bi 114 - lecture 21

Gastric mucosa

Mucosa that lines the stomach.

Secretes mucus, bicarbonate, gastric acid, histamine, pepsin, gastin, and more.

Normal oral cavity flora include…

…streptococcus, lactobaccilus, Peptostreptococcus, Veillonella, diptheroid.

Dental plaque begins as what?

Biofilm. The bacteria undergoes metabolism and produces acids that can dissolve tooth enamel.

Dental caries lead to what?

Tooth decay

Gingivitis

Inflammation of the gums

Periodontal disease

• Advanced inflammation causing the gums to bleed and pull away from the teeth.

• Caused mostly by P. GINGIVALIS

what causes thrush?

• this disease is also called oral candidiasis, so it's a FUNGAL disease.

• caused by the yeast strain Candida albicans.

What does thrush look like?

White coating resembling cottage cheese on the tongue and inner cheeks

In whom is thrush usually seen?

Newborns and patients taking antibiotics

How is thrush treated?

Anti-fungal medications, mouthwash, h2o2 as oral rinse

How many categories of diarrhea are there?

4

Osmotic diarrhea

INTESTINAL osmolarity > internal osmolarity, causing water to leave the cells.

Pathogens that prevent nutrient absorption can cause…

…osmotic diarrhea.

Secretory diarrhea

Increased ion secretion causes electrolytes to leave, leading to imbalance.

Pathogens that cause ion secretion cause…

…secretory diarrhea.

Inflammatory diarrhea

Inflammatory cytokines damage mucosal cells and prevent absorption of nutrients and water.

What bacteria are common causes of inflammatory diarrhea?

Shigella and salmonella are common causes of inflammatory diarrhea.

Motility related diarrhea

Food moves too quickly through the intestinal tract and nutrients are not absorbed.

What often causes motility related diarrhea?

Enterotoxins and rotavirus

Gastritis

Inflammation of the stomach lining

Gastroenteritis

Inflammation along the gastrointestinal tract

Enteritis

Inflammation mainly of the small intestine

Enterocolitis

Inflammation of the colon and small intestine

Colitis

Inflammation of the colon

What treats gastritis, gastroenteritis, enteritis, enterocolitis, and colitis?

NSAID (nonsteroidal anti-inflammatory drug) like ibuprofen

Hepatitis

Inflammation of the liver caused mostly by the overconsumption of alcohol.

Rotavirus disease

Non-enveloped, segmented dsRNA.

Causes severe, watery diarrhea and vomiting in infants and young children.

How is rotavirus transmitted?

Rotavirus is transmitted via the fecal-oral route

How is rotavirus treated?

• Oral rehydration solutions or IV fluid replacement.

• Oral Vaccine

what is Norovirus?

• genome: Non-enveloped, positive-sense, ssRNA.

• causes a sudden onset of symptoms: headache, malaise, and diarrhea.

• outbreaks common on cruise ships.

How is norovirus transmitted?

Norovirus is transmitted via the fecal oral route.

How is norovirus treated?

• There's no known treatment (NOrovirus = NO Vaccine).

• It's recommended to drink plenty of fluids, and do OTC oral rehydration therapy to avoid dehydration.

Hepatitis sometimes results in acute illness followed by chronic disease…

…cirrhosis, leading to liver cancer

Hepatitis A

Infectious hepatitis

Hepatitis B

Serum hepatitis

Mumps is caused by what?

Paramyxovirus, a single stranded RNA virus

What is mumps?

• inflammation of the parotid gland.

• highly infectious/self-limiting infection.

• Causes massive swelling of parotid glands and can cause harm if swelling of testes occurs.

Peptic ulcers are caused by

The gram negative bacteria: Helicobacter pylori

What does Helicobacter pylori produce?

Urease to make ammonia that can neutralize stomach acids.

How are peptic ulcers treated?

Proton pump inhibitors (PPI) therapy with antibiotics. BISMUTH.

Symptoms of peptic ulcers include what?

Dyspepsia, upper abdominal pain, bloating, belching, nausea

E. Coli causes what

Food poisoning, septic shock, meningitis, UTIs, diarrhea

Pathogenesis of E. coli

Colonization of a mucosal site, evasion of host defense, and multiplication and host cell damage

What strain of E Coli causes foodborne illnesses?

O157:H7

Different strains of E. coli produce different…

…toxins

Entertoxigenic E. coli (ETEC)

Produces Enterotoxins and colonization factors, and causes secretory, watery diarrhea.

Are there any animal reservoirs of Enterotoxigenic E. coli (ETEC)?

No, there are no animal reservoirs.

Enteroinvasive E. coli (EIEC)

pathogenic bacteria whose infection causes a syndrome that is identical to shigellosis, with profuse diarrhea and high fever

Enterohemorrhagic E. coli (EHEC)

• produces Shiga toxin

• causes bloody diarrhea.

• In servere cases, can lead to hemolytic uremia syndrome (HUS) and thrombocytopenia purpura.

Shigellosis is caused by what?

Shigella bacteria

How many species of shigella are there?

There are 4 species.

Shigella sonnei

Most common species of shigella in the U.S.

Shigella dysenteriae

Rare in the U.S.

Does shigella have an animal reservoir? How is it transmitted?

• shigella has no animal reservoir.

• transmitted between humans through fecal-oral route via food/water.

• also transmitted through gay sex.

Typhoid fever

Caused by Salmonella typhi.

Associated with food preparation.

Intermittent fever and diarrhea for 1-3 weeks.

NO ANIMAL RESERVOIR

Paratyphoid fever

• bacterial infection caused by Salmonella paratyphi.

• Non-zoonotic.

• Enteric fever.

Enterocolitis is caused by what?

• Zoonotic nontyphoidal Salmonella serotypes.

• ASSOCIATED W ANIMAL CONTACT.

• Short-term illness lasts 6-48 hrs.

Yersiniosis

• Bacterial GI disease.

• caused by Y. Enterocolitica & Y. Pseudotuberculosis.

• transmitted through food/milk/fecal-oral route.

• Associated w/ animals

• Causes general enteritis lasting up to 2 weeks.

Y. pseudotuberculosis and Y. enterocolitica

Cold tolerant, gram negative bacteria

Campylobacter jejuni

• Gram-negative, corkscrew-shaped, bipolar flagella.

• Causes Campylobacter enterocolitis.

What is the number one cause of diarrhea worldwide?

the bacteria campylobacter jejuni

Rarely, Campylobacter jejuni causes an autoimmune disease called…

…guillain barré syndrome.

Cholera is caused by what?

Vibrio cholerae, a gram negative, curved-rod shaped bacteria with a single flagellum. It's transmitted via fecal oral route.

"Rice water stools" are characteristic of what bacteria?

Vibrio cholera (gram negative, faculative anaerobe, rod)

Does vibrio cholera cause fever or bloody stools?

No, it's noninvasive so it doesn't cause fever or blood stools

Is there a vaccine routinely administered for cholera?

No, it's not given in the U.S. at least. But. The Dukoral vaccine is available for travelers.

Listeriosis is caused by what?

Listeria monocytogenes, a gram-positive non spore forming coccobacili bacteria

listeriosis

• bacteria Listeria monocytogenes.

• a foodborne illness.

• can lead to serious complications, especially in vulnerable populations like pregnant women, the elderly, and those with weakened immune systems (and severe septicemia).

Listeria monocytogenes lives inside…

…macrophages to avoid detection by the immune system

C. difficile

• Gram-positive, endospore-forming bacteria.

• causes antibiotic-associated diarrhea and colitis (pseudomembranous colitis).

C difficle prodcues what toxins?

Toxins A & B

What are the drugs of choice for antibiotic associated colitis?

Metronidazole or vancomycin (fecal bacterial treatment is utilized if these antibiotics don't work)

True or false: antibiotic associated colitis is a nosocomial infection.

True, it's a nosocomial infection that occurs due to improper cleaning and disinfection coupled with vulnerable populations

Staphyloccocus aureus

• Gram-positive cocci that cause food poisoning and GI infections.

• Characterized by a sudden start of nausea, vomiting, and stomach cramps.

• Symptoms are seen 2-6 hours upon ingestion

True or false: staphylococcal Enterotoxin (SE-B) is heat stable.

True, the staphylococcal Enterotoxin (SE-B) is heat stable.

Giardia lamblia

Flagellated protozoa that causes diarrhea worldwide (associated with freshwater sources).

Cyst -> trophozoite.

Amebic dysentery

• protozoan disease.

• Invasive diarrhea caused by entamoeba histolytica.

• Trophozoites remain in the intestine and organisms can spread to the liver, lungs, or brain.

Cryptosporidiosis

Protozoan disease.

Caused by C. hominis and C. paravum.

Contaminated drinking water -> watery diarrhea that lasts 1-2 weeks (self limiting).

Fecal oral route of transmission.

Cyclosporiasis

• Protozoan disease.

• Caused by Cyclospora cayetanensis.

• transmitted through fresh produce/water.

No, the oocysts of cyclosporiasis CANNOT be passed directly by the fecal oral route.

Can the oocysts of cyclosporiasis (the reproductive structures of parasitic protozoa) be passed directly by the fecal oral route?

What helminths cause intestinal distress?

Whip worm, pin worm, and tapeworm

What helminths cause intestinal distress WITH larval migration symptoms?

Hookworms (Necator americanus and Ancylostoma duodenale).

What helminth causes disease with MUSCLE involvement?

Trichinosis

What is the cause of Trichinosis?

Trichinella spiralis (parasite)

Once larvae are encysted in the muscle, can helminth disease with muscle involvement be cured?

Nope! Encysted larvae = no cure

How are helminths (muscle involved) transmitted?

Ingestion of pork or other meat on which cysts of this parasite are embedded

What helminth disease includes liver involvement?

Schistosomiasis

Schistosomiasis (Bilhazaria)

• Helminth infection acquired from contact with water containing infected snails.

• Causes itchiness, fever chills, diarrhea, chihuahuas.

• Parasitic.

The helminth that causes schistosomiasis is coated in what?

Host blood proteins, which helps it evade the immune system

Schistosoma, Opisthorchis, and Fasciola

What flukes/helminths cause Schistosomiasis?

when does osmotic diarrhea occur?

occurs when the body is unable to absorb enough water and electrolytes, often due to the presence of poorly absorbed solutes in the intestinal lumen

when does secretory diarrhea occur?

occurs when the body actively secretes too much fluid and electrolytes into the intestines, often in response to infections, toxins, or other conditions.