DR. DALIA M. MOHSEN 1 Dr. Dalia M. Mohsen PSEUDOMONAS
Dec 22, 2015
DR. DALIA M. MOHSEN 1
Dr. Dalia M. Mohsen
PSEUDOMONAS
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PSEUDOMONAS• A large group of aerobic, non sporing gram
negative bacteria motile by polar flagella• Found in water, soil, other moist environments
• Some of them are pathogenic to plants.
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- Widely distributed in soil and water
- Gram negative rods- Aerobic- Motile- Produce water-soluble
pigments• Opportunistic pathogens
GENERAL CHARACTERISTICS
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MORPHOLOGY• They are slender gram negative bacillus, 1.5 – 3 microbes x 0.5
microns
• Monoflgellar ?
• Non capsulated but many strains have mucoid slime layer
• Escape the defence mechanisms by loose capsule .
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P. aeruginosaForms round colonies with a fluorescent greenish color, sweet odor, and b-hemolysis.
Pyocyanin- nonfluorescent bluish pigment;
pyoverdin- fluorescent greenish pigment;
pyorubin, and pyomelanin
Some strains have a prominent capsule (alginate).
Identification of P. aeruginosa is usually based on oxidase test
and its colonial morphology: b-hemolysis, the presence of
characteristic pigments and sweet odor, and growth at 42 oC.
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CULTURAL CHARACTERS• Obligate aerobe, but grow anaerobically if nitrate is
available
• Growth occurs at wide range of temperatures 6-42 c the optimum being 37 c
• patches with metallic sheen are seen in cultures on nutrient agar.
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Motile (by single or multiple polar flagella) gram-negative rods
Obligate (strict) aerobes (most strains)Oxidase (usually) and catalase
positiveNonfermentative chemoheterotrophic
respiratory metabolism
Characteristics of Pseudomonas aeruginosa
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PIGMENT PRODUCTION Some strains produce diffusible pigments: • Pyocyanin (blue); fluorescein (yellow);
pyorubin (red) P. aeruginosa produces characteristic
grape-like odor and blue-green pus & colonies
Broad antibiotic resistance
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BIOCHEMICAL REACTIONS• Oxidative and Non fermentative• Glucose is utilized oxidatively• Indole, MR and VP and H2S tests are
negative• Catalase, Oxidase, and Arginine tests
are positive
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TYPING AND IMPORTANCE• Important cause of Hospital Infections
• Important for epidemiological purpose
• Serotyping
• Bacteriocins typing
• Pyocyanin
• Aeruginosin typing
• Restriction endonuclease typing with pulsed gel electrophoresis
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WHAT ANTIBIOTICS TO USE• Aminoglycosides• Gentamycin, Amikacin, Cephalosporins • Cefotaxime. Ceftazidime. Ofloxacin,• Piperacillin, ticarcillin• Local application, colistin, polymyxin
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PATHOGENICITY• Blue pus
• Causing the nosocomial infection
• Suppurative otitis
• Localised and generalised infections
• Urinary tract infection after catheterization
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P. aeruginosaPathogenesis and Immunity
This organism is widely distributed in nature and is commonly present in moist environments in hospitals. It is pathogenic only when introduced into areas devoid of normal defenses, e.g.,
1. Disruption of mucous membrane and skin.
2. Usage of intravenous or urinary catheters.
3. Neutropenia (as in cancer therapy).
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• Respirators• Endotracheal
tubes• Can be Infected • All equipment's to
be sterilized
INFECTION OF EQUIPMENT'S
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• Toxic extracellular products in culture filtrates
• Exotoxin A and S
• Exotoxin A acts as NADase resembling Diphtheria toxin
• Proteases,elastatese hemolysins and enterotoxin
• Slime layer and Biofilms
TOXINS AND ENZYMES IN PSEUDOMONAS
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PSEUDOMONAS PROMINENT HOSPITAL ACQUIRED INFECTIONS
It causes urinary tract infections,• respiratory system infections,
• dermatitis, soft tissue infections, bacteraemia,
• bone and joint infections,
• gastrointestinal infections
• variety of systemic infections, particularly in patients with severe burns and in cancer and AIDS patients who immunosuppressed.
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DIAGNOSIS OF P.AEROGINOSA INFECTION
Diagnosis of P,aeroginosa infection depends Isolation and laboratory identification of the bacterium.
(blood agar or eosin-methylthionine blue agar). Inability to ferment lactose, a positive oxidase reaction,
its fruity odour, and its ability to grow at 42°C. Fluorescence under ultraviolet light. Fluorescence is
also used to suggest the presence of P. aeruginosa in wounds.
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Pseudomonas sp. develop as blue-green coloured colonies, clearly visible under normal lighting conditions.
Other bacterial species are inhibited or give colourless colonies. Pseudomonas aeruginosa, Pseudomonas fluorescens, all give typical blue-green colony colouration and can be studied directly by serotyping or biochemical methods.
IDENTIFICATION WITH CHROMAGAR
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TREATING PSEUDOMONAS INFECTIONS
Combined antibiotic therapy is generally required to avoid resistance that develops rapidly when single drugs are employed.
Avoid using inappropriate broad-spectrum antibiotics, which can suppress the normal flora and permit overgrowth of resistant pseudomonads.
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PSEUDOMONAS AERUGINOSA A RESISTANT PATHOGEN
• Pseudomonas aeruginosa is frequently resistant to many commonly used antibiotics. Although many strains are susceptible to gentamicin, tobramycin, colistin, and amikacin, resistant forms have developed. The combination of gentamicin and carbenicillin is frequently used to treat severe Pseudomonas infections. Several types of vaccines are being tested, but none is currently available for general use.
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P. aeruginosa
Prevention and Control
Pseudomonas spp. normally inhabit soil, water, and vegetation and can be isolated from the skin, throat, and stool of healthy persons.
Spread is mainly via contaminated sterile equipment's and cross-contamination of patients by medical personnel.
High risk population: patients receiving broad-spectrum antibiotics, with
leukemia, burns, cystic fibrosis, and immunosuppression. Methods for control of infection are similar to those for other nosocomial pathogens. Special attention should be paid to sinks, water baths, showers, hot tubs, and other wet areas.
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Thank You