Gastrointestinal Diseases and Their Associated Infections

Guy D. Eslick

• Publisher: Elsevier
• Year: 2019
• ISBN:
  9780323548441
• Topic: Medicine
• Subtopic: Infectious Diseases

Many bacteria, viruses, protozoa, and fungi play key roles in the development of gastrointestinal diseases, and this practical reference brings you up to speed with this increasingly important area. Covering a broad range of GI diseases and cancers, this resource provides an expert overview of the field, ideal for all gastroenterologists and infectious disease physicians.

• Covers infections associated with gastroesophageal reflux disease and Barrett's esophagus, gallbladder disease, acute pancreatitis, small intestinal bacterial overgrowth, irritable bowel syndrome, inflammatory bowel disease, appendicitis, Whipple Disease, Crohn's Disease, and more.
• Discusses esophageal cancer, gastric cancer, cholangiocarcinoma, hepatocellular carcinoma, and colorectal cancer.
• Includes chapters on gut microbiome, fecal transplants, and the molecular pathgenesis of gastrointestinal infections.
• Consolidates today's available information on this timely topic into a single convenient resource.

Chapter 1

The Esophageal Microbiome

Esophageal Reflux Disease, Barrett’s Esophagus, and Esophageal Cancer

Prapti Shrestha, BMedSc(Hons), Ross Penninkilampi, BMed, and Guy D. Eslick, DrPH, PhD, FACE, FFPH

Abstract

Following a review of the anatomy and histology of the esophagus, this chapter begins by briefly discussing infectious esophagitis and Chagas disease, also known as American trypanosomiasis. The three disorders subsequently discussed, which form the focus in this chapter, differ substantially in their prevalence and prognosis. However, they are linked in a sequential etiology: chronic gastroesophageal reflux disease predisposes to the metaplastic changes characteristic of Barrett's esophagus, while Barrett's esophagus is concerning in that it confers an increased risk of esophageal adenocarcinoma. Separate from this pathway is the second major type of esophageal cancer, squamous cell carcinoma. These conditions have been shown in the past few decades to be associated with a range of infections, particularly Helicobacter pylori (H. pylori).

Keywords

Adenocarcinoma; Barrett's esophagus; Esophageal cancer; Infection; Microbiome; Squamous cell carcinoma

Infections of the Esophagus

Infective Esophagitis

The normal flora of the healthy esophagus typically contains species of Streptococcus, Neisseria, Veillonella, Fusobacterium, Bacteroides, Lactobacillus, Staphylococcus, Prevotella, Enterobacteriaceae, and yeasts. ¹ Infectious esophagitis is rare in those who are not immunocompromised, although some cases of infection with herpes simplex and Candida albicans occur on occasion. In the immunosuppressed, often for organ transplantation, chronic inflammatory diseases, or chemotherapy, as well as sufferers of acquired immune deficiency syndrome (AIDS), infective esophagitis becomes more common. ² It may be caused by cytomegalovirus, herpesvirus, Candida species, and others. The typical symptoms of infectious esophagitis are odynophagia, dysphagia, and bleeding. Choice of treatment depends on the particular pathogen implicated.

Chagas Disease or American Trypanosomiasis

Chagas disease, also known as American trypanosomiasis, is a zoonotic disease caused by the protozoan Trypanosoma cruzi. Other species of this genus, namely T. brucei gambiense and T. brucei rhodesiense are responsible for African trypanosomiasis, also known as sleeping sickness. Only Chagas disease exhibits clear esophageal involvement, and hence the discussion here is limited to this disease.

T. cruzi is only found in the Americas, and is harbored by mammals and infected triatomines. Triatomines are a subfamily of Reduviidae insects that are more commonly known as kissing bugs, assassin bugs, or vampire bugs. These insects are the vectors for Chagas disease, able to transfer the protozoans from wild or domestic mammal carriers to humans. Overall, there are more than 150 identified species of insect vectors for Chagas disease, and the parasites have been found to infect over 100 species of mammals. ³ It is estimated that there are eight million individuals with chronic Chagas disease, ⁴ and that it accounts for approximately 14,000 deaths per year. In Latin America, it represents a significant parasitic cause of morbidity and mortality, and significant efforts have been made to improve control of its spread. Even in nonendemic countries, such as Spain, Canada, the United States, and Australia, ⁵ Chagas disease has become increasingly visible, especially as it is transmissible vertically, and through both blood and organ transplantation ⁶ (Fig. 1.1).

Chagas disease acutely presents as a mild febrile illness which usually resolves spontaneously; however, most infected patients will experience an asymptomatic, chronic, subpatent parasitemia, in what is known as the indeterminate phase. Of these cases, a fraction of up to half of patients may experience serious cardiac or gastrointestinal symptoms associated with significant morbidity or mortality. ⁷ The gastrointestinal complications of chronic Chagas disease may include dilatation of the esophagus (megaesophagus) or colon (megacolon), with the former being responsible for symptoms of dysphagia, odynophagia, and regurgitation. Severe esophageal dysfunction can have grave consequences, particularly by causing aspiration that may lead to aspiration pneumonitis. Hence the symptoms of megaesophagus in chronic Chagas disease may lead to chronic aspiration, weight loss, malnutrition, cachexia, and potentially death (Fig. 1.2).

Two drugs are available for Chagas disease: nifurtimox and benznidazole. However, these drugs have limited efficacy, especially once the clinical course has progressed through to the indeterminate or chronic symptomatic phases. More research from randomized, controlled trials is required to identify more efficacious treatments, and to investigate the usefulness of treatments at each stage of the disease.

FIG. 1.1 Spread of Chagas disease from endemic Latin America to regions around the world.

FIG. 1.2 The life cycle for Chagas disease.

Gastroesophageal Reflux Disease

Introduction

Gastroesophageal reflux disease (GERD) is defined as a disorder involving the effortless transit of acidic gastric contents into the esophagus or mouth. ⁸ It is the clinical condition associated with the pathological condition of reflux esophagitis. Although highly prevalent and often associated with significant discomfort, GERD rarely causes serious or fatal sequelae. It hence represents a significant burden in terms of morbidity rather than mortality. ⁸

The disorder occurs when lower esophageal sphincter tone, which is responsible for preventing reflux ...