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39 Cards in this Set
- Front
- Back
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Classic Shigella
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S. dysenteriae
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S. dysenteriae
Classic Shigella Causes dysentary- frequent passage of small volumes of stool containing blood and mucous. Fecal leukocytes are found- invasive Produces _____ toxin An AB toxin. _ subunit disrupts protein synthesis |
S. dysenteriae
Classic Shigella Causes dysentary- frequent passage of small volumes of stool containing blood and mucous. Fecal leukocytes are found- invasive Produces Shiga toxin An AB toxin. B subunit disrupts protein synthesis |
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S. flexneri
Found in developing countries; pathogenesis similar to S. dysenteriae; more common than S. ___________ |
S. flexneri
Found in developing countries; pathogenesis similar to S. dysenteriae; more common than S. dysenteriae |
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S. sonnei
Most common species in _________ _______ |
S. sonnei
Most common species in developed countries |
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S. b_____
Uncommon |
S. boydii
Uncommon |
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Pathogenesis of Shigellosis
Ingested organisms bind to and enter _ cells of Payer’s patches M cells deliver organisms to lymphoid follicles where they enter m___________ Replicate within macrophages, released and enter colonic epithelial cells Invades and replicates in colonic epithelial cells Release of cytokines from infected macrophages attracts PMNs |
Pathogenesis of Shigellosis
Ingested organisms bind to and enter M cells of Payer’s patches M cells deliver organisms to lymphoid follicles where they enter macrophages Replicate within macrophages, released and enter colonic epithelial cells Invades and replicates in colonic epithelial cells Release of cytokines from infected macrophages attracts PMNs |
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S. ______ is the most common species of laboratory-confirmed Shigella infection in US
Mostly common in children aged <5 years Outbreaks in US associated with day care centers |
S. sonnei is the most common species of laboratory-confirmed Shigella infection in US
Mostly common in children aged <5 years Outbreaks in US associated with day care centers |
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S. dysenteriae and S. ________ cause dysentery (bloody diarrhea, fever, tenesmus)
_____ toxin produced only by S. dysenteriae Similar toxin produced by some strains of E. coli- discussed later |
S. dysenteriae and S. flexneri cause dysentery (bloody diarrhea, fever, tenesmus)
Shiga toxin produced only by S. dysenteriae Similar toxin produced by some strains of E. coli- discussed later |
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S. sonnei causes watery diarrhea that is positive for fecal l_________
Diagnosed by growth on _________ agar |
S. sonnei causes watery diarrhea that is positive for fecal leukocytes
Diagnosed by growth on MacConkey agar |
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Treatment of susceptible strains causing shigellosis with _________- or _____________ (adults)
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Treatment of susceptible strains causing shigellosis with ampicillin or ciprofloxacin (adults)
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Do not use anti-____ drugs for bloody diarrhea
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Do not use anti-motility drugs for bloody diarrhea
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Shigellosis:
Treatment: ___ (highlighted) Antibiotic Treatment: treat to decrease communicability, even if symptoms resolving resistance may be a problem, susceptibility tests should be done drug of choice - fluoroquinolone (adults) Alternatives or for children - azithromycin, TMP/SMX, ampicillin, cefixime Do not use anti-motility drugs for bloody diarrhea |
Shigellosis:
Treatment: ORT (highlighted) Antibiotic Treatment: treat to decrease communicability, even if symptoms resolving resistance may be a problem, susceptibility tests should be done drug of choice - fluoroquinolone (adults) Alternatives or for children - azithromycin, TMP/SMX, ampicillin, cefixime Do not use anti-motility drugs for bloody diarrhea |
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88% of isolates were resistant to both __________ and ________,
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88% of isolates were resistant to both ampicillin and TMP/SMX,
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Enterohemorrhagic E. coli was isolated from the stool of both the grandfather and child. It was typed by antisera as E. coli ____:__.
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Enterohemorrhagic E. coli was isolated from the stool of both the grandfather and child. It was typed by antisera as E. coli O157:H7.
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What E Coli uses Shiga toxin?
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EHEC- enterohemorrhagic E. coli
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Which E Coli makes a pedestal?
(intimin/Tir complex) |
EPEC- enteropathogenic E. coli
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Which E Coli uses enterotoxin
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ETEC- enterotoxigenic E. coli
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Antigens of E coli Used for Typing Strains
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KOH:
K= capsular antigen O= polysaccharide of LPS H= flagellar antigen |
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Most common strains of E. coli producing human disease in developed countries
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EHEC
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EHEC:
Several strains- O___:H7 is most important Highly pathogenic- 100 organisms can cause disease if ingested Disease ranges from mild diarrhea, to hemorrhagic colitis to hemolytic uremic syndrome Normal commensal in intestinal tract of cattle, possibly other animals Infections occurs when food or water contaminated with cattle feces is ingested Culprit food is past outbreaks- h________, uncooked vegetables or fruit, unpasturized fruit juices or cider |
EHEC:
Several strains- O157:H7 is most important Highly pathogenic- 100 organisms can cause disease if ingested Disease ranges from mild diarrhea, to hemorrhagic colitis to hemolytic uremic syndrome Normal commensal in intestinal tract of cattle, possibly other animals Infections occurs when food or water contaminated with cattle feces is ingested Culprit food is past outbreaks- hamburger, uncooked vegetables or fruit, unpasturized fruit juices or cider |
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Pathogenesis of O157:H7
EHEC strains that carry phage-encoded Shiga-like exotoxins (Stx-1 and Stx-2) Stx-_ is essentially identical to Shiga toxin produced by Shigella dysenteriae; Stx-2 is ~ 60% homologous Receptors for toxins are on intestinal ______ cells and glomerular endothelial cells _ subunit of toxins bind to 28S rRNA, disrupts protein synthesis…cell dies In intestine, leads to decreased absorption and increased fluid secretion Stx-2 damages g_________ endothelial cells, leads to platelet activation, thrombin deposition; this leads to decreased glomerular filtration and acute renal failure |
Pathogenesis of O157:H7
EHEC strains that carry phage-encoded Shiga-like exotoxins (Stx-1 and Stx-2) Stx-1 is essentially identical to Shiga toxin produced by Shigella dysenteriae; Stx-2 is ~ 60% homologous Receptors for toxins are on intestinal villus cells and glomerular endothelial cells A subunit of toxins bind to 28S rRNA, disrupts protein synthesis…cell dies In intestine, leads to decreased absorption and increased fluid secretion Stx-2 damages glomerular endothelial cells, leads to platelet activation, thrombin deposition; this leads to decreased glomerular filtration and acute renal failure |
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HUS = hemolytic uremic syndrome
Classic Triad R____ failure _________ anemia (Coombs-negative) ___________penia Most commonly occurs in young children 5-10% mortality rate Prior treatment with antibiotics during the initial ______ diarrhea stage MAY increase risk of HUS |
HUS = hemolytic uremic syndrome
Classic Triad Renal failure Hemolytic anemia (Coombs-negative) Thrombocytopenia Most commonly occurs in young children 5-10% mortality rate Prior treatment with antibiotics during the initial bloody diarrhea stage MAY increase risk of HUS |
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Enteroinvasive E. coli: EIEC
Rare type of E. coli Only few organisms are necessary to cause disease Pathogenesis and manifestations similar to Shigella ___________ - invades and destroys colonic epithelial cells Dysenteric disease with fever, abdominal cramps, vomiting, malaise, bloody stools, fecal leukocyte-positive |
Enteroinvasive E. coli: EIEC
Rare type of E. coli Only few organisms are necessary to cause disease Pathogenesis and manifestations similar to Shigella dysenteriae - invades and destroys colonic epithelial cells Dysenteric disease with fever, abdominal cramps, vomiting, malaise, bloody stools, fecal leukocyte-positive |
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Thing to remember about enteroaggregative E coli
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persistant diarrhea
developing country infant |
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Which organisms are associated with undercooked chicken?
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Which organisms are associated with undercooked chicken?
Salmonella Campylobacter |
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Strict human pathogen
Typhoid fever |
S. typhi
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Salmonella species that come from animals
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S. enterica
S. typhimurium S. enteritidis |
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Salmonella
Virulence factors Attachment is made possible by what? |
fimbriae
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Pathogenesis of Salmonella Infections
Ingestion and passage to intestine Specialized fimbriae bind bacteria to _ cells. Type III secretion system injects proteins into M cell that induce rearrangement of M cell a____ M cell membrane ruffles, engulfs the bacteria Bacteria replicates in _ cells, also infects adjacent cells Infected cells secrete ions and fluid in ____-dependent fashion S. typhi can invade deeper, enter m__________ and be carried throughout body |
Ingestion and passage to intestine
Specialized fimbriae bind bacteria to M cells. Type III secretion system injects proteins into M cell that induce rearrangement of M cell actin M cell membrane ruffles, engulfs the bacteria Bacteria replicates in M cells, also infects adjacent cells Infected cells secrete ions and fluid in cAMP-dependent fashion S. typhi can invade deeper, enter macrophages and be carried throughout body |
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What type of salmonella?
Found in GI tract of birds and reptiles Transmission/epidemiology Consumption of contaminated foods Handling pets Fecal-oral transmission Need large number for infection (106-108) |
Salmonella enterica
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Salmonella typhi :
Virulence factors Invasive Go through GIT cells to submucosa Macrophages engulf Survive in macrophages and are taken to _____, _____ and ____ ______ Endotoxin Vi capsule Unusual polysaccharide capsule, anti-phagocytic, inhibits complement activation |
Salmonella typhi :
Virulence factors Invasive Go through GIT cells to submucosa Macrophages engulf Survive in macrophages and are taken to liver, spleen and bone marrow Endotoxin Vi capsule Unusual polysaccharide capsule, anti-phagocytic, inhibits complement activation |
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S. Typhi
May see ____ spots on abdomen |
rose
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Yersinia enterocolitica
Presentation can mimic ____________ |
Yersinia enterocolitica
Presentation can mimic appendicitis |
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Yersinia enterocolitica
Also associated with reactive a_________ |
Yersinia enterocolitica
Also associated with reactive arthritis |
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Campylobacter sp.
Small c____ or _-shaped motile bacterium Hard to grow Require ________ temperature, increased H2 and CO2 Six different species. Most common in U.S.= C. ______ |
Campylobacter sp.
Small comma or S-shaped motile bacterium Hard to grow Require elevated temperature, increased H2 and CO2 Six different species. Most common in U.S.= C. jejuni |
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C. ______ is the 2nd most common bacterial cause of infectious diarrhea in the US
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C. jejuni is the 2nd most common bacterial cause of infectious diarrhea in the US
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The stool assay for C. difficile toxin was positive
An endoscopy of the colon revealed the presence of raised, ______-white plaques overlying an erythematous and edematous mucosa The patient was diagnosed with p________________ colitis resulting C. difficile overgrowth from antibiotic therapy |
The stool assay for C. difficile toxin was positive
An endoscopy of the colon revealed the presence of raised, yellow-white plaques overlying an erythematous and edematous mucosa The patient was diagnosed with pseudomembranous colitis resulting C. difficile overgrowth from antibiotic therapy |
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C difficile
Secrete 2 toxins: Toxin A (Enterotoxin) Disrupts tight junctions between epithelial cells, increasing permeability Induces inflammatory cytokine production Chemotactic for neutrophils Toxin B (Cytotoxin) Disrupts cytoskeleton of epithelial cells |
C difficile
Secrete 2 toxins: Toxin A (Enterotoxin) Disrupts tight junctions between epithelial cells, increasing permeability Induces inflammatory cytokine production Chemotactic for neutrophils Toxin B (Cytotoxin) Disrupts cytoskeleton of epithelial cells |
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Treatment of C difficile - dc offending antibiotic; treat with what?
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Treatment of C difficile - dc offending antibiotic; treat with metronidazole or vancomycin
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