Listeria, Pseudomonas, & Various Anaerobes Flashcards Preview

Bacteriology Lectures > Listeria, Pseudomonas, & Various Anaerobes > Flashcards

Flashcards in Listeria, Pseudomonas, & Various Anaerobes Deck (33):
1

Listeria organism

hemolysis?

metabolic profile?

motility?

  • Gram positive rod
  • Slight hemolysis
  • Acid but no gas from CHO fermentation...facultative psychrophile (facultative intracellular parasite)
  • Weird tumbling motility

2

Food sources of listeria

unpasteurized milk, cheese, processed meats

or long term storage of meats and cheese in the refrigerator

3

  • Adult presentation of listeria

 

  • Perinatal listeria from infected _____ during ____
    • What are the types?

Diarrhea & dysentery

*Followed by meningitis or bacteremia (occasionally myocarditis) in IC patients

 

From infected placenta during Third trimester

  • Early onset = stillbirth & granulomas
  • Late onset = Type 4b

4

Listeria pathogenic factors (5)

  1. Siderophores (bind iron)
  2. Intracellular growth
  3. Internalin = binds cadherin receptor (uptake into cell)
  4. Listeriolysin O = activated by low pH of phagolysosome
  5. ActA = causes actin polymerization (moves to new cell)

5

Listeria preferred antibiotic

ampicillin 

(or amp + aminoglycoside)

*erythromycin can also be used

6

Pseudomonas aeruginosa organism

respiration

other characteristics

  • gram negative rod (single polar flagellum)

 

  • respiratory metabolism but can use NO3- as electron acceptor. Can use many Carbon sources
  • Fruity aroma, blue-green fluorescent pigment

7

Major pseudomonas pathogenic factor?

How does this occur?

Biofilms

via homoserine lactones and  Quorum-sensing signal

(Pseudomonas Quinolone Signal = PQS)

8

Pseudomonas are almost always _______ infections

opportunistic, nosocomial

9

Who are susceptible to skin biofilm pseudomonas infections?

burn patients and diabetics

10

Cystic fibrosis presentation for pseudomonas

lung biofilms with high amts of persister cells

 

11

Pseudomonas causes what other localized infections? (5)

  • otitis externa
  • eye infections (#1 lasik complication...you'll get green eyes!)
  • UTI (catheters)
  • Ecthyma gangrenosum in diabetics
  • Folliculitis (from contaminated water)

12

What do ecthyma gangrenosum lesions look like?

erythematous, non-pyrogenic ulcerations

13

Does Pseudomonas cause bacteremia?

Yep.

Especially in Leukemia & burn patients, and diabetics

14

Is pseudomonas resident flora?

Yes, on moist areas of skin

NON-invasive in people with normal immunity

 

**CF patients have it as normal URT flora!

15

Pathogenic factors of pseudomonas (6)

  1. Adhesion pili
  2. Hypermutable strains in biofilm
  3. Persister cells
  4. Biofilm + Alginate capsule 
  5. LPS  (typical of G-)
  6. Type 3 Secretion System
  7. Toxins = exotoxins A and S, Elastase, Pyocyanin/Polychelin

16

Function of toxins A and S from pseudomonas

A = ADP ribosylates EF-2 (diptheria toxin analog)

S = ADP ribosylates H-ras p21; signals apoptosis

17

Pyocyanin and Pyochelin create ________

oxygen radicals

18

3 Control measures for pseudomonas

  • sterile environment (blue light?)
  • topical ABX
  • Prevention of biofilm (DNAase)

19

ABX for pseudomonas

Severe infection Tx?

Cipro is most frequently used (but resistance is problem)

Cipro + aztreonam

Severe = Gentamycin + ticarcillin or carbenicillin

**Meropenem +  levofloxacin can prevent

20

Why shouldn't we treat pseudomonas with quinolones?

Activates biofilm formation 

(PQS)

21

Other pseudomonads

Acinetobacter baumanii - ventilator associated

 

burkholderia cepacia - catheter associated

22

General anaerobes:

Infections are almost always _____

Prefer to live at ______. How is this made possible?

Mixed infections

Low redox potential (less O2) - which is generated by facultative organisms like E. coli

23

None of the anaerobes has ______. Thus...

cytochromes

...no ETC or respiration

24

Six common anaerobes

  • Bacteroides fragilis
  • Prevotella melaninogenica
  • Porphyromonas gingivalis
  • Fusobacterium
  • Peptostreptococcus
  • Propionibacterium acnes

25

Bacteroides: organism and location

virulence factors?

Gram negative rod that hangs out in colon

  • Antiphagocytic capsule
  • Can produce some SuperOxide Dismutase and CAT (so a little O2 resistant)
  • Extracellular enzymes- Neuraminidase and Heparinase

26

Prevotella organism, virulence factor, and infection location

Oral gram negative coccobacillus

Collagenase

Brain and Lung abcesses

27

Porphyromonas gingivalis organism, locations

Gram negative rod (oral)

implicated in gingivitis, oral abcesses, and infections of warm moist areas

28

Fusobacterium organism and location

gram neg fusiform

oral and colonic 

29

Peptostreptococcus organism and location

Gram positive coccus

Colonic

30

Propionibacterium acnes organism and location

Gram positive pleomorphic

Epidermal (acne, possibly brain abcesses)

31

What antibiotic is particularly good at treating anaerobes?

Metronidazole

32

What causes the abcesses in anaerobe infections?

production of tissue-destroying enzymes

33

General control of anaerobes

Drainage (also allows O2)

PenG (NOT for bacteroides or prevotella... use Metronidazole and clindamycin)

Ceph3 for brain abcess

2nd line drugs = Ceph2, Ceph3, and carbapenems