Clinical microbiological case: a heart transplant recipient with diarrhea and abdominal pain. Recurring C. difficile...

Giardiasis is a globally prevalent intestinal infection caused by the protozoan parasite Giardia duodenalis (also known as G. lamblia or G. intestinalis). This flagellated protozoan is the most frequently identified intestinal parasite in the United States and worldwide. Transmission primarily occurs via the fecal-oral route, with infection arising from ingestion of water or food contaminated with cysts. Individuals in low-resource settings, international travelers, outdoor enthusiasts, daycare...

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...

Introduction
Inflammatory bowel disease, commonly known as IBD, refers to a collection of disorders that lead to persistent inflammation of the gastrointestinal tract. The two types of IBD are ulcerative colitis, which impacts the colon, and Crohn's disease, which can involve any part of the gastrointestinal segment.
Crohn's disease
Crohn's disease is a chronic, systemic inflammatory bowel disease (IBD) that predominantly affects the gastrointestinal tract. It is marked by transmural...

Crohn’s disease is a chronic, relapsing form of inflammatory bowel disease characterized by segmental, transmural inflammation that can affect any part of the gastrointestinal tract. Its pathogenesis arises from a combination of genetic susceptibility, environmental exposures, epithelial barrier dysfunction, and immune dysregulation. Together, these factors lead to an exaggerated immune response against components of the gut microbiome.Genetic and Environmental InfluencesMultiple genetic...

The human gut microbiome includes a diverse array of microbial species, including beneficial commensals and opportunistic pathogens, which interact to support host health. These microbes contribute to essential functions such as nutrient metabolism, immune system modulation, and maintenance of intestinal barrier integrity. However, disruptions to this equilibrium—referred to as dysbiosis—can have widespread physiological consequences.Dysbiosis is often characterized by reduced microbial...

Inflammatory bowel disease is a group of chronic disorders marked by recurrent inflammation of the gastrointestinal tract due to an abnormal immune response against gut microflora. This leads to tissue damage. The two main forms are Crohn’s disease and ulcerative colitis.Crohn’s DiseaseCrohn’s disease is a relapsing inflammatory disorder that can affect any part of the GI tract, from the mouth to the anus. It involves all layers of the bowel wall (transmural) and shows “skip lesions” in which...