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81 Cards in this Set
- Front
- Back
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What are the two types of diarrhea that can occur?
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Inflammatory
Secretory |
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What causes inflammatory diarrhea?
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Invasion by microbe into intestinal mucosa
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Is there associated epithelium damage with inflammatory diarrhea?
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Yes
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What is another name for inflammatory diarrhea?
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Dysentery
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Symptoms of inflammatory diarrhea include what?
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Blood/mucous in stool
Fever Leukocytes in stool smear Abdominal pain |
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Which microbe is the most common cause of gastroenteritis?
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Viruses
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How does gastroenteritis present?
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Vommitting + diarrhea
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Secretory diarrhea is mediated by what?
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Toxin from bacterium
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What two methods can you get secretory diarrhea?
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Ingestion of preformed toxin or ingestion of the bacterium with subsequent production of the toxin.
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What are the important strains involved with gastroenteritis?
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S. aureus
B. cereus C. perfringens Listeria monocytogenes |
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What consideration do we have with listeria?
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Transfer to the fetus and subsequent CNS meningitis.
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What type of diarrhea is caused by S. aureus? How does it do it?
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Pre-formed enterotoxin
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What 3 important properties about the enterotoxin made by S. aureus make it especially damaging?
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Extremely stable
Superantigen (activation of T-cell without needing macrophage) Action on neural receptors of GI tract |
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How quickly does enterotoxin act and what symptom is indicative that the person has been poisoned with the toxin?
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Rapid onset with acute vommiting
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How does the enterotoxin stimulate vommitting?
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Acts on nerve endings of the stomach
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What is the treatment of S. aureus enterotoxin poisoning?
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It is self-limiting so rehydration and electrolytes
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Unlike B. anthracis, B. cereus shows what characteristics?
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Motility and B-hemolytic
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The emetic form of B. cereus produces what type of toxin? What is the time frame of onset?
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Pre-formed heat stable enterotoxin that causes illness in 1-5 hours
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The diarrheal form of B. cereus requires what incubation time is caused by molecule?
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10-24 hours depending on bacterial load and it is a heat sensitive enterotoxin.
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B. cereus requires medical treatment to cure? (T or F)
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False, it is self limiting in either case.
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What are the identifying features of clostridium perfringens?
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Gram-positive, anaerobic
Encapsulated Non-motile Double zone of hemolysis Part of normal flora |
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What is the big difference between C. perfringens and B. cereus?
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C. perfringens is anaerobic and is only aero-tolerant rather than being a aerob.
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What two exotoxins cause cell damage to the host?
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Alpha and theta toxin
(Alpha rips the plasma membrane while theta forms a pore that allows cytoplasm out) |
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Is the toxin of C. perfringens an emetic toxin or diarrheal?
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Diarrheal and heat labile
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What is the mechanism of action of the enterotoxin of C. perfringens?
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Disruption of ion transport
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B. cereus has two ways of making a patient ill? What are they?
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Emetic toxin and diarrheal toxin
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Following what period of time does the patient become very sick from C. perfringens?
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8-18 hours
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Why do people get sick from C. perfringens?
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They cook food that has endospores which heating stimulates the grow of the microbe that then makes a heat labile toxin.
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What is antibiotic diarrheal disease?
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Antimicrobials remove the normal flow of the gut that holds the C. difficile in check
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What is the source of C. difficile?
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Environmental colonization
(increases in people that work in hospitals) |
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What two toxins are made by difficile?
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Toxin A- enterotoxin that increases fluid secretion/chemotactic for neutrophils
Toxin B- cytotoxin that damages enterocytes |
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Toxin B by C. difficile causes secretory diarrhea or inflammatory?
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Inflammatory
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The toxin B causes damage to the intestine?
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True.
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What is the source of the pseudomembrane formation by C. deficile?
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Fibrin and mucin showing up with the cell death to make a film to try and protect the body.
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What two diseases are caused by C. difficile?
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Antibiotic associated diarrheas (associated with taking cephalosporin, ampicillin, clindamycin, etc)
Psuedomembranous colitis |
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Pseudomembranous colitis has what symptoms?
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Inflammatory fibrin based plaques and presence of leukocytes/necrotic colonic cells.
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How do you diagnosis C. dif?
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Elisa for both A and B toxin is necessary
Growth under anaerobic conditions |
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Treatment for C. dif?
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Fluid replacement and metradiazole or vancomycin
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How does one get a B. anthracis infection?
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eating a contaminated herbivore product
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What is the incubation time for B. anthracis?
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1-6 days
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There are two types of vectors. What are they?
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Mechanical
Biological |
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What is the difference between a mechanical and biological vector?
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Mechanical has no life cycle inside whereas biological has some stages of the parasitic life cycle contained within.
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What is the difference between a definitive host and an intermediate host?
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Intermediate contains the larval form while the definitive has the adult parasite contained within
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Protozoans are eukaryotic?
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Yes
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Protozoans have membrane bound nuclei?
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Yep.
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General size of protozoans?
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2-100 um
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What structure is used to make energy in a protozoan?
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Mitochondria
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What form does the protozoan take to infect a human?
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The cyst form
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Where are infections most common?
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The tropics and subtropical regions
(Typically poor sanitation and abundant vectors) |
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Gotta ask your self, does the cyst form infect immediately?
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If yes, P2P is possible
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Giardia is what phyla?
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Sarcomastigophora
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Giardia is a _______________?
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Flagellate
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Giardia exists in what form in the body?
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Trophozoite
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What form does giardia take in the colon before exiting the body?
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Cyst
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What is indicative in the fecal smear of giardia?
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4 nuclei
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Transmission occurs how?
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Fecal contamination by direct handling or water or anal sex
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Clinical features include what?
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Abdominal pain, vomiting, foul smelling secretory diarrhea.
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What is the cause of the foul smelling diarrhea?
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Fat malabsorption
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When will you see giardia trophozoites in the stool?
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During high velocity diarrhea
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Where do you see entamoeba histolytica?
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Southern states in areas of poor sanitation
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Entamoeba causes inflammatory diarrhea. What is the steps by which the giardia attacks the body?
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Invasion into the large intestine where trophozoites reside and produce cysts.
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What is unique about the virulence factors of entamoeba?
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Protease production
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How does one obtain entamoeba?
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Ingesting food or water contamination by cysts
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In 15% of cases, there is symptomatic invasion? What two variable degrees of invasion are there?
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Invasive intestinal amoebiasis that produces flask shaped lesions and dysentery by the protease production.
Extra intestinal liver and lung abcesses if it moves into the systemic circulation |
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Cryptosporidium parvum is what phyla?
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Apicomplexa
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Cryptosporidum is a sporozoan or a ciliophora?
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Sporozoan
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What is unique about cryptosporidum and sanitation?
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Not killed by routine chlorination in the cyst form.
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Oocyysts are ______________________ infective?
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Immediately
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How do they differ in size relative to cyclospora?
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Smaller
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The sporozoites from oocysts invade what cell type?
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Enterocytes
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More commonly, cryptosporidiosis causes what type of diarrheal disease?
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Secretory
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In what population is cryptosporidiosis life threatening?
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Immunocompromised individuals
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Cyclospora differs from other protozoans in life cycle by what requirement?
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Development before infection
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Cyclosporidasis is related to what type of diarrhea?
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Secretory
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Cyclosporidasis is very dangerous or minimally dangerous?
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It can be somewhat severe if the diarrhea is severe and prolonged
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Microsporidia is noted by what size difference?
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It is the smallest eukaryote
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Is microsporidia an intracellular parasite?
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Yes.
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What is unique about microsporidia vs all the other protozoans?
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They lack mitochondria.
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Their classification has recently changed to what?
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Fungi
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How is microsporidia acquired?
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By inhalation of spores.
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What population is microsporidia most commonly found in?
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AIDS patients. Seen as corneal infections and disseminated disease
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