Pseudomonas and ICU GRNs

Question 1

What drugs can treat pseudomonas infections ?

Answer 1

1) Piperacillin + Tazobactam
2) 3rd Generation Cephalosporins: ceftriaxone, ceftazidime
3) 4th generation Cephalosporins: cefepime
4) Ciprofloxacin
5) Aminoglycosides: gentimycin, amikacin (used in combination, nephrotoxinc)
6) polymyxins (used with gentimycin, highly nephrotoxic)
7) aztreonam – but usually a bad choice; only if pen allergic

Question 2

What are the common Manifestations of Pseudomonas?

Answer 2

• Pneumonia - HCAP, VAP, CAP
• Bacteremia, which can lead to endocarditis
• Ecthyma Grangrenosum (but not specific)
• Skin and soft tissue infections (burn patients)
• Wound infections
• Hot tub folliculitis
• Otits Externa (Swimmer’s ear; specific)

Rare: Osteomyelitis, UTI, eye infections

Question 3

Microbiology/Biochemistry of Pseudomonas

Answer 3

• Gram Negative Rod
• Aerobic
• Non lactose Fermenting
• Oxidase Positive
• Grape like odor

Question 4

Describe the microbiology and biochemistry of Pseudomonas?

Answer 4

○ Aerobic
		○ Gram Negative Rod 
		○ Non-lactose fermenting
		○ Glucose fermenting
		○ Oxidase Positive

Question 5

Epiemiology of Pseudomonas:

• where is it found
• who is at risk?
• where can it colonize ?

Answer 5

○ Ubiquitous in the environment
○ Throughout hospital environment
§ fluids (dialysis, ophthalmic, rinses, water taps)
§ equipment (whirlpools, respiratory, endoscopes, humidifiers, catheters)
- Airway is colonized by pseudomonas

Risk:
Disrupted physical barriers
Immune deficiencies
Chronic Lung disease (CF)

can colonize respiratory tract

Question 6

Pathogenesis of Pseudomonas:

• Describe virulence factors
• How does it form biofilms
• what toxins does it secrete?

Answer 6

Virulence: 
	 Adherence: pili, flagella 
	LPS - endotoxin -- biggest inducer of cytokine storm -- sepsis 
	Polysaccharide capsule, slime 
		○ 

Biofilm formation: Type IV pili; deposit glycopeptide

Exotoxin A - ADP Ribosylating EF2 (similar to diphtheria toxin)

Type II Secretions (Exoenzymes – ExoS)

Degredative Enzymes:
PLC, Elastase, Cytotoxin, Proteases

Question 7

What are the clinical Manifestations of Psuedomonas?

Answer 7

• PNA: (HCAP, VAP, CAP) – primarily nosocomial, possibly from hospital equipment
  worse with aspiration
• Bacteremia – which may lead to endocarditis
• Echthyma gangrenosum
• § Pseudomonas Skin and Soft tissue infections (burn patients, hot tub folliculitis, wound infections)

Otitis Externa

Osteomyelitis, Cath-UTIs, Eye infections

Question 8

Describe the biochemistry of Acinetobacter baumanii

Answer 8

- 		○ Gram Negative Coccobacillus 
		○ Non motile 
		○ Aerobic 
		○ Non-lactose fermenter 
		○ Glucose fermenter 
		○ Oxidase Negative (unlike pseudomonas)

Question 9

Epidemiology of Acinetobacter:

• where does it colonize?
• risks for infection?

Answer 9

• Colonizes the skin, respirtaory and GI tracts
• Nosocomial pathogen of the ICU
• Opportunistic

-

Question 10

Pathogenesis of Acinetobacter

Answer 10

• Survives for longer periods in dry conditions

- Polysaccharide capsule

Question 11

Clinical Presentations of Acinetobacter

Answer 11

ICU patients

	○ VAP 
	○ CAUTI  -- cathater associated blood stream infection 
	○ CLABSI -- Central line associated blood stream infection 
	○ Wound infections 
	○ Sacral decubitous ulcers

Question 12

Treatment for Acinetobacter

Answer 12

• Treatment of Acinetobacter — often use combination therapy

	○ 3rd and 4th generation cephalosporins 
	○ Carbapenems 
	○ Beta Lactams w/ beta lactamase inhibitor 
		§ Ampicillin/sulbactam 
		§ Sulbactam has activity by itself 
	○ Fluoroquonones 
	○ Aminoglycosides 
	○ Polymyxins -- high toxicity 
	○ Tigecyclin -- gets into bone and abscesses well, but leaves the blood stream too quickly for bacteremia

Question 13

name two other GN Rods of the ICU

what is the go to treatment

Answer 13

Stenotrophomonas maltophila
• Often colonizes respiratory tract (CF, Vents, etc)
Treated with TMP/SMX

• Burkholderia cepacia
  
  • seen mostly in CF