Helicobacter, Vibrio, Campylobacter, and Anaerobes – Flashcards
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| What is the source of Helicobacter pylori? |
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| Humans |
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| Why does Hp grow in the gastric mucosa? |
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| because of production of urease |
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| What facilitates colonization of Hp in the gastric mucosa? |
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| Rise in pH due to ammonia |
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| What promotes ulcer development in the stomach mucosa with Hp infection? |
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| Host immune response tries to eliminate Hp, but can't because of Hp's unusual niche, the immune response continues and promotes ulcer development. |
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| What virulence factors does Hp have? |
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| Vacuolating cytotoxin VacA Pathogenicity-associated island encoding a cytotoxin-associated protein (CagA) |
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| What type of ulcers are caused by Hp 95% of the time? |
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| Duodenal ulcers |
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| What percent of Gastric ulcers are due to Hp, what are the remaining due to? |
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| 70% 30% due to NSAIDs |
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| What are Gastric adenocarcinomas and lymphomas mostly associated with? |
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| current or past Hp infections |
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| How is Hp cultured? |
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| on Campylobacter medium with antibiotic susceptibilities Microaerophilic G- curved rod |
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| What test can be done to detect CO2 generated from Hp urease? |
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| Urease Breath test |
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| Will anti-acid secretory agents cure Hp-caused ulcers? |
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| NO! |
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| What is the treatment regimen for Hp? |
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| Control acid and 2 antibiotics Omeprazole, metronidazole + Clarithromycin (or tetracyclin or amoxicillin) |
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| What are the characteristics of Vibrio cholerae? |
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Motile (single flagella) Gram(-) oxidase(+) curved Rod Found in Aquatic ecosystems |
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| What strain of Cholerae is currently in 98 countries? |
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| O139 |
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| What type of toxin does cholerae produce? |
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| Phage-encoded cholera toxin |
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| What 2 virulence factors does cholerea have? |
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| Phage-encoded cholera toxin Toxin-co-regulated pilus |
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| What is required for the colonization of the GI tract by cholera? |
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| Toxin-co-regulated pilus |
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| What are the sources/reservoirs of Cholera? |
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| Aquatic ecosystems, Brackish water During outbreaks- contaminated water Shell fish, other aquatic organisms Gulf Coast |
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| What organism cause "rice water stool"? |
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| Vibrio cholerae |
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| What are the sypmtoms of Cholera? |
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| Acute Watery Diarrhea -mucus flacks in diarrhea (rice water) Severe dehydration, acidosis |
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| What is responsible for the severe diarrhea of cholera? |
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| cholera toxin |
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| What type of toxin is the cholera toxin? |
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AB toxin: 5 B subunits, 1 A subunit with activity (Similar to ETEC) |
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| What causes the hypersecretion of fluids and electrolytes from the Cholera toxin? |
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| ADP-ribosylated GTP-binding protein activates adenyl cyclase leading to an increased cAMP level |
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| What is the treatment of Cholera? |
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| IV Fluid/electrolyte replacement Oral rehydration therapy Antibiotics |
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| What organism is the most comon foodborne disease in Japan and epidemics of it have occured on cruises? |
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| Vibrio parahaemolyticus |
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| What organism can cause potentially lethal septicemia and is associated with consuming raw oysters? |
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| Vibrio vulnificus |
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| What 2 organisms are the most common causes of bacterial foodborne illness in the US? |
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| Salmonella and Campylobacter |
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| What are the characteristics of Campylobacter? |
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| Motile Gram(-) Oxidase(+) spiral rods (pair look like sea gulls) Microaerophilic (grows best at 42C - body temp of Birds) |
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| What is the most common source of Campylobacter jejuni? |
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| poultry, raw milk (other: GI tract of wild and domesticated animals, pets, human-human transmission) |
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| What do ~40% of Guillain Barre syndrome patients have evidence of before onset of symptoms? |
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| Campy infections |
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| What are the symptoms of Campylobacter infections? |
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| Watery to grossly bloody invasive diarrhea Abdominal cramps, fever, vomiting |
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| What Campylobacter is more likely to cause severe septicemia and disseminated infections? |
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| C. fetus |
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| How do Anaerobes get energy? |
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| from fermentation of carbohydrates or breakdown of amino acids to amines |
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| What causes anaerobes to stink? |
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| Fermentation end products -Long chain alcohols, and fatty acids -breakdown of amino acids |
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| What organism is an abscess and tissue necrosis a Hallmark lesion for? |
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| Anaerobes |
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| What should you think of when you see Foul smelling breath, sputum, abscess? |
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| Anaerobes |
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| What contributes to Anaerobes sensitivity to oxygen? |
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| Lack of SOD |
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| What is the most common anaerobic infection? |
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| B. fragilis |
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| Where do B. fragilis and P. melaninogenica both produce and both associated with? |
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| Both produce antiphagocytic capsules Both associated with abscesses |
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| How are abcesses caused by B. fragilis and P. melaninogenica treated? |
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| Surgical drainage of abscess Agressive antibiotic treatment -Erythromycin -Clindamycin -metronidazole -3rd generation cephalosporins |
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| What is the only anaerobic endospore-forming bacteria? |
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| Clostridia |
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| What is responsible for Clostridia's pathogenesis? |
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| Exotoxins and secreted hydrolytic enzymes |
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| What type of wound infections are caused by Clostridium perfringens that Diabetics are susceptible to? |
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| Gas gangrene and anaerobic cellulitis |
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| How are wound infections from C. perfringens treated? |
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| Surgical Debridement - maggots to clear necrotic tissue Massive doses of Penicillin |
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| What organism infection results from wound caused by rusty nail or other contaminated foreign object? |
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| Colstridium tetani |
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| What is the virulence factor of Clostridium tetani? what does it cause? |
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| Tetanospasmin - Exotoxin and neurotoxin Causes Spastic contraction of muscles -Rigid paralysis -Trismus (lockjaw) -Risus sardonicus -Spasmodic contraction of back muscles -Respiratory failure |
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| How does the exotoxin Tetanospamin function? |
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| Functions as a Zn metalloprotease that cuts a V-snare -Vesicles cannot fuse -Prevents release of inhibitory neurotransmitter, blocking postsynaptic inhibition of spinal motor reflexes |
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| What type of vaccine is there for Tetanus? |
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| Toxoid vaccine - Formalin-inactivated tetanospasmin |
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| What organism is associated home-canned alkaline veggies? |
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| Clostridium botulinum |
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| What foods should not be consumed by infants because of the risk of Clostridium botulinum? |
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| Raw honey and corn syrup |
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| What are the toxins produced by C. botulinum? |
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| Toxin type A, B, E, F |
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| What is Classic foodborne botulism? |
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| Results of eating toxin-contaminated food Spores germinate and vegetative cells make botulism toxin under anaerobic conditions. |
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| What is Botulism Toxin? |
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| Heat-labile 7 antigenic types Metalloproteases that clip v- and/or t-SNARES Prevents fusion of vesicles at NMJ Inhibits release of Ach at NMJ |
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| What is the Botulism toxin encoded by? |
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| lysogenic phage, plasmids, chromosome |
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| What does intoxication from botulism toxin result in? |
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| faccid muscle paralysis |
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| What are the symptoms of Botulism? |
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| Classic Triad: 1. Acute, symmetric, descending flaccid paralysis with prominent bulbar palsies. Begins with cranial nerves. 2. Absence of fever 3. Clear sensorium |
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| What is the treatment for botulism? |
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| Mechanical ventilation Horse anti-botulism immunoglobulin (A, B, E serotypes) |
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| T/F Infant Botulism is an intoxication. |
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| FALSE Infant Botulism is an infection Results from consumption of spores, outgrowth of vegetative cells and production of toxin in the gut |
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| How is Clostridium difficile spread prevented? |
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| Use of soap and water rather than alcohol wipes for hand cleaning (spores are resistant to alcohol) |
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| What type of infection is C. difficile? |
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| supra-infection Causes Drug-induced diarrhea |
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| What are the 4 most common drugs that C. difficile is responsible for drug-associated diarrhea? |
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| imipenem ceftaxidine clindamycin moxifloxacin |
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| What are the symptoms of C. difficile infection? |
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| Watery diarrhea - caused by enterotoxin Fever Drug-induced diarrhea can be bloody |
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| What is a serious sequela of C. difficile diarrhea? |
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| Pseudomembranous colitis |
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| What toxins cause the symptoms of pseudomembranous colitis? |
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| Toxins A and B |
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| What do Toxins A and B of C. difficile do? |
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| Function as monoglycosylate Rho-family GTPases Intracellular signaling disrupted Stress fibers rearranged Results in leakage of fluids and severe inflammation |
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| How is C. difficile diagnosed? |
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| Detection of cytotoxic activity of Tox B from stools RADT detection of Tox A and B in stools |
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| How is C. Difficile Treated? |
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| Discontinue antibiotics that induce diarrhea Metronidazole 10+ days Fecal material enema (gross) |
