Chapter 25

What is the primary reason for the low number of microorganisms in the stomach?

The production of hydrochloric acid (HCl) inhibits microbial growth.

What type of cells in the small intestine produce defensins?

Paneth cells, which are granule-filled phagocytic cells.

What is the primary reason for the low number of microorganisms in the stomach?

The production of hydrochloric acid (HCl) inhibits microbial growth.

What type of cells in the small intestine produce defensins?

Paneth cells, which are granule-filled phagocytic cells.

Where are many microorganisms found in the digestive system?

In the large intestine, which contains anaerobes and facultative anaerobes.

What is dental caries and what biofilm is involved in its formation?

Dental caries, or tooth decay, is formed by dental plaque, which is a biofilm.

Which organism is considered the most important cariogenic organism?

Streptococcus mutans, a gram-positive bacterium that converts sucrose into lactic acid and produces dextran.

What are the stages of decay in dental caries?

Caries penetrate from enamel into the dentin and can reach the pulp, potentially advancing to abscesses.

What is gingivitis?

Gingivitis is the inflammation and infection of the gums, often caused by streptococci, actinomycetes, and anaerobic gram-negative bacteria.

What is periodontitis?

Periodontitis is the destruction of the bone and tissue supporting teeth, often caused by Porphyromonas.

What is acute necrotizing ulcerative gingivitis, commonly known as trench mouth?

It is an infection characterized by painful ulcers and is caused by Prevotella intermedia.

What causes Staphylococcal Enterotoxicosis?

It is caused by enterotoxin produced by Staphylococcus aureus, which coagulates blood plasma.

What conditions allow Staphylococcus aureus to produce toxins?

Toxins are produced when the organism is allowed to incubate in food under temperature abuse.

What is Shigellosis and what organism causes it?

Shigellosis, or bacillary dysentery, is caused by Shigella, a facultatively anaerobic gram-negative bacterium.

What is the role of Shiga toxin in Shigellosis?

Shiga toxin damages the intestinal wall and allows the bacteria to invade the bloodstream.

How is Salmonellosis characterized?

It is characterized by fever, nausea, pain, cramps, and diarrhea caused by Salmonella, a gram-negative facultative anaerobe.

What are the common sources of Salmonella infection?

Commercial chicken and egg production, especially when food is kept in the danger zone for bacterial growth.

What is Typhoid Fever and what organism causes it?

Typhoid Fever is caused by Salmonella serotype Typhi, which spreads through human feces.

What are the symptoms of Typhoid Fever?

High fever, headache, intestinal wall ulceration, and the bacteria can be harbored in the gallbladder.

What organism causes Cholera and what is its main effect?

Cholera is caused by Vibrio cholerae, which produces a toxin that causes host cells to secrete electrolytes and water, leading to 'rice water' stools.

What are the consequences of untreated Cholera?

Severe water loss can lead to shock, collapse, organ failure, and death.

What is Enteropathogenic E. coli (EPEC) known for?

EPEC causes diarrhea in developing countries by causing host cells to form pedestals for bacterial attachment.

What type of diarrhea is associated with Enteroaggregative E. coli (EAEC)?

EAEC produces an enterotoxin that causes watery diarrhea and is often associated with Traveler's Diarrhea.

What toxin does E. coli (EHEC) produce and what are its effects?

Produces Shiga-like toxin that causes hemorrhagic colitis and hemolytic uremic syndrome.

What is the primary reservoir for E. coli (EHEC)?

Cattle are the main reservoir.

How is E. coli (EHEC) diagnosed?

By inability to ferment sorbitol and ELISA.

What is the leading cause of foodborne illness in the US?

Campylobacteriosis caused by Campylobacter jejuni.

What are the symptoms of Campylobacteriosis?

Fever, cramping, abdominal pain, diarrhea, and dysentery.

What causes Helicobacter Peptic Ulcer Disease?

Caused by Helicobacter pylori.

How does Helicobacter pylori survive in the stomach?

It produces urease, converting urea to alkaline ammonia, disrupting stomach mucosa.

What is the treatment for Helicobacter Peptic Ulcer Disease?

Treated with antimicrobials and bismuth subsalicylate.

What diagnostic tests are used for Helicobacter Peptic Ulcer Disease?

Biopsy, culture, and urea breath test.

What bacteria causes Yersinia Gastroenteritis?

Yersinia enterocolitica and Yersinia pseudotuberculosis.

What are the symptoms of Yersinia Gastroenteritis?

Diarrhea, fever, headache, abdominal pain, often misdiagnosed as appendicitis.

What is the treatment for Yersinia Gastroenteritis?

Antibiotics and oral rehydration.

What type of bacteria is Clostridium perfringens?

Gram-positive, endospore-forming, obligately anaerobic rod.

What diseases does Clostridium perfringens cause?

Gastroenteritis and gas gangrene.

What is Clostridium difficile associated with?

Causes life-threatening colitis, especially after extended antibiotic use.

What are the symptoms of Clostridium difficile-associated diarrhea?

Ulceration and perforation of the intestinal wall.

What is Bacillus cereus and what does it cause?

A large, gram-positive, endospore-forming bacterium that causes gastroenteritis.

What are the symptoms of Mumps?

Swelling of the parotid glands, orchitis, meningitis, ovary inflammation, and pancreatitis.

What vaccine prevents Mumps?

MMR vaccine.

What causes Hepatitis A and how is it transmitted?

Caused by a single-stranded RNA virus transmitted via oral or fecal route.

What are the symptoms of Hepatitis A?

Anorexia, malaise, nausea, diarrhea, fever, chills, jaundice, dark urine.

What is the treatment for Hepatitis A?

Detected via IgM and anti-HAV; treated with immune globulin.

What is unique about Hepatitis B?

It is a double-stranded DNA virus with an envelope, transmitted via blood and bodily fluids.

What are the potential outcomes of Hepatitis B infection?

Can lead to acute symptoms similar to Hepatitis A, fulminant hepatitis, chronic liver cirrhosis, or liver cancer.

What is the treatment for Hepatitis B?

Treated with interferons and nucleoside analogs.

What is the significance of Hepatitis C?

It is a single-stranded RNA virus that often leads to chronic infection and has no vaccine.

What are the symptoms of Giardiasis?

Diarrhea, malaise, weight loss, flatulence, cramps.

What is the treatment for Giardiasis?

Treated with metronidazole and nitazoxanide.

What causes Cryptosporidiosis?

Caused by Cryptosporidium parvum.

What happens when oocysts are ingested by humans in relation to sporozoites?

Ingested oocysts release sporozoites that invade the intestinal epithelium.

How is the cholera-like diarrhea transmitted and what is its resistance?

It is transmitted through drinking water and is resistant to chlorine.

What diagnostic tests are used for the disease caused by sporozoites?

Diagnosed with FA test or immunoassay test.

What is the treatment for the disease caused by sporozoites?

Treated with nitazoxanide.

Why is the disease caused by sporozoites life-threatening?

It is life-threatening to AIDS patients.

What is the causative agent of Cyclospora?

Cyclospora cayetanesis.

What are the symptoms of Cyclospora infection?

Watery diarrhea after oocysts are ingested from drinking water contaminated with feces.

What is the treatment for Cyclospora infection?

Treated with trimethoprim and sulfamethoxazole.

What organism causes amebic dysentery (Amebiasis)?

Entamoeba histolytica.

How does Entamoeba histolytica survive stomach acid?

It produces cysts that survive stomach acid.

What are the symptoms of amebic dysentery?

Feces with blood and mucus, and can perforate the intestinal wall leading to abscesses and liver invasion.

What diagnostic tests are used for amebic dysentery?

Serological EIA tests.

What is the treatment for amebic dysentery?

Treated with metronidazole.

What are the three types of tapeworms mentioned?

Beef (Taenia saginata), Pork (Taenia solium), Fish (Diphyllobothrium latum).

What is Taeniasis?

An adult tapeworm infects the intestine.

What is Cysticercosis?

Infection with the larval stage by ingesting eggs.

What is Neurocysticercosis?

Larvae develop in the central nervous system.

What is the life cycle of tapeworms?

Eggs are excreted in feces, ingested by animals, hatch into larval cysticercus in muscle, and humans ingest undercooked meat with cysticerci.

How is tapeworm infection diagnosed?

By finding eggs or segments in feces.

What is the treatment for tapeworm infections?

Praziquantel and niclosamide.

What disease is caused by Echinococcus granulosus?

Hydatid disease.

What happens when Echinococcus granulosus eggs are ingested?

They migrate to the liver, lungs, or brain and can form hydatid cysts.

What are the symptoms of hydatid cysts?

They can hold up to 15 liters of fluid and may rupture, causing anaphylactic shock.

What is the treatment for hydatid disease?

Surgical removal or albendazole.

What is the causative agent of pinworms?

Enterobius vermicularis.

What are the symptoms of pinworm infection?

Local itching around the anus.

What is the treatment for pinworm infection?

Pyrantel pamoate and mebendazole.

What are the two types of hookworms mentioned?

Nector americanus and Ancylostoma duodenale.

What are the symptoms of hookworm infection?

Anemia, lethargic behavior, and food cravings (pica).

How are hookworms transmitted?

Carried from human feces in soil that contact bare skin.

What is the treatment for hookworm infection?

Mebendazole.

What is Ascariasis and its causative agent?

A nematode infection caused by Ascaris lumbricoides.

What is the prevalence of Ascariasis worldwide?

30% of the worldwide population is infected.

What is the life cycle of Ascaris lumbricoides?

Eggs are shed in feces, ingested, hatch into larvae, migrate to the bloodstream and lungs, then develop into adult worms in the intestines.

What is the treatment for Ascariasis?

Mebendazole or albendazole.

What is the whipworm and its causative agent?

Trichuris trichiura.

What are the symptoms of whipworm infection?

Causes anemia, malnutrition, and retarded growth.

What is the treatment for whipworm infection?

Mebendazole or albendazole.

What is Trichinellosis and its causative agent?

An infection caused by Trichinella spiralis.

How is Trichinellosis contracted?

By ingesting encysted larvae from undercooked pork and other meats.

What are the symptoms of Trichinellosis?

Fever, eye swelling, and gastrointestinal upset.

What is the treatment for Trichinellosis?

Albendazole or mebendazole.