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24 Cards in this Set
- Front
- Back
GENERAL CHARACTERISTICS OF ENTEROBA CTERIA CEAE
A. Morphology; 5 things -gram |
1. Gram-negative bacilli
2. Large organisms with parallel sides and rounded ends 3. Motile strains have peritrichous flagella 4. Many strains have surface pili 5. Some species are encapsulated |
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B. Growth
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1. Grow readily on simple media after 12 to 18 hours incubation
2. Rapid growth occurs under aerobic and anaerobic conditions |
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C. Antigenic structure and related to heat
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1. O antigen (somatic) - cell wall lipopolysaccharide (causes disease), LPS (heat stable)
2. K antigens - cell surface polysaccharide antigens (heat labile) 3. H antigens - flagellar proteins (heat labile) 4. Serotyping systems for classification of these organisms have been Established based upon these antigens, (eg. E. coli 0157:H7) |
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Criteria for classification to species level
3 types |
identified on the basis of 1.growth requirements and 2.biochemical characteristics together with
3. DNA homology data |
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All Enterobacteriaceae share the following biochemical characteristics 3
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a. Ferment glucose
b. Reduce nitrates to nitrites c. Oxidase negative |
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fermenting lactose makes
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pink colonies on MacConkey agar used for screening
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ferment lactose (pink)
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a. E. coll, Klebsiella, Enterobacter
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rarely lactose positive
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Salmonella, Shigella, Yersinia
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Toxins
1. Released when -Specific effects during infection include 2.pathogenesis of |
Endotoxins
a. Synthesized by all Enterobacteriaceae -cell wall is disrupted (cell dies -fever, leukopenia, activation of blood coagulation factors . Enterotoxins are produced by some species and are important in the pathogenesis of diarrheal disease (travellers diarrhea) |
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Habitat
survive in Increased colonization |
1. Inhabitants of the lower gastrointestinal tract of humans and animals
2. Survive readily in nature - free living where water and minimal energy sources are available 3. of hospitalized patients observed |
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6 Diseases caused by Enterobacteriaceae
a liitle like what bacteria |
1.Urinary tract infections most common
2. Diarrhea (gastrointestinal) 3. Meningitis (elderly, neonates, neurosurgical patients) 4. Bacteremia (sepsis) 5. Pneumonia (especially hospital acquired) 6. Wounds and abscesses -staff |
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III. SPECIFIC GENERA AND 8 DISEASES OTHER THAN THOSE ASSOCIATED WITH DIARRHEA
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escherichia coli, klebsiella, enterobacter, serratia, citrobacter, proteus, proviencia, morganella
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3 most common associated with disease
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e. coli, klebsiella, proteus
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e. coli
found in leading cause of |
a. Most commonly encountered enteric rod in the colon
b. Leading cause of opportunistic infections |
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identify e. coli 2 things
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) lactose fermenter (pink colonies on MacConkey)
3) beta-hemolytic |
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. E. coli Infections
E. coli sp. are one of the most common cause |
a. Most common cause of urinary tract infections (35-90%)
b. Intestinal infections c. Meningitis 1) E. coli sp. are one of the most common causes of neonatal meningitis 2) 75% of strains possess Kl capsular polysaccharide d. Nosocomial and opportunistic infections 1) wounds / abscesses 2) bacteremia 3) pneumonia |
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-are the most important species of klebsiella
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(K. pneumoniae and K. oxytoca are the most important species
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1. 3 Klebsiella Bacteriology
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a. Non-motile
b. Lactose fermenter c. Possesses mucoid capsule important for virulence |
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3 Klebsiella Infections
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a. Second most common urinary pathogen
b. Pneumonia (Friedlander's pneumonia (red jelly phlem)) c. Nosocomial (hospital) infections - multiple drug resistance a problem in this setting |
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C. Enterobacter
Bacteriology -common cause of .. -more or less virulent than kelvsiella? -Associated with hospital outbreaks related to -what else is a problem? |
15 species, 11 clinically significant)
a. Motile b. bactose fermenter nosocomial infections a. Less virulent than Klebsiella b.contaminated intravenous solutions c.Multiple drug resistance is a problem |
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Serratia (10 species or groups)
3 things to know |
1. Some strains may have red pigment
2. Truly an opportunistic pathogen (S. marcescens) 4. Multiresistant |
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E. Citrobacter
most important types Biochemically, serologically similar 2. Causes |
11 species or groups C.freundii, C. koseri are most important
-to Salmonella -neonatal meningitis and bacteremia |
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Proteus (4 species
which ones swarm which one is most important -what does it cause |
P. mirabilis, P. vulgaris "swarm" over agar surface
2. P. mirabilis is the most important; causes urinary, wound and bloodstream infections |
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G. Providencia, Morganella
Frequently associated with -often... |
nosocomial spread, especially among patients with indwelling urinary catheters
H. Often very resistant to antimicrobials |