Gastroenteritis and Salmonella Quiz

Microbial Diseases of the Digestive System

• Staphylococcus aureus produces enterotoxin.
• Enterotoxin is not deactivated by boiling.
• Toxins accumulate when the organism incubates in food (temperature abuse).
• S. aureus outgrows other bacteria in high osmotic pressure and high temperatures.
• Food is cooked to kill bacteria.
• Contaminated food is left at room temperature.
• Toxins form in food.
• The food is consumed.
• Staphylococcal intoxication occurs within 1-6 hours.

Shigellosis (Bacillary Dysentery)

• Caused by the Shigella genus.
• Facultatively anaerobic; Gram-negative.
• Produces Shiga toxin.
• Small infectious dose.
• Attaches to M cells, invades, and spreads to other cells.
• Causes damage to the intestinal wall.
• Can invade the bloodstream.

Salmonellosis (Salmonella Gastroenteritis)

• Salmonella enterica.
• Gram-negative, facultative anaerobe.
• Normal inhabitant of the human intestinal tract and many animals.
• Has 2000 serotypes.
• Invades intestinal mucosa, multiplies in the mucosa.
• Passes through M cells, enters lymphatics, replicates in macrophages.
• Symptoms include fever, nausea, pain (cramps), and diarrhea.

Typhoid Fever

• Caused by Salmonella serotype Typhi.
• Spread only by human feces.
• Bacteria spread throughout the body in phagocytes.
• Releases organism into the bloodstream.
• Symptoms: high fever, headache, intestinal wall ulceration.
• 1–3% of patients become chronic carriers.
• Chronic carriers harbor the organism in the gallbladder.

Cholera

• Caused by Vibrio cholerae.
• Slightly curved, gram-negative rod with a single polar flagellum.
• Associated with salty waters.
• Produces cholera toxin.
• Toxin causes host cells to secrete electrolytes and water.
• Symptoms: "rice water stools", patient loses 12-20 liters of fluid per day.
• Can lead to shock, collapse, organ failure, and death.
• Treatment includes intravenous fluid replacement.

Escherichia Coli Gastroenteritis (EHEC)

• Enterohemorrhagic E. coli (EHEC).
• Produces Shiga-like toxin (Stx-1, Stx-2).
• Released upon the cell's lysis.
• Most outbreaks are due to serotype O157:H7.
• Cattle are the main reservoir.
• Causes hemorrhagic colitis and hemolytic uremic syndrome.

Campylobacteriosis (Campylobacter Gastroenteritis)

• Caused by Campylobacter jejuni.
• Gram-negative, microaerophilic, spirally curved.
• Foodborne illness, common in poultry.
• 60% of cattle excrete organism in feces and milk.
• Symptoms: fever, cramping, abdominal pain, diarrhea, dysentery.
• One in 1000 cases leads to Guillain-Barré syndrome (autoimmune disease damaging peripheral nerves).

Helicobacter Peptic Ulcer Disease

• Caused by Helicobacter pylori.
• Grows in stomach acid by producing urease.
• Converts urea to alkaline ammonia.
• Disrupts stomach mucosa, causing inflammation.
• Treated with antimicrobial drugs.
• Diagnostic test requires a biopsy, culture, and urea breath test.

Clostridium Difficile-Associated Diarrhea

• Gram-positive, endospore-forming anaerobe.
• Causes more deaths than all other intestinal infections combined.
• Mostly in health care settings.
• Life-threatening colitis with ulceration and perforation of the intestinal wall.
• Precipitated by the extended use of antibiotics.
• Antibiotics eliminate competing intestinal bacteria.

Mumps

• Virus targets the parotid glands causing painful swelling (16-18 days after exposure).
• Transmitted in saliva and respiratory secretions.
• Multiplies in respiratory tract, reaches salivary glands via the bloodstream.
• Can cause orchitis (swelling of testes), meningitis, ovary inflammation, and pancreatitis.
• Prevented by MMR vaccine.

Hepatitis A

• Hepatitis A virus (HAV).
• Entry via oral route; multiplies in the epithelial lining of the intestinal tract, spreads to the liver, kidneys, and spleen.
• Symptoms include anorexia, malaise, nausea, diarrhea, fever, chills.
• Later symptoms include jaundice and dark urine.
• Symptoms last 2–21 days; low mortality.
• Inactivated vaccine for prevention.

Hepatitis B

• Hepatitis B virus (HBV).
• Transmitted through blood and bodily fluids.
• Up to 1 billion viruses per ml of blood.
• Prevented by vaccine.
• Acute hepatitis B: similar symptoms to hepatitis A, gradual recovery.
• Chronic hepatitis B: involves 10% of infected patients, can lead to liver cirrhosis or liver cancer, treated with interferons.

Hepatitis C

• Hepatitis C virus (HCV).
• Often transfusion-transmitted.
• Destroys liver by using genetic variation to evade the immune response.
• 85% of cases become chronic.
• 25% develop liver cirrhosis or cancer.
• No vaccine.

Rotavirus Gastroenteritis

• Common in children, low mortality.
• Low-grade fever, diarrhea, vomiting.
• Prevented by a live oral vaccine.

Norovirus Gastroenteritis

• Fecal-oral transmission.
• Low infectious dose.
• Diarrhea and vomiting.

Giardiasis

• Caused by Giardia intestinalis (flagellated protozoan).
• Attaches to the intestinal wall.
• Symptoms include prolonged diarrhea, malaise, weight loss, flatulence, cramps.

Amebic Dysentery (Amebiasis)

• Caused by Entamoeba histolytica.
• Produces cysts that survive stomach acid.
• Trophozoites produced from cysts in intestines.
• Multiply in wall of the large intestine.
• Feces contain blood and mucus.
• Can perforate the intestinal wall, causing abscesses.
• Organisms invade the liver.

Hydatid Disease

• Caused by the tapeworm Echinococcus granulosus.
• Eggs are ingested and migrate to the liver, lungs, or brain.
• Develops a hydatid cyst; can grow and hold up to 15 liters of fluid.
• May rupture, causing anaphylactic shock.
• Diagnosis with serological tests, X-rays, CT, and MRI.
• Treatment with surgical removal or albendazole.

Test your knowledge on gastroenteritis, with a focus on common pathogens such as Salmonella and Rotavirus. This quiz covers symptoms, transmission routes, and treatment options related to these conditions. Challenge yourself to understand the implications of fluid loss and viral infections.