver passaged HM1 (virulent HM1), which was much greater than the changes on the liver passage of virulent HM1. Also, transcriptomic analysis of a laboratory strain revealed that continuous environmental stress enhances its virulence via a shift in its gene expression profile. Changes in gene expression patterns on liver abscess formation were not consistent between clinical and laboratory strains.
... [3] Blastocystis sp. that infected specimens without associating with other parasites was cultivated in the Robinson culture medium. [14] After mass culture, the parasite was isolated from the culture medium, washed off with a sterile ringer solution and centrifuged for 1.5 min at 2000 rpm three times. Approximately 2 ml of each positive sample sediment was stored at − 20°C for the molecular analysis. ...
Original ArticleAims: Blastocystis species are one of the most common enteric protist infections in humans and some animals worldwide. Molecular
studies have shown that there is a high level of genetic variation among Blastocystis isolates. The aim of this study was to identify the
subtypes and frequency of Blastocystis isolates in patients who referred to the medical diagnostic laboratories in Kashan, Central Iran.
Materials and Methods: This cross‑sectional study was conducted on 1118 patients, from December 2017 to June 2018. Fecal specimens were
evaluated by the microscopic examination. Positive samples were cultivated in Robinson media. After massive growth and DNA extraction,
a 550 bp from the small subunit ribosomal RNA gene was amplified by the polymerase chain reaction (PCR) for subtype identification. The
PCR products have been sequenced, identified, and compared at the NCBI site. The results were analyzed using the SPSS software version 16.
Results: The frequency of Blastocystis sp. was 8.58%, (confidence interval = 6.94%–10.22%) from which 76% were men and 24% were
women. Of the 51 PCR positive samples, ST3 (41.2%), ST1 (39.2%), ST2 (11.8%), and 7.8% isolates were identified as mixed. ST3 and ST1
have been more common. The highest levels of infection were observed in the food‑handlers, the age group of 31–40, and people with high
school education. Conclusion: The results showed that the frequency of Blastocystis was lower than other studies and the most common
Blastocystis subtype was subtype 3, followed by subtype 1, and subtype 2.
... The modified Schaudinn's fixation preserved stool samples were permanently stained using a trichrome staining. Fresh stool samples were immediately inoculated into approximately 100-200 mg Robinson culture medium [33]. The remaining sample was stored in Eppendorf ® tubes at − 20 °C for DNA isolation and further assessments. ...
Background
Dientamoeba fragilis is a protozoan parasite of the human gastrointestinal tract and still controversial in association with gastrointestinal symptoms.
Purpose
We present cross-sectional study of the prevalence of D. fragilis, and sociodemographic and clinical features in the patients with gastrointestinal symptoms.
Methods
A total of 490 fecal specimens were collected from outpatients with gastrointestinal symptoms in the Department of Parasitology, Faculty of Medicine, Ege University and Celal Bayar University, Turkey. Fecal specimens were examined with microscopy and inoculated in Robinson medium. D. fragilis-positive samples were examined for the presence of other intestinal parasites using enzyme immunoassay. Real-time PCR analysis was performed on all samples.
Results
Of the 490 stool specimens examined by real-time PCR, 59 patients were positive for D. fragilis infection with prevalence rate of 12.04%. Forty-four of positive patients (74.5%) were found to be infected with only D. fragilis, while 23.7% were co-infected with Blastocystis and 1.7% were co-infected with Rotavirus. No statistically significant difference was found in all the examined patients in terms of D. fragilis positivity for all sociodemographic parameters. Loose stool consistency was associated with the presence of D. fragilis, with 18.3% (P = 0.001). When the clinical symptoms of all the patients participating in this study were examined, diarrhea was statistically more significant in patients with the presence of D. fragilis (16.3%; P = 0.001). The rate of diarrhea in D. fragilis-positive patients (84.09%; P = 0.0005) was higher than that of D. fragilis-negative patients and it was statistically significant.
Conclusion
This study is important for assessing the prevalence of D. fragilis and its association with other factors in symptomatic patients in a large sample group in Turkey, as well as investigating the relationship of identified symptoms with the D. fragilis pathogenicity. It is suggested that D. fragilis in this case is not a commensal parasite but a pathogenic parasite and that the most common clinical symptom is diarrhea.
... Ideally, future studies can use axenic cultures (confirmed through NGS) to fully characterize the morphology of trophozoites and cysts of Entamoeba OTU_12. Techniques for establishing and maintaining axenic cultures of Entamoeba are well described in the literature, as are the use of preferred stains, such as iodine and iron hematoxylin, to characterize the morphology of different life cycle stages (9)(10)(11)(12)(13). ...
Additional methods and results for study of invasive colonic entamoebiasis in wild cane toads, Australia.
... Ideally, future studies can use axenic cultures (confirmed through NGS) to fully characterize the morphology of trophozoites and cysts of Entamoeba OTU_12. Techniques for establishing and maintaining axenic cultures of Entamoeba are well described in the literature, as are the use of preferred stains, such as iodine and iron hematoxylin, to characterize the morphology of different life cycle stages (9)(10)(11)(12)(13). ...
... Pellets obtained from centrifuged toddy samples were used for microscopic examination and cultured in Robinson's medium [13]. Briefly, pelleted toddy samples were inoculated in the Robinson's medium and incubated at 37°C for 48 to 72 h and checked for motile trophozoites. ...
Background:
Clinically diagnosed amoebic liver abscess (ALA) caused by Entamoeba histolytica has been an important public health problem in Jaffna district, northern Sri Lanka for last three decades. In order to draw up a control strategy for elimination of this condition, knowledge of its epidemiology and factors associated with this condition in the local context is vital.
Methods:
All clinically diagnosed ALA patients admitted to the Teaching Hospital, Jaffna during the study period were included in the study and the data were collected using an interviewer administered questionnaire. One hundred blood samples from randomly selected toddy (a local alcoholic drink consisting of the fermented sap of the Palmyrah palm) consumers and 200 toddy samples were collected. Toddy samples were cultured in Robinson's medium to establish the presence of Entamoeba histolytica in the sample. Climatic data and the total toddy sales in the district were obtained from the Meteorological and Excise Departments respectively. A sub group of randomly selected 100 patients were compared with 100 toddy consumers who were negative for E. histolytica antibody to explore the potential risk factors.
Results:
Between July 2012 and July 2015, 346 of 367 ALA patients were enrolled in this study. Almost all patients (98.6%) were males with a history of heavy consumption of alcohol (100%). Almost all (94.2%) were within the age group 31-50 years. None of the cultured toddy samples grew E. histolytica. The monthly incidence of disease peaked in the dry season, matching the total toddy sales in the district. Age, type of alcohol and frequency of drinking were identified as potential risk factors whereas frequency of alcohol consumption and type of alcohol (consuming toddy and arrack) were identified as the independent risk factors. Moreover, the knowledge, attitude and practices towards ALA were poor among participants and the control group.
Conclusions:
Though the number of cases has declined in recent years, ALA still remains as an important public health problem in Jaffna district. The transmission route of E. histolytica leading to ALA has to be further explored. Moreover, greater awareness among the public who are at risk would be beneficial in order to eliminate the disease.
... Then Robinson culture medium was used for mass culture and the adaptation of trophozoites. 9,10 3. Preparation and molecular study: After 3-4 subcultures, the upper layer of Robinson medium was removed and the deposit was kept in centrifuge tube. Then 10 mL of PBS solution with pH:7.2 was added to the tube and mixed adequately twice at 1600 rpm for 5 minutes using centrifugation. ...
Background: Amebiasis with up to 100 000 human deaths each year is the third cause of human deadly parasitic disease. With regard to the fact that cysteine protease 5 is known to be one of the most important pathogenicity factors of the Entamoeba histolytica and also, CP5 gene has been observed only in E. histolytica, hence we discriminated E. histolytica from E. dispar on CP5 gene by polymerase chain reaction (PCR) and characterized CP5 gene variation in E. histolytica isolated from patients in both cold regions and tropical regions of Iran at molecular level.
Materials and Methods: In the present study, a total of 2332 stool samples (1550 from Tabriz and 782 from Bandar Abbas) were studied microscopically. DNA extraction and PCR method were performed on the positive specimens, infected with E. histolytica/E. dispar. Finally we characterized CP5 gene in E. histolytica isolates from 10 positive samples in the cold regions (Tabriz) and 10 positive samples in the tropical regions (Bandar Abbas) by sequencing and studied the polymorphism of the gene.
Results: Of 1550 subjects studied from Tabriz and 782 from Bandar Abaas, 83/1550 (8.3%) and 65/782 (5.35%) persons were infected with E. histolytica/E. dispar, respectively. The molecular results on 20 E. histolytica PCR positive isolates from both regions revealed that nucleotides substitution and polymorphism on CP5 gene was more in samples from Bandar Abbas than those from Tabriz.
Conclusion: Prevalence of amebiasis was high in the tropical region (Bandar Abbas) compared with the cold region (Tabriz). In this study, CP5 gene variation in the pathogenicity and virulence of this parasite in the tropical region was higher than that in the cold region.
... Treatment of isolate 980 with 70 μmol/L metro nidazole, also reduced thioredoxin reductase expression at the mRNA level and also at the enzyme activity level though not significantly. Thioredoxin reductase enzyme plays a role in the activation of metronidazole by its nitro reductase activity [15] . This decrease in its expression may contribute to the higher metronidazole tolerance of isolate 980 compared to the other clinical isolate 989. ...
Auranofin has been recently been identified by a High Throughput Screening technique as active against trophozoites of E. histolytica and cysts of E. invadens. Auranofin inhibits E. histolytica thioredoxin reductase and it was shown that thioredoxin reductase protects trophozoites from oxidative attack and therefore in auranofin treated cells, thioredoxin was found in the oxidized state[10,11]. Auranofin has received orphan drug status and clinical trials are being carried out to treat amoeba and giardia infections. It shows promise as a broad-spectrum drug against Entamoeba, giardia and cryptosporidium, which are a major cause of diarrhea.
When Auranofin (0.5 μmol/L) treatment was given for 24 h to isolate 989, it gave an increase in thioredoxin reductase expression at the mRNA level though not significant and a similar increase at the protein level, which was significant. The downregulation of TrxR expression was not observed in this isolate perhaps due to the low concentration of auranofin used. In case of mRNA expression of peroxiredoxin and superoxide dismutase there was no significant change on treatment of isolate 989 with 0.5 μmol/L auranofin for 24 h, compared to untreated controls. At this concentration of auranofin perhaps the toxic effects of the drug were not seen, and therefore the detoxifying enzymes were not upregulated.
Clinical isolates of E. histolytica from Delhi show different tolerance to antiamoebic drugs metronidazole and auranofin. Isolate 980 shows a higher tolerance to metronidazole with MIC’s of 80 μmol/L compared to other clinical isolates studied. In the isolate 980, mRNA expression levels of thioredoxin reductase, FeSOD and Peroxiredoxin were downregulated with auranofin treatment. TrxR enzyme activity also showed an inhibition at the protein level. Our results further confirm that in clinical isolates auranofin acts by inhibition of TrxR and perhaps the treated isolate has a lower capacity to combat oxidative stress as is evident by the downregulation of FeSOD and Peroxiredoxin. Metronidazole treatment also inhibited the mRNA expression of Thioredoxin reductase and the TrxR enzyme activity showing a higher tolerance to metronidazole. Lack of metronidazole activation could be the reason for the increase in tolerance of isolate 980 to metronidazole.
... Parasite culture was performed as per the method described by Robinson [13]. Briefly, freshly collected pus and faecal samples were inoculated separately in Robinson medium and incubated at 37°C for 48-72 h. ...
Background
Since 1985, amoebic liver abscess (ALA) has been a public health problem in northern Sri Lanka. Clinicians arrive at a diagnosis based on clinical and ultrasonographic findings, which cannot differentiate pyogenic liver abscess (PLA) from ALA. As the treatment and outcome of the ALA and PLA differs, determining the etiological agent is crucial.
Methods
All clinically diagnosed ALA patients admitted to the Teaching Hospital (TH) in Jaffna during the study period were included and the clinical features, haematological parameters, and ultrasound scanning findings were obtained. Aspirated pus, blood, and faecal samples from patients were also collected. Pus and faeces were examined microscopically for amoebae. Pus was cultured in Robinson’s medium for amoebae, and MacConkey and blood agar for bacterial growth. ELISA kits were used for immunodiagnosis of Entamoeba histolytica infection. DNA was extracted from selected pus samples and amplified using nested PCR and the purified product was sequenced.
Results
From July 2012 to July 2015, 346 of 367 clinically diagnosed ALA patients admitted to Jaffna Teaching Hospital were enrolled in this study. Almost all patients (98.6%) were males with a history of heavy alcohol consumption (100%). The main clinical features were fever (100%), right hypochodric pain (100%), tender hepatomegaly (90%) and intercostal tenderness (60%). Most patients had leukocytosis (86.7%), elevated ESR (85.8%) and elevated alkaline phosphatase (72.3%). Most of the abscesses were in the right lobe (85.3%) and solitary (76.3%) in nature. Among the 221 (63.87%) drained abscesses, 93.2% were chocolate brown in colour with the mean volume of 41.22 ± 1.16 ml. Only four pus samples (2%) were positive for amoeba by culture and the rest of the pus and faecal samples were negative microscopically and by culture. Furthermore, all pus samples were negative for bacterial growth. Antibody against E. histolytica (99.7%) and the E. histolytica antigen were detected in the pus samples (100%). Moreover, PCR and sequencing confirmed these results.
Conclusion
To our knowledge, this is the first report from Sri Lanka that provides immunological and molecular confirmation that Entamoeba histolytica is a common cause of liver abscesses in the region.
... Blastocystis also grows extremely well in it, which can be a problem for Entamoeba researchers. The original Robinson's medium (Robinson, 1968) was diphasic, using an agar slant with an overlay; however, for growing Blastocystis only the liquid overlay is needed. There is no evidence that the source or lot of the reagent has a significant impact on growth; potential sources for many reagents are given for convenience rather than being a requirement. ...
Blastocystis is an intestinal parasite that is very easily isolated in culture from fresh stool samples. In fact, the parasite grows so readily in culture that short-term in vitro culture is sometimes used as a diagnostic tool in the absence of DNA-based methods. While axenizing Blastocystis cultures remains a significant challenge, the parasite can be propagated for several months in the presence of metabolically active bacteria (xenic culture). Hence, culture can be used for maintaining live Blastocystis strain libraries. This enables the production of a stable resource of reference material, which for instance can be used for DNA-based assays and research. Blastocystis isolates can also be cryopreserved with a view to reestablishing them in culture. Here, we provide protocols for xenic in vitro culture and cryopreservation of Blastocystis. © 2016 by John Wiley & Sons, Inc.
... Cultures have been established in (LE (Lock-egg slant medium) modification of Boeck and Drbohlav's medium), and Robinson's media, but as mentioned before it is difficult to keep many isolates for long. [9,10] Whether this is a deficiency of the media or is dependent on the bacterial flora composition or on some other factor is not known. [7] Positive cultures containing B. coli survived for 14 days with subcultures done every 24 h. ...
Introduction: Balantidium coli (B. coli) is considered as the largest protozoon and the only parasitic ciliate known to infect humans. Objective: This study describes the cultivation and maintenance of B. coli isolated from a stool specimen of patient during the routine examination. Materials and Methods: B. coli was identified microscopically and then successfully cultivated and maintained in home-produced culture media. Four media, Water (W), water with fecal matter (WF), WF and blood (WFB), and water with serum (WS) were used to cultivate and maintain the parasite. Inoculated culture media were observed daily and then weekly. Results: WF and WFB exhibited good growth of the parasite as well as maintenance up to 5 months. W and WS showed good maintenance of the parasite up to 7 months and no growth, respectively. Conclusion: The present study depicts the simple and cost-effective techniques that help us in cultivation and maintenance of B. coli for a long time without doing subcultures again and again.
... After the modified Bailenger sedimentation, 200 lL aliquots of each collected sample were cultured in Robinson medium (Robinson 1968) at 24°C to promote E. moshkovskii growth or 36.5°C to promote E. histolytica/ E.dispar growth. Microscopic identification and quantification was performed for each culture. ...
We conducted an observational study to determine the prevalence of Entamoeba spp., in samples collected in a waste water treatment plant that provides water for agricultural irrigation. Samples were collected weekly over a period of 10 weeks at representative contamination stages from within the treatment plant. Protozoan identification was performed via light microscopy and culture. PCR amplification of small subunit rRNA gene sequences of E. histolytica/dispar/moshkovskii was performed in culture positive samples. Light microscopy revealed the presence of Entamoeba spp., in 70% (14/20) of the raw waste water samples and in 80% (8/10) of the treated water samples. PCR amplification after culture at both 24 and 37°C revealed that 100% (29/29) of the raw waste water samples and 78.6% (11/14) of the treated waste water were positive for E. moshkovskii. We report the first isolation of E. moshkovskii in Colombia, confirmed by PCR. Recent reports of E. moshkovskii pathogenic potential suggest this finding could constitute a public health risk for people exposed to this water.
... Briefly, a small fraction of feces was mixed with a small drop of Lugols iodine (diluted 1: 5 with water) on a microscope slide, and observed under microscope after placing a cover slip over the preparation. Irrespective of the microscopic analysis results, all fecal samples were cultured for Entamoeba species under xenic condition using biphasic (solid and liquid) Robinson's medium within 5-6 h of collection as previously described [20]. The presence of characteristic spherical, oval or round shaped quadrinucleated cyst or trophozoites in fecal sample; and trophozoites emerging out of excysted cysts with ingested starch particles in xenic culture often showing clear pseudopodia were considered as the keys to confirm sample as positive microscopically. ...
BACKGROUND:Epidemiological studies carried out using culture or microscopy in most of the amoebiasis endemic developing countries, yielded confusing results since none of these could differentiate the pathogenic Entamoeba histolytica from the non-pathogenic Entamoeba dispar and Entamoeba moshkovskii. The Northeastern part of India is a hot spot of infection since the climatic conditions are most conducive for the infection and so far no systemic study has been carried out in this region. METHODOLOGY/PRINCIPAL FINDINGS:Following a cross-sectional study designed during the period 2011-2014, a total of 1260 fecal samples collected from the Northeast Indian population were subjected to microscopy, fecal culture and a sensitive and specific DNA dot blot screening assay developed in our laboratory targeting the Entamoeba spp. Further species discrimination using PCR assay performed in microscopy, culture and DNA dot blot screening positive samples showed E. histolytica an overall prevalence rate of 11.1%, 8.0% and 13.7% respectively. In addition, infection rates of nonpathogenic E. dispar and E. moshkovskii were 11.8% (95% CI = 10.2, 13.8) and 7.8% (95% CI = 6.4, 9.4) respectively. The spatial distributions of infection were 18.2% (107/588) of Assam, 11.7% (23/197) of Manipur, 10.2% (21/207) of Meghalaya, and 8.2% (22/268) of Tripura states. Association study of the disease with demographic features suggested poor living condition (OR = 3.21; 95% CI = 1.83, 5.63), previous history of infection in family member (OR = 3.18; 95% CI = 2.09, 4.82) and unhygienic toilet facility (OR = 1.79; 95% CI = 1.28, 2.49) as significant risk factors for amoebiasis. Children in age group
... On the other hand, headache, dry mouth, a metallic taste, and neurotoxicity and gastrointestinal disturbances, especially nausea is among the most common side effects of metronidazole. In some patients, vomiting and diarrhoea or constipation may also occur (38,39). E. histolytica can show multidrug resistance during the treatment (40). ...
Background: The aim of this study was to determine phenolic acid composition and anti-parasitic effects of Peucedanum caucasicum, P. palimbioides, P. longibracteolatum and P. chryseum on Entamoeba histolytica.
Methods: Methanol extracts of the plant species were prepared by soxhlet extraction. Phenolic acid compositions were determined by HPLC. Anti-proliferative effect of extracts on trophozoites was determined by using trypan blue dye exclusion test. For counting the cells, approximately a hundred of E. histolytica trophozoites were examined in each time. The data were presented as mean values with standard deviations and analyzed by repeated measures of ANOVA followed by Tukey test for post-hoc pairwise comparisons. The P-value was set at 0.05 for significance level.
Results: All of the extracts showed a time and dose dependent amoebicidal action on trophozoites. Among the extracts tested, P. longibracteolatum showed the strongest amoebicidal effect on the trophozoites. As expected, this plant species also exhibited time and dose dependent activity on the trophozoites. At 4.0 mg/ml extract concentration, all of the trophozoites were killed by the extract in 72nd hour. Gallic (11.144 mg/g), P-hydroxybenzoic (17.646 mg/g), and o-coumaric acids (14.442 mg/g) were determined as the major phenolic acids of P. longibracteolatum. Gallic and P-hydroxybenzoic acids found in P. longibracteolatum could not be determined in other extracts. Therefore, high activity potential of this plant could probably be attributed to the presence of these phytochemicals.
Conclusion:
P. longibracteolatum can be further evaluated as potential therapeutic drugs for the treatment of Entamoeba infections.
... Evolution of the Society of Protozoontologists taxonomisch zum Stamm der Sarcomastigophora, Unterstamm III Sarcodina, Superklasse Rhizopoda, Klasse Lobosea, Unterklasse Gymnamoebia und zur Ordnung der Amoebida, Unterordnung Tubulina (Levine ND et al. 1980 (Boeck WC und Drbohlav J 1925), später wurden auch andere Methoden der kulturellen Anzüchtung beschrieben (Diamond LS 1968;Robinson GL 1968). ...
... Amöbenkultivierung nach ROBINSON(17) Etwa 50 mg frischer unbehandelter Stuhl wird in eine Kulturflasche mit biphasischem Robinson-Medium gegeben. Neben der salinischen Agarfläche enthält das Medium Reisstärke, Pepton, Erythromycin, Phthalat und im definierten "BR"-Medium einen Stamm von Escherichia coli. ...
... Ten of the patients had intestinal symptoms (constipation alternating with diarrhea or semiformed stools, abdominal cramps), and 19 patients were asymptomatic. The Faust method [15] was used, and the cysts were cultured in Robinson medium [16]. To identify E. histolytica isolates, amplification was performed for the 530-bp enhhic gene, which encodes the 30-kDa cysteine protease (data not shown) [17]. ...
To identify sequences of Entamoeba histolytica associated with the development of amebic liver abscess (ALA) in hamsters, subtractive hybridization of cDNA from E. histolytica HM-1:IMSS under 2 growth conditions was performed: 1) cultured in axenic medium and 2) isolated from experimental ALA in hamsters. For this procedure, 6 sequences were obtained. Of these sequences, the mak16 gene was selected for amplification in 29 cultures of E. histolytica isolated from the feces of 10 patients with intestinal symptoms and 19 asymptomatic patients. Only 5 of the 10 isolates obtained from symptomatic patients developed ALA and amplified the mak16 gene, whereas the 19 isolates from asymptomatic patients did not amplify the mak16 gene nor did they develop ALA. Based on the results of Fisher's exact test (P<0.001), an association was inferred between the presence of the mak16 gene of E. histolytica and the ability to develop ALA in hamsters and with the patient's symptoms (P=0.02). The amplification of the mak16 gene suggests that it is an important gene in E. histolytica because it was present in the isolates from hamsters that developed liver damage.
... Routinemäßige bakteriologische Untersuchungen wurden zum kulturellen Nachweis folgender Erreger vorgenommen: Salmonella, Shigella, Yersinia, Campylobacter, Aeromonas, Plesiomonas, Staphylococcus aureus, Bacillus cereus und enterotoxigene E. coll. Zur kulturellen Anzüchtung von E, histolytica wurde das Robinson Medium benutzt (18). Lysate für die Isoenzymuntersuchung wurden so schnell wie möglich nach der Isolierung hergestellt, sobald eine Anzahl von 5 X 10 4 X ml~1 Trophozoiten erreicht war. ...
... Clinical isolate 654 was from a patient sample from Safdarjung hospital, New Delhi, while MS96 3382 (henceforth referred as MS96) was isolated from an urban slum in Dhaka. They were isolated from stool samples and maintained in Robinson's BRS medium with added Escherichia coli [18,19] and subcultured thrice a week. ...
Entamoeba histolytica infections are endemic in the Indian subcontinent. Five to eight percent of urban population residing under poor sanitary conditions suffers from Entamoeba infections. Metronidazole is the most widely prescribed drug used for amoebiasis. In order to understand the impact of metronidazole stress on the parasite, we evaluated the expression of two antioxidant enzymes, peroxiredoxin and FeSOD, in Entamoeba histolytica isolates during metronidazole stress. The results reveal that, under metronidazole stress, the mRNA expression levels of these enzymes did not undergo any significant change. Interestingly, immunolocalization studies with antibodies targeting peroxiredoxin indicate differential localization of the protein in the cell during metronidazole stress. In normal conditions, all the Entamoeba isolates exhibit presence of peroxiredoxin in the nucleus as well as in the membrane; however with metronidazole stress the protein localized mostly to the membrane. The change in the localization pattern was more pronounced when the cells were subjected to short term metronidazole stress compared to cells adapted to metronidazole. The protein localization to the cell membrane could be the stress response mechanism in these isolates. Colocalization pattern of peroxiredoxin with CaBp1, a cytosolic protein, revealed that the membrane and nuclear localization was specific to peroxiredoxin during metronidazole stress.
Accurate diagnosis of Entamoeba histolytica is important, as it is known as a causative agent for both invasive intestinal and extra-intestinal amoebiasis. Amoebiasis has a worldwide distribution, especially in developing countries, and it is responsible for up to 100,000 fatal cases annually. A number of diagnostic methods, including microscopy, culture, antigen detection, molecular based methods, and serological assays have been proposed to assist in diagnosing amoebiasis. The present study aimed to gather new data and review the available diagnostic tests of both intestinal and extra-intestinal amoebiasis and to highlight pitfalls and challenges of each of them. A broad literature of electronic databases was conducted and covered articles published up to March 2022. For laboratory diagnosis of intestinal amoebiasis, direct microscopy stool examinations and cultures should be held as the high-performance diagnostic strategies. Molecular and immunological-based assays are also recommended as complementary tests. To diagnose extra-intestinal infection, the use of serological tests is still considered the method of choice. However, serodiagnosis requires further improvement for the accurate differential diagnosis of active infection from past infections.
Accurate diagnosis of Entamoeba histolytica is important, as it is known as a causative agent for both invasive intestinal and extraintestinal amoebiasis. Amoebiasis has a worldwide distribution, especially in developing countries, and it is responsible for up to
100,000 fatal cases annually. A number of diagnostic methods, including microscopy, culture, antigen detection, molecular based
methods, and serological assays have been proposed to assist in diagnosing amoebiasis. The present study aimed to gather new data
and review the available diagnostic tests of both intestinal and extra-intestinal amoebiasis and to highlight pitfalls and challenges of
each of them. A broad literature of electronic databases was conducted and covered articles published up to March 2022. For
laboratory diagnosis of intestinal amoebiasis, direct microscopy stool examinations and cultures should be held as the highperformance diagnostic strategies. Molecular and immunological-based assays are also recommended as complementary tests. To
diagnose extra-intestinal infection, the use of serological tests is still considered the method of choice. However, serodiagnosis
requires further improvement for the accurate differential diagnosis of active infection from past infections
Aim:
The current study investigated the prevalence and genotypes of Blastocystis sp. in individuals who referred to medical laboratories in Kermanshah, Iran.
Background:
Blastocystis sp. is a common intestinal protozoan found in humans and a wide range of animals, and it is involved in the development of gastrointestinal disorders.
Methods:
A total of 950 stool samples were examined using the standard formalin-ether concentration technique. All specimens were cultured in Robinson xenic medium. Subsequently, DNA extraction and PCR amplification of subtype specific sequence-tagged site (STS) were conducted.
Results:
Microscopic examination showed that 86 out of 950 samples (9.05%) were infected with Blastocystis sp. Subsequently, 33 of 86 positive samples were cultured and molecularly confirmed by conventional PCR, indicating six subtypes (ST1-ST6). Of note, ST3 (45.0%) was the predominant subtype, followed by ST1 (15.15%) and ST5 (12%).
Conclusion:
Based on the current findings, ST3 was the most frequent subtype among all positive samples. Having a better understanding of Blastocystis sp. subtype distribution and risk factors would lead to improved preventive measures.
Blastocystis infection accounts for one of the causes of gastrointestinal problems with the prevalence rate of 3-100% worldwide. There is a wide range of drugs examined for the treatment of infected patients, among them metronidazole (MTZ) has been introduced as one of the efficient drugs. Besides to the suitable clinical effects, the administration of MTZ has some reported side-effects which emphasize on the identification of putative alternates. To this end, we aimed to evaluate the cytotoxicity effect of a newly-introduced synthetic antimicrobial peptide (AMP) named CM11 on in vitro cultured Blastocystis. Our results exhibited that CM11 treatment affected the viability of parasites in two cultural conditions including culturing alone and in co-culture with the Caco-2 cell line. The time- and dose-dependent effect of CM11 was consistent with the effect of MTZ which was used as control positive. The highest toxicity effect of CM11 was observed at the concentration of 24 μg/ml, leading to 28.7% and 25% viable parasites after 24 h and 48 h incubation times, respectively. Interestingly, the disruption of the Blastocystis cell membrane could be observed in the treated parasites. Therefore, CM11 can be suggested as a potential treatment for Blastocystis-infected patients after further in vitro and in vivo assessments.
Certain Desulfovibrio sp. (anaerobic sulfate-reducing bacteria) are indigenous to swine cecum and colon, which are also common habitats for parasitic amoebae such as Entamoeba polecki and Entamoeba suis. In this study, we evaluated the growth-promoting effects of D. desulfuricans co-cultured with Escherichia coli (DH5α) and its products [e.g., hydrogen sulfide (H2S) and certain iron-sulfide (FeS) compounds] using Robinson's medium, on the 4 amoeba isolates from swine-Entamoeba polecki subtype (ST)-1, E. polecki ST-3, Entamoeba suis, and Endolimax sp., and, consequently, a continuous culture system for these amoebae was established. However, this novel culture system was required to regulate the excess H2S dissolved in the medium by increasing air space as amoeba isolates thrive only in large air spaces (30-40%). The effects of air space and H2S and FeS compounds on the growth of E. polecki ST-1 (TDP-5) were determined. E. polecki ST-1 (TDP-5) thrived well in culture bottles with an air space of 30-40% (aerobic) (H2S: ~250-400 μmoles/L), but did not grow at all in an air space < 5% (microaerobic) ( H2S:~800 μmoles/L) and in anaerobic vessels (H2S: 20-30 μmoles/L). In both H2S-depleted and FeS compound-depleted conditions, the amoebae sp. could not thrive either. It was hypothesized that an appropriate concentration of H2S and FeS compounds might function as important physiologically active components of electron carriers such as FeS and ferredoxin.
Only one in ten Entamoeba histolytica infections is invasive but they are responsible for an annual death toll of up to 100,000 people. A key question in amoebiasis is, therefore, what is responsible for the variable outcome of infection. To investigate whether it is linked to the genotype of the infecting strain, we developed 6 pairs of species-specific primers for genotyping after investigating 46 potentially polymorphic short tandem repeat loci adjacent to tRNA genes that were identified during the E. histolytica genome project. We tested the primers using E. histolytica samples from Bangladesh and 11 other countries. Results revealed that the genotypes present in 3 different clinical populations - asymptomatic, diarrhoeal/dysenteric and liver abscess - were different from each other. A few individual genotypes also showed links to the outcome of infection although their sample coverage was low and therefore they had little predictive value. Although the loci used as polymorphic markers are unlikely to be directly responsible for the outcome of infection, the results do suggest that parasite genetic factors are at least partly responsible. Our multilocus genotyping method is simple and reliable as it amplifies DNA extracted from axenic or xenic culture, stool samples, and liver abscess pus samples. We believe that these markers will help in studying the patterns of transmission of this important disease and the epidemiological links between individual infections.
It is now well established that Entamoeba histolytica was indeed a species complex comprising of pathogenic E. histolytica and morphologically indistinguishable non-pathogenic E. dispar and E. moshkovskii. A greater hindrance is the different and inconsistent use of diagnostic methods in different areas of the world. Though microscopy has poor sensitivity, it seems that till today, many epidemiological studies are either based on microscopy alone or PCR assay carried out on microscopy screened samples or PCR assay performed on a very small sample size and thus fails to figure out the true magnitude of amoebiasis. The present review recommends DNA-based systematic approach like rDNA-based DNA dot blot screening followed by PCR assay to determine the true prevalence rate, suggesting its implication in the large-scale epidemiological study. DNA-based studies from across the world showed that the prevalence rate varies from 0.55% to 69.6% among human populations. The studies indicate that various unhygienic practices like unhygienic toilet facilities, poor living conditions, hand washing habits, etc. HIV infection and mutation in LEPR are among common factors that increase the likelihood of amoebiasis. On the other hand, till today it remains unclear if the E. histolytica causing intestinal and extra-intestinal amoebiasis is a similar or different strain.
This Practical Guidance for Clinical Microbiology document on the laboratory diagnosis of parasites from the gastrointestinal tract provides practical information for the recovery and identification of relevant human parasites. The document is based on a comprehensive literature review and expert consensus on relevant diagnostic methods. However, it does not include didactic information on human parasite life cycles, organism morphology, clinical disease, pathogenesis, treatment, or epidemiology and prevention. As greater emphasis is placed on neglected tropical diseases, it becomes highly probable that patients with gastrointestinal parasitic infections will become more widely recognized in areas where parasites are endemic and not endemic. Generally, these methods are nonautomated and require extensive bench experience for accurate performance and interpretation.
Protozoa of several genera have successfully colonized the human alimentary canal, although only a few are important pathogens. Rare but potentially very dangerous infections occur with coccidian parasites of the genera Eimeria and Isospora; however, they will not be considered further here. Toxoplasma is discussed in Chapter 14. Of the flagellates. Trichomonas tenax inhabits the oral cavity, and Pentatrichomonas hominis the large intestine. The most important human pathogen is, however, Trichomonas vaginalis, which infects the genitourinary tract of both men and women. Of the amebas. Entamoeba histolytica, E. hartmanni, E. coli*, Iodamoeba buetschlii, and Endolimax nana are found in the large intestine, while Entamoeba gingivalis is confined to the mouth. Three other protozoa may also be present: Giardia lamblia† in the small intestine, and Dientamoeba fragilis and the ciliate Balantidium coli in the large intestine.
The cellular immune response was evaluated in a C3H/HeJ mouse model of intestinal amebiasis at 5-60 days postinoculation with Entamoeba histolytica. At various intervals, spleen lymphocytes were obtained from infected and noninfected control mice and cultured with concanavalin A (Con A), pokeweed mitogen (PWM), or ameba antigen. E. histolytica infection induced a cyclic depression of DNA synthesis when spleen lymphocytes were stimulated with a T-cell mitogen (Con A), a T- and B-cell (PWM) mitogen, or an ameba antigen. A similar response was observed in the determinations of interleukin-2 in the supernatants of Con A-stimulated spleen cells from infected mice. When spleen cells from E. histolytica-infected mice were stimulated with phorbol myristate acetate plus ionomycin, results indicated a signal-transduction defect. These alterations, observed at the cellular level, might facilitate invasion of the host by the parasite.
Entamoeba histolytica is an intestinal parasite causing significant morbidity and mortality in the developing world. More tools are needed to understand the epidemiology and molecular pathogenesis of amebiasis. Virulence pattern of E. histolytica could be linked with the genotype of a strain. Several loci showing insertion polymorphism of retrotransposable short interspersed nuclear elements EhSINE1 and EhSINE2 have been reported among laboratory strains of E. histolytica. The present study was undertaken to validate this observation in clinical isolates from north India. Our results indicate that the Indian samples show a different propensity of SINE retention or loss at two of the polymorphic loci compared with non-Indian samples. Statistical analysis of different loci revealed Locus 17 of EhSINE1as a potential geographical marker for distinguishing Indian isolates from non Indian isolates.
Leishmaniases are endemic in 88 countries of five continents (only Australia is safe); 72 of these are distributed in tropical and subtropical areas, whereas 16 are included in the Temperate Zone [1].
Four cases of amoebiasis are described: two symptomatic with intestinal and hepatic involvement and two asymptomatic, diagnosed in two, heterosexual, Italian couples. Infection was probably acquired first by the men, via an indirect faecal-oral route, and then transmitted to their partners in the same way. The two amoebic strains isolated, from the woman of one couple and the man of the other, were characterized by electrophoresis as zymodemes II α—and XIX of Entamoeba histolytica. These four cases emphasise once more the role of cyst-passers in the spread of infection and the importance of biochemical identification of the amoebic isolates, enabling more specific treatment.
Of 550 mentally retarded patients in an Italian institution, 125 (23%) were found to be infected with intestinal parasites. The infections were most frequent in young men, those with severe mental retardation, the chronically institutionalized and those living in older wards. Ninety-four (75.2%) of the parasitised subjects were infected only with protozoa, 25 (20%) only with helminths, and six (4.8%) with protozoa and helminths. Entamoeba histolytica and E. dispar infections were detected, but at low prevalences; in-vitro culture in Robinson's medium and isoenzyme electrophoresis of the cloned amoebic isolates indicated one infection with E. histolytica (zymodeme XII) and two infections with E. dispar (zymodemes I and III). All three Entamoeba-positive subjects were asymptomatic cyst-passers. Antibodies to E. histolytica were detected in seven (1%) of the sera from the 550 patients examined; only one of these was a carrier of an E. dispar strain at the time of investigation.
The low prevalences of all the parasitic infections and of the amoebic infections in particular (compared with those observed previously in institutions for the mentally retarded) reflect relatively good facilities and sanitary conditions, an adequate number of well trained staff and good control of the more susceptible subjects.
Résumé
Dientamoeba fragilis est un protozoaire flagellé du gros intestin dont certains aspects épidémiologiques demeurent mal connus à ce jour. Afin d’évaluer sa prévalence au laboratoire de parasitologie du CHU Mustapha d’Alger et d’étudier ses caractéristiques épidémiologiques et diagnostiques, nous avons mené une étude prospective du 1er janvier au 31 décembre 2012 sur une population de 2 603 sujets chez lesquels nous avons pratiqué un examen parasitologique des selles, avec une coloration permanente systématique par la méthode de trichrome de Gomori modifiée par Wheatley. Un « scotch test » anal, proposé systématiquement à tous les sujets, n’a pu être réalisé que chez 513 sujets l’ayant accepté. Dientamoeba fragilis a été retrouvé à 228 reprises soit une prévalence de 8,76% IC 95% [7,62%-9,78%], ce qui le place en deuxième position après Blastocystis sp., auquel il est d’ailleurs associé dans 51,31% des cas. Les signes cliniques les plus fréquemment retrouvés sont les flatulences/ballonnement, douleur abdominale et constipation. La relation entre Enterobius vermicularis et Dientamoeba fragilis a été étudiée chez 513 sujets et laisse supposer un lien entre ces deux parasites. L’examen direct seul a donné une fréquence de Dientamoeba fragilis de 4,65%, le trichrome de Wheatley l’a corrigée à 8,76%. Enfin le traitement n’a été efficace que dans 47,61%. Notre étude montre que Dientamoeba fragilis existe en Algérie, qu’il est assez fréquent, et suggère qu’il pourrait être à l’origine de troubles digestifs. Elle met en évidence la nécessité pour tous les laboratoires de coprologie parasitaire d’inclure la recherche de Dientamoeba fragilis dans sa pratique quotidienne, par une coloration permanente systématique.
Because specific treatment for trichomoniasis is available, it is important to identify infected people so that disease in the individual can be terminated and the sexual transmission of the organism prevented. The classic symptoms of the disease in women are a thin yellow offensive vaginal discharge, pruritus vulvae or vulval soreness, dyspareunia, and dysuria. A reddened vaginal wall with frothy thin yellow exudate in the posterior fornix and punctate red spots on the ectocervix (“strawberry cervix”) may be seen.1 These features, however, are not always present and are not pathognomonic of trichomoniasis. Although about 50% of women infected with T. vaginalis notice an increased vaginal discharge, a similar proportion of non-infected women give a similar history.23 Since about 18% and 12% of infected and nonin-fected women respectively have dysuria, this is not a helpful diagnostic feature.2 An abnormal discharge in the vaginal fornices may be seen more frequently in infected women (about 50%) than in noninfected individuals (about 22%),3 but this is described as “frothy” in only 12% of cases.2 The strawberry cervix is rarely seen.
Amebiasis is a ubiquitous disease which is a particularly important problem in developing tropical countries. The causative agent, Entamoeba histolytica, was first described in 1875 by Lösch, a Russian physician in St. Petersburg.1 He described the organisms in detail and called them Amebae coli. In a careful pathologic and clinical review in 1891, Councilman and Lefleur2 described amebic dysentery as a distinct entity characterized by ulceration of the colon wherein the ulcers were undermined without products of inflammation. They furthermore indicated that liver abscess often complicated intestinal disease with occasional extension of the abscess to the lung. The true pathogenic potential of E. histolytica for humans was established in 1911–1913 by a series of studies of experimental infection induced in volunteers.3,4 Filipino prison volunteers who ingested E. histolytica cysts developed dysentery, and stools were shown to contain the amebae. In 1919, the four species of commensal amebae were distinguished from E. histolytica.5
The science of immunology was born of attempts to understand and, more importantly, cure the infectious diseases which in the past had taken so many lives. Together with public health measures and antibiotics, practical immunology, particularly in the form of vaccination, has succeeded to the point where infectious diseases have become relatively trivial as causes of death in economically advanced nations. It was natural, therefore, that immunolo-gists should try to repeat their success when faced with the parasitic diseases which cause so much illness and death in the underdeveloped world. It is fair to say that, on balance, this aim has proved much harder to realize than was expected, and the feeling has grown that there is something special (and probably malign) about the immune response to protozoa. Although the subject has produced many fascinating surprises (such as antigenic variation) it seems wrong to base a general review on what may be special cases. It seems safer to consider briefly what is known of the immune responses to the major human protozoal parasites and then see if any general conclusions emerge. The order in which the organisms are discussed has been chosen to bring together those which occupy the same sort of habitats and which elicit the same sort of host response: thus, in this context, Trypanosoma cruzi is more like Leishmania tropica than the African trypanosomes.
Amoebiasis ist eine durch Entamoeba histolytica hervorgerufene Krankheit. Der Erreger ist ein Protozoon, das als Kommensal des Dickdarmlumens bei Menschen aller Kontinente gefunden werden kann (Elsdon-Dew, 1964). Eine Krankheit entsteht, wenn dieser Schmarotzer in die Dickdarmschleimhaut eindringt, sich dort anpaßt, vermehrt und dabei Gewebenekrosen und Entzündungen hervorruft. Von der Darmwand aus können die Amoeben in andere Organe gelangen und dort wiederum Nekrosen und Entzündungen verursachen. Man unterscheidet also zwischen der intestinalen Amoebiasis, einer ulcerierenden Rektokolitis, und einer extra-intestinalen Amoebiasis, deren häufigste Lokalisation die Leber ist und die als tropischer Leberabsceß bezeichnet wird. Es handelt sich hier um metastatische Komplikationen der Darminfektion.
Examinations of wet mounts and iron hematoxylin stained sediments preserved in PVA-fixative from 878 diagnostic fecal cultures were made, and the results compared. Of a total of 391 infections found by the two examinations, 366 infections (or 94 per cent) were identified in the stained films as compared to 212 (or 56 per cent) identified in the wet mounts of the same cultures. The increased number was due (a) to the addition of infections found only in the stained films and (b) to the identification of infections seen but not identified in the wet mounts. The numbers of infections of all five species of amebae were increased to varying degrees.
The sediment from routine diagnostic fecal cultures for amebae can be fixed with PVA-fixative and stained by permanent staining techniques with good results. In order to reduce the work involved in the cultivation procedure, it is suggested that the preparation of stained smears be reserved for those cultures in which organisms are observed in wet mounts. In this study 94 per cent of the infections would have been identified by this limited number of examinations of stained slides (250 slides rather than 878).
- Faust