Foodborne and Waterborne Bacterial Diseases

Vocabulary practice flashcards covering foodborne and waterborne bacterial infections, intoxications, oral microbiology, and enteric virulence mechanisms.

Dental Plaque

A biofilm on the tooth surface composed of salivary proteins, food debris, bacterial cells, and microbial products; an acquired pellicle can be colonized by 50 to 100 million bacterial cells.

Dental Caries

Tooth decay resulting from plaque buildup and dietary carbohydrate fermentation by acidogenic Gram-positive cocci, primarily Streptococcus mutans and Streptococcus sobrinus.

Periodontal Disease

A group of infections affecting supporting dental tissues (alveolar bone, periodontal ligament, cementum, and gingiva) driven by bacteria such as Actinobacillus, Porphyromonas, Bacteroides, and Treponema species.

Gingivitis

Inflammation of the gums caused by plaque accumulation between teeth and gums, characterized by ulcers and bleeding along the gingival margin without initial loss of bone attachment.

Infective Endocarditis

Inflammation of the heart valves and inner endocardium caused by microbial agents (>80% due to streptococci or staphylococci), frequently seeded from oral infections and periodontal disease.

Subacute Bacterial Endocarditis (SBE)

A slowly developing endocardial infection that progresses over weeks to months, typically caused by low-virulence streptococci (such as the Viridans group) with low propensity to seed extracardiac sites.

Acute Bacterial Endocarditis (ABE)

A fulminant, rapidly progressive heart valve infection occurring over days to weeks, predominantly caused by virulent Staphylococcus aureus and frequently causing metastatic infections.

HACEK Group

A consortium of fastidious Gram-negative oral bacteria linked to infective endocarditis: Haemophilus, Aggregatibacter (Actinobacillus), Cardiobacterium, Eikenella corrodens, and Kingella.

Foodborne Intoxication

An illness resulting from the ingestion of preformed bacterial toxins present in contaminated food; it features a short incubation period (hours) because live bacterial growth inside the host is not required.

Foodborne Infection

An illness caused by ingesting viable pathogenic bacteria that establish colonization and multiply within the host digestive tract before producing toxins or tissue invasion, resulting in longer incubation periods.

Staphylococcal Food Poisoning

The most common bacterial intoxication, caused by ingestion of heat-stable enterotoxins (A–E) produced by Staphylococcus aureus that withstand boiling at $100^\text{o}\text{C}$ for 30 minutes.

Staphylococcal Enterotoxin B (SEB)

A superantigen exotoxin that bridges MHC class II molecules and T-cell receptors, triggering massive cytokine release from mucosal T cells in the intestinal lamina propria to induce vomiting and diarrhea.

Clostridial Food Poisoning

An intoxication caused by Clostridium perfringens, an obligate anaerobic sporeformer contaminating protein-rich foods; ingested spores germinate and produce enterotoxin, leading to cramps and watery diarrhea in 8 to 24 hours.

Cereulide

A heat-stable emetic toxin produced by Bacillus cereus when growing in cooked grains (such as fried rice), inducing extensive vomiting within 30 minutes to 5 hours.

Botulism

A severe neuroparalytic intoxication caused by the heat-labile neurotoxin of Clostridium botulinum, typically contracted from improperly canned, low-acid foods.

Botulinum Neurotoxin Mechanism

An AB toxin whose catalytic light chain enters peripheral motor neurons and proteolytically cleaves SNARE complex proteins (synaptobrevin, SNAP-25, or syntaxin), blocking acetylcholine release and causing flaccid paralysis.

Infant Botulism

A form of botulism caused by the ingestion of Clostridium botulinum endospores (frequently from raw honey) that germinate and produce neurotoxin inside an infant's intestine, accounting for ~65% of U.S. cases.

Limber Neck

Avian botulism occurring in aquatic birds like mallards that ingest Clostridium botulinum toxin in stagnant ponds, leading to flaccid neck muscle paralysis and drowning.

Inflammatory Gastroenteritis

A noninvasive infection of the gastrointestinal tract (typically the small bowel) characterized by fever, vomiting, and watery diarrhea without blood in the feces.

Invasive Gastroenteritis

A gastrointestinal infection characterized by pathogen invasion of the mucosa (primarily in the colon), leading to dysentery with small-volume stools containing blood, mucus, and inflammatory cells.

Vibrio cholerae

A curved Gram-negative bacterium that colonizes the small intestine following ingestion of contaminated water or raw shellfish; it requires an infectious dose of $10^6$ to $10^8$ cells due to susceptibility to gastric acid.

Cholera Toxin Mode of Action

An AB enterotoxin whose B subunits bind GM1 ganglioside, allowing the A subunit to ADP-ribosylate a G protein; this constitutively activates adenylate cyclase, raising cAMP and stimulating CFTR-mediated secretion of $Cl^-$ and $HCO_3^-$ followed by massive osmotic water loss.

Rice-Water Stool

Watery, colorless stool containing flecks of mucus and epithelial cells produced at rates up to 1 liter per hour during severe cholera, leading rapidly to hypovolemic shock.

Enterotoxigenic Escherichia coli (ETEC)

A noninvasive pathotype of E. coli that produces cholera-like heat-labile (LT) and heat-stable (ST) enterotoxins, serving as the primary cause of traveler's diarrhea ('Montezuma's revenge').

Enteropathogenic Escherichia coli (EPEC)

An E. coli strain that adheres to enterocytes, effaces microvilli, and deforms intestinal mucosa, leading to severe nutrient malabsorption and potentially fatal watery diarrhea in infants.

Pseudomembranous Colitis

Severe colon inflammation characterized by elevated white-yellow mucosal plaques of dead epithelial cells and fibrin, triggered by Clostridium difficile overgrowth following broad-spectrum antibiotic therapy.

Fecal Microbiota Transplant (FMT)

The administration of filtered donor stool via nasogastric tube or colonoscopy to restore normal gut microbiota diversity, curing approximately 90% of recurrent, severe Clostridium difficile infections.

Vibrio parahaemolyticus

A halophilic Gram-negative marine bacterium found in warm seawater and raw oysters that secretes enterotoxin to cause acute abdominal cramps, vomiting, and watery diarrhea within 24 hours.

Vibrio vulnificus

A virulent halophilic bacterium found in brackish coastal waters and raw oysters capable of crossing the gut barrier into systemic circulation, carrying a mortality rate as high as 50%.

Salmonella enterica Serotype Typhi

The acid-resistant etiological agent of typhoid fever that penetrates small intestinal M cells over Peyer's patches to invade the reticuloendothelial system.

Rose Spots

Faint maculopapular, erythematous lesions appearing on the abdomen and chest in approximately 30% of typhoid fever patients, caused by bacterial emboli lodging beneath the skin.

Five Fs

The traditional transmission vectors for Salmonella typhi and typhoid fever: Flies, Food, Fingers, Feces, and Fomites.

Mary Mallon ('Typhoid Mary')

An infamous asymptomatic carrier of Salmonella typhi who worked as a cook across New York households and hospitals, chronically harboring the bacilli in her gallbladder.

Salmonellosis

Foodborne gastroenteritis caused by non-typhoidal Salmonella serotypes (such as S. typhimurium and S. enteritidis), requiring an infectious dose of 100,000 to 200,000 cells ingested from poultry, eggs, or contaminated produce.

Shigellosis

Bacterial dysentery caused by Shigella species (such as S. sonnei and S. dysenteriae) that requires an infectious dose of only 10 to 200 organisms to produce intense cramps and small-volume bloody, mucoid stools.

Shiga Toxin

A potent AB enterotoxin produced by Shigella dysenteriae and STEC strains that halts eukaryotic protein synthesis by cleaving ribosomal RNA, leading to capillary endothelial injury and bloody diarrhea.

Enterohemorrhagic Escherichia coli (EHEC / STEC)

Acid-resistant strains of E. coli (predominantly serotype O157:H7 in the U.S.) that produce Shiga-like toxins 1 and 2, causing hemorrhagic colitis with an infectious dose of ~100 bacilli.

Hemolytic Uremic Syndrome (HUS)

A severe STEC complication caused by Shiga-like toxins binding Gb3 receptors in glomerular endothelial cells, presenting with microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure.

Campylobacter jejuni

A microaerophilic, curved Gram-negative rod and leading cause of bacterial gastroenteritis in the U.S., transmitted via raw poultry and unpasteurized milk, causing mucosal invasion and explosive bloody diarrhea.

Guillain-Barré Syndrome

A rare post-infectious autoimmune neuromuscular disorder linked to Campylobacter jejuni where cross-reactive antibodies damage peripheral myelin, producing ascending weakness, tingling, and flaccid paralysis.

Listeria monocytogenes

A psychrophilic Gram-positive coccobacillus that contaminates refrigerated unpasteurized milk, soft cheeses, and processed meats, causing invasive listeriosis, meningitis, and fetal death in pregnant women.

Yersinia enterocolitica

A psychrophilic Gram-negative rod transmitted via undercooked pork or unpasteurized milk that invades the ileum, producing fever, diarrhea, and abdominal pain that mimics appendicitis.

Helicobacter pylori

A spiral, microaerophilic Gram-negative bacterium that colonizes the gastric antrum, produces urease and cytotoxins to damage stomach mucosa, and acts as the primary cause of peptic ulcers and gastric adenocarcinoma.

Urea Breath Test

A noninvasive diagnostic test for Helicobacter pylori where a patient ingests $^{13}\text{C}$-labeled urea; bacterial urease cleaves it into ammonia and $^{13}\text{CO}_2$, which is absorbed into the blood and measured in expired air.

Rapid Urease Test (CLO Test)

A diagnostic gastric biopsy assay that detects Helicobacter pylori urease activity; ammonia generation increases the pH, turning a phenol red indicator solution from yellow-orange to pink-red.

Barry Marshall and Robin Warren

Australian medical researchers awarded the 2005 Nobel Prize in Physiology or Medicine for identifying Helicobacter pylori as the bacterial etiology of gastritis and peptic ulcer disease.

Brucellosis (Undulant Fever)

A zoonotic infection caused by Brucella species transmitted via unpasteurized dairy, characterized by intracellular replication in spleen and lymph nodes and a fluctuating fever that rises in the daytime and drops with chills at night.

Intestinal Anthrax

A rare, severe form of Bacillus anthracis infection acquired by consuming undercooked meat from infected livestock, causing inflammatory gastroenteritis, hematemesis, and up to 60% mortality if untreated.