Gram -ve Bacilli -Pseudomonas

Question 1

The most common pseudomonads

Answer 1

P.aeruginosa

Question 2

General characteristics of pseudomonads

Answer 2

1. Gram -ve rods
2. arranged in pairs
3. motile
4. obligate aerobes
5. oxidase +ve
6. non fermentive
7. Some strains are mucoid

Question 3

Pseudomonads are non-fermentive then how do they use carbohydrates?

Answer 3

they use carbohydrates through respiratory metabolism through oxidation

Question 4

Diffusable pigments of pseudomonads

Answer 4

1. Yellow flouroscein
2. Blue pyocyanin

they don’t appear seperated on culture they appear green

Question 5

Habitats of pseudomonads

Answer 5

1. water
2. soil
3. plants

Question 6

Epidemiology of pseudomonads

Answer 6

• They survive well in domestic environments
• Rarely it can be a part of normal flora

Question 7

pseudomonads is transmitted by:

Answer 7

• Ingestion of contaminated food or water
• exposure to contaminated medical devices and solutions
• penetrating wounds

Question 8

Question

Pseudomonads can ferment :
a. glucose
b. maltose
c.lactose
d. none of the following

from past papers

Answer 8

d. non of the following

pseudomonads are non fermentive

Question 9

Question

**Pseudomonas cause pulmonary infection with: **
a. Cystic Fibrosis patients
b. Immunocompriised patients
c.none of the above
d. all of the above

from past papers

Answer 9

a. cystic fibrosis patients

Question 10

Why do some strains contain mucoid

Answer 10

polysaccharide capsule

Question 11

Pseudomonads can be transmitted by:

Answer 11

1. Ingestion of contaminated food or water
2. Exposure to contaminated medical devices and solutions
3. Penetrating wounds
4. Rarely to be transmitted by person to person

Question 12

People at risk to get infected by pseudomonads :

Answer 12

1. Hospitalised patients
2. Ambulatory
3. Immuno-compromised patients

Question 13

Polysaccharide capsule protects the organism from:

Answer 13

1. phagocytosis
2. Activity of antibiotics

Question 14

The mucoid strains can revert to:

Answer 14

nonmucoid phenotype when cultured in vitro

Question 15

Pyocyanin

Answer 15

• Can mediate tissue damage
• Leads to enhanced attraction of neutrophils

Question 16

Resistance to antibiotics :

Answer 16

P.aeruginosa is one of the most resistant bacteria to many groups of antibiotics

Question 16

The exotoxins of pseudomonads :

Answer 16

1. Exotoxin A
2. Exoenzymes S and T
3. Elastases
4. Alkaline protease
5. Rhamnolipid

Question 17

Mechanism of resistance :

Answer 17

1. Production of many β- lactamases and carbapenemase

Question 18

clinical presentation of pseudomonads

Answer 18

• Pulmonary infections
• UTI infections
• Ear infections
• Eye infections
• Bacteremia

Question 19

culture media :

Answer 19

• can grow in most culture media

Question 20

Incubation conditions :

Answer 20

• can grow at 42 °C

Question 21

Biochemical Tests

Answer 21

1. oxidase+ve
   2.catalase +ve
2. non fermentive
3. nitrate reduction +ve
4. pyocyanin green pigment production