Microbial Diseases of the Digestive System – Key Vocabulary

A comprehensive set of vocabulary flashcards covering anatomical structures, microbial pathogens, toxins, diseases, and relevant treatments from the digestive-system microbiology lecture.

Gastrointestinal (GI) Tract

Continuous tube from mouth to large intestine where digestion and absorption occur.

Accessory Digestive Structures

Organs aiding digestion outside the GI tract—teeth, tongue, salivary glands, liver, gallbladder, pancreas.

Digestion

Mechanical and chemical breakdown of food into small molecules.

Absorption

Uptake of digested nutrients from intestinal lumen into blood or lymph.

Gut-Associated Lymphoid Tissue (GALT)

Immune tissue in intestines (lymph nodes, Peyer’s patches) comprising ~70 % of body’s immunity.

Normal Oral Microbiota

Millions of bacteria per milliliter of saliva, forming biofilms such as dental plaque.

Dental Plaque

Bacterial biofilm on teeth; precursor to caries.

Streptococcus mutans

Primary cariogenic bacterium; converts sucrose to lactic acid and dextran.

Dextran

Polysaccharide produced by S. mutans that helps form dental plaque.

Gingivitis

Inflammation/infection of gums due to mixed bacterial flora.

Periodontitis

Destruction of bone and tissues supporting teeth, often caused by Porphyromonas spp.

Bacterial Infection (GI)

Illness after pathogen enters and multiplies in digestive tract.

Bacterial Intoxication

Illness from ingesting preformed exotoxin; rapid onset, usually afebrile.

Dysentery

Severe diarrhea with blood and mucus.

Gastroenteritis

Inflammation of stomach and intestinal mucosa causing vomiting and diarrhea.

Oral Rehydration Therapy

Replacement of lost fluids/electrolytes to treat diarrheal dehydration.

Shigellosis (Bacillary Dysentery)

Shigella infection producing Shiga toxin; causes bloody diarrhea, cramps, fever.

Shiga Toxin

Potent cytotoxin produced by Shigella and EHEC that halts protein synthesis.

Salmonellosis

Gastroenteritis by Salmonella enterica; invades M cells, replicates in macrophages.

Typhoid Fever

Systemic infection by Salmonella Typhi producing typhoid AB toxin; high fever, ulceration.

Cholera

Severe watery diarrhea (“rice-water stools”) from Vibrio cholerae cholera toxin.

Enterohemorrhagic E. coli (EHEC)

E. coli O157:H7 producing Shiga-like toxin; causes hemorrhagic colitis and HUS.

Actin Pedestal

EHEC-induced host cell actin rearrangement forming pedestal for bacterial attachment.

Hemolytic Uremic Syndrome (HUS)

EHEC complication of kidney failure, hemolysis, and low platelets.

Helicobacter pylori

Spiral bacterium causing peptic ulcers; produces urease to neutralize acid.

Urease

Enzyme converting urea to ammonia, allowing H. pylori survival in stomach acid.

Clostridioides difficile

Gram-positive spore-former causing antibiotic-associated diarrhea and pseudomembranous colitis.

Pseudomembranous Colitis

Inflammation with pseudomembrane formation in colon from C. difficile toxins.

Fecal Microbiota Transplant (FMT)

Therapy transferring stool from healthy donor to restore gut flora, especially for C. difficile.

Bacillus cereus

Spore-forming soil bacterium; produces emetic and diarrheal toxins after food reheating.

Hepatitis

Inflammation of liver from toxins or viral infection (HAV, HBV, HCV, HDV, HEV).

Hepatitis C Virus (HCV)

Enveloped RNA virus; transfusion-transmitted, often chronic, major cause of liver transplants.

Ergot Poisoning

Claviceps purpurea mycotoxin exposure from grains causing vasoconstriction and hallucinations.

Aflatoxin

Aspergillus flavus mycotoxin on peanuts leading to liver cirrhosis and cancer.

Giardiasis

Prolonged diarrheal disease by flagellate Giardia duodenalis; acquired via cyst ingestion.

Giardia Cyst

Infective dormant stage of Giardia resistant to environmental stress.

Trophozoite (Giardia)

Motile feeding stage that attaches to intestinal wall via ventral disk.

Platyhelminths

Flatworms including trematodes (flukes) and cestodes (tapeworms).

Cestode Scolex

Head region of tapeworm bearing suckers/hooks for attachment.

Proglottid

Segment of tapeworm containing reproductive organs; released in feces.

Taeniasis

Intestinal infection by adult Taenia tapeworm (beef or pork).

Cysticercosis

Infection by Taenia larval cysts after ingesting eggs; may reach CNS (neurocysticercosis).

Hydatid Cyst

Fluid-filled larval stage of Echinococcus granulosus in organs; can grow large and rupture.

Pinworm (Enterobius vermicularis)

Small nematode laying eggs peri-anally; diagnosed by scotch tape prep.

Hookworm

Necator americanus/Ancylostoma duodenale; larvae penetrate skin, cause anemia and pica.

Pica

Craving for non-food substances, seen with hookworm-induced anemia.

Ascariasis

Large roundworm Ascaris lumbricoides infection; larvae migrate through lungs before maturing.

Mebendazole/Albendazole

Anthelmintic drugs treating nematode infections such as pinworms, hookworms, ascariasis.