Pseudomonas aeruginosa

1
Pseudomonas aeruginosa

• By Jason Tidwell

2
Characteristics

• Gram negative
• Motile
• Aerobic
• Nonfermentive
• Two forms

3
Forms of P. aeruginosa

• Biofilm
• Planktonic form

4
Characteristics

• Gram negative
• Motile
• Aerobic
• Nonfermentive
• Two forms
• Planktonic
• Biofilm
• Optimum growth
• 37C, can grow in 42 C
• Minimal nutritional requirements
• Three colony types
• Rough
• Smooth
• Mucoid

5
Colony types
Small rough colonies
Large smooth colonies
Mucoid colonies
6
Virulence

• Elastase
• Elastase has several activities that relate to
  virulence. The enzyme cleaves collagen, IgG, IgA,
  and complement. It also lyses fibronectin to
  expose receptors for bacterial attachment on the
  mucosa of the lung. Elastase disrupts the
  respiratory epithelium and interferes with
  ciliary function.
• Protease
• Alkaline protease interferes with fibrin
  formation and will lyse fibrin.
• Exotoxin A
• Exotoxin A prevents elongation in eukaryotic
  protein synthesis

7
Virulence

• P. aeruginosa produces three other soluble
  proteins involved in invasion
• a cytotoxin (mw 25 kDa)
• The cytotoxin is a pore-forming protein.
• Two hemolysins.
• a phospholipase
• a lecithinase.
• One Pseudomonas pigment is probably a determinant
  of virulence for the pathogen.
• Pyocyanin
• The blue pigment impairs the normal function of
  human nasal cilia, disrupts the respiratory
  epithelium, and exerts a proinflammatory effect
  on phagocytes.

8
Pathogenesis

• Opportunistic pathogen that can infect almost any
  body site given the right predisposing
  conditions.

9
Diseases

• Endocarditis
• Respiratory infections
• Bacteremia and Septicemia
• Central Nervous System infections
• Ear infections including external otitis
• Eye infections
• Bone and joint infections
• Urinary tract infections
• Gastrointestinal infections
• Skin and soft tissue infections, including wound
  infections, pyoderma and dermatitis

10
Bacterial Endocarditis

• Pseudomonas aeruginosa infects heart valves.
• IV drug users
• prosthetic heart valves.
• The organism establishes itself on the
  endocardium by direct invasion from the blood
  stream.

11
Repiratory Infections

• Pneumonia
• Bacteremic pneumonia commonly occurs in
  neutropenic cancer patients undergoing
  chemotherapy.
• Lower respiratory tract colonization of cystic
  fibrosis patients

12
Cystic Fibrosis

• The most common lethal inherited disorder among
  Caucasians, with an incidence of approximately 1
  in 2500 live births.
• Characteristics
• pancreatic insufficiency
• abnormal sweat electrolyte concentrations
• production of very viscid bronchial secretions
• tend to lead to stasis in the lungs and this
  predisposes to infection.

13
Cystic Fibrosis
14
Bacteremia and Septicemia

• Primarily in immunocompromised patients.
• Predisposing conditions
• hematologic malignancies,
• immunodeficiency relating to AIDS
• Neutropenia
• diabetes mellitus
• severe burns.

15
Bacteremia and Septicemia

• Ecthyma gangrenosum
• Think Pseudomonas aeruginosa in neutropenic
  patients

16
Central Nervous System Infections

• Pseudomonas aeruginosa causes meningitis and
  brain abscesses.
• Portal of Entry
• Inner ear or paranasal sinus
• Inoculated directly
• Surgery
• Invasive diagnostic procedures
• Spreads from a another site of infection like the
  urinary tract

17
Ear infections

• External otitis
• "swimmer's ear"

18
Eye infections

• It is one of the most common causes of bacterial
  keratitis, and has been isolated as the etiologic
  agent of neonatal ophthalmia, which occurs in
  1-12 of newborn infants.

19
Bone and Joint Infections

• Direct inoculation of the bacteria or the
  hematogenous spread of the bacteria from other
  primary sites of infection.
• Blood-borne infections are most often seen in IV
  drug users, and in conjunction with urinary tract
  or pelvic infections.
• Chronic contiguous osteomyelitis
• The most common sites of involvement are the
  vertebral column, the pelvis, and the
  sternoclavicular joint
• Osteochondritis
• puncture wounds of the foot

20
Urinary tract infections

• Usually hospital-acquired and related to urinary
  tract catheterization, instrumentation or
  surgery.
• 3rd leading cause of hospital-acquired UTIs
• about 12 percent of all infections of this type.
• The bacterium is among the most adherent of
  common urinary pathogens to the bladder
  uroepithelium.
• Pseudomonas can invade the bloodstream from the
  urinary tract.
• source of nearly 40 percent of Pseudomonas
  bacteremias.

21
Gastrointestinal infections

• It can produce disease in any part of the
  gastrointestinal tract.
• Perirectal infections
• Pediatric diarrhea
• Gastroenteritis
• Necrotizing enterocolitis.
• The GI tract is also an important portal of entry
  in Pseudomonas septicemia.

22
Skin and Soft tissue infections

• wound infections, pyoderma and dermatitis
• Pseudomonas aeruginosa can cause a variety of
  skin infections, both localized and diffuse. It
  has also been implicated in folliculitis and
  unmanageable forms of acne vulgaris.
• The common predisposing factors
• are breakdown of the integument
• Burns, trauma or dermatitis
• high moisture conditions
• ear of swimmers and the toe webs of athletes and
  combat troops, in the perineal region and under
  diapers of infants, and on the skin of whirlpool
  and hot tub users
• AIDS

23
Resevoirs

• Ubiquitous to the soil, water, and vegetation
• can be isolated from the skin, throat, and stool
  of healthy persons
• In a hospital, it can be found in
• Disinfectants
• Respiratory
• Equipment
• Food
• Sinks
• Taps
• Mops

24
Transmission

• Patients usually become infected by contact
  spread, directly or indirectly, from
  environmental sites.

25
Transmission

• Visitors
• Patient transfers
• Hospital personnel
• Contact with fomites
• Ingestion of contaminated foods and water

26
Treatment

• Pseudomonas aeruginosa is frequently resistant to
  many commonly used antibiotics.
• Although many strains are susceptible to
  gentamicin, tobramycin, colistin, and amikacin,
  resistant forms have developed. 
• The combination of gentamicin and carbenicillin
  is frequently used to treat severe Pseudomonas
  infections.

27
Immune Defenses

• Phagocytosis by polymorphonuclear leukocytes is
  important in resistance to Pseudomonas
  infections. Antibodies to somatic antigens and
  exotoxins also contribute to recovery.
• Once P. aeruginosa infection is established,
  other antibodies, such as antitoxin, may be
  important in controlling disease.
• Cell-mediated immunity does not seem to play a
  major role in resistance or defense against
  Pseudomonas infections.

28
References

• Todar , Kenneth . "Pseudonmonas aeruginosa."
  Todar's Online Textbook of Bacteriology. 2004.
  University of Wisconsin-Madison Department of
  Bacteriology . 13 Mar. 2006 lthttp//textbookofbac
  teriology.net/pseudomo nas.htmlgt.
• Mims, Cedric, Hazel M Dockrell, Richard V.
  Goering, and Ivan Roitt. Medical Microbiology.
  3rd ed. Spain Mosby, 2004.
• Iglewski, Barbara H. . "Pseudomonas." 13 Mar.
  2006lthttp//gsbs.utmb.edu/microbook/ch02 7.htmgt.