Pseudomonas

Pseudomonas

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  1 Chapter NO #06 PSEUDOMONAS Introduction:  Large group of aerobic  Non sporing  Gram negative  Motile by polar flagella  Ubiquitous  Oppurtunistic infections  Newer genera-Burkholderia Stenotrophomonas Species  Pseudomonas aeruginosa  Stenotrophomonas maltophila  Burkholderia cepacia  Burkholderia mallei  Burkholderia pseudomallei Pseudomonas aeruginosa About Pseudomonas aeruginosa  gram-negative aerobe bacteria  Commonly found in the environment  At any moist location  Common cause of nosocomial infections P. aeruginosa is an opportunistic pathogen  Hardly any infections in the normal human host  Severe immunodeficiencies and medical devices predispose the patients to P. aeruginosa infections  Broad spectrum of clinical symptoms  Urinary tract infections  Pulmonary infections
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  2 Chapter NO #06  Soft tissue infections  Sepsis  Bone and joint infections  Endocarditis Health Problems with Cystic Fibrosis
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  3 Chapter NO #06 P. aeruginosa infections  P. aeruginosa infections are of particular concern for Cystic fibrosis patients  Burn patients  Hospitalised patients  Case mortality rate for patients infected with P. aeruginosa approaches 50% Nosocomial infections  Fourth most common isolated nosocomial pathogen accounting for approx.  10 % of all hospital acquired infections.  Patient-to-patient spread and direct patient contact with environmental reservoirs  disinfectants,  respiratory equipment,  food,  sinks, taps Cultural characteristics  Obligate aerobe  Wide range of temperature 5°c-42°c  optimum 37°c  Ordinary media –  large,opaque,irregular,with distinctive earthy smell Nutrient agar-  Colonies are smooth,large,translucent,low convex,2-4mm in diameter.  Produce sweetish aromatic odor  Greenish blue pigment diffuses
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  4 Chapter NO #06 Blood agar  Similar to nutrient agar  Many are haemolytic Mac conkey agar  Colourless,non lactose fermenters Cetrimide agar  selective media  Cetrimide agar is a type of agar used for the selective isolation of the gram- negative bacterium, Pseudomonas aeruginosa.  As the name suggests, it contains cetrimide, which is the selective agent against alternate microbial flora.  Cetrimide also enhances the production of Pseudomonas pigments such as pyocyanin and fluorescein, which show a characteristic blue-green and yellow-green colour, respectively.
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  5 Chapter NO #06 Diagnosis ofP. aeruginosa  Isolation and lab identification of the pathogen  P. aeruginosa grows wellon most laboratory media  Identified on the basis of its:  Gram morphology,  inability to ferment lactose,  a positive oxidase reaction,  its characteristic odor,  its ability to grow at 42° C. Biochemical reactions 1. O/F test-oxidative 2. Catalase-positive 3. Oxidase-positive 4. Nitrate reduction-positive 5. Indole test-negative 6. Methyl red test-negative 7. Vp test-negative 8. Citrate test-positive 9. Urease test-negative Mechanism OfPathogenesis Caused by exotoxins,proteases,elastases,haemolysins,lipases and enterotoxins  Exotoxin A-lethal toxin  Elastases-haemorrhagic lesions  Enterotoxins-diarrhoeal disease  Slime layer acts as a capsule and enhances virulence Treatment of P. aeruginosa infections  P. aeruginosa is frequently resistant to many commonly used antibiotics.  To archive synergy a combination of e.g. gentamicin and carbenicillin is frequently used.  No vaccines so far Prepared By Amjad Khan Afridi Date: 18th March, 2017