(1/29/15) Gram-Negative Pathogens of Mucosal Surfaces [2] (Bailey) Flashcards
what are the two types of toxin-producing bacterial pathogens?
- vibrio spp (primarily V. choloerae)
- entertoxigenic E. coli (ETEC)
what are the two types of “hybrid” misfit bacterial pathogens
- enterohemorrhagic E. coli (EHEC)
- enteropathogenic E. coli (EPEC)
what are the 5 characteristics of TOXIN-PRODUCING bacterial pathogens?
- occur in small intestine
- copious amounts of watery stool
- no blood in the stool
- no leukocytes in stool
- no tissue damage
what are the 4 types of vibrio?
- V. cholerae
- V. parahaemolyticus
- V. vulnificus
- V. alginolyticus
what two types of vibrio are involved with diarrhea?
- V. cholerae
- V. parahaemolyticus
what two types of vibrio are involved with tissues and blood?
- V. vulnificus
- V. alginolyticus
what are the two main cholera types?
- El Tor
- classical (thought to be the only one to cause disease till 1960’s)
the new El Tor strand of cholera causes disease because of what?
- a mutated O1 antigen (changed the lipopolysaccharide)
- encapsulated
what age groups were affected by the new El Tor outbreak in the 1960’s?
all age groups
in the 1960’s outbreak, about 1 in _____ people developed cholera
20
what is V. cholera primarily transferred by?
shellfish
what are the three virulence factors used by V. cholera?
- flagella
- pili (to adhere to mucosal tissue)
- cholera toxin (phage encoded)
for V. cholera, a shift from saltwater to reduced ion levels found in the body leads to expression of _____ and to the _____
- pili
- toxin
two types of E. coli that are used for secretory diarrhea
- ETEC
- EPEC
type of E. coli that is dysentery-like (causes blood in the stool)
EHEC
type of E. coli that is associated with urinary tract infections
UPEC
what are the 4 steps to the identification of secretory diarrhea agents?
- rule out Vibrio cholera (want to rule out bc dangerous)
- inoculate plates with diluted stool samples
- not very rich medium, so fastidious G- won’t grow
- aerobic incubation kills the anaerobes
what is the ideal treatment for secretory diarrhea?
oral rehydration (NOT IV)
mix of sugar and salt
what antibiotic is used to shorten the duration or reduce the severity of vibrio infections?
tetracyclines
what antibiotic is used to shorten the duration or reduce the severity of ETEC infections
2nd generation flouroquinolones (ex. ciprofloxacin)
what type of E. coli is prevalent in new borns?
EPEC
what type of E. coli has an absence of traditional exotoxins?
EPEC
what type of E. coli has a characteristic intimate adherence pattern (aka attaching and effacing lesion)
EPEC
what type of E. coli has a large infectious dose and colonizes the DISTAL SMALL intestine
EPEC
what are the three stages to intimate adherence (attaching and effacing lesion) by EPEC and EHEC?
- bundle-forming pili (Bfp) assist in adherence from relative long distance
- syringe-like secretion system injects Tir into host cell
- Tir binds to intimin on E. coli resulting in pedestral formation (actin polymeriszation) [PUTS BACTERIA ON A PEDESTAL]
what two factors cause the diarrhea for EPEC?
- malabsorption due to microvilli disruptions
- disruption of epithelial tight junctions
type of E. coli that has a set of EPEC genes so it produces an attaching effacing lesion but also produces toxin that can lead to hemolytic uremic syndrome (bleed form the kidneys)
EHEC
what type of E. coli is the most common, comes from cattle, causes an attaching effacing lesion and produces a shiva-like toxin?
EHEC
what do shiva-like toxins of EHEC attack?
small blood vessels of the large intestines
the shiva-like toxins of EHEC can be intensified when ____ _____ are present
inflammatory cytokines
a good way to test for the presence of EHEC is to test for _____ bc it is unable to ferment it
sorbitol
why is the treatment of EHEC with antibiotics controversial?
bc antibiotics are only used in the most severe cases so it is unsure whether the disease is due to the antibiotics of the severity of the disease itself
most common form of bacterial infection of an organ system (not including the mouth) and the most frequent cause of doctor’s visits by adults (not including trips to the dentist)
urinary tract infections
inflammation of the bladder
cystitis
why do more women tend to get UTI’s than men?
bc women have shorter urethras so the bacteria can move up them easier
why do men have UTI’s more frequently later in life?
bc the prostate fails to keep working at normal levels
3 characteristics of an uncomplicated UTI
- normal defense mechanisms intact
- no recent hospital visits
- disease limited to lower urinary tract
3 characteristics of a complicated UTI
- some structural abnormality in urinary tract
- recently admitted to the hospital
- disease spread to the kidneys
what are the 6 natural defenses found in the urinary tract?
- complete voidance of bladder
- peristalsis (pushes urine down ureters)
- ureterovesicle valves
- mucous layer
- normal microbiota
- pH
UTI’s can spread to the kidneys and cause _______
pyelonephritis
retrograde flow of urine from bladder to the kidneys can be caused by what three things?
- neurological disorders
- incomplete closing of ureterovesical valves in children
- dialation and decreased peristalsis in pregnant women
some bacteria, like proteus spa., neutralize pH of urine and cause the formation of “struvite” calculi or ____ ____ ____
urinary tract stones
type of E. coli that can adhere to uroepithelial cells through fimbriae, cause a production of aerobactin and hemolysin, and have a genetic link to recurrent disease
UPEC (uropathogenic E. Coli)
Proteus mirabilis is an additional cause of an _____ _____
uncomplicated UTI
causes a more abnormal urinary tract structure and is often more severe of a UTI than those caused by E. coli
P mirabilis
what are the 5 virulence factors for Proteus mirabilis?
- flagella
- fimbriae (special adhesion for urinary epithelium)
- hemolysins
- IgA protease (avoids immune system by degrading IgA on host cell surfaces)
- Urease (increases pH of urine, allows bacteria to grow)
it is surprisingly difficult to positively ID the causative agent of a UTI, but you could count the bacteria in the ______
urine
proteus can be diagnosed by what two things?
- consistently alkaline urine
- production of urease
the treatment of proteus UTI’s are a variety of antimicrobials but ___/_____ is the first choice
TMP/SMX
for treatment of proteus UTI’s in acute cystitis, how many days should treatment be done?
3
for treatment of proteus UTI’s in polynephritis, how many days should treatment be done?
10-14
for treatment of proteus UTI’s in pregnant females, what should be used?
asymptomatic bacteriuria
completely non-motile forms of bacteria that form large, mucoid colonies due to large capsule
klebsiella
type of klebsiella pili that are important for adherence to urinary tract epithelial cells
type 1
type of klebsiella pili that are important for respiratory tract epithelial cells
type 3
klebsiella have ______ that is an iron sequestering protein
aerobactin
what is the primary virulence factor for klebsiella?
antipagocytic capsule (bc if defends against the phagocytic microphages)
among the most prevalent Gm- GI bugs
Heliobacter pylori
unlike the other GI bugs we’ve studied, heliobacter pylori is transmitted through what two types of contact?
- oral to oral
- fecal to oral
______ _____ is a “slow” bacterium that takes weeks or years to cause symptoms
helicobacter pylori
what always precedes the major symptoms of H. Pylori infection?
chronic superficial gastritis
H. pylori is readily killed by ____ ____, and is an efficient producer of _____
- gastric acid
- urease
H. pylori is readily killed by gastric acid so it embeds itself in border epithelial cells that have their pH neutralized by _____
urease
regarding H. pylori, the inflammatory effector molecules cause epithelial cells to produce _____ which recruit neutrophils into the site of infection
IL-8
regarding H. pylori, ______ is associated with peptic ulcer disease (induces vascuolation and apoptosis of epithelial cells)
cytotoxin
H. pylori downregulates _____ which increases ____ and ____ ____ which over time can lead to ulcers
- somatostatin
- gastrin
- gastric acid
treatment of ______ is intense with many side effects
H. Pylori
what are the two stages of the first line of treatment of H. pylori
- proton pump inhibitor
- antibiotic cocktail
what are the two stages of the second line of treatment of H. pylori?
- proton pump inhibitor (same as first)
- numerous pills taken multiple times daily for 2 weeks
