General Aspects带 Ecology Found throughout the environment Very simple nutritional requirements Not usually in normal flora unless hospitalized or immunocompromised BIOL 533 Lecture 13
BIOL 533 2 Lecture 13 General Aspects • Ecology – Found throughout the environment • Very simple nutritional requirements – Not usually in normal flora unless hospitalized or immunocompromised
General Aspects带 Virulence Possess number of structural factors and toxins Resistant to most common antibiotics Surprising that they do not constitute problem in general population BIOL 533 Lecture 13
BIOL 533 3 Lecture 13 General Aspects • Virulence – Possess number of structural factors and toxins – Resistant to most common antibiotics – Surprising that they do not constitute problem in general population
Microbial Physiology and structure Morphology Straight or slightly curved Gram bacterial Polar flagella; motile Some strains appear mucoid due to polysaccharide capsule Some produce diffusible pigments Pyocyanin(blue), fluorescin (yellow), pyorubin (red-brown) BIOL 533 Lecture 13
BIOL 533 4 Lecture 13 Microbial Physiology and Structure • Morphology – Straight or slightly curved Gram— bacterial • Polar flagella; motile – Some strains appear mucoid due to polysaccharide capsule – Some produce diffusible pigments • Pyocyanin (blue), fluorescin (yellow), pyorubin (red-brown)
Microbial Physiology and structure Physiolog Carbohydrate fermentation Use only few CHO using oxidative pathways Glucose, ribose, gluconate Oxygen is terminal electron acceptor Presence of cytochrome oxidase Distinguishes from Enterobacteriaceae Anarobic growth can occur by using mitrate as terminal acceptor BIOL 533 Lecture 13
BIOL 533 5 Lecture 13 Microbial Physiology and Structure • Physiology – Carbohydrate fermentation • Use only few CHO using oxidative pathways – Glucose, ribose, gluconate • Oxygen is terminal electron acceptor • Presence of cytochrome oxidase – Distinguishes from Enterobacteriaceae – Anarobic growth can occur by using mitrate as terminal acceptor
Virulence factors Adhesins: pili and nonplus adhesins Production of neuraminidase enhances adherence Alginate(mucoid layer): Protects against phagocytosis and facilitates adherence to host cells BIOL 533 Lecture 13
BIOL 533 6 Lecture 13 Virulence Factors • Adhesins: pili and nonpilus adhesins – Production of neuraminidase enhances adherence • Alginate (mucoid layer): Protects against phagocytosis and facilitates adherence to host cells
Virulence factors Elastase: cause damage to blood vessel walls, resulting in hemorrhagic lesions (ecthyma gangrenosum) Associated with disseminated Pseudomonas infections Pyocyanin: mediates tissue damage through toxic oxygen radicals BIOL 533 7 Lecture 13
BIOL 533 7 Lecture 13 Virulence Factors • Elastase: cause damage to blood vessel walls, resulting in hemorrhagic lesions (ecthyma gangrenosum) – Associated with disseminated Pseudomonas infections • Pyocyanin: mediates tissue damage through toxic oxygen radicals
Toxins EXotoxin A: mechaism like diphtheria toxin but much milder Two toxins are structurally and immunologically different Exoenzyme S: also ADP-ribosyltrnasferaser but heat stabile Found in 33. 3 clinical isolates BIOL 533 Lecture 13
BIOL 533 8 Lecture 13 Toxins • Exotoxin A: mechaism like diphtheria toxin, but much milder – Two toxins are structurally and immunologically different • Exoenzyme S: also ADP-ribosyltrnasferase, but heat stabile – Found in 33.3% clinical isolates
Clinical Syndromes of Pseudomonas aeruginosa Bacteremia Common in patients with neutropenia diabetes mellitus, extensive burns, d hematologic malignancies Originate from infections of lower respiratory tract, urinary tract, skin, and soft tissue Associated symptoms: minority of patients have ecthyma gangrenosum BIOL 533 Lecture 13
BIOL 533 9 Lecture 13 Clinical Syndromes of Pseudomonas aeruginosa • Bacteremia – Common in patients with neutropenia, diabetes mellitus, extensive burns, a hematologic malignancies – Originate from infections of lower respiratory tract, urinary tract, skin, and soft tissue – Associated symptoms: minority of patients have ecthyma gangrenosum
Clinical Syndromes of Pseudomonas aeruginosa Endocarditis Observed primarily in drug abusers Source is contaminated drug equipment Anatomy of heart affected Tricuspid valve: chronic and more favorable prognosis Aortic or mitral valve acute and frequently fatal BIOL 533 Lecture 13
BIOL 533 10 Lecture 13 Clinical Syndromes of Pseudomonas aeruginosa • Endocarditis – Observed primarily in drug abusers – Source is contaminated drug equipment – Anatomy of heart affected • Tricuspid valve: chronic and more favorable prognosis • Aortic or mitral valve: acute and frequently fatal
Clinical Syndromes of Pseudomonas aeruginosa Pulmonary infections Range from colonization to severe necrotizing bronchopneumonia Colonization seen in patients with cystic fibrosis, other chronic lung diseases, and neutropenia BIOL 533 Lecture 13
BIOL 533 11 Lecture 13 Clinical Syndromes of Pseudomonas aeruginosa • Pulmonary infections – Range from colonization to severe necrotizing bronchopneumonia – Colonization seen in patients with cystic fibrosis, other chronic lung diseases, and neutropenia
