Polar flagellated (motile), Gram- rod

Oxidase+

Lactase- (nonfermenter): White colonies on MacConkey's agar

Note: Very hardy. Survives in soaps, antieptics, low pH, chlorine; requires minimal nutrients (can eat oil)

Note: "Grape-like" aroma

Note: Fluoresces under polarized light (greenish pigment)

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Immunocompromised patients. Psuedomonas is an opportunistic pathogen; it is everywhere, but won't cause disease in healthy people (doesn't stick).

Cystic fibrosis and neutropenic patients are notoriously at risk. P. aeruginosa also sticks to burns, indwelling catheters, or any other breach of the immune system.

Culture medium designed to grow Gram- bacteria and to detect fermentation (tests for lactase). 

-- Contains bile salts, which kills most Gram+ organisms.

-- Lac+ organisms grow pink colonies; Lac- organisms grow white colonies. Color is based on pH indicator (lactose fermentation).

Fermenters on left, non-fermenters on right

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1. Reduced mucociliary function/ antibacterial capacity leads to chronic inflammation/damage; now P. aeruginosa can stick.

2. CF lung selects for P. aeruginosa variants with:

-- Increased alginate: P. aeruginosa surround selves with protective alginate gel; which makes it tough to cough up

-- Decreased proteases (don't understand why this matters)

Ubiquitous in the environment (soil, water, everywhere). Not a typical member of human flora.

*Remember: Relevant epithelia must be damaged for Pseudomonas to stick.*

1. Bacteremia

Note: 10-20% of all Gram- bacteremias; 30-70% mortality

2. Endocarditis

Note: Particularly in IV drug abusers (right-sided endocarditis from venous inoculation)

3. Respiratory Infection

Note: 10% of nosocomial pneumonia; high mortality rate (up to 70%)

Note: Repeated infections in CF patients often critical to respiratory failure that leads to their death. Sputum samples can have 10⁸bacteria/ml (lots!)

4. Skin and soft tissue infections (burns, wounds)

Note: Skin infections often from whirlpool; remember Pseudomonas can survive pretty much anywhere.

The following can also be caused by Pseudomonas, but are usually caused by other organisms:

5. UTI: Usually ascending infection from biofilm formed on indwelling catheter, rarely descending (hematologic spread from bacteremia)

6. Meningitis/ brain abscesses: Spread from ear infection, direct inoculation, hematologic spread

7. GI infection: Anywhere along GI tube, diarrhea, several necrotizing enterocolitis

7. Ear, eye, bone, joint infection.

Adhesion

1. Pili

*. (Capsule)

Spread

2. Flagella

3. Proteases and phospholipases: Digest ECM and host membrane components. (E.g. elastase, phospholipase C, heat-stable phospholipase)

Immune Evasion

4. Capsule: Antiphagocytic, aids in adhesion, elicits cytokines (IL-1, IL-8, TNF)

5. Can form biofilm

Pathophysiologic

6. Exotoxin A: Inhibits protein synthesis.

7. Exoenzyme S: Alters host proteins. 

8. Endotoxin (LPS): Stimulates host inflammatory response.

Note: ENDOtoxin because it is part of Gram- outer membrane; it is not released. Not Pseudomonas-specific.

*. (Proteases and phospholipases) 

Hair-like protein projections from (bacterial) cell surface that are important in adhering to host epithelium. The tips contain lectins that bind to specific carbohydrate antigens on host epithelial cells.

(Aka Pseudomonas toxin.) Toxin produced by P. aeruginosa that ADP-ribosylates EF2, inhibiting protein synthesis. Similar to Diphtheria toxin.

Note: Repressed by iron (turned on in intracellular environments, where free iron is low).

Note: Tested as immunotoxin when fused to CD22, which is hyper-expressed on B cells in leukemia patients. 

Toxin produced by P. aeruginosa that alters host cell proteins by ADP-ribosylation (like exotoxin A). Transferred by type III secretion (needle-injection into host cell).

Class of bacteria that used to be classified as Pseudomonas.

B. cepacia (formerly P. cepacia) is associated with CF, septicemia, otitis

B. pseudomallei causes meliodosis (what the fuck is that?). Primarily seen in tropics.