Gastrointestinal disease in the immunocompromised patient

ECCO Topical Review on Clinicopathological Spectrum and Differential Diagnosis of Inflammatory Bowel Disease

INTRODUCTION

Many diseases can imitate inflammatory bowel disease [IBD] clinically and pathologically. This review outlines the differential diagnosis of IBD and discusses morphological pointers and ancillary techniques that assist with the distinction between IBD and its mimics.

METHODS

European Crohn's and Colitis Organisation [ECCO] Topical Reviews are the result of an expert consensus. For this review, ECCO announced an open call to its members and formed three working groups [WGs] to study clinical aspects, pathological considerations, and the value of ancillary techniques. All WGs performed a systematic literature search.

RESULTS

Each WG produced a draft text and drew up provisional Current Practice Position [CPP] statements that highlighted the most important conclusions. Discussions and a preliminary voting round took place, with subsequent revision of CPP statements and text and a further meeting to agree on final statements.

CONCLUSIONS

Clinicians and pathologists encounter a wide variety of mimics of IBD, including infection, drug-induced disease, vascular disorders, diverticular disease, diversion proctocolitis, radiation damage, and immune disorders. Reliable distinction requires a multidisciplinary approach.

Gastroenterological complications in kidney transplant patients

Kidney transplantation is the surgical operation by which one of the two original kidneys is replaced with another healthy one donated by a compatible individual. In most cases, donors are recently deceased. There is the possibility of withdrawing a kidney from a consenting living subject. Usually, living donors are direct family members, but they could be volunteers completely unrelated to the recipient. A much-feared complication in case of kidney transplantation is the appearance of infections. These tend to arise due to immune-suppressor drugs administered as anti-rejection therapy. In this review, we describe the gastrointestinal complications that can occur in subjects undergoing renal transplantation associated with secondary pathogenic microorganisms or due to mechanical injury during surgery or to metabolic or organic toxicity correlated to anti-rejection therapy. Some of these complications may compromise the quality of life or pose a significant risk of mortality; fortunately, many of them can be prevented and treated without the stopping the immunosuppression, thus avoiding the patient being exposed to the risk of rejection episodes.

Neutropenic enterocolitis in pediatric leukemia patients treated with intensive chemotherapy in Upper Egypt

IMPORTANCE

In low resource countries, there has been scarcity of research on the risk factors associated with neutropenic enterocolitis, a serious complication that commonly develops during treatment of cancer patients.

OBJECTIVE

To identify the pattern of intestinal complications in pediatric leukemia patients treated with intensive chemotherapy, including those with neutropenic enterocolitis; to assess the outcome; and to evaluate the risk factors associated with the mortality in these patients.

METHODS

During the period from June 2015 to December 2016, a prospective study was carried out on pediatric patients diagnosed with acute leukemia who received induction/or re-induction phases of chemotherapy at South Egypt Cancer Institute. Patients with documented episodes of intestinal complications were included in the study. Recovery or death from an episode of intestinal complication was utilized as the primary outcome measure for the study. Using univariable and multivariable methods, potential risk factors associated with mortality were delineated by logistic regression analysis, both for the entire intestinal complications episodes as a whole and for those episodes of neutropenic enterocolitis only.

RESULTS

Out of 88 documented episodes of intestinal complications from 77 patients; 58 episodes were identified as neutropenic enterocolitis from 47 patients. In those patients who were having episodes of neutropenic enterocolitis, the presence of abdominal tenderness (OR 4.529, 95%CI 1.062-19.317, P = 0.041); a longer duration of neutropenia (OR 1.215, 95%CI 1.030-1.434, P = 0.021); and hemodynamic instability (OR 17.023, 95%CI 4.095-70.772, P < 0.001), were found to be independently associated with worse outcome.

INTERPRETATION

In Upper Egypt, the use of intensive systemic chemotherapy during the induction phase of acute leukemia was found to be associated with potentially lethal intestinal complications. A high index of clinical suspicion is warranted.

Histopathology

The detection of fungal elements and their characterization in patient specimens provides fundamental information. On histological sections fungi are most frequently seen on skin or mucosal surfaces or as mycotic thrombi or emboli that can occlude both arteries and veins in surgical specimen from immunocompromised patients or tissues obtained from autopsies. Microbial culture continues to be the central method for diagnosing fungal infection but is complemented by histomorphology using specific stains capable of identifying previously unsuspected fungal infections or for evaluating tissue invasion. These stains employ oxidizing reagents to create aldehyde binding sites on polysaccharides (1,2-glycol groups) of fungal cell walls for either Schiff's reagent or Silver ions. Gomori methenamine silver (GMS) and Periodic acid-Schiff (PAS) or their modifications are the most commonly used for tissue sections and in cytology specimens.

Neutropenic Enterocolitis: New Insights Into a Deadly Entity

Neutropenic enterocolitis (NE) is a deadly ileocecal-based disease seen in patients with a recent history of chemotherapy. As histology is not included in the current diagnostic criteria, the pathologic features of NE are poorly understood. We undertook a multi-institutional study of NE, and report helpful clinical clues, such as immunosuppression (n=20/20), recent chemotherapy (n=17/18), neutropenia (n=16/18) gastrointestinal symptoms (n=19/19), abnormal imaging studies of the cecum/right colon (n=11/14), and positive microbiological studies (n=13/15). Fever (n=9/15) and sepsis (n=8/16) were also common. Pathologically, the cecum/right colon was always involved (n=17/17), but findings were identified in other bowel segments as well. NE lesions consisted of patchy necrosis (n=18/20), infiltrating organisms (n=17/20), hemorrhage (n=15/20), ulcer (n=15/19), edema (n=15/20), and depletion of inflammatory cells (n=15/20). Seventy-nine percent (n=15/19) of patients with histologically confirmed NE died: 47% (n=7/15) of these deaths were attributed to NE and the remainder to the patients' underlying conditions. Importantly, we observed a clinical diagnostic discordancy rate of 35% (n=9/26): 15% (n=3/20) of histologically confirmed NE were clinically unsuspected, and 26% (n=6/23) of clinically suspected NE represented a different disease process. Alternative diagnoses included unspecified colitis, infection, graft-versus-host disease, relapsed malignancy, mycophenolate injury, appendicitis, and ischemia. The causes of death in patients with NE mimics included unrecognized appendicitis and unrecognized graft-versus-host disease. To improve diagnostic accuracy, we propose that histology be required for a diagnosis of "definitive NE," with other clinically suspicious cases reported as "suspicious for NE" until all other possible diagnoses have been reasonably excluded.

Screening, prevention, and treatment for hyperinfection syndrome and disseminated infections caused by Strongyloides stercoralis

PURPOSE OF REVIEW

This review discusses the latest approaches to the diagnosis and treatment of patients with strongyloidiasis, with an emphasis on infection in the immunocompromised host and the risk for disseminated strongyloidiasis.

RECENT FINDINGS

The differences in acute, chronic, accelerated autoinfection, and disseminated disease in Strongyloides stercoralis infection are explored with particular emphasis on early diagnosis, treatment, and prevention. The goals of treatment are investigated for the different infection states. Predisposing risks for dissemination are delineated, and the roles played for newer diagnostics in the identification of at-risk individuals are detailed.

SUMMARY

The use of newer diagnostic tests and broader screening of immunocompromised patients from Strongyloides-endemic areas is of paramount importance, particularly if prevention of life-threatening dissemination is the goal.

High-throughput sequence-based analysis of the intestinal microbiota of weanling pigs fed genetically modified MON810 maize expressing Bacillus thuringiensis Cry1Ab (Bt maize) for 31 days

The objective of this study was to investigate if feeding genetically modified (GM) MON810 maize expressing the Bacillus thuringiensis insecticidal protein (Bt maize) had any effects on the porcine intestinal microbiota. Eighteen pigs were weaned at ~28 days and, following a 6-day acclimatization period, were assigned to diets containing either GM (Bt MON810) maize or non-GM isogenic parent line maize for 31 days (n = 9/treatment). Effects on the porcine intestinal microbiota were assessed through culture-dependent and -independent approaches. Fecal, cecal, and ileal counts of total anaerobes, Enterobacteriaceae, and Lactobacillus were not significantly different between pigs fed the isogenic or Bt maize-based diets. Furthermore, high-throughput 16S rRNA gene sequencing revealed few differences in the compositions of the cecal microbiotas. The only differences were that pigs fed the Bt maize diet had higher cecal abundance of Enterococcaceae (0.06 versus 0%; P < 0.05), Erysipelotrichaceae (1.28 versus 1.17%; P < 0.05), and Bifidobacterium (0.04 versus 0%; P < 0.05) and lower abundance of Blautia (0.23 versus 0.40%; P < 0.05) than pigs fed the isogenic maize diet. A lower enzyme-resistant starch content in the Bt maize, which is most likely a result of normal variation and not due to the genetic modification, may account for some of the differences observed within the cecal microbiotas. These results indicate that Bt maize is well tolerated by the porcine intestinal microbiota and provide additional data for safety assessment of Bt maize. Furthermore, these data can potentially be extrapolated to humans, considering the suitability of pigs as a human model.

Human Immunodeficiency Virus–Related Gastrointestinal Pathology: A Southern Africa Perspective With Review of the Literature (Part 2: Neoplasms and Noninfectious Disorders)

Context.—Human immunodeficiency virus (HIV) infection is rife in sub-Saharan Africa and in southern Africa in particular. Despite the increasing availability of antiretroviral therapy in this region, HIV-associated neoplasms remain common and frequently involve the gastrointestinal tract, which may also demonstrate other noninfectious, HIV-related pathology.

Objective.—To review the histopathologic findings and distinguishing features of neoplastic and noninfectious, HIV-associated gastrointestinal disorders in southern Africa and relate those findings to the documented international literature.

Data Sources.—The available literature on this topic was reviewed and supplemented with personal experience in a private histopathology practice in South Africa.

Conclusions.—In southern Africa, a diverse range of HIV-related neoplasms and noninfectious gastrointestinal disorders is seen, but published data for the region are scarce. The gastrointestinal disorders include drug-associated pathology, gastrointestinal manifestations of the immune reconstitution inflammatory syndrome, idiopathic chronic esophageal ulceration, and the controversial entity of HIV enteropathy.

Global distribution, public health and clinical impact of the protozoan pathogen cryptosporidium

Cryptosporidium spp. are coccidians, oocysts-forming apicomplexan protozoa, which complete their life cycle both in humans and animals, through zoonotic and anthroponotic transmission, causing cryptosporidiosis. The global burden of this disease is still underascertained, due to a conundrum transmission modality, only partially unveiled, and on a plethora of detection systems still inadequate or only partially applied for worldwide surveillance. In children, cryptosporidiosis encumber is even less recorded and often misidentified due to physiological reasons such as early-age unpaired immunological response. Furthermore, malnutrition in underdeveloped countries or clinical underestimation of protozoan etiology in developed countries contribute to the underestimation of the worldwide burden. Principal key indicators of the parasite distribution were associated to environmental (e.g., geographic and temporal clusters, etc.) and host determinants of the infection (e.g., age, immunological status, travels, community behaviours). The distribution was geographically mapped to provide an updated picture of the global parasite ecosystems. The present paper aims to provide, by a critical analysis of existing literature, a link between observational epidemiological records and new insights on public health, and diagnostic and clinical impact of cryptosporidiosis.

Gastrointestinal opportunistic infections in human immunodeficiency virus disease

Gastrointestinal (GI) opportunistic infections (OIs) are commonly encountered at various stages of human immunodeficiency virus (HIV) disease. In view of the suppressive nature of the virus and the direct contact with the environment, the GI tract is readily accessible and is a common site for clinical expression of HIV. The subject is presented based on information obtained by electronic searches of peer-reviewed articles in medical journals, Cochrane reviews and PubMed sources. The spectrum of GI OIs ranges from oral lesions of Candidiasis, various lesions of viral infections, hepatobiliary lesions, pancreatitis and anorectal lesions. The manifestations of the disease depend on the level of immunosuppression, as determined by the CD4 counts. The advent of highly active antiretroviral therapy has altered the pattern of presentation, resorting mainly to features of antimicrobial-associated colitis and side effects of antiretroviral drugs. The diagnosis of GI OIs in HIV/acquired immunodeficiency syndrome patients is usually straightforward. However, subtle presentations require that the physicians should have a high index of suspicion when given the setting of HIV infection.

The SEEDs of two gastrointestinal diseases: socioeconomic, environmental, and demographic factors related to cryptosporidiosis and giardiasis in Massachusetts

OBJECTIVES

We assessed associations between community-level socioeconomic, demographic, and environmental characteristics, and the presence of two potentially waterborne infectious diseases, cryptosporidiosis and giardiasis, as reported to the Massachusetts Department of Public Health.

METHODS

We created a series of maps showing the spatial distribution of cryptosporidiosis and giardiasis in Massachusetts (1993-2002) overall and by age, using logistic regression to analyze associations between community-level characteristics and the presence of at least one reported case of each disease. This analysis was repeated for communities with predominantly private water supplies.

RESULT

After adjusting for population size, higher population density and larger than average household sizes were associated with increased odds of reported cases of cryptosporidiosis. Giardiasis was also associated with high population density, but was not associated with household size. In the elderly, income was positively associated with the presence of giardiasis.

DISCUSSION

These findings suggest that greater population density and larger household sizes may increase the likelihood of protozoan gastrointestinal infection. The results emphasize the necessity to account for distal factors, such as demographic characteristics, that may ultimately play a role in the transmission or reporting of disease.

Cytomegalovirus colitis presenting as massive lower gastrointestinal bleeding in an immunocompetent patient

Cytomegalovirus infection is ubiquitous but often remains asymptomatic in affected patients. Symptomatic cytomegalovirus infection usually occurs in immunocompromised patients- patients who are infected with the Human Immunodeficiency Virus, have received organ transplantations, or are on immunosuppressive therapies. Cytomegalovirus colitis can present with abdominal pain, diarrhea and significant per rectal blood loss. It is a rare entity in immunocompetent patients and can often be missed unless one has a high index of suspicion. We describe a case of CMV colitis in a 78-year-old patient with no known risk factors for immunosuppression who was admitted for respiratory diseases and then subsequently developed transfusion dependent lower gastrointestinal bleeding. She ultimately required surgical resection of her colon. A literature review on CMV colitis, its myriad manifestations and therapeutic outcomes was conducted, with particular emphasis on its occurrence in immunocompetent patients.

Difficult decisions in the intensive care unit: an illustrative case

Difficult clinical decision-making is a common experience in intensive care units. There is often considerable pressure on time and decisions may have to be made in a stressful environment. Patients in the intensive care unit not infrequently present with extreme or rare manifestations of a disease process. Clinical evidence to guide management of such patients may be incomplete, non-existent, or its relevance to the problem at hand may be questionable. In this context, formal decision-making analytical tools are often impractical. Unconscious cognitive biases have been shown to play an important role in medical decision-making, particularly in these settings. While mostly these contribute to doctors making appropriate and timely decisions, occasionally they lead to errors. Despite 30 years of research into models of clinical reasoning, most doctors are unaware of how biases affect their thinking and are unfamiliar with techniques of detecting and neutralising bias in clinical practice. We present the case of a patient with Wegener's granulomatosis, which highlights many of the difficulties outlined above. We review the clinical evidence for our decisions at each stage and explain the rationale for our choices, highlighting the many situations for which high quality evidence was lacking. Examples of cognitive bias are identified and techniques of metacognition (thinking about thinking) that can be useful in limiting the effects of bias on complex decision-making are reviewed. The intensivist's evaluation of management alternatives has an important role in steering medical management towards optimal patient outcomes.

Gastrointestinal malignancies in HIV-infected or immunosuppressed patients: pathologic features and review of the literature

The gastrointestinal (GI) tract is a common internal organ to be involved by human immunodeficiency virus (HIV)-related malignancies. It is the second most common site for Kaposi sarcoma after skin, and the commonest visceral site, for Kaposi sarcoma in AIDS patients. GI lymphomas have been documented in approximately 25% of AIDS patients with systemic lymphomas. Moreover, GI involvement of AIDS-lymphoma has been associated with poor prognosis and short survival. Several other malignancies that occur in the GI tract are also closely related to HIV-infected or immunosuppressed individuals; these include posttransplant lymphoproliferative disorder, Epstein-Barr virus-associated smooth muscle tumors, anal precancerous lesions, and squamous cell carcinoma. As a result of active antiretroviral therapy, patients infected with HIV are living longer and are consequently at increased risk for development of cancer. Therefore, it is possible that the number of AIDS-associated malignancies will rise and the pattern of tumors may change in the future. In this paper, the clinicopathologic features of GI malignancies associated with AIDS patients are reviewed and the differential diagnosis with other mimic lesions is discussed.

Treatment of an infant with X‐linked severe combined immunodeficiency (SCID‐X1) by gene therapy in Australia

OBJECTIVE

To report the outcome of gene therapy in an infant with X-linked severe combined immunodeficiency (SCID-X1), which typically causes a lack of T and natural killer (NK) cells.

DESIGN AND SETTING

Ex-vivo culture and gene transfer procedures were performed at The Children's Hospital at Westmead, Sydney, NSW, in March 2002. Follow-up to March 2005 (36 months) is available.

PATIENT

A 9-month-old male infant with confirmed SCID-X1 (including complete absence of T cells) with an NK+ phenotype (a less common variant of SCID-X1), and no HLA-identical sibling donor available for conventional bone marrow transplantation.

PROCEDURE

CD34+ haemopoietic progenitor cells were isolated from harvested bone marrow and cultured with cytokines to stimulate cellular replication. Cells were then genetically modified by exposure to a retrovirus vector encoding human gamma c (the common gamma chain of several interleukin receptors; mutations affecting the gamma c gene cause SCID-X1). Gene-modified cells (equivalent to 1.3 x 10(6) CD34+/gamma c+ cells/kg) were returned to the infant via a central line.

RESULTS

T cells were observed in peripheral blood 75 days after treatment, and levels increased rapidly to 0.46 x 10(9) CD3+ cells/L at 5 months. Within 2 weeks of the appearance of T cells, there was a distinct clinical improvement, with early weight gain and clearance of rotavirus from the gut. However, T-cell levels did not reach the reference range, and immune reconstitution remained incomplete. The infant failed to thrive and developed weakness, hypertonia and hyperreflexia in the legs, possibly the result of immune dysregulation. He went on to receive a bone marrow transplant from a matched unrelated donor 26 months after gene therapy.

CONCLUSIONS

This is the first occasion that gene therapy has been used to treat a genetic disease in Australia. Only partial immunological reconstitution was achieved, most likely because of the relatively low dose of gene-corrected CD34+ cells re-infused, although viral infection during the early phase of T-cell reconstitution and the infant's NK+ phenotype may also have exerted an effect.

Sudden onset of colitis after ablation of secretin-expressing lymphocytes in transgenic mice

Though secretin mRNA was demonstrated in mouse lymphoid organs, its role in the immune system is unknown. Here, secretin gene-expressing cells were ablated by ganciclovir infusion in mice transgenic for the rat secretin promoter (Sec) directing the expression of herpesvirus thymidine kinase (Sec-HSVTK). Thymus, spleen, blood, and colon were investigated by histology. Lymphoid cells were extracted and quantified, and CD19+ B-cells and CD3+, CD103+, CD4+, and CD8+ T-cells were analyzed by flow cytometry. Protein extracts from spleen and thymus were assayed for secretin by Western blotting, and isolated lymphocytes were investigated for HSVTK, secretin, and secretin receptor (Sec-R) mRNA by reverse transcription-polymerase chain reaction (RT-PCR). Ablation of secretin-expressing cells produced severe colitis with morphological features similar to those observed in graft-versus-host (GVH) disease. Profound lymphoid depletion was observed in spleen, thymus, and peripheral blood. The relative percentage of B- and T-cell subsets were unaffected. Analysis of colonic lymphocytes revealed a marked depletion of CD4+ T lymphocytes. Colitis and lymphoid depletion were not reversed by secretin cotreatment. Immunoblot analysis of protein extracts from spleen and thymus identified secretin-like immmunoreactant. RT-PCR of lymphocyte mRNA from spleen and thymus identified secretin and secretin receptor transcripts. We conclude that GVH-like colitis in ganciclovir-treated Sec-HSVTK mice arises from depletion of secretin gene-expressing lymphoid cells and not from the failure of secretin production.

A preliminary study of the prevalence of intestinal parasites in immunocompromised patients with and without gastrointestinal manifestations

The objective of the present study was to determine the prevalence of the intestinal parasites most commonly found in immunocompromised patients. A group of 111 individuals with acute lymphoid leukaemia (ALL), chronic myeloid leukaemia (CML), human immunodeficiency virus (HIV) and other immunocompromised conditions (principally haematological disorders) was selected. A battery of tests was performed on each individual to identify the presence of parasites (three stool specimens with saline solution and Lugol both directly and by concentration, culture and special staining). No significant differences were found among the frequencies of the different parasites with the several types of immunocompromised conditions. The overall frequencies of potentially pathogenic and opportunistic parasites were 32.4% (36/111) and 9% (10/111) respectively, the most frequently encountered among the latter being Cryptosporidium sp., Microsporidia spp. and Strongyloides stercoralis.

Chronic diarrhoea caused by Cryptococcus neoformans in a non-human immunodeficiency virus-infected patient

A 43-y-old woman with underlying cervix carcinoma stage IIIB, status postirradiation, and diabetes mellitus with tripathy suffered from chronic diarrhoea for more than 6 months. Stool examination showed few white blood cells and red blood cells. Rectal swab cultures disclosed Cryptococcus neoformans in 2 samples obtained 2 weeks apart. The diarrhoea responded to treatment with oral fluconazole for 4 weeks. Repeated rectal swabs revealed no yeast growth. During follow-up for 4 y, she had no problems with diarrhoea. Chronic diarrhoea caused by C. neoformans is rare and clinical suspicion is needed.

Gastrointestinal complications in the neutropenic patient: characterization and differentiation with abdominal CT

PURPOSE

To characterize the computed tomographic (CT) findings of gastrointestinal complications in neutropenic patients and to identify CT features that can help differentiate these complications.

MATERIALS AND METHODS

Abdominal CT scans obtained during a 6-year period were reviewed retrospectively to identify 76 neutropenic patients with radiologic bowel abnormalities. Scans were analyzed for wall thickening, pneumatosis, wall nodularity, mucosal enhancement, bowel dilatation, ascites, and mesenteric stranding. The location and extent of abnormalities were noted. Independent chart and pathology report reviews were used to determine the patients' final diagnoses: neutropenic enterocolitis (n = 53), Clostridium difficile colitis (n = 14), graft-versus-host disease (n = 7), cytomegaloviral colitis (n = 1), and ischemic bowel (n = 1). Results were assessed with the Student t test for quantitative wall thickness and the chi2 test for the number of patients with each diagnosis who demonstrated each CT finding.

RESULTS

Mean bowel wall thickening was greatest in C difficile colitis (12 mm) and least in graft-versus-host disease (5 mm). Pneumatosis was limited to neutropenic enterocolitis (21% [11 of 53 patients]) and bowel ischemia. Wall nodularity was significantly more common (P <.01) in C difficile colitis (36% [five of 14 patients]). In graft-versus-host disease, the rates of mucosal enhancement and bowel dilatation were highest (P <.05) (71% [five of seven patients] and 86% [six of seven patients], respectively). In C difficile colitis, the rates of ascites and mesenteric stranding were highest (57% [eight of 14 patients] and 71% [10 of 14 patients], respectively). Although findings in neutropenic enterocolitis and graft-versus-host disease could involve any bowel segment, C difficile colitis was always limited to the colon.

CONCLUSION

Several CT findings can help differentiate specific gastrointestinal complications in neutropenic patients.

Infections gastro-intestinales chez le patient immunocompromis

Le tractus gastro-intestinal est fréquemment le siège de manifestations infectieuses chez les patients immunocompromis.

Les symptômes les plus fréquemment rencontrés sont l'odynophagie, la dysphagie et les diarrhées.

Ces affections sont plus souvent observées chez les patients HIV.

Ces affections gastro-intestinales sont de différents types: soit liées au virus HIV lui-même (entérite liée au HIV, œsophagite ulcérée idiopathique), soit liées à des germes également responsables d'infections chez les patients immunocompétents (Salmonellose, shigellose, …), soit des infections opportunistes (CMV, Mucormycose,Cryptosporidium, Mycobactéries,Isospora belli, …).

La prévalence, la pathogenèse, les manifestations cliniques, les aspects macroscopique et microscopique sont discutés pour chaque entité.

Gastrointestinal infections in the immunocompromised host

Gastrointestinal disease is a significant cause of morbidity and mortality in the immunocompromised patient. This article focuses on the infectious gastrointestinal complications associated with the treatment of malignant disease and with solid organ transplantation but not HIV. Gastrointestinal defenses and the various mechanisms by which they are impaired are reviewed. The major pathogens and malignancies of this patient population and an approach to their diagnosis, treatment, and prevention are discussed.

Interpretation of ileal biopsies: morphological features in normal and diseased mucosa

One of the advantages of flexible colonoscopy is that the terminal ileum can easily be reached and biopsied by an experienced operator. Thus, the pathologist will, with increasing frequency, receive ileal biopsies from patients who have or may not have ileal disease and it is therefore useful to have a good knowledge of the spectrum of ileal mucosal histology and pathology, of its normal function, and of the changes seen in different conditions. It is also desirable to be aware of diseases that occur less frequently. The ileal microscopic features are related to its absorptive function on the one hand, and to non-specific and specific defence mechanisms of the organism against potential hazardous components on the other. As a consequence the mucosa features a constant physiological and controlled inflammatory process. Part of the ileal mucosal structure is determined by the presence of the gut-associated lymphoid tissue (GALT) which plays a key role in discriminating harmless nutrients and harmful pathogens. It will be important to distinguish this normal situation from alterations seen in infectious or inflammatory pathology. Further, because of the therapeutic implications, it is necessary that acute and chronic (idiopathic) inflammation are recognized. This will in general be possible by evaluating the composition of the inflammatory infiltrate and the occurrence of epithelial and mucosal architectural changes.

Coinfection of visceral leishmaniasis and Mycobacterium in a patient with acquired immunodeficiency syndrome

We report a case of coinfection of visceral leishmaniasis and Mycobacterium avium-intracellulare in the same lesions in the small bowel and bone marrow of a 33-year-old man with acquired immunodeficiency syndrome who complained of abdominal pain and chronic diarrhea. The duodenal mucosa and bone marrow biopsy specimens showed numerous foamy macrophages packed with two forms of microorganisms that were identified histologically and ultrastructurally as Leishmania and Mycobacterium species. Visceral leishmaniasis is rarely suspected in patients residing in nonendemic countries including the United States. It should be included in the differential diagnosis for opportunistic infection in patients with acquired immunodeficiency syndrome. An appropriate travel history is important. To our knowledge, this is the first reported case showing coinfection of visceral leishmaniasis and Mycobacterium avium-intracelluulare in the same lesion in a patient with acquired immunodeficiency syndrome.

Coexistent gastric MALT lymphoma and Kaposi sarcoma in an HIV positive patient

A 47 year old HIV positive male presented with haematemesis and epigastric pain. A gastrectomy was performed for intractable bleeding. The cause of the haematemesis proved to be a Kaposi sarcoma of the stomach which had resulted in mucosal ulceration. Several other smaller foci of Kaposi sarcoma were also present. Coexistent with the Kaposi sarcoma was a dense lymphoid infiltrate with lymphoid follicles and reactive germinal centres. Centrocyte-like cells caused marked effacement and destruction of gastric glands with the formation of lymphoepithelial lesions, typical of a MALT lymphoma. These cells were of B cell lineage and some expressed the HIV antigen, p24. Follicular dendritic cells and macrophages within germinal centres were also p24 positive. Immunohistochemistry and in situ hybridisation did not detect Epstein-Barr virus. Although Helicobacter pylori was not identified by light microscopy in the sections sampled, this does not preclude its possible role, with other cofactors such as HIV, in the causation of the MALT lymphoma.

Cytomegalovirus colitis mimicking a colonic neoplasm or ischemic colitis 4 years after heart transplantation

BACKGROUND

Cytomegalovirus (CMV) colitis is a polymorphous disease presenting in immunodepressed patients in a variety of clinical forms that can delay diagnosis and therapy. We report the case of a patient who presented with abdominal pain 4 years after heart transplantation; clinical and x-ray findings were suggestive of a neoplastic or ischemic stenosis, and histopathological examination likewise initially suggested an ischemic etiology.

METHODS

Tissue samples were fixed in 10% formaldehyde, embedded in paraffin, cut, and stained with hematoxylin/eosin and periodic acid-Schiff-Alcian Blue. Immunohistochemistry with monoclonal antibodies was performed using an indirect immunoperoxidase method.

RESULTS

CMV colitis was eventually diagnosed and resolved with surgery and specific anti-CMV therapy.

CONCLUSIONS

CMV colitis should be suspected in any heart transplant patient with signs or symptoms of abdominal pathology, even without classical signs or symptoms of CMV infection. If stenotic lesions are present, surgery may be required not only to remove the obstruction but also to rule out malignancy.

A double-blind placebo-controlled phase II trial of thalidomide in asymptomatic HIV-positive patients: clinical tolerance and effect on activation markers and cytokines

A randomized double-blind, placebo-controlled study was performed to determine the safety, efficacy, and effect of thalidomide on a variety of immunological and biochemical parameters in asymptomatic human immunodeficiency virus (HIV)-positive patients. Nineteen male patients with elevated markers of immune activation and CD4 cell counts above 400/mm3 were randomized to either placebo or thalidomide at 100 mg/day for 24 weeks. However, only 3 (of 10) patients receiving thalidomide completed all 24 weeks compared to 6 (of 9) patients receiving placebo. This was mainly due to fatigue (somnolence is a recognized side effect), although this was also seen to a lesser extent in the placebo group and so may not be drug attributable. No significant changes in CD4/CD8 count, activation markers, TNF-alpha, or TNFR1 were observed. However, a nonsignificant trend toward inhibition of mitogen-induced TNF-alpha production was observed in the thalidomide arm. The lack of systemic effect and the lower tolerance of thalidomide (at this dose) in asymptomatic patients highlights the need for pharmacokinetic analysis to address possible absorption problems and the need for more potent and less toxic TNF-alpha inhibitors to be developed for use in this type of study.

Pneumocystis carinii infection in heart transplant recipients. Efficacy of a weekend prophylaxis schedule

Most series of heart transplant patients report incidences of Pneumocystis carinii pneumonia (PCP) below 5% but do not individually describe the cases. From August 1988 to March 1994, 138 patients received 1 or more heart transplants at our institution. No anti-PCP chemoprophylaxis was provided, and 5 (3.6%) patients developed PCP. Incidence for listeriosis was 0.7% and for nocardiosis, 3.6%. We found descriptions of 14 more heart transplant patients with PCP in the medical literature. Data from the 19 patients follow. Mean age was 52 years, and PCP was diagnosed a median of 75 days after heart transplant (range, 37-781 d). Clinical presentation was acute (less than 48 h) with fever (89%), shortness of breath (84%), dry cough (74%), and hypoxia (63%). Cytomegalovirus was isolated from lung or blood in 74% of patients. Chest X-ray usually showed interstitial pneumonia (84%). Three patients required ventilatory support. All patients were treated with trimethoprim-sulfamethoxazole (TMP/SMX) (4 also with corticosteroids and 5 with ganciclovir). Mortality was 26%. Older age was the only significant poor prognostic factor (61 versus 49 years; p < 0.03). From March 1994, 50 heart transplant patients were given TMP/SMX prophylaxis at our institution (1 double-strength tablet, 160/800 mg, every 12 hours on Saturdays and Sundays), and no new cases of PCP, Listeria or Nocardia have been detected since then. Tolerance has been excellent. Heart transplant recipients are at a substantial risk of PCP pneumonia, which presents with an abrupt onset and a high mortality. Weekend TMP/SMX chemoprophylaxis was very effective at our institution.

Pathology of human immunodeficiency virus infection: noninfectious conditions

Diagnostic anatomic pathologists play a crucial role in the battle against acquired immunodeficiency syndrome (AIDS). Not only are they intimately involved in the treatment of individual patients with human immunodeficiency virus (HIV) infection, but also they make important observations that result in the expansion of the scientific understanding of its pathogenesis. Pathologists studying tissue from patients with HIV infection should be familiar with the conditions to which these patients are susceptible. Although opportunistic infections are important causes of morbidity and mortality, noninfectious conditions frequently make substantial contributions to the disease course. Patients with HIV infection may be at increased risk for neoplastic disease. They do not, however, have an increased incidence of the most common tumors affecting the general population, such as breast, colon, and prostate carcinoma. Immunodeficiency results in increased susceptibility to malignant neoplasms, both by decreased immunologic response to abnormal cells and increased susceptibility to infection by viruses. All of the malignant neoplastic diseases that are Centers for Disease Control and Prevention (CDC) AIDS indicator conditions have been shown to have an association with a virus: Kaposi sarcoma (KS) with herpes hominis virus 8 (HHV-8), malignant lymphoma with Epstein-Barr virus (EBV), and cervical carcinoma with human papilloma virus (HPV). Patients with HIV infection also can develop reactive processes that are attributable to direct effects of HIV or immune system alterations. Such conditions include salivary gland cystic lymphoepithelial lesion, lymphadenopathy, lymphocytic interstitial pneumonitis, encephalopathy, enteropathy, nephropathy, hepatic conditions, dermatologic conditions and anemia.

Molecular diagnosis of gastrointestinal infections associated with HIV infection

Developments in medical microbiology in the past 20 years have had a profound impact on our understanding of infectious diseases and have led the way in the development of new diagnostic techniques. Molecular diagnostic techniques are generally more sensitive, specific, and rapid than conventional methods by which infectious agents are detected. For many of the opportunistic infectious agents of the gastrointestinal tract found in HIV-infected individuals, the application of molecular diagnostic techniques to the clinical laboratory is in its infancy. In this article, methods by which these techniques can be evaluated are demonstrated, and the current status and potential future application of these techniques for each gastrointestinal opportunistic pathogen are described.

Diarrheal diseases associated with HIV infection

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.

Salivary and mucosal immune responses to HIV and its co-pathogens

The profound effects that HIV induces in systemic immunity have been well characterised, but the situation with regard to mucosal immune responses is less clear. Oral cavity fluids have been used as a marker of the mucosal immune system. Whole and parotid saliva IgA, IgA1 and IgA2 concentrations have been found to be lower in both HIV infection and AIDS subjects, whereas serum IgA and IgA subclasses are markedly raised, suggesting a dichotomy between systemic and secretory immunity. Salivary antibodies to HIV can be readily detected and secretory IgA antibody can be neutralising to some strains of HIV. HIV vaccines can also induce antibody responses in saliva, but vaccination routes other than parenteral immunisation are needed. Antibody responses to oral microbes have also been studied and it has been shown that IgA, IgA1 and IgA2 subclass antibody titres to Candida albicans and to Streptococcus mutans are increased in whole or parotid saliva from HIV patients, but reduced in AIDS patients, suggesting a compensatory response which is overcome with progressive immunodeficiency. The avidity of salivary IgA antibodies to Candida in HIV seems unimpaired, whereas relative avidities of serum antibodies in HIV patients with candidiasis are lowered. Non-specific factors which may inhibit Candida and other opportunist pathogens are also found in saliva. The candidacidal, myelomonocytic protein calprotectin is present in saliva at levels which are biologically active, although levels are lowered in HIV infection. Overall, HIV infection appears to be associated with disregulation of a number of immune factors at the mucosal surface, but the ability of patients with HIV infection to mount specific antibody secretory responses seems to be relatively intact until late in infection.

Guidelines for the initial biopsy diagnosis of suspected chronic idiopathic inflammatory bowel disease. The British Society of Gastroenterology Initiative

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Perturbations of glucose metabolism associated with HIV infection in human intestinal epithelial cells: a multinuclear magnetic resonance spectroscopy study

OBJECTIVE

To analyse the effect of HIV-1 infection on the glucose metabolism of human intestinal epithelial cells.

METHODS

HT-29 cells were infected with HIV-1NDK and studied 3 weeks (acutely infected cells) or 9 months (chronically infected cells) post-infection. Perchloric acid extracts were analysed by high-resolution 1H, 31P and 13C nuclear magnetic resonance spectroscopy. Metabolite concentrations and specific 13C enrichments were quantified for chronically infected, acutely infected and control cells grown in Dulbecco's modified Eagle's medium containing natural-abundance or 1-13C-enriched glucose to determine significant differences between infected and non-infected cells.

RESULTS

Chronically HIV-infected cells showed alterations in glycerol-3-phosphate (+40%), fructose-1,6-diphosphate (-66%), uridine diphosphate glucuronic acid (-33%), lactate (+75%) and [1-13C]glucose (+181%) levels, and in specific lactate 3-13C enrichment (+19%) when compared with controls. Acutely infected cells exhibited decreased fructose-1,6-diphosphate (-58%) and increased nicotinamide adenine dinucleotide (+33%) levels relative to controls.

CONCLUSION

HIV-1 infection results in a disturbance of glycolytic and oxidative activities in human intestinal epithelial cells. This finding supports the concept that HIV-1 may directly impair some metabolic functions of the intestinal epithelium, and that it can be considered a potential aetiological agent for HIV-associated enteropathy.