Amoebiasis: Advances in Diagnosis, Treatment, Immunology Features and the Interaction with the Intestinal Ecosystem.

This review of human amoebiasis is based on the most current knowledge of pathogenesis, diagnosis, treatment, and Entamoeba/microbiota interactions. The most relevant findings during this last decade about the Entamoeba parasite and the disease are related to the possibility of culturing trophozoites of different isolates from infected individuals that allowed the characterization of the multiple pathogenic mechanisms of the parasite and the understanding of the host-parasite relationship in the human. Second, the considerable advances in molecular biology and genetics help us to analyze the genome of Entamoeba, their genetic diversity, and the association of specific genotypes with the different amoebic forms of human amoebiasis. Based on this knowledge, culture and/or molecular diagnostic strategies are now available to determine the Entamoeba species and genotype responsible for invasive intestinal or extraintestinal amoebiasis cases. Likewise, the extensive knowledge of the immune response in amoebiasis with the appearance of new technologies made it possible to design diagnostic tools now available worldwide. Finally, the understanding of the interaction between the Entamoeba species and the intestinal microbiota aids the understanding of the ecology of this parasite in the human environment. These relevant findings will be discussed in this review.

Massive Lower Gastrointestinal Bleeding Due to Fulminant Necrotizing Amebic Colitis: A Diagnostic and Therapeutic Challenge.

Acute fulminant necrotizing amebic colitis rarely presents with massive lifethreatening lower gastrointestinal bleeding without diarrhea. Diagnosis is difficult as colonoscopy is suboptimal due to active bleeding, stool testing is often negative and a positive serology cannot confirm the diagnosis. We herein report a case of a 39-year-old male who presented with profuse bleeding per rectum, without associated significant antecedent history of fever or diarrhea. Colonoscopy was inconclusive as active bleeding obscured the vision. Computed tomography of abdomen revealed non-specific thickening of the caecum. Emergency laparotomy with right hemicolectomy and temporary ileostomy was performed. Microscopic examination of colonic mucosa revealed Entamoeba histolytica trophozoites with erythrophagocytosis suggestive of fulminant amebic colitis. Intravenous metronidazole was given subsequently and patient recovered completely. Ileocolonic anastomosis was done after closing the ileostomy three months later. This case highlights this exceedingly rare presentation of fulminant amebic colitis which poses a diagnostic challenge and can be life threatening without early surgical intervention.

Approach to amoebic colitis: Epidemiological, clinical and diagnostic considerations in a non-endemic context (Barcelona, 2007-2017).

BACKGROUND: Amoebic colitis is the most frequent clinical manifestation of invasive intestinal infection due to Entamoeba histolytica and a common cause of diarrhoea worldwide. Since higher transmission rates are usually related to poor health and exposure to unhygienic conditions, cases reported in Europe usually involve immigrants and international travellers. The goal of this study was to characterise both the clinical and the epidemiological features of a European population diagnosed with amoebic colitis and then to evaluate the diagnostic tools and therapeutic options applied. METHODS AND RESULTS: This was a retrospective observational study in which data from all patients diagnosed with amoebic colitis attending at the International Health Units of two tertiary referral hospitals, Germans Trias i Pujol University Hospital (Badalona, North Barcelona Metropolitan Area) and Vall d'Hebron University Hospital (Barcelona city) between 2007 and 2017 were analysed. During the study period 50 patients were diagnosed with amoebic colitis. Thirty-six (72%) were men, and immigrants accounted for 46% of all cases. Antecedents of any international travel were reported for 28 (56%), the most frequent destinations having been the Indian subcontinent, South and Central America and sub-Saharan Africa. Preexisting pathological conditions or any kind of immunosuppression were identified in 29 (58%) patients; of these, 13 (26%) had HIV infection-all of them men who have sex with men-and 5 (10%) had inflammatory bowel disease. Diarrhoea, abdominal pain and dysentery were the most frequently recorded symptoms of invasive amoebae. Diagnosis was made through microbiological study in 45 (90%) and/or histological identification of amoebae in colon biopsies in 10 (20%). After treatment with metronidazole (82%) or tinidazole (8%), all patients had good outcomes. Post-acute intraluminal treatment was indicated in 28 (56%). CONCLUSIONS: Amoebic colitis should be suspected in patients with diarrhoea and compatible epidemiological risk factors (immigration, travelling abroad or men who have sex with men), especially if some degree of immunosuppression concurs. These risk factors must be taken into account in any diagnostic approach to inflammatory bowel disease (IBD), and active searches for stool parasites should be performed in such cases to rule out misdiagnosis or simultaneous amoebic infection. Treatment should include intraluminal anti-amoebic treatment in order to avoid relapse and prevent further spread of the disease.

[Breaking paradigms. Intestinal microbiota transplantation: Preliminar report]. / Rompiendo paradigmas. Trasplante de microbiota intestinal: reporte preliminar.

In the fourth century, during the Chinese Dong Jin dynasty, the doctor Ge Hong described good results after the oral administration of a suspension prepared from human faeces in patients with severe diarrhoea or food poisoning. Faecal microbiota transplantation has been used for five years in order to treat different diseases in addition to the severe diarrhoea caused by Clostridium difficile1. This paper aims to confirm that intestinal microbiota transplantation succeeds in reducing the negative impact of diseases such as severe diarrhoea, irritable bowel syndrome, anxiety, allergies, metabolic syndrome and others and that it is not only indicated for severe diarrhoea caused by C. difficile. This preliminary study included six patients who underwent faecal microbiota transplantation, aged 83, 76, 66, 37 and 36 years (four men and two women). An improvement in symptoms of 70% was observed. The methodology and criteria to be followed with donors are described and the results are listed in three tables. The methodology followed for the microbiota transplant is the same as that reported by other researchers for the treatment of C. difficile diarrhoea and other diseases. The discussion addresses the issues raised in other parts of the world in handling different pathologic entities, as well as genetic advances. The conclusions show encouraging results.

Gut microbiome diversity in acute infective and chronic inflammatory gastrointestinal diseases in North India.

The disease profile in the Indian population provides a unique opportunity for studying the host microbiome interaction in both infectious (amebiasis) and autoimmune diseases like inflammatory bowel disease (IBD) from a similar environment and genetic background. Analysis of fecal samples from untreated amebic liver abscess (ALA) patients, Entamoeba histolytica (Eh)-negative and -positive asymptomatic individuals, and pus samples from naive ALA patients revealed a significant reduction in Lactobacillus in asymptomatic individuals (Eh +ve) and ALA patients. Two anaerobic genera, namely Bacteroides and Peptostreptococcus, were detected in naive ALA pus samples. Analysis of fecal samples from amoebic colitis patients showed a significant decline in population of Bacteroides, Clostridium coccoides and leptum subgroup, Lactobacillus, Campylobacter, and Eubacterium, whereas a significant increase in Bifidobacterium was observed. Mucosa-associated bacterial flora analysis from IBD patients and healthy controls revealed a significant difference in concentration of bacteria among predominating and subdominating genera between ulcerative colitis (UC), Crohn's disease (CD) patients, and controls. In contrast to the mucosal studies, we found a significant increase in lactobacilli population in fecal samples of active UC patients. Another study revealed a significant decrease of Clostridium coccoides and leptum clusters in fecal samples of active UC patients along with decreased concentrations of fecal SCFAs, especially of n-butyrate, iso-butyrate, and acetate. We therefore found similar perturbations in gut microbiome in both infectious and autoimmune diseases, indicating inflammation to be the major driver for changes in gut microbiome.

Fulminant amoebic colitis: a rare fierce presentation of a common pathology.

We conducted a retrospective study of patients with fulminant amoebic colitis (FAC) over a 20 year period in an urban tertiary care hospital in Pakistan. After consideration for inclusion and exclusion criteria 25 cases were identified as FAC with the most common presentations being abdominal pain (84%). Nineteen (76%) underwent laparotomy for peritonitis with evidence of: colonic perforation in 10 (40%); faecal peritonitis in eight (32%); bowel gangrene in one (4%); and intra-abdominal abscess in two (8%). Nine (36%) deaths were recorded in the series - eight (53%) in the operated group and one (16.6%) in the medically-treated group. The optimal outcome can be achieved in FAC with aggressive resuscitation, intravenous broad-spectrum antibiotics, including metronidazole, and total colectomy without anastomosis in patients with peritonitis.

Amebic infection in humans.

Clinical human infections with the protozoa Entamoeba histolytica is still estimated to occur in 50 million people worldwide, of which approximately 100,000 die annually. Although most clinical symptoms are due to involvement of the large intestine, 1 % present with involvement of the liver in the form of a liver abscess, a potentially fatal condition. Distinguishing an invasive form (E. histolytica) from a morphologically identical non-invasive one (E. dispar) requires molecular or enzymatic characterization. Further, the pattern of infection, interpretation of presence of antibodies in the host, manifestations of disease, approach to investigations and strategies for management remain complex. This article also provides a comprehensive review of the parasite and host factors that govern the complex relationship of the prozoa and humans, and tries to explain why some develop a particular form of the disease in endemic zones. Application of modern imaging and image guided therapy seems to be playing a major role in diagnosis and management of the potentially most serious form of the disease, amebic liver abscess. Despite lack of controlled studies there is a tendency to lower the threshold of their use in clinical practice, and indeed in-hospital mortality rate seems to be falling for amebic liver abscess. In a world getting increasingly swamped by non-infectious metabolic diseases, awareness of amebic infections, its bed-side diagnosis, the use of appropriate laboratory tests, and decision making in management are shrinking. This review tries to update the scientific developments in amebiasis.

[A case of fulminant amoebic colitis with an abscess in the abdominal cavity rescued by conservative management].

A 75-year-old man was admitted because of watery diarrhea, hematochezia and right lower abdominal pain. Many deep undermining colonic ulcers were found by colonoscopy, and we detected trophozoite amoeba pathologically. Metronidazole was administered orally from 3 days after admission. However, since CT demonstrated a huge abscess in the abdominal cavity, we performed percutaneous drainage from 17 days after admission. On day 157, the patient was discharged, because the colonic ulcers had almost healed, and trophozoite amoebas were not recognized pathologically.

[Complicated sigmoid tumor: perforated amebiasis]. / Une tumeur sigmoïdienne compliquée: amoebome perforé.

Amoeboma is an inflammatory mass of the colon. It can be an inaugural symptom and thus pose the problem of differential diagnosis with colon cancer. The purpose of this report is to describe the case of a 43-year-old patient who presented with acute abdomen. Physical examination revealed a perforated circumferential mass in the sigmoid colon. Based on a presumptive diagnosis of colonic cancer complicated by perforation, segmental colectomy was performed. Histological examination of the surgical specimen demonstrated colonic amoeboma. The patient was treated using metronidazole. Although rare, amoeboma must be considered in differential diagnosis of cancer of any colonic mass.

Efficacy and safety of Saccharomyces boulardii in amebiasis-associated diarrhea in children.

The efficacy and safety of adding Saccharomyces boulardii to antibiotic treatment for amebiasis-associated acute diarrhea in children were assessed in this study. Forty-five children in Group I received only metronidazole per oral for 10 days while 40 patients in Group II received S. boulardii in addition to the same medication. The major outcomes investigated were duration of acute and bloody diarrhea, frequency and consistency of stools, resolution time of the symptoms, and the tolerance and side effects of the treatment regimens. The median duration of acute diarrhea was 5 (1-10) days in Group I and 4.5 (1-10) days in Group II (p=0.965). The median number of stools on follow-up and duration of bloody diarrhea, fever, abdominal pain and vomiting were similar in the two groups. S. boulardii was well tolerated by the children and no side effects were recorded. Addition of S. boulardii to antibiotic treatment of amebiasis-associated acute diarrhea in children does not seem to be more effective than metronidazole treatment alone.

Amebic colitis: new insights into pathogenesis and treatment.

Amebiasis, caused by the protozoan parasite Entamoeba histolytica, affects more than 50 million people worldwide, with over 100,000 deaths annually. The majority of cases are asymptomatic; however, significant morbidity and mortality are associated with illness in the remaining 10% of cases. Recent advances in the understanding of the mechanism of infection by E. histolytica, the role of the innate immune system, and the role of genetic disposition to infection will allow the development of novel detection and treatment methods. The disease mechanisms, clinical findings, therapeutic strategies, and important developments regarding amebiasis are discussed here.

Massive Trichuris trichiura infection as a cause of chronic bloody diarrhea in a child.

The differential diagnosis of chronic diarrhea is extensive and requires the investigation of several diseases, such as celiac disease, inflammatory bowel disease and irritable bowel syndrome. A few patients infected by Trichuris trichiura may present a chronic dysentery-like syndrome in the context of a massive infestation of the colon leading to anemia and growth retardation, but the rarity of that finding demands a high level of suspicion. Herein we report the case of an 8-year-old boy from the rural zone who had suffered diarrhea without blood or mucus for 4 years and was taken to our Service because his mother had noticed the presence of blood on the feces on the 3 previous months. The diagnosis of a massive Trichuris trichiura infestation as the cause of the process was only reached by colonoscopy. We stress that Trichuris trichiura infection can mimic other forms of inflammatory bowel disease and lead to physical growth retardation and that prolonged regimens of albendazole may be required to the effective treatment of massive infestations.

Cellular and molecular mechanisms that underlie Entamoeba histolytica pathogenesis: prospects for intervention.

The protozoan parasite Entamoeba histolytica is the causative agent of amoebic dysentery. It is prevalent in developing countries that cannot prevent its fecal-oral spread and ranks second in worldwide causes of morbidity by parasitic infection. Improvements in sanitation would help curb disease spread. However, a lack of significant progress in this area has resulted in the need for a better understanding of the molecular and cellular biology of pathogenesis in order to design novel methods of disease treatment and prevention. Recent insight into the cellular mechanisms regulating virulence of E. histolytica has indicated that processes such as endocytosis, secretion, host cell adhesion and encystation play major roles in the infectious process. This review focuses on components of the molecular machinery that govern these cellular processes and their role in virulence, and discusses how an understanding of this might reveal opportunities to interfere with E. histolytica infection.

Conocimientos, creencias y prácticas de médicos de Cienfuegos en relación con la amebiasis intestinal: resultados de una intervención

Se demostró, con el empleo de herramientas inmunológicas y biomoleculares, en un estudio realizado en la provincia de Cienfuegos, que en aquella provincia la amebiasis intestinal era un problema de salud sobredimensionado. Una encuesta sobre conocimientos, percepciones y prácticas aplicada a médicos relacionados con el diagnóstico, tratamiento y control de esta parasitosis evidenció que la sobredimensión podía estar asociada a una inadecuada percepción del problema y a un marcado desconocimiento que sobre importantes aspectos de esta entidad poseían. Para contribuir a la solución de la sobredimensión, y de sus consecuencias, se ejecutó un grupo de acciones en la citada provincia. A 1 año de completada la puesta en práctica de esas medidas, una segunda aplicación de la encuesta, cuyos resultados se publican en este documento, permitió conocer de una significativa mejoría de los encuestados en la casi totalidad de los aspectos cognoscitivos (6,73 y 11,23 medias de respuestas correctas antes y después, respectivamente, de la intervención) y perceptuales evaluados.

In a study conducted in the province of Cienfuegos, it was proved by using immunological and biomolecular tools that intestina amebiasis in that province was an overdimensioned health problem. A survey on knowledge, perceptions and practices applied to those physicians related to the diagnosis, treatment and control of this parasitosis showed that the overdimensioning may be associated with an inadequate perception of the problem and with a marked lack of knowledge about important aspects of this entity. To contribute to the solution of the ovedimensioning and of its consequences, a set of actions were taken in that province. After a year, a second survey was done, whose results are published in this document, allowing to know about a significant improvement of the surveyed in almost all the evaluated cognitive and perceptual aspects (6.73 and 11.23 means of correct answers before and after. the intervention, respectively).

Treatment of infectious diarrhea in children.

Diarrheal diseases remain an important cause of childhood morbidity and death in developing countries, although diarrheal deaths have significantly declined in recent years, mostly due to successes in the implementation of oral rehydration therapy (ORT), which is the principal treatment modality. Diarrhea may occur for varied reasons; however, most episodes of diarrhea in developing countries are infectious in origin. Three clinical forms of diarrhea (acute watery diarrhea, invasive diarrhea, and persistent diarrhea) have been identified to formulate a management plan. Acute diarrhea may be watery (where features of dehydration are prominent) or dysenteric (where stools contain blood and mucus). Rehydration therapy is the key to management of acute watery diarrhea, whereas antimicrobial agents play a vital role in the management of acute invasive diarrhea, particularly shigellosis and amebiasis. In persistent diarrhea, nutritional therapy, including dietary manipulations, is a very important aspect in its management, in addition to rehydration therapy. Rehydration may be carried out either by the oral or intravenous route, depending upon the degree of dehydration. Oral rehydration salts (ORS) solution (World Health Organization formula) is recommended for ORT. Intravenous fluid is recommended for initial management of severe dehydration due to diarrhea, followed by ORT with ORS solution for correction of ongoing fluid losses. Antimicrobial therapy is beneficial for cholera and shigellosis. Antiparasitic agents are indicated only if amebiasis and giardiasis are present. Appropriate feeding during diarrhea is recommended for nutritional recovery and to prevent bodyweight loss. Antidiarrheal agents do not provide additional benefit in the management of infectious diarrhea. Although some probiotics have been shown to be beneficial in the treatment of acute diarrhea due to rotavirus, their use in the treatment of diarrhea is yet to be recommended, even in developed countries. The children of developing countries might benefit from zinc supplementation during the diarrheal illness, but its mode of delivery and cost effectiveness are yet to be decided.

[Knowledge, believes and practices of physicians from Cienfuegos in relation to intestinal amebiasis: results of an intervention]. / Conocimientos, creencias y prácticas de medicos de Cienfuegos en relación con la amebiasis intestinal: resultados de una intervención.

In a study conducted in the province of Cienfuegos, it was proved by using immunological and biomolecular tools that intestina amebiasis in that province was an overdimensioned health problem. A survey on knowledge, perceptions and practices applied to those physicians related to the diagnosis, treatment and control of this parasitosis showed that the overdimensioning may be associated with an inadequate perception of the problem and with a marked lack of knowledge about important aspects of this entity. To contribute to the solution of the ovedimensioning and of its consequences, a set of actions were taken in that province. After a year, a second survey was done, whose results are published in this document, allowing to know about a significant improvement of the surveyed in almost all the evaluated cognitive and perceptual aspects (6.73 and 11.23 means of correct answers before and after the intervention, respectively).

Intestinal amebae.

Although the intestinal amebae that infect humans are not thought of as classic agents of food-borne disease, food plays an important role in the transmission of these protozoa. This is particularly true for areas of the world where the organisms are endemic. Transmission of most intestinal protozoa occurs by the fecal-oral route via contaminated food or water. Among the four genera of amebae that infect man, only Entamoeba histolytica and Blastocystis hominis are causes of disease. This article focuses on E. histolytica because of the organism's medical and economic impact on humans. In addition, the epidemiology, control, and laboratory diagnosis of these protozoa are addressed.