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Gram negative bacilli, not Enterobacteriaceae? (5)
Medically important Pseudomonads? Why such a problem?
(also P. fluorescens, P. putida, P. stutzeri but RARE)
Problem bc can grow on basically anything where there's moisture
- think faucets and drains in hospitals
--> never wash respiratory equiptment in tap water***
- soil, water, man-made solutions
- even in IV bags and disinfectants
- artificial nails
Can use many different organic compounds for growth
--> notorious hospital acquired infections
Previously classified as Pseudomonas? Clinical disease?
- respiratory colonization in CF
- hospital acquired pathogen
- resistant to most common Abx
Which species has associated parts/toxins? Function?
LasA and LasB
Pili --> adherence
Exotoxin A --> ADP-ribosylates EF2
- mucoidy phenotype in CF
LasA +LasB = elastase
- degrade elastin
Endotoxin = LPS
- all gram negative bacteria
- TLR 4 trigger
Mechanism of quorum sensing?
Way for bacteria to sense their numbers
- Bacteria express QS autoinducer and R' for autoinducer
- if only a few bacteria, small concentration of autoinducer
--> keep virulence low bc if trigger immune system, bacteria will lose
If numbers high
- high concentration of autoinducer
--> increase virulence factors
- power in numbers
Pseudomonas aeruginosa clinical disease? (5)
- copious purulent secretions
--> repeated bouts of respiratory infections
- cannot eradicate
- esp mechanically ventilated patients***
- may cause necrotizing pneumonia (remember have elastase proteins - LasA, LasB)
- bacteremia, sepsis
Hot tub folliculitis
- ecthyma gangrenosum**
How dx pseudomonas aeruginosa? Tx?
- produces grape like odor
- produces fluorescent pigments
- blue/pyocanin and yellow/pyoverdin --> blue-green pigment
- can sometimes see in infected skin (remember foot pic)
- Oxidase positive (from electron transport chain - must be aerobic)
- intrinsic and acquired resistance
to penicillins, cephalosporins
- use 2 Abx at once
- Aminoglycosides and a cell wall agent (piperacillin, ceftazidime, imipenem, aztreonam)
Medically important Legionella and disease they cause?
17 other spp can infect humans
- most common of these --> L. micdadei
- Legionairre's disease
- headache, change in mental status
- nausea, V/D
- hyponatremia*** (low blood Na)
Transmission of Legionella pneumophila? Who at risk?
Aspiration of contaminated water
Inhalation of aerosol
-think vegetable mister at grocery store
Natural bodies of water
Cooling towers, water distribution systems
- parasitize ameobae
***NO human to human transmission
yet get nosocomial and community outbreaks
- people more prone to aspirate
Legionella unique mech of infection?
**facultative intracellular pathogen (like Listeria)
- primarily infect macs (Listeria does epithelial cells)
- thin pseudopod from mac
- engulfs in coiled vesicle
Fusion with lysosome to make a phagolyzosome blocked
- ER membranes with ribosomes are recruited to the phagosome
- bacteria survive and multiply WITHIN the phagosome
- eventually lyses cell
Factors associated with which species? Function?
- facultative intracellular pathogen
- lives and divides INSIDE phagosome
--> defect in organelle trafficking
--> blocks phagolysosome fusion
--> ribosome recruitment
(type IV secretion system - function same as type III)
- hydrolyze phosphatidyl choline in eukaryotic membranes
How dx Legionella pneumophila?
- poorly stained by gram stain
--> use silver staining
- grows on buffered charcoal-yeast extract agar (needs L-cysteine)
- need Abx bc grows so slowly
**ex of selective agar
Ab test, urinary antigen test
Clinical: low Na
- maybe not typical pneumonia
Tx with Abx
Vibrios spp and associated diseases? Transmission? (3)
- comma shaped
- cholera = severe diarrhea
- salt and fresh water
- from raw/undercooked seafood
- wound infections that are exposed to seawater** (think step on clam shell)
- life threatening bacteremia (liver disease pts, iron overload pts)
Helicobacter pylori disease? Risk factor for?
Peptic ulcer disease
- grows in mucus of gastric mucosa
Infection usually asymptomatic even with gastric inflammation (30% of pop infected)
Risk factor for adenocarcinoma, non-Hodgkin's lymphoma, low-grade B cell mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach
**ex. of cancer that can treat with Abx
Grows best in microaerophilic conditions
- slender spiral shape
Factors associated with which bacteria spp? Function?
flagella and curved shape
Type IV secretion system
- splits urea into ammonia
--> alkaline environment so can survive in acid stomach
flagella and curved shape
- allows motility through mucus lining (burrowing)
- adherance to gastric epith cells
--> vacuolation of epith cells (in culture)
- may contribute to ulcer formation
Type IV secretion
- secrete in toxins
- stimulates inflammation
How dx H. pylori?
- Giemsa stain (same as Y. pestis)or
- silver stain (same as Legionella)
Urease test - in bx
Urea breath test
- exhale radio labeled CO2 (liberated by urease)
Blood IgG test
- do not decrease for 6 months after successful Abx therapy
- not good for monitoring tx
Ab tests that measure antigens in stool
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