infectious small intestine and colon Flashcards
robbins
generic clinical presentation that suggests infectious enterocolitis
diarrhea, abd pain, urgency, perianal discomfort, incontinence, hemorrhage
with what population is infectious enter-colitis associated
children before 5
pediatric infectious diarrhea is associated with what kind of organism
enteric virsus
shape+type - cholera
comma shaped with flagella, gram (-), anaerobe, toxin producing
describe the virulence of cholera, and its activity within the GI tract
noninvasive, remain in intestinal lumen
have flagella, use to colonize
I A subunit, 5 B subunits
cholera toxin’s B subunits will bind the GM1 ganglioside on the membrane of the epithelial cell–> A subunit goes in–> Gs–> cAMP–> Cl- release via CFTR gene –> osmotic driving force that causes diarrhea
transmission, clinical presentation, complications of cholera
fecal-oral route, water, shellfish
endemic/epidemic or sporadic: asx or mild diarrhea OR abrupt RICE WATER profuse diarrhea may smell like fish
dehydration and electrolyte imbalances, LOC, death within 24 hours. if survive, last 1 week
what organisms will affect the small intestine specifically
cholera salmonellosis typhoid fever ETEC EPEC whipple ds mycobacterial infection
what organism will act in the ileum, appendix, and right colon
yersinia
what organisms specifically affect the colon
campylobacter salmonellosis EHEC EIEC EAEC C Dif
what organisms affects the L colon and the ileum
shigellosis
transmission, clinical presentation, complications of campylobacter
poulty, milk, other foods, wild birds
children and travelers: watery or bloody diarrhea (dysentery)
reactive arthritis, guillain-barre, syndrome, enteric fever
transmission, clinical presentation, complications of shigellosis
fecal-oral, food, water
children, migrant workers, travelers, nursing home
(watery–>bloody+pus) diarrhea, fever, abd pain
SELF LIMITED= 1 week of sx, up to a month of constitutional sx
subacute presentation in adults: several weeks of waxing and waning
can be confused for UC
reactive arthritis, urethritis, conjunctivitis, HUS, toxic megacolon
transmission, clinical presentation, complications of salmonellosis
meat, poultry, eggs, milk
in children and older adults, watery or bloody diarrhea,
anywhere from loose stools to cholera like profuse diarrhea
sepsis, abscess
transmission, clinical presentation, complications of typhoid tumor
fecal-oral route
children, adolescents, travelers bloody diarrhea (can persist for a week), fever (resolves within 2 days), anorexia, bloating, short asx phase that gives way to bacteremia and fever like flu sx LLQ abd pain, rose spots on chest and abd
chronic infection, carrier state, encephalopathy, myocarditis, intestinal perforation
transmission, clinical presentation, complications of yersinia
pork, milk, water
clusters of people: abd pain, fever, bloodydiarrhea,
can mimic appendicitis
reactive arthritis, erythema nodosum
transmission, clinical presentation, complications of ETEC
food or fecal-oral,
infants, adolescents, travelers: severe watery diarrhea
dehydration, electrolyte imbalance
transmission, clinical presentation, complications of EPEC
fecal-oral route
infants: watery diarrhea
dehydration, electrolyte imbalance
transmission, clinical presentation, complications of EHEC
beef, milk produce
sporadic/epidemic: bloody diarrhea
HUS
transmission, clinical presentation, complications of EIEC
cheese, deli meats, water
young children, bloody diarrhea
–
transmission, clinical presentation, complications of EAEC
unknown
children, adults, travelers: non-bloody diarrhea, afebrile
–
transmission, clinical presentation, complications of C. Dif
us of abx in hospitals,
old, immunosuppressed, prolonged use of abx: watery diarrhea, fever, leukocytosis, cramps, dehydration, hypoalbuminemia
relapse, toxic megacolon
transmission, clinical presentation, complications of whipple ds
–
caucasian men, farmers and others working with exposure to soil/animals
rare: malabsorptive diarrhea, weight loss, arthralgia
arthritis, CNS disease
transmission, clinical presentation, complications of mycobacterial infection
immunosuppressed, endemic: malabsorption
pneumonia, infection at other sites
trx for cholera
timely fluid replacement, oral rehydration
most common enteric pathogen in developed countries, traveler’s diarrhea
campylobacter jejuni
virulence factors of campylobacter
flagella, cholera toxin-like enterotoxin
what patients are especially likely to develop reactive arthritis with a campylobacter infection
those with an HLA-B27
describe the etiology of Guillain-Barre w campylobacter
molecular mimicry as Ab against C. jejuni lipopolysaccharide cross react with PNS and CNS gangliosides
shape+type - campylobacter
comma shaped, flagellated, G(-)
how do you diagnose campylobacter
stool culture, showing increased neutrophil infiltrates, cryptitis+crypt abscesses with crypt architecture is preserved
shape+type - shigella
G(-), unencapsulated, nonmotile, FACULTATIVE ANAEROBE
most shigella infections and death occur in ___
children under 5
outline the etiology of a shigella infection
resistant to the harsh acidic environment of the stomach so can get through into the stomach, get to the intestine where it will be taken up by M cells, phagocytosed by Mø at which point they cause apoptosis
ensuing inflammation–> shigella now has access to an invasion route
shigella has a tropism for what cell
M cells (lymphoid cells)
with shigella infection, while duration is much shorter in ___ than ___, severity is often much ____
children than adults
greater
what complication triad presents with Shigella, and which population is most likely to develop this
reactive arthritis, urethritis, conjunctivitis
HLA-B27 (+) men between 20 and 40
what syndrome can develop post shigella or shiga-like toxin (EHEC/S. dysenteria) infection
HUS
describe treatment methods for shigella
abx treatment shortens the clinical course and reduces the duration of organism shedding in stools
ampcillin or flouroquinolone
ANTIDIARRHEAL MEDS ARE CONTRAINDICATED
shape+type - salmonella
enterobacteriaceae family of G(-) bacilli
causative agent of typhoid/enteric fever
salmonella typhi
causative agent of salmonellosis
nontyphoid salmonella
when is salmonella incidence highest
summer and fall
salmonella virulence
type 3 secretion system, transferring bacterial proteins into M cells and enterocytes, through peyer’s patches
trigger actin rearrangement via Rho GTPase and bacterial endocytosis
flagellin –> TLR5 –> increase local inflammatory response
some prevent TLR4 activation
what population is at a high risk of disseminated salmonellosis
genetic defects in Th17 immunity, immunosuppression
____ can prolong the carrier state or cause relapse of salmonella infection and doesn’t help with shortening diarrheal duration
abx
what populations are at a high risk of severe illness due to salmonella
malignancies immunosuppressed alcoholics CV dysfunction sickle cell hemolytic anemia
gallbladder colonization w S. typhi/paratyphi can be associated with..
gallstones
chronic carrier state
describe the path of S. typhi in the body
survive through the stomach, once in the small intestine are taken up by and invade M cells
disseminate via lymphatic and blood vessels
what histologic changes can be seen with salmonella infection
peyers patches in the terminal ileum enlarge and plateau-like elevate
draining mesenteric LNs are also enlarged
large oval ulcers
small and scattered perenchymal necrosis
typhoid nodules= in the BM, LN, hepatocytes replaced by Mø (phagocyte hyperplasia)
during the febrile phase of typhoid fever, almost all ____ are positive and ____ can prevent further disease progression, and the phase can last up to ___
blood cultures
abx
2 weeks
what are some complications of typhoid fever
encephalopathy, meningitis, seizures, endocarditis, myocarditis, pneumonia, cholecystitis
what population is particularly susceptible to salmonella osteomyelitis
sickle cell disease
agent for pulmonic and bubonic plague
Y. pestis
when are yersinia infections most common
winter
what does yersinia do in the body
invade M cell, use adhesins to bind to host B integrins–> increase iron import to stimulate systemic dissemination
what populations are more likely to develop sepsis and death from a yersinia infection
chronic anemics or hemochromatosis
too much iron in body
where does yersinia preferentially infect
ileum, appendix, right colon
histologic changes w yersinia infection
regional LN and peyer patch hyperplasia, bowel thickening
enteritis and colitis secondary to yersinia is common in what population
younger children
extraintestinal sx of yersinia
pharyngitis, arthralgia, erythema nodosum
how do you detect yersinia
stool culture and yersinia selective agar
LN/blood cultures
fecal leukocytes (+)
[clinically indistinguishable from salmonella + shigella)
what are post infectious complications of yersinia infection
reactive arthritis with urethritis and conjunctivitis, myocarditis, erythema nodosum, and kidney ds
shape+type - E Coli
G-
what is the main type of EHEC
E Coli O157:H7
predisposing factor for C Dif
immunosuppression + PPI use
etiology of C. Dif infection
toxins released lead to disruption of epithelial cytoskeleton, tight junction barrier loss, cytokine release, apoptosis
histologic changes seen w C Dif
pseudomembranes
dense infiltrates of neutrophils and occasional fibrin thrombi within capillaries
distended crypts w abscesses, volcanic like disruptions IS PATHOGNOMONIC
trx for C Dif
metronidazole
vancomycin
complications with C. Dif
recurrent infections
pathogenesis of Whipple
malabsorption (–>malabsorptive diarrhea), lymphadenopathy, arthritis
histologic changes with whipple
foamy Mø, large numbers of argyrophilic rods in the LNs
sx appear when organism laden Mø accumulate within the small intestine and mesenteric LNs–> lymphatic obstruction
white-yellow plaques
HALLMARK: dense accumulation of foamy macrophages in the small intestine
what stains can be done for whipple disease
PAS +
acid fast stain to differentiate from TB
whipple ds, you can find bacteria laden Mø built up in
mesenteric LN, synovial membranes of effected joints, cardiac valves, brain
family+type - norovirus
single stranded DNA
caiciviridae gamily
most common cause of acute gastroenteritis requiring medical attention
norovirus
top to causes of severe diarrhea in infants and young children
- rotavirus
2. norovirus
ASCARIS LUMBRICOIDES
method of invasion+ morphology
clinical presentation + epidemiology
diagnostic feature
nematode=roundworm
fecal oral: ingested eggs hatch in intestine and penetrate the intestinal mucosa–> splanchnic Vs–> systemic circulation–> grow in alveoli–> swallow and mature in intestine
physical obstruction of the intestine or biliary tree
can form hepatic abscess
ascaris pneumonitis
diagnosis with eggs in stool
STRONGYLOIDES
method of invasion+ morphology
complications
=roundworm
larvae live in fecally contaminated tropical ground soil, can penetrate through unbroken skin–> migrate through lungs–> mature in intestine–> hatch and release larvae that penetrate the mucosa–> autoinfection
can persist for life, immunosuppressed can developing overwhelming autoinfection
induce peripheral eosinophilia
NECATOR+ANCYLOSTOMA DUODENALE
method of invasion+ morphology
clinical presentation + epidemiology
test
hookworms
larval penetration through skin–>lungs–>trachea–>swallowed–> in duodenum will suck blood and reproduce
cause significant morbidity
multiple superficial erosions, focal hemorrhage, inflammatory infiltrates, irone deficiency anemia
diagnose by finding eggs in fecal smears
ENTEROBIUS VERMICULARIS
method of invasion+ morphology
clinical presentation + epidemiology
test
pinworms
fecal oral route–> from intestine migrate to the anal orifice at night and cause intense irritation
rarely cause serious illness
rectal and perineal pruritis, contamination of the fingers
diagnosis with cellophane tape on the perianal skin
TRICHURIS TRICHIURA
clinical presentation + epidemiology
diagnostic feature
whipworms infect young children
does not penetrate intestinal mucosa, so doesn’t cause serious disease
blood diarrhea and rectal prolapse with heavy infection
SCHISTOSOMIASIS
method of invasion+ morphology
clinical presentation + epidemiology
in the intestines, adult worms reside within the mesenteric Vs
one version bone in the portal V–> esophageal varices
sx present when eggs are trapped within the mucosa and submucosa, granulomatous immune reaction can cause bleeding and/or obstruction
intestinal cestodes
method of invasion+ morphology
clinical presentation + epidemiology
diagnostic feature
tapeworms
three types: fish, pork, and dwarf tapeworms
ingestion of raw/under-cooked meat and fish
attached to intestinal mucosa, gets its nutrients from the food stream and enlarges into a proglottids
adult worms can grow up to METERS
abd pain, diarrhea, nausea
(via tiniea d. ) B12 deficiency–> megaloblastic anemia
(t solium) –> cystacercosis= seizures and eye ds
dx by finding proglottids and eggs in stool
ENTAMOEBA HISTOLYTICA
method of invasion+ morphology clinical presentation + epidemiology diagnostic feature complication prognosis trx
protozoan that causes amebiasis
spread the fecal oral route
reside in cysts= chitin wall and four nuclei, resistant to gastric acid so can get to small intestine
colonize the epithelial surface of the colon and release trophozites–> reproduce anaerobically
seen in india, mexico, and columbia,
causes dysentery and liver abscess, abd pain, weight loss
most common cause of dysentery worldwide
create FLASK SHAPED ulcers with a narrow neck and broad base
can penetrate the splanchnic vessels and embolize to the liver, persisting after the infection has passed
go on to lung, heart, kidneys, brain
huge abscess, persist after the acute illness has passed
necrotizing colitis and megacolon
significant mortality
metronidazole
where do E. histolytica most often effect
cecum and ascending colon
GIARDIA
method of invasion+ morphology
clinical presentation + epidemiology
diagnostic feature
complication
fecal-oral route
resistant to chlorine
cause decreased expression of brush border enzymes, microvillous damage, apoptosis of small intestine epithelium
found in rural streams, campers–>swallowed while swimming
villous blunting with increased intraepithelial lymphocytes
chronic diarrhea, malabsorption, weight loss
characteristic pear shaped, two nuclei
despite oral antimicrobial therapy, recurrence is common
most common parasitic pathogen in humans
giardia
what elements are responsible and necessary for clearance of giardia
secretory IgA and mucosal IL-6
at risk populations for giardia
immunosuppressed
agammaglobulinemic
malnourished
classic clinical presentation with cryptosporidium
chronic diarrhea in AIDS
is acute and self-limited in the immunologically normal host
cryptosporidium
method of invasion+ morphology
clinical presentation + epidemiology
diagnostic feature
resistant to chlorine so is present in unfiltered water
ingested oocyte will release sporozoites upon activation–> enterocyte will engulf the parasite
–> Na malabsorption, chloride secretion, increased tight junction permeability
watery diarrhea in children and the immunosuppressed
causes villous atrophy, crypt hyperplasia, inflammatory infiltrates
intestinal TB has a similar infiltrate as __. how do you differentiate between the two?
Whipple
W= no acid fast, TB= acid fast
