1、Lecture 13BIOL 5331PseudomonaceaeBIOL 533Lecture 13Medical MicrobiologyLecture 13BIOL 5332General Aspects Ecology Found throughout the environment Very simple nutritional requirements Not usually in normal flora unless hospitalized or immunocompromisedLecture 13BIOL 5333General Aspects Virulence Pos
2、sess number of structural factors and toxins Resistant to most common antibiotics Surprising that they do not constitute problem in general populationLecture 13BIOL 5334Microbial Physiology and Structure Morphology Straight or slightly curved Gram bacterial Polar flagella;motile Some strains appear
3、mucoid due to polysaccharide capsule Some produce diffusible pigments Pyocyanin(blue),fluorescin(yellow),pyorubin(red-brown)Lecture 13BIOL 5335Microbial Physiology and Structure Physiology Carbohydrate fermentation Use only few CHO using oxidative pathways Glucose,ribose,gluconate Oxygen is terminal
4、 electron acceptor Presence of cytochrome oxidase Distinguishes from Enterobacteriaceae Anarobic growth can occur by using mitrate as terminal acceptor Lecture 13BIOL 5336Virulence Factors Adhesins:pili and nonpilus adhesins Production of neuraminidase enhances adherence Alginate(mucoid layer):Prote
5、cts against phagocytosis and facilitates adherence to host cells Lecture 13BIOL 5337Virulence 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 ox
6、ygen radicals Lecture 13BIOL 5338Toxins 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 Lecture 13BIOL 5339Clinical Syndromes of Pseudomonas ae
7、ruginosa 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 gangrenosumLecture 13BIOL 53310Clinical S
8、yndromes 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 fatalLecture 13BIOL 53311Clinical Syndromes of Pseudomon
9、as aeruginosa Pulmonary infections Range from colonization to severe necrotizing bronchopneumonia Colonization seen in patients with cystic fibrosis,other chronic lung diseases,and neutropeniaLecture 13BIOL 53312Clinical Syndromes of Pseudomonas aeruginosa Ear infections Swimmers ear:can be managed
10、with topical antibiotics and drying agents Malignant external otitis:more virulent;can invade underlying tissues and cause death Surgical and antimicrobial intervention requiredLecture 13BIOL 53313Clinical Syndromes of Pseudomonas aeruginosa Burn infectionssevere burns Colonization of wound followed
11、 by local vascular damage and tissue necrosis Leading to bacteremia Predisposition Moist tissue surface and absence of neutrophils Topical creams and wound management has had only limited successLecture 13BIOL 53314Clinical Syndromes of Pseudomonas aeruginosa Other infections Localized in gastrointe
12、stinal and urinary tracts Eye and central nervous system Musculoskeletal systemLecture 13BIOL 53315Clinical Syndromes of Pseudomonas aeruginosa Prerequisites for infection Presence of organism in moist reservoir Circumvention or absence of host defenses Cutaneous trauma Elimination of normal flora N
13、eutropeniaLecture 13BIOL 53316Laboratory Diagnosis Grow on most common laboratory media Identification Morphology Colony size and hemolysis:flat colony with spreading border Pigmentation:green Odor:sweet,grape-like Oxidase+Lecture 13BIOL 53317Treatment Resistant to large number of antibiotics Proble
14、ms:Production of-lactamase Aminoglycosides ineffective in acidic environment of abscess Successful treatment Combination of-lactum antibiotic and amioglycosideLecture 13BIOL 53318Prevention Possibly impossible in hospital environment Prevent inappropriate use of broad-spectrum antibioticsLecture 13BIOL 53319Lecture 13 Questions?Comments?Assignments.
