Wk4 Lower GI micro Flashcards
Normal flora associated with breast feeding:
bifidobacteria
Toxin type responsible for food poisoning:
eXOtoxin
**secreted by bacteria
Gram +
Cocci
Catalase +
Coag +
S. aureus
Onset of sx for S. aureus food poisoning:
1-7 hours after ingestion
One of the most resistant non-spore forming human pathogens:
S. aureus
15-45 degrees C
NaCl up to 15%
Abx for S. aureus food px?
nope
Box-car shaped?
Bacillus cereus
B. cereus VF that can be transmitted via medical devices:
biofilms
Gram +
Large bacilli
endospore forming
Facultative anaerobe
mostly motile
Beta hemolytic
B. cereus
B. cereus
? hemolytic
beta
Commonly found in soil and foods that grow close to ground:
B. cereus
rice
B. cereus
**spores can survive rice cooking process
Resembles vomiting like S. aureus
onset 1-6 hours
B. cereus
Emetic form
Similar to C. perfringens infx
watery diarrhea
6-15 hours incubation
B. cereus
Diarrheal
Cereulide
B. cereus toxin for EMETIC form
pre-formed
pore forming
pH stable
heat and protease resistant
self limiting
B. cereus toxin for Diarrheal form:
large molecular weight enterotoxin causes intestinal fluid secretion
not likely pre-formed
small intestine
need lots of bacteria
Gram +
Bacilli
spore-forming
Obligate anaerobe
Motile
Clostridium botulinum
**perfringens is NON-motile
Neurotoxin from canned food
Clostridium botulinum
live in canned food because they are obligate anaerobes
botulinum toxin
pre-formed, acts as soon as hits GI –> blood
anticholinergic –> muscle weakness/paralysis
Difference in infant botulism:
Longer incubation period
spores have to produce toxin forming bacteria
spores in honey or similar
Big 3 food borne bacteria in USA:
- Campylobacter jejuni
- intestinal cell invasion - Salmonella enterica
- intestinal cell invasion - C. perfringens
- enterotoxin
Mech of disease for C. perfringens in GI:
enterotoxins generate pores in host mucosa
C. perfringens
motile?
nope
C. perfringens
Fever?
Vomiting?
no
no
Cafeteria food
large quantities kept warm for long time
NON-motile
C. perfringens
Gram -
Spirilli
microaerophilic
motile
cold sensitive
Campylobacter jejuni
Chicken (poultry)
C. jejuni
Karmali agar
charcoal based
C. jejuni
**sometimes killed before culture
“comma, or S-shaped”
Diarrhea, cramping, fever
2-5 days incubation
diarrhea can be BLOODY – inflammatory response
C. jejuni
Guillain Barre
C. jejuni
Salmonella species that cause gastroenteritis:
S. enteritidis
S. typhimurium
Salmonella sp. that causes typhoid fever:
S. paratyphi A
S. typhi
Gram -
Bacilli
NON spore forming
H2S positive, lactose NEGATIVE
motile, flaggelated
Salmonella
“Salmonella has flagella”
Shigella agar
Ferric citrate –> H2S (black appearance)
Salmonella enterica
reactive arthritis
Salmonella enterica
Turtles (pets)
Salmonella
Salmonella mech of disease?
host cell invasion
Gram -
(curved rod)
facultative anaerobe
Flagellated, motile
Oxidase +
Vibrio spp.
Kovacs oxidase reagent
Vibrio
mild, bloody diarrhea
sx last less than a week
G -
curved rod
Vibrio parahaemolyticus
raw seafood
V. parahaemolyticus
hemolysins TDH or TRH
V. parahaemolyticus
leading cause of death from food borne illness:
Listeria monocytogenes
Gram +
Bacillus
Non-fastidious
Flagellated, motile
NON-sporeforming
oxidase -
Listeria monocytogenes
Listeria monocytogenes
? hemolytic
Beta
fever and chills in pregnant women
Listeria monocytogenes
stiff neck
Listeria monocytogenes
Meningitis in vulnerable populations
Listeria monocytogenes
Place to ID Listeria?
blood/CSF – normally sterile fluids
**not stool
Listeria moncytogenes mech of disease:
Invasive
**immune cells can “Trojan Horse” to other organs (LIVER)
Uncooked foods: deli meat, dairy
Listeria maybe
most common Shigella GI illness
Shigella sonnei
bacillary dysentery
Shigella flexnori
severe dysentery
Shigella dysenteriae
**invasive AND produces toxin
Frequent, small bowel movements with blood and MUCUS, accompanied by rectal pain and tenesmus:
dysentery
**different than bad diarrhea
Difference between Shigella and E. coli
Shigella is lactose NEGATIVE
Shigella have no flagella
Gram -
Bacillus
Facultative anaerobe
NONmotile
non spore forming
lactose negative, H2S negative
Shigella
actin rockets
Shigella
hemolytic uremic syndrome
Shigella
or
STEC E. coli
Shigella
reactive arthritis
S. flexnori
Toxin that acts on vascular endothelial cells:
Shiga(vero)toxin aka AB5
-Phage borne toxin
Receptor for AB5 (shigatoxin)
Gb3
Gram -
Bacillus
Facultative anaerobe
motile
non spore forming
lactose POSITIVE
E. coli
Strain of E. coli that produces Shiga toxin:
STEC
aka
VTEC
aka
EHEC
E. coli
traveller’s diarrhea
ETEC
Main difference between E. coli strains ETEC and STEC:
degree of attachment
STEC gets intimate to deliver shiga toxin
ETEC delivers LT or ST toxin from the edge of cells
E. coli
profuse watery diarrhea –> bloody
STEC
Incubation for ETEC:
1-3 days
Incubation for STEC:
3-8 days
hemorrhagic colitis
hemolytic uremic syndrome
STEC
cows
beef
E. coli
stxA stxB ???
genes for STEC AB5 toxin
come form bacteriophage
Pssoble prob with abx for E. coli?
Dead bacteria release toxin –> HUS
What not to give in E. coli infx?
Anti-diarrheals
water source
Vibrio cholerae
Mech of disese for cholera toxin
incresed cAMP
decreased Na+ absorption –> Cl- excretion
water follows
rice-water stools
cholera
loss of skin elasticity
dry mucous membranes
cholera
water source, not VIbrio
Salmonella typhi
**typhoid fever – not a GI disease
103-104 fevers
weakness, headache
Typhoid fever
S. typhi
Abx for S. typhi??
YES
Review slide 98
infection doses
Pseudomembranous colitis
C. diff