Pseudomonas

Question 1

What is Pseudomonas?

Answer 1

A genus of Gram‑negative, aerobic, rod‑shaped bacteria found in diverse environments

Question 2

Which species is most clinically significant?

Answer 2

Pseudomonas aeruginosa — an opportunistic pathogen with intrinsic multidrug resistance

Question 3

What is LPS and what is its role?

Answer 3

Lipopolysaccharide (LPS) — a component of the outer membrane providing structural integrity and contributing to immune evasion

Question 4

What is the function of the flagellum?

Answer 4

Provides motility and helps trigger immune responses

Question 5

What is the function of pili?

Answer 5

Short hair‑like projections enabling attachment to surfaces and biofilm formation.

Question 6

What is the capsule/slime layer?

Answer 6

A protective barrier against antibiotics and phagocytosis; essential for biofilm formation

Question 7

What is a biofilm?

Answer 7

A community of bacteria encased in a self‑produced matrix called extracellular polymeric substances (EPS)

Question 8

Why are biofilms clinically important?

Answer 8

-Increase antibiotic resistance

-Protect bacteria from immune cells

-Allow survival for months on surfaces

-Provide resistance to desiccation, pH changes, toxins

Question 9

What is EPS?

Answer 9

Extracellular Polymeric Substances — a matrix of polysaccharides, proteins, and DNA that shields bacteria.

Question 10

What are multidrug efflux pumps?

Answer 10

Transport proteins that actively expel antibiotics from the bacterial cell

Question 11

What are beta‑lactamases?

Answer 11

Enzymes that break down beta‑lactam antibiotics, making them ineffective

Question 12

What are aminoglycoside‑modifying enzymes?

Answer 12

Enzymes that chemically alter aminoglycosides, preventing their antibacterial action

Question 13

What is the role of alginate?

Answer 13

A biofilm component that protects against antibiotics and phagocytosis.

Question 14

How does LPS contribute to virulence?

Answer 14

Causes inflammation and helps evade immune detection.

Question 15

What is Exotoxin A?

Answer 15

A toxin that inhibits protein synthesis → causes host cell death.

Question 16

What do elastases do?

Answer 16

Degrade immunoglobulins and structural proteins.

Question 17

What is alkaline protease?

Answer 17

An enzyme that breaks down phospholipids → tissue damage.

Question 18

What is pyocyanin?

Answer 18

A blue‑green pigment that generates reactive oxygen species (ROS) → damages host cells.

Question 19

What is pyoverdine?

Answer 19

A green iron‑chelating compound that transports iron into bacterial cells, supporting growth

Question 20

What environmental sources harbour Pseudomonas?

Answer 20

Soil, water, sinks, showers, humidifiers, air‑conditioning units.

Question 21

What healthcare sources harbour Pseudomonas?

Answer 21

Ventilators, catheters, dialysis equipment, contaminated dressings.

Question 22

Can Pseudomonas be part of human flora?

Answer 22

Rarely — mainly in hospitalised or immunocompromised patients.

Question 23

What lung infections does Pseudomonas cause?

Answer 23

Pneumonia, especially in cystic fibrosis, bronchiectasis, and ventilator‑associated pneumonia.

Question 24

What urinary infection does it cause?

Answer 24

Catheter‑associated UTI (urinary tract infection).

Question 25

What bloodstream infection does it cause?

Answer 25

Bacteraemia and sepsis, especially in immunocompromised patients.

Question 26

What skin/soft tissue infections occur?

Answer 26

Burn wound infections, diabetic foot infections

Question 27

What ear infections does it cause?

Answer 27

Otitis externa and malignant otitis externa (severe, invasive)

Question 28

What are respiratory symptoms of Pseudomonas infection?

Answer 28

Cough, green sputum, fever, dyspnoea

Question 29

What are urinary symptoms?

Answer 29

Dysuria, frequency, foul‑smelling urine.

Question 30

What are wound infection signs?

Answer 30

Green discharge, fruity odour, delayed healing.

Question 31

What causes the characteristic “grape‑like” smell?

Answer 31

2‑aminoacetophenone, a volatile organic compound (VOC).

Question 32

What patient factors increase risk?

Answer 32

-Hospitalisation (especially ICU) -Immunosuppression -Prolonged antibiotics -Devices (catheters, ventilators) -Cystic fibrosis or structural lung disease

Question 33

Why is susceptibility testing essential?

Answer 33

Pseudomonas has high intrinsic and acquired resistance → therapy must be guided by MIC (Minimum Inhibitory Concentration).

Question 34

What IV antipseudomonal beta‑lactams are used empirically?

Answer 34

Piperacillin/tazobactam (Tazocin), ceftazidime, cefepime

Question 35

What carbapenem is used?

Answer 35

Meropenem

Question 36

Why add aminoglycosides in severe infection?

Answer 36

Synergistic effect. Examples: amikacin, gentamicin, tobramycin

Question 37

What oral antibiotics treat Pseudomonas?

Answer 37

Fluoroquinolones — ciprofloxacin, levofloxacin (only oral options).

Question 38

What monobactam can be used?

Answer 38

Aztreonam

Question 39

What determines dosing adjustments?

Answer 39

EUCAST breakpoints and MIC values (susceptible, susceptible‑increased exposure, resistant).

Question 40

What infection control measures prevent Pseudomonas spread?

Answer 40

-Strict hand hygiene -PPE (gloves, apron) -Environmental cleaning -Isolation of multidrug‑resistant cases -Proper sterilisation of equipment

Question 41

Why is Pseudomonas aeruginosa clinically challenging?

Answer 41

Biofilm formation + multidrug resistance + potent virulence factors.

Question 42

What is the only oral antibiotic class effective against Pseudomonas?

Answer 42

Fluoroquinolones