Lecture 15 Flashcards
L. monocytogenesis stain
GramPos
L. monocytogenesis on a plate
Thin, tannish rods
L. monocytogenesis environment
Produces acid but no gas from fermentation
Psycrophile (cold temps-deli meat)
Motile at room temp but not 37° (diphtheriods are)
Facultative intracellular anaerobe
L. monocytogenesis transmission
Is a native flora in animals
Infection usually from food
L. monocytogenesis clinical manifestation
Diarrhea and dysentary
Followed by meningitis or bacteremia (occassionaly myocarditis) in IC patients and infants
Also two perinatal versions from infected placenta (can cross during 3rd trimester)
What are two outcomes of fetal infection from L. monocytogenesis
Early onset-fetal sepsis and still birth (granulomatosis infantiseptica)
Late onset-Infant bacterial meningitis
L. monocytogenesis pathogenesis
Iron binding protein (found in meat)
Intracellular growth (hijacks the actin-internalin)
Low pH of phagolysosome produces listeriolysin O (phospholipase)
Break out of phagolysosome via listeriolysin O
ActA protein causes actin to polymerize (shigella does this too)
Spread cell to cell (avoid Ab response and Abx Tx)
L. monocytogenesis control
No vaccines Amp preferred (also e-mycin)
Pseudomonas aeruginosa stain
GramNeg
Pseudomonas aeruginosa appearance
Rods with single flagellum
Pseudomonas aeruginosa oxygen?
Generally called obligate aerobe (can grow with nitrate as a final electron acceptor)
Pseudomonas aeruginosa found where?
Soil and aquatic habitat
Can use many carbon sources
Lives in moist areas of skin
What are two easy ways to identify Pseudomonas aeruginosa?
Fruit aroma
Green appearance
How does Pseudomonas aeruginosa colonize?
Quorum sensing for biofilm production (pseudomonas quinolone system-maybe quinolones Abx make this harder to treat?)
How does Pseudomonas aeruginosa often attack?
Almost always opportunistic
Nosocomial infection
Especially in burn PTs and diabetics (ecthyma gangrenosum)
CF PTs with biofilms in lungs (carry as URT flora)
Otitis externa (swimmer’s ear)
Eye infection (after trauma or surgery)
UTI from catheter or irrigation
Bacteremia in leukemia PTs, burn PTs, diabetics
Folliculitis (hot tub folliculitis) and acne
Pseudomonas aeruginosa pathogenesis
Adhesion pili for biofilm
Persister strains
Location in biofilms and alginate capsule inhibit phagocytosis
LPS
Exotoxin A (Dtx homolog-ADP ribosylates EF-2)
Exotoxin S (Signals apoptosis via inhibiting signal pathways)
Elastase (Destroys elastin in lungs)
Pseudomonas aeruginosa control?
Sterile precautions for burn PTs Topical Abx for wounds Prevent BF formations Very resistant to many Abx (cipro is good) Avoid monotherapy
Besides Pseudomonas aeruginosa what is another opportunistic in CF PTs?
Burkholderia cepacia (this is another pseudomonas) Also on cathetars (UTI)
What can cause ventilator-associated pneumonia?
Actinobacter baumanii (this is another pseudomonas)
Can cause septicemia
Very resistant
What is characteristic of almost all anaerobe infections?
They are mixed
Need facultative anaerobes (have enzymes to detoxify ROS) and to keep a reduced environment
When we talk about anaerobes, were are most infections?
Colon and mouth
Bacteroides fragilis is found where? Oxygen requirement? Stain
Colon
Anaerobe
GramNeg rod
Bacteroides fragilis virulence factors?
Has some enzymes for O2 detox
Antiphagocytic capsule
Neuraminidase and heparinase
LPS is not as toxic here
Bacteroides fragilis clinical manifestation? Tx?
Can cause abdominal abscesses
Aminoglycoside Tx
