bacterial infect, GI tract, Lect 5 Flashcards
cholera is due to what organism
vibrio cholerae infection
where do cholera colonize?
- Bacteria colonize the small intestine mucosa with the colonized mucosa showing NO change in physical integrity
what is the main clinical feature of cholera
- Acute and massive watery diarrhea (1 liter/hour) is the main feature of this disease.
- “rice water” stools
- Rapid depletion of fluids and electrolytes leading to hypo-volemic shock, metabolic acidosis, death
cholera has abrupt onset of what symptoms
- watery diarrhea
- Muscle cramps, poor skin turgor, wrinkle skin over fingers, (“washerwoman hands”), sunken eyes, missing pulse in extremities.
the watery diarrhea in cholera is created by
cholera toxin
cholera toxin has identical toxin in what organism that causes traveler’s diarrhea
enterotoxigenic E-coli
describe the cholera agent: gram status
- gram negative
describe the cholera agent: shape, does it form spores
- bent rod shape
- nonspore-former
can the cholera agent live in aerobic environement? is it motile?
- facultative anaerobe
- motile, polar flagellum
identify V. Cholerae serogroups
- serogroup O-1: classic epidemic cholera
- serogroup O-139
cholera treatment
- For the majority of patients, successful therapy usually only requires replacement of fluids and electrolytes.
- Provide by IV route if patient cannot take oral fluids
causative cholera microbes are found naturally in what environments
The causative microbes are found naturally in marine coastal areas and estuaries, including the United States Gulf Coast region.
how is cholera spread
- This disease is spread through contaminated drinking water and food.
- Not easily spread by person-to-person route
who are important reservoirs for cholera
- Asymptomatic human carriers important as reservoirs
- carrier rate 1-20% in endemic regions
- a carrier may have initiated the current cholera epidemic in Haiti
are vaccines available for cholera
- two killed organism vaccines
- Shanchol: O-1 killed whole cells plus toxoid
- Dukoral: bivalent O-1 and O-139 killed whole cells
primary prevention for cholera
proper control of sewer
travelers to cholera endemic regions can take
Prophylactic tetracycline treatment
what is the most common cause of food-borne illness in Japan.
Vibrio. parahaemolyticus
Vibrio. parahaemolyticus causes
gastroenteritis to a mild cholera-like illness
V. parahaemolyticus normal habitat
This organism is normal inhabitant of coastal ocean and estuary waters
US cases with V. parahaemolyticus is most frequently associated with
mishandling infected seafood
- improper refrigeration
vibrio vulnificus normal habitat
Also a normal inhabitant of coastal marine and estuary waters.
vibrio vulnificus infection is associated with
Infection is frequently associated with oysters
-
Wound infections
- Through direct contact of open wound with seawater or oysters.
-
sepsis
- Due to consumption of raw oysters
- Acute self-limiting diarrhea associated with raw oyster consumption
clinical presentation
- Eruption of bullous skin lesions, shock.
- History of oyster consumption with suspicion of liver dysfunction (alcoholism commonly)
sepsis from V. vulnificus
treatment of sepsis caused by V. vulnificus
tetracycline
E-coli have two means by which to cause disease
-
O antigen (LPS) = serogroup
- At least 160 serogroups exist
- H antigen (flagella) = serotype
MOA of Enterotoxigenic E. coli (ETEC)
- adheres to mucosa of small intestine and produces symptoms by elaboration of toxinds that induce diarrhea
Enterotoxigenic E. coli (ETEC) causes what condition
traveler’s diarrhea
- afebrile, watery
Enterotoxigenic E. coli (ETEC) can be fatal in what patient population
ETEC disease is like cholera, but far less severe. May be fatal in infants
clinical presentation
- primarily in developed world
- diarrhea that becomes bloody after 1-3 days with cramps, vomiting
- fever in 50% patients
Enterohemorrhagic E. coli (EHEC)
Enterohemorrhagic E. coli (EHEC) express what toxin (key virulence factor)
Shiga-like toxin (SLT)
Enterohemorrhagic E. coli (EHEC) complications
- develop hemolytic uremic syndrome (HUS): can be fatal.
- acute renal failure
- 8-10% of O157:H7
Enterohemorrhagic E. coli (EHEC): which One form predominates
O157:H7
STEC also induces hemolytic uremic syndrome. what does STEC stand for
Shiga toxin producing E. coli
- other forms of E-coli that may produce same disease syndrome
Enterohemorrhagic E. coli (EHEC) is more common in what patient populations
elderly and young
how is EHEC (O157:H7) Diagnosed
-
MacConkeys’s sorbitol agar can differentiate this pathogen from normal flora E. coli
- This pathogenic strain cannot ferment sorbitol and appears white on MAC sorbitol plates while other nonpathogenic E. coli strains are a bright red/pink color.
EHEC (O157:H7) treatment
- oral rehydration
-
avoid Abx
- Risk of HUS induction
- do NOT use antimotility agents in children and infants
EHEC O157:H7 is associated with what food source
- reservoir is CATTLE
- beef
- raw milk
route of transmission of EHEC O157:H7
- This is an extreme low-dose pathogen
- Person-to-person transmission documented
what is E. coli O104:H4
a new form of enterogaggregative E. coli O104:H4 emerged in Europe
E. coli O104:H4 traced to what food source
alfalfa sprouts
E. coli O104:H4 expresses what toxin
shiga toxin
- ability to produce HUS, high case fatality rate
Campylobacter jejuni is widely distributed in what food products
undercooked chicken
Give the characteristics of Campylobacter jejuni
- gram status
- aerobic?
- what temp it grows best at
- Gram negative
- curved rod (sea gull shaped)
- Motile
- Microaerophilic
- Grows well at 42º C
clinical presentation
- Very commonly patient has prodrome with fever, headache, malaise, myalgia 12-24 hours before diarrhea onset.
- Enteritis with diarrhea
- Loose stools to dysentery (bloody diarrhea)
- Fever
- abdominal pain (cramping)
- Self-limiting (improvement after several days).
- Severe acute abdominal pain in lower right quadrant (mimics appendicitis).
Campylobacter jejuni
reservoir of Campylobacter jejuni
- intestinal tract of animals
- birds especially
Campylobacter has the highest infection rate in what patient population
This GI pathogen is unusual in that the highest infection rate is in young adults (college age)
complications of Campylobacter infection
- Reiters syndrome
- HLA-B27 individuals
- Guillain-Barre syndrome
- C. jejuni is the chieg precipitant of Guillain-Barre syndrome
which bacteria has these characteristics
- copious production of urease
Helicobacter pylori
- Urease - Produces CO2 and NH4 + that raises pH and protects H. pylori
which bacteria has these characteristics
- gram negative
- curved rods
- highly motile
- stain best in tissue biopsy with Giemsa
- copious production of urease
Helicobacter pylori
What is H. Pylori’s primary target in the host
Epithelial cells of pylorus
clinical presentation
- gastritis
- cramps
- halitosis: bad breath
- N/V
- eradication of bacteria is not correlated with relief of symptoms
H. Pylori
reservoir of H. pylori
humans
- gastritis has been produced by ingestion of large inoculum
which bacteria associated with stomach adenocarcinoma
H. Pylori
how is H. Pylori diagnosed
CLO test – detection of urease activity in biopsy tissue by pH change
treatment for H. Pylori
- The optimal antibiotic therapy has not yet been evolved.
- Combination of antibiotics (tetracycline) plus bismuth-containing drugs are used
- Patient may be re-infected after antibiotic eradication (by family/contacts)
