Gram - Rods: Enteric bacteria like E. coli Flashcards
What bacteria is great for studying mutants?
E. coli because they define biochemical pathways
T/F: E. coli grow slowly
False!
They actually grow rapidly and easily aerobically and anaerobically on most lab media. Have a 20 min doubling time
What are the major pathogens of E.coli?
Escherichia, Shigella, Salmonella, and Vibrio
What are the types of infections involved with E. coli?
intestinal, urinary, respiratory, wound, bloodstream, and meningeal infections
What is the O antigen in E.coli?
carbohydrate LPS repeat
T/F: E. coli is not normal intestinal flora
False!
It IS normal intestinal flora but this can cause some diseases/infections
How does E. coli get in the bloodstream?
if capsule present
Can happen when E.coli ends up in the wrong place (e.g. puncture wound)
What is the potent trigger of inflammation?
LPS- endotoxin (which is important in sepsis and meningitis)
What does heat liable toxin do (involved in the enterotoxin of E. coli)?
activate adenylate cyclase which leads to fluid secretion/diarrhea
How does E. coli cause 85-90% of UTI’s?
- intestines -> vagina -> urethra
- adhere to uroepithelial cells via fimbriae and ascend to bladder which then colonize and cause inflammation
How does E. coli cause invasive infections neonatal meningitis?
vaginal normal flora colonize the infant at birth during the passage through the birth canal which then travel through intestines then blood and finally to meninges
How common is a capsule on E. coli in neonatal meningitis?
90%
How does E. coli cause bacteremia/septic shock?
in patients with immune impairment of mechanical damage, intestinal E. coli invade blood stream and large amounts of endotoxin stimulate systemic inflammation and septic shock
What makes Shigella different from E. coli?
it has a virulence plasmid that allows cell invasions and intracellular growth
AND not normal flora
What does shigella cause?
mild disease= shigellosis… diarrhea without blood
severe disease= dysentery… blood in stool cause specifically by S. dysenteriae
How does the Virulence plasmid in Shigella work?
encodes proteins for attachment/entry into intestinal epithelial cells
How does Shigella dysenteriae work?
cause erosion of large intestine epithelia
What is only found in diseased humans aka not normal flora?
salmonella
What are the 2 different serotypes of salmonella?
S. e. Typhimurium (causes food poisoning)
S. e. Typhi (causes typhoid fever)
What is the most common salmonella infection?
gastroenteritis due to improper food handling
Which is the invasive serotype of salmonella that can get in the bloodstream?
S. typhi
- due to the Vi capsule giving typhoid fever
Is there a vaccine for typhoid fever (S.typhi) ?
Yes!
2 current vaccines. a purified Vi capsule polysaccharide or a live attenuated Ty21a strain
Which is the curved, gram - rod?
vibrio cholera
Where does Vibrio live?
common in surface waters worldwide with fecal pollution
- oysters are common to have this
What is exotoxin involved in V. cholerae?
cholera enterotoxin which chemically modifies adenylate cyclase and stimulates fluid secretion
T/F: Cholera invades tissue
False!
It does not invade in tissue
What is the pathology associated with cholera?
dehydration and electrolyte imbalance
What’s the treatment for cholerae?
fluid replacement is critical
What is the vaccine for cholera?
Vaxchora- live V. cholerae 01
which triggers protective mucosal Ab to whole bacterium and to toxin B subunit
Is E. coli gram- or gram +?
gram -
What is the number one medical infection?
Staph aureus
- E.coli is the next one
Which don’t have the LPS but the LOS?
Haemophilus meningitis and bordetella pertussis
which helps hide the bacteria is an important virulence factor
How is E. coli transmitted?
fecal-oral spread of unique strains
What is an important relative to E. coli worth knowing that has a thick mucous layer that prevents drugs from getting into it?
Klebsiella
What allows for Shigella to cause dysentary?
shiga toxins
Where is the normal reservoir of salmonella?
intestinal tract of animals especially reptiles
What are the 2 vaccines for that are live strains?
for typhoid fever and cholera enterotoxin
