3. Gastrointestinal Infections Flashcards
(30 cards)
The comparison of the morbidity and mortality of gastrointestinal infection with other enteric diseases.
Diarrhea disease: ____ estimated morbidity (thousands/year); ____ estimated mortality (thousands/year)
Amoebiasis: ____ estimated morbidity (thousands/year); ____ estimated mortality (thousands/year)
Schistosomiasis: ____ estimated morbidity (thousands/year); ____ estimated mortality (thousands/year)
Colorectal cancer: ____ estimated mortality (thousands/year)
300,000-500,000
5,000-10,000
1,500
7-10
20,000
600-1,000
500
Main Pathogenic Enterobacteriaceae and Vibrionaceae
E.coli: ____, dysentery, ____ infection
Shigella sp.: ____
Salmonella sp: ____, enteritis, ____ fever
V. cholerae: ____
* Majority of GI infection - \_\_\_\_ * E.coli - most strains are \_\_\_\_ - some strains can cause a variety of diseases
diarrhea urinary tract dysentery diarrhea enteric diarrhea
gram-negative rod
avirulent
Virotypes of Pathogenic E. coli
MEMORIZE/ADD THIS TABLE!
• Some of them cause disease (different virotype, bc they present a different virulence for different diseases) • Difficult to tell commensal and pathogenic bacteria apart - how can we tell them apart? ○ Most common way: use \_\_\_\_ differences - \_\_\_\_ assays to do quick test whether it's normal or virulent
antigenic
immunologic
• Two antigen are used for identificaition of ____ bacteria
• O antiegn - ____ antigen - most external component of oligopolysacc. - very ____ from organism to organism and species to species
○ E.coli - ____ different types of O
• H antigen - ____ protein
• Based on O and H, you can tell the diff E.coli apart
surface
variable
different
flagella
- For second from bottom - ____
* Using antigenic differences can divide them into different strains
O157:H7
• In US, shigella outbreaks happen in ____ - need to ingest large amount of bacteria to manifest disease; but for shigella, you only need to ingest a few ____ (10-20 cells)
• In day care, changing ____ and ____ in same room > a lot of outbreaks in day care centers
• Shigella happens in ____ adult - has something to do with sexual behavior
○ STD
day care center cells diaper eat homosexual
• Salmonella - similar to ____ (cannot tell diff under microscope)
○ ____ homology - 90%
○ ____ pure pathogen (unlike E.coli)
• Normal ____ bacteria in many animals (domestic animals, chicken, cow) > ends up in our kitchen
○ Cross-____ (using same bowls)
• Used as indicator for ____ of food and water supply
• V. Cholerae - develops \_\_\_\_ ○ Earthquake in Haiti, followed by cholera outbreaks > within months millions dead
E. coli DNA 100% flora contamination safety
cholera
Gram stain of vibrio cholerae
• Cholerae bacteria > \_\_\_\_ > \_\_\_\_ rod
gram-negative
curved
Vibrio cholerae
* Curved rod, \_\_\_\_, with a single \_\_\_\_ * Polar?
gram-negative
flagella
Two types of intestinal infection
____ diarrhea
____ diarrhea and ____
• Bacteria are different, but the mechanisms are different • Watery diarrhea ○ Bacteria colonizes the \_\_\_\_ > produce toxin > poisons and makes you have diarrhea § Enterhogenic, \_\_\_\_ ○ No \_\_\_\_ invasion • Bloody diarrhea and dysentery (and mucus) ○ Bacteria colonize surface, and invade the cell > destruction of the tissue > \_\_\_\_ § \_\_\_\_, and some E.coli (hemorhaggic)
watery
bloody
dysentery
small intestine
cholerae
cell
inflammation
shigella
Symptoms of Cholera
- ____
- nausea/vomiting
- ____
- electrolyte imbalance
- ____
- seizures
- ____
- shock• Paradigm for watery diarrhea
• Water/food contaminated with human ____ > after few hours symptoms start with diarrhea (lose gallons of fluid) > dehydration and ____ imbalance
○ Muscle cramps, seizures, coma and shock
• Without any treatment > only takes ____ hours to develop coma/shock
• Death in ____ hours
• Mortality rate - 50/60%
diarrhea
dehydration
muscle cramps
coma
feces
electrolyte
4-12
18
• Colonize small intestine following ingestion of dirty water/food
○ Not easy to do > bacterial surface and surface of intestine are interacting > mutually ____ each other
○ Another problem > SI is being washed by ____ > if bacteria don’t have ____, then the bacteria are flushed away
§ Have to promote themselves
reject
liquids
adherence
• Most common way > have an ____ (factor how bacteria adhere)
• Enteroggo bacteria > ____ > used to adhere to mucosal surface
○ Stat from bacterial surface and interact with ____ on cell membrane
§ Usually a ____ (glycoprotein or glycolipid)
○ Use interaction bt bacterial and human component
• Makes bacteria stay on surface and ____ intestine
adhesin pilli receptor carbohydrate colonize
- Structure of pili
- Two parts: ____ like structure (composed of array of single ____ - pilli), and then the tip (made of diff protein > interact with receptor on human surface; determines what ____ the bacteria can interact with)
fiber
protein
tissue/organ
Virulence factors of v. cholerae and ETEC
- Adhesins
- V. cholerae ____ pilli
- Enterotoxigenic E. coli (ETEC) ____ and ____
- Toxins
- cholera toxin - shares a high degree of homology with ____ of ETEC• Tcp > toxin [???] regulated pilli?
○ Expressed together
○ Interaction with human tissue
○ The receptor in our intestine is unidentified
• ETEC > CFA-I and CFA-II > many types of pilli
○ More important for ____ diarrhea, any bacteria carrying these pilli• After colonization, the second stage > bacteria produces ____ > cause diarrhea
• Cholera toxin
• ETEC - ____ (and heat stable)
○ Similar to ____ toxin, both structurally and functioanlly
- cholera toxin - shares a high degree of homology with ____ of ETEC• Tcp > toxin [???] regulated pilli?
Tcp
CFA-I
CFA-II
heat labile toxin (LT)
watery
toxins
heat labile toxin
cholera
heat-labile enterotoxin (LT) and cholera toxin (CT)
* Structure of cholera and E.coli toxin * Five identical \_\_\_\_ subunits, and then one \_\_\_\_ subunit * B subunit - one responsible for the \_\_\_\_ to the cell surface, and the entrance of the \_\_\_\_
B
A
binding
toxin
• ____ > on surface of cell
○ B triggers the ____, and then the ____ is released into the cells
• The B subunit is the ____, and the A subunit is the ____ (B subunit stays ____)
complex A/B internalization A carrier real toxin outside
- Cholera toxin A subunit
- ____ enzyme
- Can catalyze a chemical reaction and remove ____ ribose group into the target protein
- Target protein is ____ and sometimes enhanced activity
ADP ribosylation
ADP ribose
activated
In cholera
• A subunit into the cell, it targets ____ subunit of G protein
○ Activating a protein
○ As a consequence, alpha can travel on cell > ____ > responsible to convert ATP to ____ > secondary messenger
○ result of the toxin is this activation through the GPCR and get more cAMP in the cell
○ Activates ____ > phosphorylate membrane protein > prevents ____ and ____ from entering the cell
Lose a lot of ____
alpha adenylate cyclase cAMP PKA Cl- Na+ fluid
• Involve cell invasion and destruction of tissue - bloody/dysentery
○ ____, salmonella, and ____ E.Coli
• Frequent passage of stool - ____ times a day, involving blood and mucus
• This type of diarrhea involves ____
shigella
hemorrhagic
30
fever
• Uses shigella as paradigm to talk about this
• Key feature > bacteria invades the cell
• ____ identified from bacteria > responsible for the entrance and the multiplication and spread to neighbor cells
• ____ (invasion plasmid antigen)
○ Carried in ____, not in bacterial genome
• IpaD > responsible for itneraction with ____ surface, and ____ of the bacteria
○ Can interact with receptor > ____ > triggers the internalization of the bacteria > endolytic vesicle
§ Bacteria do not ____ here, bc this vesicle gets fused with lysosome and will get destroyed
• They have to get out > ____ > responsible for lysing membrane and releasing the abcteria from vesicle and cytoplasm
• They are safe in ____, have nutrition and can multiply > can spread to neighbor cell (____ - intercellular spread)
gene Ipa plasmid epithelial entrance integrin
multiply
IpaB
cytoplasm
IcsA
• How invasion/cell-to-cell spread occurs > can use laboratory technique
• Can reproduce what happens in intestine in a dish
○ Grow a layer of human epi cells, and as you add bacteria and grow (1 hr) > add ____ to get rid of bacteria that haven’t gotten into cell
○ Incubator overnight > 24 hours > the bacteria eats up cells > makes ____
○ Under microscope can see it more clearly
• Each ____ comes from original one bacteria, can lyse one cell and spread to other
antibiotic
holes
plaque
Salmonella infections
- ____
- typhoid fever
- ____• In addition to water/bloody diarrhea > salmonella infections (third category)
• Salmonella - true pathogen > develop a problem
• Most common, but less serious - enteritis
○ Do not need any ____, stops after a few days
• Some species cause more severe infection - typhoid fever
○ Different type of species - ____
enteritis
asymptomatic colonization
treatment
salmonella typhi
Typhoid Fever
- result of systemic infection by ____
- the incubation period can be one ____ to more than one month (ranging ____ days)
- ____ inreasing fever up to ____ oC
- headache, chills, abdominal pain and diarrhea or constipation
- the microorganisms penetrate mucosa, reach ____ lymph nodes, and multiply
- in 7-10 days, s. typhi enter ____ and spread to liver, gall bladder, spleen and bone marrow
- typhoid fever can be ____ if not treated
salmonella typhi week 3-60 gradually 39-41 mesenteric blood stream fatal
