Pseudomonas

• What are the main topics covered in the outline of the document on Pseudomonas Sp?

  • Historical perspectives
  • Pathogen characteristics
  • Epidemiology
  • Transmission
  • Virulence factors
  • Antimicrobial resistance
  • Treatment
  • Control
• When was Pseudomonas first noted in medical literature?

  In the 1800s
• What did physician Sedillot note about Pseudomonas in 1850?

  He noted blue-green discolouration of bandages with a peculiar odour
• Who extracted the blue-green pigment (pyocyanin) and in what year?

  Fordos in 1860
• What organism did Carle Gessard isolate in 1882?

  The organism previously called Bacillus pyocyaneus
• What are the characteristics of Pseudomonas species?

  • Ubiquitous Gram-negative bacteria
  • Found in soil, water, plants, insects, and animals
  • Pseudomonas aeruginosa is the most important species affecting humans
  • Genus includes more than 140 species
• What type of bacteria is Pseudomonas aeruginosa?

  Obligate aerobic Gram-negative motile rods
• What is the significance of the blue-green pigment (pyocyanin) in Pseudomonas aeruginosa?

  It is a characteristic pigment produced by the bacteria
• How does Pseudomonas aeruginosa derive energy?

  By oxidative mechanisms
• What is the oxidase reaction status of all Pseudomonas aeruginosa strains?

  All strains are oxidase positive
• What types of infections does Pseudomonas aeruginosa cause?

  • Community-acquired infections
  • Hospital-acquired infections (HAIs)
  • Ventilator-associated pneumonia
  • Catheter-associated urinary tract infections
  • Surgical site infections
  • Burn wound infections
  • Otitis externa
  • Keratitis
  • Endophthalmitis
  • Bloodstream infections
  • Cystic fibrosis
• Who is most commonly affected by Pseudomonas aeruginosa infections?

  Immunosuppressed patients such as those with leukaemia, AIDS, or transplant patients
• What are the two main types of transmission for Pseudomonas aeruginosa?

  • Endogenous transmission
  • Exogenous transmission
• What are some community reservoirs for Pseudomonas aeruginosa?

  • Home humidifiers
  • Whirlpools, hot tubs, spas
  • Swimming pools
  • Water-damaged homes
• What are some hospital reservoirs for Pseudomonas aeruginosa?

  • Sinks, taps, shower heads
  • Potable water
  • Respiratory therapy equipment
  • Hydrotherapy pools
  • Cleaning equipment
  • Endoscopes
• What are the virulence factors of Pseudomonas aeruginosa?

  • Pili: allows adherence, motility, and biofilm formation
  • Flagella: allows adherence and motility
  • Quorum sensing molecules: enable cell communication and biofilm control
  • Proteases: key role in corneal ulceration
  • Exotoxins and proteases (elastase): important in burn infections and sepsis
  • Pyoverdin and pyochelin: act as siderophores
• What role do efflux pumps play in Pseudomonas aeruginosa's antimicrobial resistance?

  They actively pump antimicrobial agents out of the bacteria
• What is intrinsic resistance in Pseudomonas aeruginosa?

  It relies on porins for nutrient entry and alteration reduces antibiotic entry
• What does OprD allow in Pseudomonas aeruginosa?

  It allows entry of carbapenems but not other beta-lactam agents
• What is the role of antimicrobial modifying enzymes in Pseudomonas aeruginosa's resistance?

  They confer resistance to beta-lactams except for fourth-generation cephalosporins and carbapenems
• What is acquired resistance in Pseudomonas aeruginosa?

  It predominantly confers resistance to beta-lactams and aminoglycosides, usually plasmid-mediated
• What is the commonest aminoglycoside-modifying enzyme in Pseudomonas aeruginosa?

  Aminoglycoside nucleotidyl transferase
• What are the active agents used in the treatment of Pseudomonas aeruginosa infections?

  • Beta-lactam agents: piperacillin, ticarcillin, ceftazidime, carbapenems
  • Aminoglycosides: gentamicin, tobramycin
  • Fluoroquinolones: ciprofloxacin
  • Polymyxins: colistin
• What are the control measures for Pseudomonas aeruginosa infections?


  • Avoid admitting critically ill patients to wards with established infections
  • Prevent contamination of antibiotics and therapeutic solutions
  • Monitor hospital water sources for contamination
• What is the main challenge in treating established Pseudomonas aeruginosa infections?

  They are difficult to eradicate
• What should be monitored to control Pseudomonas aeruginosa in hospitals?

  Water sources for contamination
• What is the significance of the yellow-green pigment (pyoverdin) in Pseudomonas aeruginosa?


  It acts as a siderophore
• What is the significance of the red pigment (pyorubin) in Pseudomonas aeruginosa?

  It is another pigment produced by the bacteria
• What is the significance of the black pigment (pyomelanin) in Pseudomonas aeruginosa?

  It is another pigment produced by the bacteria
• What confers resistance to penicillin?

  Extended-spectrum beta lactamases
• Extended-spectrum cephalosporins confers resistance to?

  Aztreonam
• What role do efflux pumps play in antimicrobial resistance for Pseudomonas aeruginosa?


  They actively pump antimicrobial agents out of the bacteria, conferring multidrug resistance
• What is acquired resistance in Pseudomonas aeruginosa?

  It predominantly confers resistance to beta-lactams and aminoglycosides, usually plasmid-mediated
• What are the active agents used to treat Pseudomonas aeruginosa infections?

  Beta-lactam agents, aminoglycosides, fluoroquinolones, and polymyxins
• What precautions should be taken to control Pseudomonas aeruginosa infections?


  • Avoid admitting critically ill patients to wards with established infections
  • Prevent contamination of antibiotic and therapeutic solutions
  • Monitor water sources in hospitals for contamination