33-Pseudomonas

Question 1

What is a nonfermenter?

Answer 1

a) Bacteria that are able to catabolize glucose and therefore do not ferment

Question 2

Where are pseudomonas found?

Answer 2

i) soil, decaying organic matter, vegetation, and water.
ii) Also, it is found throughout hospitals on the surface of many things in rooms including equipment.
iii) Pseudomonads are not part of normal human flora, except in hospitalized patients and ambulatory, immunocompromised hosts.

Question 3

What is an opporunistic infection?

Answer 3

a) Opportunistic Infection: infection that is restricted to patients receiving broad-spectrum antibiotics that suppress the normal intestinal bacterial population or patients with compromised host defenses. Ex Pseudomonas

Question 4

What is a nosocomial infection?

Answer 4

b) Nosocomial Infection: an infection that is acquired while in a hospital

Question 5

What is the role of the adhesins in P. aeruginosa infections?

Answer 5

a) Adhesins (flagella, pili, LPS, alginate capsule): adherence to host cells is critical to establish infection, and the four adhesins assist P. aeruginosa in doing this.
i) Alginate capsule can form biofilms.

Question 6

What is the role of secreted toxins and enzmes in P. aeruginosa infections?

Answer 6

b) Secreted Toxins and Enzymes (exotoxin A, pyocyanin, pyoverdin, elastases, proteases, phospholipase C, exoenzymes S and T): toxins can be the causative agent for a disease, they cause tissue damage. Enzymes normally are used to degrade host cells to release the nutrients within.

Question 7

What is the role of the Exotoxin A in P. aeruginosa infections?

Answer 7

i) Most important toxin in P. aeruginosa is Exotoxin A which inhibits host cell protein synthesis.

Question 8

What is the role of the Phospholipase C in P. aeruginosa infections?

Answer 8

ii) Phospholipase C breaks down lipids and lecithin, facilitating tissue destruction

Question 9

Why is P. aeruginosa resistant to many antibiotics?

Answer 9

P. aeruginosa is inherently resistant to many antibiotics and can mutate to become more resistant, the major mechanism is mutation of porin proteins. P. aeruginosa produce many B-lactamases.

Question 10

P. aeruginosa- lab findings

Answer 10

(1) colonial characteristics: beta hemolysis, green pigment, grapelike odor
(2) simple biochemical tests: positive oxidase reaction; oxidative utilization of carbohydrates

Question 11

What pt’s are at risk for Burkholderia cepacia infections?

Answer 11

a) Pts with cystic fibrosis or chronic granulomatous disease (a primary immunodeficiency in which white blood cells have defective intracellular microbicidal activity).

Question 12

What pt’s are at risk for Stenotrophomonas maltophilia infections?

Answer 12

a) S. maltophilia (gram- rod) is a well-known opportunistic pathogen. S. maltophilia is resistant to most commonly used β-lactam (ex carbapenems which most gram- rods are sensitive too) and aminoglycoside antibiotics, so immuno-compromised pts who are receiving long-term antibiotic therapy with these drugs are at risk for S. maltophilia infection.

Question 13

Acinetobacter- clinical presentation

Answer 13

b) Acinetobacter (gram- coccobacilli) are ubiquitous opportunistic pathogens that infect the respiratory/urinary tracts and wounds. There are two groups, 1) A. baumannii: glucose oxidizing and 2) A. lwoffii and A. haemolyticus: glucose nonoxidizing
i) Like S. maltophillia, A. baumannii are often resistant to antibiotics including carbapenems, making treatment difficult.