Pseudomonas

Question 1

P. aeruginosa

Answer 1

G-
Rod
Lactose/glucose-non-fermenting
Catalase +
Oxidase +
Motile
Obligate aerobe
Can grow in water (non-fastidious)
Ability to mutate --> mucoid
**opportunistic pathogen**
encapsulated

Question 2

P. aeruginosa Sx

Answer 2

yellow-green mucus, crackles
inflammation and sepsis
kidneys, lungs, urinary tract

Common w/clubbing/mild cyanosis cystic fibrosis and burns

CXR:
interstitial peribronchial markings

Question 3

P. aeruginosa virulence factors

Answer 3

Alginate: exopolysacc and glycocalix capsule that provides mucoid aspect; acts as adhesin, lowers phago/abx capabilities, and promotes biofilm formation

Adhesins: fimbriae/pili, flagella (respiratory tract), elastase/protease to digest fibronection and expose receptor

Question 4

P. aeruginosa Toxins

Answer 4

Exotoxin A:
fxn like diptheria toxin, ADP-ribosylation of EF-2 which inhibits elongation –> necrosis

Exoenzyme S:
ADP-ribosylating toxin, impair phago

LPS
-important for septicemic infection

Pyoverdin:
Yellow-green pigment, siderophore, regulator of other virulence factors

Pyocyanin:
blue pigment, catalyzes prod of superoxide/H202, stimulates IL-8 attracting neutrophils

Alkaline phosphatase:
tissue destruction, interfere w/host immune response

Phospholipase C:
Hemolysin, facilitates tissue destruction

Question 5

P. aeruginosa AbxR Mechanisms

Answer 5

low perm cell wall
mutations
resistance genes
biofilms

In CF, lungs surrounded by layer of alginate making them highly resistant to Abx tx

Question 6

Opportunities for P. aeruginosa

Answer 6

skin breakage/abrasions
artificial innoculation (catheters, etc.)
immunodeficiency/immunosuppression

Question 7

P. aeruginosa Clinical Diseases

Answer 7

Range: a-Sx to necrotizing bronchopneumo

1. pulmonary infections (CF, chronic lung disease, CHF, neutropenic pts)
2. skin/soft tissue (common w/burns and folliculitis – hot tub contaminations) nail infections, osteochondritis
3. eye infections (bacterial keratitis)
4. Swimmer’s Ear (otitis externa/chronic otitis media)
5. UTI (catheters–nosocomial)
6. endocarditis (IV drug users)
7. Bacteremia (neutropenia, diabetes, extensive bruns, AIDS, hematological malignanicies)

Question 8

P. aeruginosa Dx

Answer 8

Pigmentation and odor

• Pyoverdin: fluorescent light “wood’s lamp”
• Pycyanin: blue pus
• grape like odor

Culture
g-, b-hemolytic, oxidase +

Question 9

P. aeruginosa Tx

Answer 9

MDR – combo of b-lactam and aminoglycosides used

fluroquinolones, aminoglycosides, Zosyn (piperacillin and tazobactam)

Question 10

Burkholderia pseudomallei

Answer 10

G-
non-lactose fermenting
non-hemolytic
oxidase +
obligate aerobe
encapsulated

Question 11

B. pseudomallei Sx

Answer 11

bilateral pleural effusion
causative agent of melioidosis (pneumo, multiple abscesses, septicemia), found in soil
L50: < 10 organisms

Question 12

B. cepacia complex (BCC)

Answer 12

Gen: tough to kill, colonize surfaces, opportunistic

Sx: similar range of disease as pseudomonascan lead to fatal pneumo and sepsis w/high mortality

Virulence Fac: 
LPS
Lipase
Proteases
Flagella
Biofilms

infxn = contraindication for transplant in CF pts

Question 13

B. mallei

Answer 13

Normally found in equids, causes glanders

Aerosol, difficult dx, high mortality rate, intrinsic resistant to abx; encapsulated

Question 14

B. pseudomallei Tx

Answer 14

1st/2nd gen cephalo

genta, tobra, strepto

(usually pen/amp resistant)