1. Pseudomonas
Dr. Dalia M. Mohsen
Dr. Dalia M. mohsen

2. 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.
Dr. Dalia M. mohsen

3. General Characteristics
Widely distributed in soil and water
Gram negative rods
Aerobic
Motile
Produce water-soluble pigments
Opportunistic pathogens
Dr. Dalia M. mohsen

4. 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 .
Dr. Dalia M. mohsen

5. P. aeruginosa
Forms 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.
Dr. Dalia M. mohsen

6. 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.
Dr. Dalia M. mohsen

7. Characteristics of Pseudomonas aeruginosa
Motile (by single or multiple polar flagella) gram-negative rods
Obligate (strict) aerobes (most strains)
Oxidase (usually) and catalase positive
Nonfermentative chemoheterotrophic respiratory metabolism
Dr. Dalia M. mohsen

8. 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
Dr. Dalia M. mohsen

9. 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
Dr. Dalia M. mohsen

10. 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
Dr. Dalia M. mohsen

11. What antibiotics to use
Aminoglycosides
Gentamycin, Amikacin, Cephalosporins
Cefotaxime. Ceftazidime. Ofloxacin,
Piperacillin, ticarcillin
Local application, colistin, polymyxin
Dr. Dalia M. mohsen

12. Pathogenicity Blue pus Causing the nosocomial infection
Suppurative otitis
Localised and generalised infections
Urinary tract infection after catheterization
Dr. Dalia M. mohsen

13. P. aeruginosa
Pathogenesis 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).
Dr. Dalia M. mohsen

14. Infection of Equipment's
Respirators
Endotracheal tubes
Can be Infected
All equipment's to be sterilized
Dr. Dalia M. mohsen

15. Toxins and enzymes in pseudomonas
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
Dr. Dalia M. mohsen

16. 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.
Dr. Dalia M. mohsen

17. 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.
Dr. Dalia M. mohsen

18. Identification with Chromagar
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.
Dr. Dalia M. mohsen

19. 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.
Dr. Dalia M. mohsen

20. 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.
Dr. Dalia M. mohsen

21. 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.
Dr. Dalia M. mohsen

22. Thank You
Dr. Dalia M. mohsen