Pseudomonas aeruginosa original .pptx pptx

Pseudomonas aeruginosa original .pptx pptx

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  Pseudomonas aeruginosa Sneha kpaul II-MScMICROBIOLOGY Sri Ramakrishna college of arts and science for women
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  History  Pseudomonas aeruginosais a bacterium that was first isolated in 1882 by French pharmacist Carle Gessard from wound infections in soldiers whose bandages had a blue and green colour.  Gessard's study, titled "On the blue and green coloration of bandages", likely described pyocyanin, a blue/green compound with antimicrobial and toxin properties.  The name Pseudomonas comes from two Greek words, pseudo meaning "false" and monas meaning "single unit", while aeruginosa comes from the Latin word aerūgō meaning "rusted copper".
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  Morphology  It isa slender gram negative bacillus, 1.5-3μm × 0.5μm , motile by a polar flagellum.  Occasional strains have two or three flagella. Clinical isolates are often piliated. The flagella yield heat-labile antigens (H antigen).  It is noncapulated but many strains have a mucoid slime layer. Mucoid strains particularly isolates from cystic fibrosis patients.
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  Cultural characteristics  Itis obligate aerobe, but can grow anaerobically if nitrate is available. Growth occurs at a wide range of temperatures, 6-42C, the optimum being 37C.  It grows well on ordinary media, producing large, opaque, irregular colonies, with a distinctive, musty, or earthy smell.  Iridescent patches with metallic sheen are seen in cultures on nutrient agar.  It grows on MacConkey and DCA media, forming non- lactose- fermenting colonies. Many strains are hemolytic on blood agar.
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  Cont…  Ps. aeruginosaproduces a number of pigments, the best known being pyocyanin and fluorescin.  Pyocyanin is a bluish green pigment soluble in water and chloroform. Fluorescin is a greenish yellow pigment soluble in water not in chloroform. In old cultures it may be oxidized to a yellowish brown pigment.  Pyocyanin only produces Ps.aeruginosa but fluorescin may produced many other species also. Others pigments produced are pyorubin and pyomelanin. Ps aeruginosa emerging as the dominant bacterium in mixed infections.
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  Biochemical reactions  Themetabolism is oxidative and nonfermentive.  Indole, MR, VP, and H2S tests are negative.  Nitrates are reduced to nitrites and further to gaseous nitrogen.  Catalase, Oxidase and Arginine dihydrolase tests are positive.
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  Epidemiology  Pseudomonas speciesnormally inhabit soil, water, and vegetation and can be isolated from the skin, throat, and stool of healthy persons.  They often colonize hospital food, sinks, taps, mops, and respiratory equipment.  Spread is from patient to patient via contact with fomites or by ingestion of contaminated food and water.
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  Pathogenicity  pseudomonas aeruginosainfections varies from localized infections of the skin to life threatening systemic diseases.  Localized wound infections  Systemic infections – cystic fibrosis  Nosocomial infections – device associated infections - environmental moist conditions
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  clinical significance
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  Resistance  The bacillusnot particularly heat resistant, being killed at 55C in one hour but exhibits a high degree of resistance to chemical agents.  It is resistant to the common antiseptic quaternary ammonium compounds, chloroxylenol and hexachlorophene and may even grow profusely in bottles of such antiseptic lotions kept for use in hospitals.  Indeed, selective media have been devised for Ps. aeruginosa incorporating Dettol or cetrimide.  It is sensitive to acids, beta glutaraldehyde, silver salts and strong phenolic disinfectants.  Its susceptibility to silver has been applied clinically in the use of silver sulphonamide compounds as topical cream in burns.
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  Laboratory diagnosis  Thebacterium grows readily on the most media.  The identification of pigmented strains of the bacillus from clinical specimens is easy.  But about 10 percent of isolates may be nonpigmented.  It may be necessary to use selective media such as cetrimide agar for isolation from feces or other samples with mixed flora.  Repeated isolation help to confirms diagnosis.
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  How is aPseudomonas aeruginosa infection diagnosed?  A healthcare provider can diagnose a Pseudomonas aeruginosa infection after reviewing your medical history, asking about your symptoms and conducting a physical examination, which may include: Using a stethoscope to listen to your heart and lungs (auscultation).  Feeling your abdomen. Examining your skin. Looking at your eyes.  They'll also order tests to confirm their diagnosis. What tests will be done to diagnose a Pseudomonas aeruginosa infection? • A healthcare provider may order imaging tests to look for signs of infection in other areas of your body. • These tests may include: X-rays. Ultrasound. Magnetic resonance imaging (MRI).Computed tomography (CT) scan. • They may also take body fluid or tissue samples and send them to a lab to look for Pseudomonas bacteria.
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  control  Prevention ofPs aeruginosa cross-infection in hospitals requires constant vigilance and strict attention to asepsis.  Antibiotic treatment is not always satisfactory.  Pseudomonas vaccines are being tried in cystic fibrosis patients who are highly vulnerable to pseudomonas infection.  Specific antibacterial therapy constitutes only one aspect of the management of serious pseudomonas infections.  Occasional opportunist infection may be caused by a few other species, such as Ps. Fluorescens and Ps. putida.
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  Treatment  Ceftazidime isthe drug of choice, along with cotrimoxazole , tetracycline, amoxycillin clavulanate, or chloramphenicol . Prolonged treatment, for many months may be necessary.  Several types of vaccines are being tested, but none is currently available for general use. REFERENCE • Ananthanarayanan and panikers Text book of Microbiology.