Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
117 Cards in this Set
- Front
- Back
|
what does mac inhibit?
|
gram-positive growth
|
|
|
what will turn pink on mac?
|
gram-negative lactose fermenters (eg e coli)
|
|
|
what will remain colorless on mac?
|
gram-negative non-lactose fermenters (eg shigella)
|
|
|
what does HE agar inhibit?
|
normal flora of the colon
|
|
|
what will produce a black colony on HE agar?
|
H2S producers (eg salmonella)
|
|
|
what will remain white on HE agar?
|
non-H2S producers (eg shigella)
|
|
|
what is significant about fecal leukocytes?
|
normally not found because normal pathogens will not cross the epithelium
|
|
|
what is the most useful and fastest way to analyze stool?
|
ELISA
|
|
|
how does GALT normally respond to pathogenic bacteria?
|
innate immunity and IgA
|
|
|
what is the source of ETEC?
|
contaminated water often due to traveling
|
|
|
where does ETEC attach?
|
small intestine via pili
|
|
|
what are the 2 toxins for ETEC?
|
ST and LT
|
|
|
what is ST?
|
small toxin, used by ETEC
prevents activation of guanylate cyclase |
|
|
what is LT?
|
heat labile toxin used by ETEC
a single A subunit surrounded by 5 B subunits; works at the ADP ribosylation of the G protein and activation of adenylate cyclase |
|
|
what type of diarrhea will ETEC cause?
|
watery
|
|
|
whop is ETEC most common in?
|
younger than 5 or older than 15
|
|
|
what will antibiotics for ETEC do?
|
usually only shorten the course by a day but can be given to travelers prophylactically
|
|
|
what is the source of EPEC?
|
usually adults are carriers and infants will get the disease so there can be large outbreaks in nurseries, day care centers, etc
|
|
|
where will EPEC attach?
|
small intestine
|
|
|
what type of pathogen is EPEC?
|
attachment and effacement - manipulates the epithelium and modifies the cytoskeleton to create a nest/pedestal
|
|
|
what is type III secretion mechanism? (4)
|
initial adherence
injection of Tir (type III secretion system) tight adherence (pedestal/nest formation) diarrhea |
|
|
what is another way EPEC may induce diarrea?
|
loss of villi and lack of absorption
|
|
|
what type of diarrhea will EPEC cause?
|
watery with lots of mucous
|
|
|
what type of e. coli is O157-H7?
|
EHEC
|
|
|
what is the source of EHEC?
|
insufficiently cooked or cleaned foods
|
|
|
what is usually the reservoir of EHEC?
|
adult cattle who are asymptomatic
|
|
|
where will EHEC attach?
|
large intestine
|
|
|
what type of pathogen is EHEC?
|
attachment and effacement - manipulates the epithelium and modifies the cytoskeleton to create a nest/pedestal
|
|
|
what type of toxin does EHEC have?
|
AB toxin in which the A toxin interacts with the cellular ribosome and cleaves a single adenine residue from the 28S rRNA (inhibits ribosomes)
|
|
|
what type of diarrhea will EHEC have?
|
watery that progresses to bloody
|
|
|
what is a complication of EHEC?
|
hemolytic uremic syndrome
|
|
|
what is hemolytic uremic syndrome?
|
toxins released into the bloodstream lyse erythrocytes, thrombocytes, and glomerular capillary endothelial cells leading to mortality and permanent disability
|
|
|
what are 3 things hemolytic uremic syndrome can cause?
|
chronic renal insufficiency
HTN neuro deficits |
|
|
what can you do to identify EHEC?
|
Mac using sorbitol instead of sorbitol
|
|
|
what is unique about EHEC?
|
it does not produce beta-glucuronidase
|
|
|
what is the source of EIEC?
|
contaminated food/water
|
|
|
what is the source of shigella?
|
contaminated food/water especially during travel
|
|
|
where will EIEC/shigella attach?
|
large intestine
|
|
|
how does EIEC/shigella cause damage? (3)
|
1) secretion of factors that induce uptake and transmission by M cells
2) entry into the inferior or lateral sides of intestinal epithelial cells 3) replication in epithelial cells then spread to neighboring cells by actin tells |
|
|
what type of diarrhea will shigella/EIEC cause?
|
early - watery
late - bloody |
|
|
how can you diagnose EIEC/shigella?
|
culture on HE and Mac
|
|
|
what is the source of EAEC?
|
unknown
|
|
|
where will EAEC attach?
|
large intestine epithelia
|
|
|
what is unique about the pathogenesis of EAEC?
|
aggregate in a stacked brick fashion
|
|
|
what type of diarrhea will EAEC have?
|
watery
may have a long course |
|
|
what are the toxins of EAEC? (3)
|
ShET1
EAST1 Pet |
|
|
what is ShET1?
|
a toxin of EAEC
contributes to diarrhea in a mechanism that does not involve cAMP, cGMP, or Ca++ |
|
|
what is EAST1?
|
a toxin of EAEC
prevents activation of guanylate cyclase |
|
|
what is Pet?
|
a toxin of EAEC
serine protease that alters the enterocyte cytoskeleton |
|
|
what will cause watery diarrhea? (4)
|
EPEC
ETEC most viral EAEC |
|
|
what will cause bloody diarrhea? (4)
|
EHEC
shigella/EIEC campylobacter possible EAEC |
|
|
what will cause mucoid diarrhea? (3)
|
EPEC
protozoans some worms |
|
|
what should be suspected with recent travel? (3)
|
ETEC
EAEC rotavirus |
|
|
what should be suspected with recent meal of beef?
|
EHEC
|
|
|
what should be suspected when symptoms last more than 6 days? (3)
|
EAEC
shigella/EIEC ETEC |
|
|
what type of bacteria is yersinia?
|
gram negative bacillus
|
|
|
what will yersinia produce?
|
urease
|
|
|
what does yersinia lack? (3)
|
oxidase
phenylalanine deaminase lysine carboxylase |
|
|
are yersinia motile?
|
at 25 degrees but not 37
|
|
|
what is yersinia sensitive to?
|
iron levels
|
|
|
how does yersinia respire?
|
facultative anaerobe
|
|
|
what is the source of yersinia?
|
handling of infected animals or carcases, specifically swine
very rarely through blood transfusion |
|
|
where is yersinia common?
|
northern europe
|
|
|
where will yersinia attach?
|
intestinal epithelial (temporarily)
|
|
|
how does yersinia cause damage?
|
invade M cells of the gut and start replicating
phagocytic cells ingest yersinia, spreading them to the reticuloendothelial system phagocytic cells are then killed by the bacteria, delaying the immune response |
|
|
what is yersinia eventually cleared by?
|
adaptive immune response
|
|
|
what type of diarrhea will yersinia cause?
|
mucoid and bloody
|
|
|
what is important about yersinia?
|
is can mimick appendicictis
|
|
|
what are 3 extra-GI things that yersinia can cause?
|
exudative pharyngitis
erythema nodosum reactive arthritis |
|
|
what is a common feature in yersinia toxins?
|
all inhibit the immune system in some fashion
|
|
|
what is the best way to diagnose yersinia?
|
stool culture
|
|
|
what will yersinia produce that limits treatment?
|
beta-lactamases
|
|
|
what type of bacteria is francicella?
|
gram-negative rod
|
|
|
how does francicella respire?
|
strict anaerobe
|
|
|
is francicella motile?
|
no
|
|
|
what does francicella require to grow?
|
special media that is enriched in cysteine
|
|
|
what subspecies of francicella are found in the US?
|
A and B
|
|
|
what is the source of francicella?
|
insect bites (spring and summer exposure to ticks, flies)
contact with infected animal no human-human infection |
|
|
how does francicella cause damage?
|
penetrates the skin, leaving an ulcer at the site of entry
transports to the regional lymph nodes where it grows lymph nodes drain spontaneously and spread the organism to other body areas |
|
|
how is francicella cleared?
|
cell-mediated immunity (or the host dies)
|
|
|
what type of symptoms will the ulceroglandular type of francicella have? (3) (from a bite, ingestion, or animal)
|
inflamed blister that fills with pus and opens to form an ulcer
swollen lymph nodes |
|
|
what type of symptoms will the glandular type of francicella have? (from a bite)
|
swollen lymph nodes
|
|
|
what type of symptoms will the oropharyngeal type of francicella have? (from ingestion)
|
severe sore throat
|
|
|
what type of symptoms will the typhoidal type of francicella have? (3)
|
chest pain
abd pain rash on forearm or hand |
|
|
what type of symptoms will the pulmonic type of francicella have?
|
dry cough
|
|
|
what type of symptoms will the oculograndular type of francicella have? (from a contaminated hand) (2)
|
swollen and painful eyelid
photosensitivity |
|
|
how do you treat francicella?
|
gentamycin or ciprofloxacin
|
|
|
is there a vaccine for francicella?
|
yes, available to high risk occupations
|
|
|
how do you diagnose francicella?
|
serology is negative for the first week but is the best means for dx
|
|
|
what type of bacteria is brucella?
|
small gram-negative rod
|
|
|
how do you diagnose brucella?
|
must culture for 8-10 days
|
|
|
what will brucella not ferment?
|
carbohydrates
|
|
|
what will brucella produce? (3)
|
catalase
oxidase urease |
|
|
is brucella motile?
|
no
|
|
|
can brucella form spores?
|
no
|
|
|
what is the source of brucella?
|
direct contact with infected animals
ingestion of unpasterurized dairy from infected animals |
|
|
how can brucella cause damage?
|
penetrates skin or mucous membranes
transports to the regional lymph nodes and grows in lymphoid cells spreads from lymph nodes to reticuloendothelial system bursts of bacteria |
|
|
how is brucella contained?
|
cell mediated immunity
|
|
|
what are the symptoms of brucella? (4)
|
back pain/generalized arthralgias
depression undulant fever splenomegaly/hepatic dysfunction |
|
|
what are the 3 categories of brucella?
|
febrile illness resembling typhoid but less severe
fever and acute monoarthritis (typically hip or knee) in young child long lasting fever, misery, and low back pain in an older man |
|
|
how do you treat brucella?
|
attenuated vaccine to control livestock
antibiotics which must be taken for the entire course given |
|
|
what type of bacteria is C. diff?
|
gram-positive bacillus
|
|
|
can C. diff form spores?
|
yes, readily
|
|
|
what type of diarrhea will C. diff cause?
|
watery
|
|
|
what are the 3 toxins of C. diff?
|
Toxin A
Toxin B binary toxin |
|
|
what is toxin A?
|
glucosyl transferase targeting small GTPases
toxin for C. diff if patient does not have a good response to toxin a, course will be severe |
|
|
what is toxin B?
|
similar to toxin A, not enterotoxigenic
toxin for C. diff |
|
|
what is binary toxin?
|
toxin for C. diff
ADP ribosylating enzyme targeting actin |
|
|
how do you treat C. diff?
|
high level antibiotics
|
|
|
what type of bacteria is bacteroides?
|
gram-negative rod
|
|
|
what agar will bacteroides grow on?
|
blood agar
|
|
|
how does bacteroides cause damage?
|
capsule resists phagocytosis leading to abscess formation
secretes heparinase to promote clotting |
|
|
what will some strains of bacteroides secrete/
|
a metalloprotease toxin which will cause diarreha without epithelial breaks
|
|
|
what is the source of bacteroides?
|
normal gut flora that requires a break in the anatomic mucosal barriers (eg perforated appendix, ruptured peptic ulcer)
|
|
|
what is the pathogenesis of normal flora bacteroides strains?
|
bacteria crosses into tissues or blood stream and replicates,
bacteremia spreads to a variety of tissues immune system corrals bacteria forming tissue absesses resiulting in soft tissue damage |
|
|
what is the pathogenesis of pathogenic bacteroides strains?
|
acute diarrhea
ingestion of diarrhea causing strain secretion of metalloproteinase toxin and assumption of symptoms |
|
|
how do you treat bacteroides?
|
abscess drainage and antibiotics
|
