Fulminant amebic colitis: analysis of 55 cases

Fulminant Amebic Enteritis in the Perinatal Period

Pregnancy is a known risk factor for amebic enteritis, which develops into potentially fatal fulminant amebic enteritis in some cases. We describe a case of a 27-year-old non-immunosuppressed pregnant woman with fulminant amebic enteritis complicated with cytomegalovirus enteritis. She improved with intensive care and intravenous metronidazole and ganciclovir but eventually required subtotal colectomy for intestinal stenosis. It is difficult to diagnose amebic enteritis, especially in a non-endemic area. Amebic enteritis must be considered as a differential diagnosis for refractory diarrhea with bloody stools in women in the perinatal period, even those without immunosuppression.

Updates on the worldwide burden of amoebiasis: A case series and literature review

BACKGROUND

Amoebiasis is an intestinal and tissue parasitic infection caused by the protozoan Entamoeba histolytica. Despite significant medical importance and worldwide dispersion, little is known about the epidemiology and distinct geographical distribution of various clinical forms of amoebiasis in the world. In this study, we present an amoebiasis case series referred to Avicenne Hospital (Bobigny, France) from 2010 to 2022 followed by an overview of the released literature to explore diverse clinico-pathology of amoebiasis and to update the actual epidemiological situation of this parasitosis worldwide.

METHODS

The referred patients underwent a combination of clinical and parasitological examinations and imaging. The study was followed by an overview of released literature performed based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline.

RESULTS

A total of 15 patients with amoebiasis were diagnosed with an average age of 48.5 years old at the occurrence time of infection. Men (78%) were the most affected patients. Most of the cases were reported following a trip to endemic regions, such as Mali, India, Nepal, Algeria, Cameroon or Congo. All of the processed patients exhibited a hepatic amoebiasis. Amoebic abscess was observed in all cases with an average size of 6.3 cm. Of these patients, seven cases (46.7%) benefited from drainage following a risk of rupture or superinfection of the abscess. A compilation of findings extracted from 390 scientific publications via seven major medical databases, allowed us to update the main epidemiological and clinical events that has led to the current worldwide expansion of amoebiasis. We presented a clinical and epidemiological overview of the amoebiasis accompanied with a worldwide illustrative map displaying the current distribution of known amoebiasis foci in each geographical ecozone of Asia, Europe, Africa, Americas, and Australia.

CONCLUSIONS

Although Metropolitan France is not known as an endemic region of amoebiasis, amoebic liver abscess was the most frequent clinical form observed among our 15 patients processed. Most of infected patients had a history of travel to or lived-in endemic areas before arriving in France.

Amebiasis and Amebic Liver Abscess in Children

Although rare in the developed world, amebiasis continues to be a leading cause of diarrhea and illness in developing nations with crowding, poor sanitation, and lack of clean water supply. Recent immigrants or travelers returning from endemic regions after a prolonged stay are at high risk of developing amebiasis. A high index of suspicion for amebiasis should be maintained for other high-risk groups like men having sex with men, people with AIDS/HIV, immunocompromised hosts, residents of mental health facility or group homes. Clinical presentation of intestinal amebiasis varies from diarrhea to colitis and dysentery. Amebic liver abscess (ALA) is the most common form of extraintestinal amebiasis. Various diagnostic tools are available and when amebiasis is suspected, a combination of stool tests and serology should be sent to maximize the yield of testing. Treatment with an amebicidal drug such as metronidazole/tinidazole and a luminal cysticidal agent such as paromomycin for clinical disease is indicated. However, for asymptomatic disease treatment with a luminal cysticidal agent to decrease chances of invasive disease and transmission is recommended.

Histologic features of colonic infections

Background

The histopathologic diagnosis of infectious colitis remains relevant despite recent advances in microbiologic techniques.

Objective

This article aims to describe the histologic features of selected infectious diseases of the colon.

Materials and methods

Existing reports on histopathologic and clinical aspects of colonic infectious agents were reviewed.

Results

While histology alone may not be as sensitive as current microbiologic methods, tissue identification of infectious agents still plays an important role in patient care. Infectious colitis can have a variety of clinical manifestations, ranging from strongyloidiasis, which can cause a smoldering, subclinical infection for decades, to syphilis, which can clinically mimic cancer or inflammatory bowel disease. Therefore, the histopathologic identification of infection as the cause of a patient’s colitis has a considerable impact on treatment decisions. Morphologic overlap can occur between infection and other diseases, however. Moreover, some infections can elicit various tissue responses beyond acute colitis. Immunosuppressed patients may not mount an inflammatory response to pathogens such as cytomegalovirus or adenovirus. Sexually transmitted proctocolitis can cause plasma-cell-rich inflammation. Gastrointestinal histoplasmosis is more likely to cause diffuse histiocyte infiltration rather than the expected granuloma formation. In some cases, ancillary tests are useful, but equivocal results can cause diagnostic dilemmas.

Conclusion

Given the range with which colonic infectious disorders can manifest, pathologists should be aware of the typical features of infectious colitis, as well as findings beyond the classic morphologies.

Fulminant necrotising amoebic colitis after corticosteroid therapy for severe COVID-19

Acute fulminant necrotising colitis is an uncommon presentation of amoebiasis, which can be precipitated after corticosteroid therapy. Clinicians treating patients with COVID-19 with corticosteroid therapy should be familiar with this condition to avoid delay in diagnosis. The disease is associated with high mortality, and prompt diagnosis and management are essential for salvaging patients. We report successful management of a patient who developed this complication following administration of steroids for COVID-19.

Fulminant amebic colitis in a patient with concomitant cytomegalovirus infection after systemic steroid therapy: A case report

BACKGROUND

Amebic colitis is an infection caused by Entamoeba histolytica and most commonly observed in regions with poor sanitation. It is also seen as a sexually transmitted disease in developed countries. While amebic colitis usually has a chronic course with repeated exacerbations and remissions, it may also manifest as a fulminant form that rapidly progresses and leads to severe, life-threatening complications, such as intestinal perforation, peritonitis, and sepsis, that have a high mortality rate.

CASE SUMMARY

A 68-year-old man was admitted to our hospital with chest pain and acute dyspnea. He was diagnosed with acute coronary syndrome, acute heart failure, and bacterial pneumonia. His respiratory condition worsened despite receiving intensive care and intravenous antibiotics. On the fifth day of hospitalization, he was diagnosed with acute respiratory distress syndrome and was started on steroid therapy. He subsequently developed bloody stools and was diagnosed with cytomegalovirus (CMV) enterocolitis based on biopsy results and a peripheral blood CMV pp65 antigenemia test result. Although we started antiviral therapy with ganciclovir, which was successful in reducing his antigen titers, he continued to have bloody diarrhea. Three weeks after initiation of ganciclovir therapy and six weeks after his admission, the patient died from intestinal perforation. We only posthumously diagnosed him with amebic colitis and CMV enterocolitis based on autopsy findings of transmural necrosis of the entire colon with massive ameba infiltration.

CONCLUSION

We urge clinicians to consider Entamoeba histolytica infection if severe colitis progresses after steroid therapy. Preemptive treatment is recommended then.

Lethal multiple colon necrosis and perforation due to fulminant amoebic colitis: a surgical case report and literature review

Background

Amoebiasis caused by the protozoan species Entamoeba histolytica rarely develops into fulminant amoebic colitis (FAC), but when it does, it shows an aggressive clinical course including colonic perforation, necrotizing colitis, and high mortality. Surgical treatment for FAC patients should be carried out urgently. However, even after surgery, the mortality rate can be 40–50%. Although FAC is one of the most unfavorable surgical diseases with a poor prognosis, there are a few reports on the perioperative diagnosis and management of FAC based on autopsy findings. We herein report the surgical case of a 64-year-old man who developed multiple colon necrosis and perforation due to FAC. A detailed autopsy revealed FAC as the cause of death. Additionally, we reviewed the existing literature on FAC patients who underwent surgery and followed their perioperative diagnosis and management.

Case presentation

A 64-year-old man presented with anorexia, diarrhea, and altered consciousness on arrival to our hospital. Computed tomography revealed a large mass in the upper right lobe of his lung, and the patient was admitted for close investigation. Bloody diarrhea, lower abdominal pain, and hypotension were observed soon after admission. Urgent abdominal contrast-enhanced computed tomography scan revealed extensive intestinal ischemia, intestinal pneumatosis, and free intra-abdominal gas. The preoperative diagnosis was bowel necrosis and perforation with intussusception of the small intestinal tumor. Emergency subtotal colectomy and enterectomy were performed soon after the contrast-enhanced computed tomography. He was taken to an intensive care unit after surgery. However, he could not recover from sepsis and died with disseminated intravascular coagulation and multiple organ failure on the 10th-day post-surgery. A histopathological examination of the resected colon showed transmural necrosis and massive amoebae invasion. He was diagnosed with FAC. An autopsy revealed that he had developed pulmonary large cell carcinoma with small intestinal metastasis. The death was caused by intestinal ischemia, necrosis and the perforation of the residual bowel caused by amoebae invasion.

Conclusions

Since FAC is a lethal disease with a high mortality rate and antibiotic therapies except metronidazole are ineffective, preoperative serological testing and perioperative metronidazole therapy in FAC patients can dramatically improve their survival rates.

Fulminant amebic colitis: An unusual postoperative complication of intraabdominal malignancy

Amebiasis caused by protozoa Entamoeba histolytica (EH) is the third leading parasitic cause of human mortality. Although amebiasis is endemic in India, only about 10% of the infected individuals manifest disease. Clinical spectrum of amebiasis ranges from asymptomatic colonization to amebic colitis to hemorrhagic and fulminant colitis. Factors causing an invasive infection are not completely understood. Pathogen virulence, host immunity, and ability of the pathogen to evade host immune response play vital role in determining the disease course. Host factors such as immunocompromised states may make an individual susceptible to develop symptomatic infection. Malignancies usually result in chronic debilitation which may make the individual prone to develop invasive amebiasis with rapid progression. We report two cases of invasive amebiasis which developed a fulminant course in the immediate postoperative period after abdominal surgeries for visceral malignancies.

Acute fulminant necrotizing amebic colitis in a pediatric patient: a rare complication of amebiasis with high mortality-a case report

Background

The majority of amebic infections among humans remain asymptomatic. Rarely, the disease takes a fulminant acute course due to the development of necrotizing amebic colitis. This complication is usually found in adult patients. However, on the contrary, this case was diagnosed in a 9-year-old patient. He was transferred to the Sirimavo Bandaranayake Specialized Children’s Hospital (SBSCH), Peradeniya from the District General Hospital, Kilinochchi. To our knowledge, this is the first report of this rare complication in a child in Sri Lanka.

Case presentation

We present a case of acute fulminant necrotizing amebic colitis in a 9-year-old boy. Surgical exploration revealed extensive ulceration and multiple perforations in the entire colon. PAS-Martius Yellow 40 stain highlighted amebae with erythrophagocytosis within the necrotic debris of the ulcers. The polymerase chain reaction (PCR) that was conducted to confirm the diagnosis was positive for Entameba histolytica. The post-operative course was marked with antimicrobial treatment for septicemia and the need for ventilator assistance. Antimicrobial treatment included intravenous metronidazole. The patient progressively recovered and was discharged on a normal diet.

Conclusion

This case reports an acute fulminant necrotizing amebic colitis in a 9-year-old patient. After the treatments, the patient progressively recovered and was discharged on a normal diet. E. histolytica infections in northern Sri Lanka should be given attention as a public health concern. Furthermore, this case highlights that acute fulminant amebic colitis requires early surgical intervention, aggressive supportive and anti-amebic treatments. Clinicians should be cognizant of this potentially fatal complication of amebic colitis.

Parasite-Produced MIF Cytokine: Role in Immune Evasion, Invasion, and Pathogenesis

Protozoan parasites represent a major threat to health and contribute significantly to morbidity and mortality worldwide, especially in developing countries. This is further compounded by lack of effective vaccines, drug resistance and toxicity associated with current therapies. Multiple protozoans, including Plasmodium, Entamoeba, Toxoplasma, and Leishmania produce homologs of the cytokine MIF. These parasite MIF homologs are capable of altering the host immune response during infection, and play a role in immune evasion, invasion and pathogenesis. This minireview outlines well-established and emerging literature on the role of parasite MIF homologs in disease, and their potential as targets for therapeutic and preventive interventions.

Tissue Destruction Caused by Entamoeba histolytica Parasite: Cell Death, Inflammation, Invasion, and the Gut Microbiome

Purpose of Review

Entamoeba histolytica is a protozoan parasite that causes amebiasis, which remains a significant cause of morbidity and mortality worldwide. E. histolytica causes tissue destruction which leads to clinical disease. This review outlines some of the recent advances that have furthered our understanding of the processes that lead to the tissue damage caused by E. histolytica.

Recent Findings

Recent studies have identified new mechanisms involved in E. histolytica–induced tissue damage. These include (i) new form of contact-dependent killing called trogocytosis; (ii) parasite-produced cytokine, macrophage migration inhibitory factor, that contributes to inflammation; (iii) exploitation of host immune response to promote invasion; and (iv) the contribution of the gut microbiome to clinical disease.

Summary

Targeting these mechanisms that result in tissue injury should be a focus of future research for the development of improved preventive and therapeutic strategies for amebiasis.

Entamoeba Histolytica: Updates in Clinical Manifestation, Pathogenesis, and Vaccine Development

Entamoeba histolytica is the responsible parasite of amoebiasis and remains one of the top three parasitic causes of mortality worldwide. With increased travel and emigration to developed countries, infection is becoming more common in nonendemic areas. Although the majority of individuals infected with E. histolytica remain asymptomatic, some present with amoebic colitis and disseminated disease. As more is learned about its pathogenesis and the host's immune response, the potential for developing a vaccine holds promise. This narrative review outlines the current knowledge regarding E. histolytica and E. dispar and insight in the development of a vaccine.

Primary cecal pathologies presenting as acute abdomen and critical appraisal of their current management strategies in emergency settings with review of literature

Background:

The importance of cecal pathologies lie in the fact that being the first part of the large intestine, any disease involving the cecum affects the overall functioning of the large bowel. Primary cecal pathologies presenting as acute abdomen have not been described in any previous study in terms of presentation, management, and outcome.

Objectives:

The objective of this study was to identify the reported causes of primary cecal pathologies presenting as acute abdomen and the various causes presenting in our setting, the to discuss morbidity and mortality associated with cecal pathologies, and to critically analyze the various management modalities employed in an emergency setting.

Materials and Methods:

This is a retrospective analysis of a prospectively collected data of all adult patients admitted to our unit in the last 10 years for acute abdomen, in whom cecal pathology was identified as the primary offending agent.

Results:

Our analysis of 43 patients revealed cecal perforation secondary to amebic colitis along with the simultaneous presence of liver abscess to be the most common primary cecal entity met in practice as acute abdomen. Other pathologies that were encountered included volvulus, diverticulitis, and idiopathic typhlitis. Primary acute cecal pathologies are associated with high mortality rates (≈42%). Delay in diagnosis seems to be the most important factor contributing to high mortality as these conditions are commonly misdiagnosed as appendicular pathology. Most of our patients were managed by conservative colonic resection with proximal diversion. This seems to be a more plausible option in current practice in an emergency setting (mortality rate ≈ 36%) as hemicolectomy is associated with proportionately higher mortality rates (67%).

Conclusion:

A high index of suspicion, timely and adequate pre-operative workup, optimal resuscitation, and surgical conservatism with proximal diversion might help in early accurate identification of these conditions and possibly improved outcome.

Fulminant Amebic Colitis after Corticosteroid Therapy: A Systematic Review

BACKGROUND

Amebic colitis, caused by intestinal infection with the parasite, Entamoeba histolytica, is a common cause of diarrhea worldwide. Fulminant amebic colitis is the most devastating complication of this infection, associated with both high mortality and morbidity. We conducted a review of the English literature to describe cases of fulminant amebic colitis associated with exposure to corticosteroid medications in order to identify the risk factors for poor outcome and determine difficulties in diagnosis and treatment.

METHODOLOGY AND PRINCIPAL FINDINGS

Articles reporting severe and fulminant forms of amebic colitis between 1991 and 2016 were collected. 525 records were screened to identify 24 cases for qualitative analysis associated with corticosteroid use. Cases arose from areas of high endemicity or travel to such areas. Most cases (14 of 24, 58%) were given corticosteroids for initially misdiagnosed colitis, mainly inflammatory bowel, resulting in rapid progression of disease. Nearly half of all cases underwent surgical intervention, and 25% of cases died, despite all patients eventually receiving treatment with metronidazole. The odds of death did not differ significantly by prior misdiagnosis, co-morbidities, bowel perforation or need for surgery.

CONCLUSIONS AND SIGNIFICANCE

Infection with E. histolytica should be considered prior to the administration of corticosteroids, in particular for patients residing in endemic areas or those with appropriate travel history, especially prior to the diagnosis of inflammatory bowel disease. The development of preventative and treatment interventions are needed to improve outcomes of fulminant disease.

Clinical manifestations and endoscopic findings of amebic colitis in a United States-Mexico border city: a case series

Background

Invasive amebiasis is not frequently seen in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We report a case series of patients with amebic colitis in a United States-Mexico border city to alert physicians to the varied clinical manifestations.

Case presentation

Nine patients were diagnosed with amebic colitis. Mean age was 56 (38–83), 6 were males, and all were Hispanic. Common symptoms were diarrhea (56 %), hematochezia (33 %) and abdominal bloating (11 %). The diagnosis of amebic colitis was established in the following ways: 8 patients by colonoscopy with biopsy, 1 by surgery for colonic obstruction. The diagnosis of amebic colitis was confirmed in 8 patients (89 %) by amebic trophozoites present in histopathologic sections. One patient was diagnosed with amebic colitis based upon clinical symptoms, colitis on colonoscopy and visualization of amebic trophozoites on stool examination. In the 8 patients in whom colonoscopy was done, 6 (75 %) had inflammation with rectosigmoid involvement and 5 (62.5 %) had ulcerations. Infection resolved after treatment with metronidazole in most patients; however, one patient developed a liver abscess and another had a colonic perforation and later developed a liver abscess.

Conclusion

The occurrence of amebic colitis in this United States-Mexico border city hospital population was low, but in some cases potentially life-threatening. Physicians should be alert to the less common presentations of amebic colitis, such as overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, and the incidental finding of association with colon cancer, or a surgical abdomen. Rectosigmoid involvement was typically found on colonoscopy.

Fulminant amoebic enteritis that developed in the perinatal period

We present a case of a 30-year-old postpartum woman who delivered by caesarean section at 34 weeks. On postoperative day 9, she was admitted to our hospital in shock. Emergency abdominal surgery was performed. Massive purulent ascites collected in the abdominal cavity and was associated with intestinal necrosis, which extended from the ascending colon to one-third of the descending colon. The necrotic lesion was excised, and an artificial anus was constructed at the ileum end. A histological finding on the 15th day indicated the possibility of amoebic enteritis, and the patient was started on metronidazole therapy. The diarrhoea improved dramatically after metronidazole treatment was started. The patient was able to walk unassisted on the 45th day and was subsequently discharged. Amoebic enteritis has been thought to be epidemic in developing countries, but today, the incidence of amoebic enteritis as a sexually transmitted disease is increasing in developed countries.

Fulminant amoebic colitis: a clinicopathological study of 30 cases

AIMS

To review the clinical and pathological factors associated with fulminant amoebic colitis (FAC) requiring colonic resection and its outcome.

METHODS

We retrospectively identified adult patients admitted to our centre between June 2007 and December 2011 with FAC who underwent colonic resection and were diagnosed with amoebic colitis based on the presence of trophozoites on histological examination. The clinical details were extracted from the medical notes and correlated with the pathological findings.

RESULTS

Thirty patients (18 men and 12 women) met the inclusion criteria. Their mean age was 50.1 years (range 21-89). The most frequent symptoms were abdominal pain, vomiting and fever. More than half the patients (16/30) had underlying conditions associated with immunosuppression including diabetes mellitus and tuberculosis. Pathological investigation of colonic resections showed predominantly right-sided involvement with geographic colonic ulcers covered with a creamy-white pseudomembrane, perforations, gangrenous changes, amoeboma and lesions mimicking inflammatory bowel disease. All showed basophilic dirty necrosis with abundant nuclear debris and amoebic trophozoites on histological examination. 21/30 patients (70%) had involvement beyond the caecum. 17/30 patients (57%) died. Those with involvement beyond the caecum were more likely to die (15/21, 71.4%) than those with less extensive disease.

CONCLUSIONS

FAC presents as acute abdomen and can mimic appendicitis, ischaemic bowel disease, tuberculosis and malignancy. Comorbidities causing immunosuppression frequently associated. Mortality remains high despite surgery, so FAC should be suspected in every case of acute abdomen with colonic perforation if associated with typical gross and microscopic findings and a history of stay in an endemic area.

Current Status of the Treatment of Fulminant Colitis

Fulminant colitis is not a well-defined entity, that constitutes a severe complication. It usually occurs in the course of úlcerative colitis and Clostridium difficile colitis. A multidisciplinary management combining gastroenterologist and surgeons is crucial with intensive medical treatment and early surgery in non-responders. It is important to distinguish if we are facing a flare of IBD or, on the contrary, it is an infectious colitis, due to the fact that although general therapeutic measures to adopt will be the same, they will demand opposed specific measures.

Fulminant colitis

Fulminant colitis is an ill-defined entity that is usually viewed as the most severe form of uncomplicated acute colitis. It usually occurs in the course of ulcerative colitis and infectious colitis, but can also be seen in other forms of colitis. Every patient with clinical criteria for severe or fulminant colitis should be approached in a systematic way, based on two premises - intense medical treatment and early surgery in non-responders.

Amoebic toxic colitis: analysis of factors related to mortality

BACKGROUND

Toxic or fulminant colitis due to Entamoeba histolytica infrequently presents but is very serious. Unfortunately, there are numerous contradictory factors related to mortality.

METHODS

We analyzed several cases of E. histolytica infection to determine the factors related to mortality. We included patients >15 years of age who were histopathologically diagnosed with amoebic toxic colitis and treated from January 2000 through December 2006. We evaluated demographic, clinical, laboratorial, surgical, and histopathological characteristics.

RESULTS

We examined 24 patients and recorded 12 deaths (50%). Twenty patients underwent surgery within a mean time of 24 hours (range: 8-120 hours). Tenesmus and intestinal perforation were determined to be statistically significant (P<0·05) by univariate analysis. Three models of logistic regression were able to determine three statistically significant factors that affected mortality: (1) tenesmus and a lymphocyte count <1·5×10(3) cell/μl; 2) depth of invasion beyond the mucosa and a lymphocyte count <1·5×10(3) cell/μl; 3) time spent with symptoms and perforation.

CONCLUSIONS

The mortality rate determined in this study is similar to previously reported series. A low lymphocyte count, significant depth of invasion, and intestinal perforation were determined to be the factors related to increased mortality, while tenesmus and limited amount of time spent with symptoms were associated with survival. Quick diagnosis and appropriate treatment are important factors that reduce mortality.

Protozoan infections of the gastrointestinal tract

The review provides current views on human protozoan parasites of the gut. The recognition of the importance of cryptosporidium, cyclospora and microsporidia over the last three decades emphasises the possibility that more pathogenic intestinal protozoa are presently unrecognized. Each of these is a zoonotic infection and the potential for a zoonotic element to the transmission of giardiasis has been recognized. A common theme in increased understanding of the biology and pathological mechanisms involved in causing disease is the application of molecular techniques to the various stages of the parasite life cycle. Molecular methods are increasingly contributing to laboratory diagnosis of these conditions with increased yields of positive results though in the tropics it is likely that fecal microscopy will remain the standard for some time to come. The nitroimidazole compounds are the mainstay of treatment for giardia and amebiasis with no major advance in therapeutics since their role was appreciated. Nitazoxanide was shown to be effective for cryptosporidiosis in the 1990s.

Short report: Amebiasis-related mortality among United States residents, 1990-2007

Despite the endemic nature of Entamoeba histolytica infection in the United States there is a lack of data on amebiasis-related mortality. We analyzed national death certificate data from 1990 to 2007 to assess the occurrence of amebiasis-related deaths and determine demographic and regional associations. A total of 134 deaths were identified. Mortality rates were highest in males, Hispanics, Asian/Pacific Islanders, and persons 75 years of age and older. An association with human immunodeficiency virus infection was also observed. A declining trend of amebiasis deaths was noted over the 18-year study period. Over 40% of fatal amebiasis cases occurred in residents of California and Texas. United States-born persons accounted for the majority of amebiasis deaths; however, all of the fatalities in Asian/Pacific Islanders and 60% of the deaths in Hispanics were in foreign-born individuals. Although uncommon, amebiasis-related deaths routinely occur in the United States.

Fulminant amebic colitis in an HIV-infected homosexual man

We present a case of fulminant amebic colitis in a human immunodeficiency virus (HIV)-infected homosexual man. The patient developed colonic perforation over a short time despite empirical therapy with metronidazole, and underwent right hemicolectomy. Amebic colitis was pathologically diagnosed by identifying invasive trophozoites of Entamoeba in a surgical specimen. Amebic colitis is one of the important differential diagnoses of acute abdomen in HIV-infected patients and/or homosexual men, especially in East Asia. Although fulminant amebic colitis is a rare manifestation of amebiasis, early diagnosis and treatment are thought to be important to improve the outcome of this highly fatal complication.

In vivo visualization of trophozoites in patients with amoebic colitis by using a newly developed endocytoscope

BACKGROUND

The endocytoscopy system (ECS) is a new method to provide real-time super-magnifying microscopic imaging in vivo. Routine diagnosis of amebic colitis requires multiple tests that are both time consuming and costly.

OBJECTIVE

To determine the feasibility of ECS to directly detect the amebic parasites in vivo.

DESIGN

Prospective, single-center, pilot study.

SETTING

Tertiary-care university hospital.

PATIENTS

This study involved 5 patients who were suspected to have amebic colitis by conventional colonoscopy in our institute.

INTERVENTIONS

A super-magnifying ECS with 450 x magnification.

MAIN OUTCOME MEASUREMENTS

We compared ECS findings with those of conventional methods-serum antibody tests and histology of colon biopsy specimens.

RESULTS

We successfully visualized the amebic trophozoites in all 5 cases. In contrast, 3 specimens had positive results on serology, and 3 had positive histology results on hematoxylin and eosin staining.

LIMITATIONS

Pilot study with a limited number of patients. Findings were compared only with serology and histology findings.

CONCLUSIONS

ECS would be a useful tool for the prompt diagnosis of amebic colitis via the real-time in vivo visualization of amebic trophozoites.

Evolution of surgical treatment of amebiasis-associated colon perforation

BACKGROUND

Amebiasis is a worldwide health problem that mainly affects developing countries. Invasive amebiasis tends to develop complications, and among these, perforation of the colon, although infrequent (1.9-9.1%), is the most lethal. Surgical treatment in these cases should be carried out in a timely fashion prior to the presentation of systemic repercussions or death. In the present study, we analyzed a total of 122 cases of invasive amebiasis-associated colon perforation.

METHODS AND STUDY DESIGN

We conducted a clinical, retrospective, and observational study and presented cases of colonic perforation observed over the past 30 years at the Medical-Surgical Emergency Service of the Mexico City-based Hospital General de México OD during the 1970-1999 period.

RESULTS

During this time, a total of 19,916 emergency abdominal surgeries were performed. One hundred twenty-two of these procedures corresponded to cases of colon perforation by ameba, which represents 0.6%; 80 patients were men (65.6%) and 42 were women (34.4%), with an average age of 48 years. Multiple colon perforation was 74%, with right colon the most affected (90.5%). Depending on the perforation's extension and localization, right hemicolectomy with ileostomy were performed in 53 patients (43.45%), subtotal colectomy with ileostomy in 43 (35.25%), left hemicolectomy with transverse colostomy in 12 (9.83%), exteriorization of perforated left colon (stoma) in 13 (10.65%), and primary closure with exteriorization in one patient (0.8%). Post-operative complications were present in 48 patients (39.3%), and 20 cases were related with the creation of a stoma. Eighteen of these cases were due to persistent abdominal sepsis and ten due to toxic colon; the latter correspond solely to patients with initial nonresective treatment. General mortality was 40%, with 32% (17 of 53 cases) of mortality in those submitted to right hemicolestomy, 16.7% (two of 12) of left hemicolestomy, 44.2% (19 of 43) in those in whom a subtotal colectomy was performed, with 76.9% (ten of 13) patients with exteriorization of the perforated right colon, and with 100% (one of one patient) mortality with primary closure.

CONCLUSIONS

Perforation is the most frequent surgical complication of invasive amebiasis of the colon, occurring principally in masculine gender and in the fourth decade of life. Resection and stoma creation is the procedure of choice that can resolve the septic focus from the first surgical procedure, depending on the general status of the patient. However, morbidity and mortality are high, and there is a tendency for these to be lower on comparing initial cases with those with recently conducted surgical procedures.

Acute fulminant necrotizing amoebic colitis: a rare and fatal complication of amoebiasis: a case report

Acute Fulminant Necrotizing Amoebic Colitis is a rare complication of amoebiasis that is associated with high mortality. Only one to four such cases are seen per year in large hospitals of India, and only few such cases have been reported in the literature. The condition requires early diagnosis and surgical intervention. We recently cared for a patient who presented with acute abdomen with history of intermittent abdominal pain and diarrhea. Before presenting to our institution he was misdiagnosed as a case of inflammatory bowel disease and had been treated with steroids. On emergency exploration, extensive necrosis and multiple perforations in retroperitoneum involving entire colon were seen. Total colectomy with ileostomy was performed. Postoperative course was marked by septicaemia and multi-organ failure followed by death. This case report emphasizes the importance of early diagnosis and treatment of acute FAC, and associated high mortality.

Acute fulminant necrotizing amoebic colitis: a rare and fatal complication of amoebiasis: a case report

Acute Fulminant Necrotizing Amoebic Colitis is a rare complication of amoebiasis that is associated with high mortality. Only one to four such cases are seen per year in large hospitals of India, and only few such cases have been reported in the literature. The condition requires early diagnosis and surgical intervention. We recently cared for a patient who presented with acute abdomen with history of intermittent abdominal pain and diarrhea. Before presenting to our institution he was misdiagnosed as a case of inflammatory bowel disease and had been treated with steroids. On emergency exploration, extensive necrosis and multiple perforations in retroperitoneum involving entire colon were seen. Total colectomy with ileostomy was performed. Postoperative course was marked by septicaemia and multi-organ failure followed by death. This case report emphasizes the importance of early diagnosis and treatment of acute FAC, and associated high mortality.

Fulminant amoebic colitis during chemotherapy for advanced gastric cancer

A 52-year-old man had bloody stools during chemotherapy for gastric cancer. A colonoscopy revealed necrotizing ulcer-like changes. A biopsy confirmed the presence of amoebic trophozoites. Subsequently, peritonitis with intestinal perforation developed, and emergency peritoneal lavage and colostomy were performed. After surgery, endotoxin adsorption therapy was performed and metronidazole was given. Symptoms of peritonitis and colonitis resolved. However, the patient’s general condition worsened with the progression of gastric cancer. The patient died 50 d after surgery. Fulminant amoebic colitis is very rarely associated with chemotherapy. Amoebic colitis should be considered in the differential diagnosis of patients who have bloody stools during chemotherapy.

Vaccine prospects for amebiasis

Entamoeba histolytica is a eukaryotic protozoan parasite and is the causative agent of amebic colitis and amebic liver abscess. Many insights into the innate and acquired immune responses to infection with E. histolytica have been made in recent years. These findings have provided a foundation for producing a vaccine that could help to prevent the initial establishment of infection in the intestinal wall. The galactose and N-acetyl-D-galactosamine-specific lectin on the surface of the ameba is an immunodominant molecule that is highly conserved and has an integral role in the stimulation of these immune responses. The structure of the lectin has been defined, and the heavy subunit with its cysteine-rich region has been demonstrated in animal models to have some efficacy as a possible vaccine agent for prevention of amebic infection. Finding an ideal animal model of amebic intestinal infection has been difficult, but the C3H mouse and severe combined immunodeficient mouse-human intestinal xenograft models have both provided valuable insights into the first line of immune defense at the mucosal wall of the colon. Providing safe food and water to all people in the developing world is a formidable task that is not achievable in the foreseeable future. However, a vaccine for amebiasis could make a significant impact on the morbidity and mortality from the disease. Many components of the ameba are immunogenic and may serve as targets for a future vaccine, including the galactose and N-acetyl-D-galactosamine lectin, the serine-rich E. histolytica protein, cysteine proteinases, lipophosphoglycans, amebapores and the 29-kDa protein.

Laboratory diagnostic techniques for Entamoeba species

The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.

Diabetes and Amoebiasis: a high risk encounter

Amoebiasis is the second most common parasitic disease worldwIde. It occurs mainly in developing countries. A high percentage of people in countries where it is endemic are asymptomatic carriers. It results in severe disease that can be fatal in rare cases. Diabetics are at increased risk of exposure as travel to countries where it is endemic becomes more frequent, as indicated by the present case. This patient suffered from amoebiasis that produced an amoeboma which is most rare in cases of colonic amoebiasis. The clinical picture was that of an occluding gut tumor, but it was treated only with drugs. Retrospective studies show that diabetics are at increased risk of suffering severe complications after amoebic infection. The frequency and severity of this diabetes-amoeba association requires patients to take prophylactic measures, especially when travelling in developing countries.

Amoebiasis

Amoebiasis is the second leading cause of death from parasitic disease worldwide. The causative protozoan parasite, Entamoeba histolytica, is a potent pathogen. Secreting proteinases that dissolve host tissues, killing host cells on contact, and engulfing red blood cells, E histolytica trophozoites invade the intestinal mucosa, causing amoebic colitis. In some cases amoebas breach the mucosal barrier and travel through the portal circulation to the liver, where they cause abscesses consisting of a few E histolytica trophozoites surrounding dead and dying hepatocytes and liquefied cellular debris. Amoebic liver abscesses grow inexorably and, at one time, were almost always fatal, but now even large abscesses can be cured by one dose of antibiotic. Evidence that what we thought was a single species based on morphology is, in fact, two genetically distinct species--now termed Entamoeba histolytica (the pathogen) and Entamoeba dispar (a commensal)--has turned conventional wisdom about the epidemiology and diagnosis of amoebiasis upside down. New models of disease have linked E histolytica induction of intestinal inflammation and hepatocyte programmed cell death to the pathogenesis of amoebic colitis and amoebic liver abscess.

Amebiasis

Human amebiasis is caused by the protozoan parasite Entamoeba histolytica. Invasion of the colonic mucosa by the trophozoite form of this parasite generally results in the clinical syndrome of amebic dysentery, although there is a wide range of clinical presentations. Some patients will progress to disseminated disease, with resulting amebic liver abscesses. Although it is estimated that 10% of the world's population is infected with E. histolytica, only 1% of these patients will manifest disease. The diagnosis is usually made by microscopically identifying the microorganism in a stool specimen. The antibiotic of choice for treatment of amebiasis is metronidazole, 750 mg, three times daily for 10 days.

Toxic pseudomembranous colitis in a patient with ulcerative colitis

Toxic colitis is a severe disease that may be caused by several inflammatory and/or infectious diseases. Ulcerative colitis is one of the most frequent causes of toxic colitis in the United States. Toxic megacolon complicating Clostridium difficile colitis is a rare occurrence with significant morbidity and mortality.

CASE REPORT

A 52-year-old male presented with rectal bleeding and tenesmus. He had been treated for amebiasis with metronidazole, and had improved. Two weeks later, symptoms recurred, and he was referred to our hospital. A sigmoidoscopy and biopsies demonstrated mucosal ulcerative colitis. He underwent treatment with systemic prednisone, mesalamine, and hydrocortisone enemas with adequate response. He was asymptomatic for 2 months, but later presented with a tender abdomen and rectal bleeding. Plain abdominal and thorax films showed colonic distention and free intraperitoneal air. Emergency laparotomy was performed, and an inflamed and distended colon, with free inflammatory liquid in the peritoneum, was found. A total abdominal colectomy with temporary ileostomy and Hartmann's pouch was performed. The histopathology analysis demonstrated a Clostridium difficile pseudomembranous colitis.

CONCLUSION

The presence of toxic megacolon due to Clostridium difficile in patients with ulcerative colitis is a rare complication that may be suspected in patients with initial relapse who are on antibiotics.

Hepatobiliary infections

Major hepatobiliary infections include cholangitis and liver abscess. Liver abscess is typically either of pyogenic or amebic origin. Amebic liver abscess usually occurs in individuals from endemic areas or those traveling to endemic areas and is associated with an excellent prognosis if properly managed, usually with one of several antiamebicidal drugs alone. Pyogenic liver abscess is most often cryptogenic in origin, although sophisticated advanced interventional procedures such as transarterial embolization and cryoablation are leading to a new generation of patients with pyogenic liver abscess. A distinct clinical entity appears to be evolving, namely that of monomicrobial Klebsiella pneumoniae pyogenic liver abscess, characterized by the same symptoms and signs as classic pyogenic liver abscess, but further distinguished by the presence of diabetes mellitus, a paucity of coexistent intra-abdominal pathology, a single cavity, and an excellent prognosis. As of 1999, the vast majority of pyogenic liver abscesses should be approached therapeutically by percutaneous aspiration or drainage techniques. The overall prognosis for patients with pyogenic liver abscess is improving, although poor outcomes are common in patients with serious underlying medical disorders, especially malignancy.

Intestinal parasitic infections

Our understanding of the biology of several intestinal parasites has progressed considerably in the past year, especially in the area of molecular biology. Information from molecular and genetic analyses has been used increasingly to improve understanding of pathogenesis, to apply improved diagnostic methods, and to seek new vaccination strategies. There were fewer relevant clinical studies than in previous years, but some are notable. Control of helminth infections by mass chemotherapy in school age children appears an achievable goal in many communities. Vaccine trials against some protozoan infections continue to show promise in animal models.