3.31.09 Pillinger. Pseudomonas

8/2/2019 3.31.09 Pillinger. Pseudomonas

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Pseudomonas Aeruginosa

A basic review

A Basic Review


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The basics

Aerobic, opportunistic pathogen

Gram-negative bacillus

Flagella


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Pathogenesis

Virulence Factors (structural components)

Alginate

Adherence proteins and pili

Lipopolysaccharide (LPS)

Procyanin


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Structure


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Structural Components

Adherence to host cells mediated by pili and nonpilusadhesins.

LPS (lipopolysaccharide) inhibiting antibiotic killing and

suppress neutrophil and lymphocyte activity

Alginate mucoid exopolysaccharide that forms a shinybiofilm protecting from antibodies, complement,

phagocytosis, and antibiotics

Procyanin impairs ciliary function, mediates tissuedamage through production of oxgen radicals


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Pathogenesis

Virulence Factors (toxins and enzymes):

Exotoxin A

Exoenzyme S Endotoxins

Phospholipase C

Elastase and Alkaline Protease


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Exotoxin A

Similar in structure to Diptheria toxin

Inhibits protein synthesis by ADP-ribosylating

EF-2 (G-protein)

Causes Dermatonecrosis in burn wounds,corneal damage in ocular infections, and tissue

damage in chronic pulmonary infections.

Also this toxin is immunosuppressive


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Exoenzyme S & T

ADP-ribosylates G-proteins including p21RAS interfering with host cell growth


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Phospholipase C

Heat labile hemolysin

Breaks down lipids and lecithin causingtissue destruction

Stimulates inflammatory response


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Elastase and Alkaline Protease

Destruction of elastin-containing tissues(blood vessels, lung tissue, skin), collagen,immunoglobulins, and complement factors

Can produce hemorrhagic lesions(ecthyma gangrenosum) associated withdisseminated infection

Inactivation of interferon and TNF-Alpha


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Epidemiology

Ubiquitous in moist environmental sites inthe hospital as well as nature

No seasonal incidence

Can transiently colonize the respiratory

and GI tract of hospitalized patients

Minimal nutritional requirements and can

tolerate broad temperature spectrum


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Clinical Disease

Pulmonary Infections

Burn Wound Infections and other skin and soft tissueinfections (life threatening)

UTIs (especially catheterized)

External Otitis (malignant OE, swimmers ear)

Eye Infections and corneal ulceration via contaminatedcontact lens cleaning fluids

Pseudomonal Endocarditis


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Pulmonary Infections

Can range from asymptomatic colonization to severe necrotizingbronchopneumonia

Colonization is seen in patients with cystic fibrosis, chronic lungdisease, and neutropenia

Mucoid strains are commonly isolated from chronic pulmonarypatients and are more difficult to eradicate

Predisposing conditions include previous therapy with broadspectrum abx (disrupts normal protective bacteria population and

use of respiratory therapy equipment (can introduce the organism tolower airways)

Mortality rate can be as high as 70% for invasive bronchopneumonia


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Pseudomonas PNA


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Ecthyma Gangrenosum

Ecthyma gangrenosum is a wellrecognized cutaneous manifestation ofsevere, invasive infection by

Pseudomonas aeruginosathat is usuallyseen in immunocompromised, burnpatients, and other critically ill patients


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Echtyma Gangrenosum


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Malignant Otitis Externa


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Pseudomonas Keratitis andCorneal Ulceration


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Endocarditis


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Antibiotic Resistance

Inherently resistant to many abx

Can mutate to more resistant strains duringtherapy

Penetration of abx highly dependent on outermembrane pores which can be altered

Production of B-lactamases

Combination of active abx generally required forsuccessful therapy

3.31.09 Pillinger. Pseudomonas

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