microbio ch. 24 - digestive system infections

Be familiar with the components of the upper digestive system.

oral cavity, salivary glands, esophagus, stomach

Be familiar with the components of the lower digestive system.

pancreas, liver, gallbladder, small intestine, large intestine

What disease/condition is associated with Helicobacter pylori infections?

peptic ulcers

How is Helicobacter pylori transmitted?

fecal-oral or oral-oral transmission.

What body site is affected with Helicobacter pylori?

mucus and epithelium cells of the stomach

How does the urease enzyme contribute to the ability of the bacterium to survive the acidic conditions of the stomach?

converts urea to ammonia and carbon dioxide to neutralize the stomach acid

Describe how H. pylori infections can lead to ulcer formation?

H. pylori cells survive stomach acidity by producing ammonia-generating urease and by burrowing into the stomach's mucus coating. Bacterial products and inflammation damage the mucosal layer, which can lead to peptic ulcers.

What infectious agent is associated with mumps?

Mmumps virus, a single-stranded RNA virus

How is the agent transmitted?

Humans the only reservoir. Saliva of symptomatic and asymptomatically infected people is infectious.

What symptoms are associated with mumps?

fever, headache, loss of appetite, followed by painful swelling of parotid gland(s). complications include painful enlargement of the testicles in men, pelvic pain in females, and neurological involvement.

How is the disease treated and prevented?

no antiviral therapy is available; vaccination (MMR or MMRV).

What are the three main groups of bacteria associated with diseases of the lower alimentary system? 

vibrio species (vibrio cholera), campylobacter (poultry products), enterobacteriaceae

Which bacteria are classified as Enterobacteriaceae?

salmonella, shigella, escherichia (different strains of e coli)

How are Enterobacteriaceae transmitted?

fecal-oral route and causes some form of diarrhea disease

Be familiar with the main pathogenic mechanisms used by bacteria that cause disease in the lower alimentary system.

attachment: alters the epithelium after attaches to host

toxin production: increase secretion of water, electrolytes, and causes cell death

cell invasion: replicates in host cells

alterations in host cells/loss of microvilli

What disease is associated with Clostridium difficile?

Clostridioides difficile, a Gram-positive, rod-shaped, endospore-forming, toxin-producing anaerobe

How does antibiotic treatment promote Clostridium difficile infection?

disrupts the normal flora of the body and allows the c. diff to expand

Describe the pathogenesis of Clostridium difficile infection.

Toxins disrupt host cell actin and cell signaling, causing lethal effects to the intestinal epithelium and inducing inflammation.

What is the epidemiology of Clostridium difficile infection?

Primarily occurs in patients on antibiotic therapy.

How is Clostridium difficile infection prevented/treated?

for initial CDI, stop any predisposing antibiotics if possible; treat with an antibiotic that targets C. difficile. If CDI recurs, treat using an antibiotic course different from that used previously; a monoclonal antibody may be given as well. If CDI recurs again, a new microbiota-based biotherapy may be used following treatment to prevent an additional recurrence. Fecal microbiota transplants are used experimentally; avoid inappropriate antibiotic use and prevent transmission by proper handwashing, wearing gloves, keeping surfaces disinfected, and isolating CDI patients.

Viral diseases of the lower digestive system

rotaviral: triple-walled capsule with double-stranded segmented

norovirus: single-stranded RNA genome

What populations are affected by each virus (rotaviral/norovirus)?

younger kids; all ages

What are the symptoms associated with rotaviral/norovirus?

vomiting, abdominal cramps, diarrhea

How is each condition rotaviral treated/prevented?

none; RVI or RVS vaccine, handwashing, disinfectant use, etc.

How is each condition norovirus treated/prevented?

none; no vaccine - handwashing, disinfectant use, etc.

What are the symptoms of hep. A?

fever, fatigue, nausea, vomiting, clay-colored feces, dark urine, and jaundice. no chronic stage

What are the symptoms of hep. B?

acute stage: similar to hep A but more severe; chronic stage: can lead to cirrhosis and cancer

What are the symptoms hep. C?

acute stage: usually few or no symptoms; chronic stage: can lead to cirrhosis and cancer

What are the symptoms hep. D?

worsening hep. B symptoms (infection occurs only in patients with HBV)

What are the symptoms of hep. E?

similar to hep. A, except sever in pregnant women. no chronic stage

How is the virus hep. A transmitted?

Fecal-oral transmission

How is the virus hep. B transmitted?

Transmitted in body fluids (blood, semen); chronic carriers are an important infection source; infection in infants and children most likely to become chronic, but adults also at risk.

How is the virus hep. C transmitted?

Transmitted in blood, possible semen; chronic carriers are an important infection source

How is the virus hep. D transmitted?

Transmitted in blood, semen.

How is the virus hep. E transmitted?

Fecal-oral transmission

What are the treatments/prevention for hep A?

no specific treatment available; vaccine, post-exposure prophylaxis, handwashing

What are the treatments/prevention for hep B?

no curative treatment available, but chronic infections improve with an antiviral; vaccine, post-exposure prophylaxis, avoid exposure to contaminated body fluids

What are the treatments/prevention for hep C?

high effective treatments are newly available; no vaccine, avoid exposure to contaminated blood

What are the treatments/prevention for hep D?

no specific treatment available; protect against hep B infection

What are the treatments/prevention for hep E?

no specific treatment available; no FDA-approved vaccine (only in China)