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45 Cards in this Set
- Front
- Back
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true or false
all members of Enterobacteriaceace family have Endotoxins and are Gram Negative |
True
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Describe the antigenic structure of the Enterics family
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K antigen (capsule): polysaccharide
H antigen (flagella): protein O antigen (somatic): LPS (endotoxin) |
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what is an important characteristic that divides the family Enterobacteriaceae?
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Lactose Fermentation
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the rapid lactose fermenters of the Enterics family are:
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Escherichia
Klebsiella Enterobacter |
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what are the frank pathogens of the Enterics?
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Salmonella, Shigella, Yersinia
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where are the enterics usually found?
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in or on man, in animals, on plants, and in soil and water
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what do the Enterics do in the intestine?
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synthesize vitamins and deconjugate bile acids
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who are the slow non-lactose fermenters of the Enterics?
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Proteus
Citrobacter Serratia Yersinia Shigella Salmonella |
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what can genetic exchange result in within the family of Enterics?
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transfer of lactose fermentation to Salmonella
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what does it mean for a enterotoxin to be cytotonic vs. cytotoxic
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Cytotonic: causes changes in cellular activity
Cytotoxic: cause cell destruction |
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what are the organisms in the Enterics family that have enterotoxin activity?
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E. coli
Salmonella Shigella Klebsiella |
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what correlates with decreased frequency of shock and death in gram negative bacteremia caused by the Enterics?
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high titers of O-specific IgG in man correlates with decreased frequency of shock and death in gram negative bacteremia
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Is E.coli a lactose fermenting microbe?
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YES
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what are the distinguishing characteristics of E. coli?
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Gram Negative
Facultative aerobe Non-spore forming LACTOSE fermenting rod |
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since E.coli is part of the normal flora of the gut how does it cause disease?
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when virulence factors are transfered to it from other Enteric family members
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what are the virulence factors of E. coli?
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1. Mucosal interactions
2. Exotoxin production: heat labile and stable toxin, shiga-like toxin 3. Endotoxin: Lipid A portion of LPS 4. Iron binding siderophore: obtains iron from human transferrin or lactoferrin |
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What type of disease is caused by E.coli with virulence factors?
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Diarrhea
Urinary tract infection Neonatal meningitis Gram-negative sepsis |
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what type of E.coli causes "traveler's diarrhea"?
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Enterotoxigenic E. coli.
affects the small intestine watery diarrhea, cramps, nausea, vomiting, low grade fever Plasmid mediated heat stable enterotoxins stimulate hypersecretion of fluids and electrolytes |
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what strain of E.coli causes Hemorrhagic Uremic Sydrome?
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mostly caused by 0157:H7 E.coli
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describe an infection of Enterohemorrhagic E.coli
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affects large intestine
initial watery diarrhea followed by bloody diarrhea with abdominal cramps and NO fever may progress to hemolytic uremic syndrome (HUS) |
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what is the toxin responsible for Enterohemorrhagic E. coli?
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mediated by cytotoxic Shiga toxins which disrupt protein synthesis > lesions with destruction of intestinal microvillus resulting in decreased absorption
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what can be used to screen for E.coli?
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sorbitol MacConkey (SMAC) media to screen and commercial antiserum on sorbital negative colonies
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what does Proteus most commonly cause?
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UTI
but can cause hospital acquired wound infections, septicemia, pneumonia in compromised host |
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Is Proteus a lactose fermenter?
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NO
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what is Proteus able to breakdown?
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UREA producing urease
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describe some distinguishing features of Proteus
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Non-fastidious
Facultative anaerobe bile tolerant Alkaline pH unpleasant odor Highly motile |
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how do you differentiate between Proteus mirabilus and Proteus vulgaris?
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P. mirabilus: indole -
P. vulgaris: indole + |
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what is it important to differentiate between Proteus infection and what other bacteria?
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Rickettsia
this is done by mixing serum with Proteus strains to determine if there are antibodies in the serum that react with Proteus antigens. If these antibodies are present this suggest that the patient has been infected with Rickettsia |
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what is the 2d most common cause of neonatal meningitis?
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E. coli (group B streptococcus is the first)
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If you examine your patients urine and find: alkaline pH and suspect Proteus infection, what is this pH due to?
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the Proteus ability to split urea into ammonia and cardon dioxide
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an infection by the genus Serratia is most commonly found in:
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compromised patients
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what type of disease does Serratia cause in compromised patients?
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Endocarditis
Bacteremia Pulmonary |
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True or False
Serratia is typically quite resistant to antibiotics |
TRUE
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How is Serratia distinguished from other Enteric family members?
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Motile
DNase lipase gelatinase resistant to colistin and cephalathin |
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what type of bacteria is chromogenic at room temperature?
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Serratia
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what are the organisms in the Enterics family that have enterotoxin activity?
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E. coli
Salmonella Shigella Klebsiella |
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|
what correlates with decreased frequency of shock and death in gram negative bacteremia caused by the Enterics?
|
high titers of O-specific IgG in man correlates with decreased frequency of shock and death in gram negative bacteremia
|
|
|
Is E.coli a lactose fermenting microbe?
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YES
|
|
|
what are the distinguishing characteristics of E. coli?
|
Gram Negative
Facultative aerobe Non-spore forming LACTOSE fermenting rod |
|
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since E.coli is part of the normal flora of the gut how does it cause disease?
|
when virulence factors are transfered to it from other Enteric family members
|
|
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what are the virulence factors of E. coli?
|
1. Mucosal interactions
2. Exotoxin production: heat labile and stable toxin, shiga-like toxin 3. Endotoxin: Lipid A portion of LPS 4. Iron binding siderophore: obtains iron from human transferrin or lactoferrin |
|
|
What type of disease is caused by E.coli with virulence factors?
|
Diarrhea
Urinary tract infection Neonatal meningitis Gram-negative sepsis |
|
|
what type of E.coli causes "traveler's diarrhea"?
|
Enterotoxigenic E. coli.
affects the small intestine watery diarrhea, cramps, nausea, vomiting, low grade fever Plasmid mediated heat stable enterotoxins stimulate hypersecretion of fluids and electrolytes |
|
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what strain of E.coli causes Hemorrhagic Uremic Sydrome?
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mostly caused by 0157:H7 E.coli
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|
|
describe an infection of Enterohemorrhagic E.coli
|
affects large intestine
initial watery diarrhea followed by bloody diarrhea with abdominal cramps and NO fever may progress to hemolytic uremic syndrome (HUS) |
