By-Pratyush Harsh & Sourav Nayak

PSEUDOMONAS

AERUGINOSA

A PROJECT ON

Pseudomonas aeruginosa

• Gram-negative aerobe bacteria.

• Commonly found in the environment.– At any moist

location

General Characteristics

- Widely distributed in soil and water

- Motile- Produce water-

soluble pigments• Opportunistic

pathogens

Pratyush Harsh and Sourav Nayak

Structure of Pseudomonas

Pratyush Harsh and Sourav Nayak

• The bacterial cell contains an outer capsule and a tough cell wall made up of lipopolysaccharide as a plays a main role in protection and as a barrier between host and pathogen. It has a flagella and pili that helps in locomotion. It can form a biofilm or alginate membrane that can be beneficial or harmful to the environment. It has a single stranded DNA. Ribosomes are free in cytoplasm and the plasmids that are extra nuclear DNA.

• Pseudomonas bacteria are generally aerobic rod-shaped bacteria that are known for their metabolic diversity

• Some species of this bacteria, such as P. aeruginosa, are opportunistic pathogens that secrete extracellular proteases and adhere and invade host tissue. More than half of the clinical isolates of Pseudomonas bacteria produce pyocyanin, a blue-green pigment.

Growing on

• NUTRIENT AGAR• Blood agar• Mac conkey agar

7Pratyush Harsh and Sourav Nayak

Mac Conkey Agar

Blood Agar Nutrient Agar

Gram Staining• The Gram-positive bacterial cells showed violet but Gram-negative

cells turned pink/red coloration . Result: Stained Pink color: Gram –ve

The Gram negative cell wall contains a thin Peptidoglycan layer and does not hold onto the crystal violet stain.

NUTRIENT AGAR• Nutrient agar- Colonies,large,

translucent. Produce sweetish

aromatic odor Greenish blue pigment

diffuses

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TOXINS AND ENZYMES IN PSEUDOMONAS

• Toxic extracellular products in culture filtrates

• Exotoxin A and S• Exotoxin A acts as

NADase resembling Diphtheria toxin

• Proteases, hemolysins and enterotoxin

• Slime layer and Biofilms10

P. AERUGINOSA IS AN OPPORTUNISTIC PATHOGEN

• Extremely broad host spectrum• Hardly any infections in the

normal human host• Severe immunodeficiencies • Broad spectrum of clinical

symptoms– Urinary tract infections – Pulmonary infections– Soft tissue infections– Bone and joint infections– Endocarditis

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12Pratyush Harsh and Sourav Nayak

PYOCYNIN PYOVERDIN

TREATMENT OF P. AERUGINOSA INFECTIONS

To archive synergy a combination of e.g. gentamicin and carbenicillin is frequently used. • No vaccines so far• P. aeruginosa is resistant to many

antibiotics. It becomes dominant when more susceptible bacteria of the normal flora are suppressed.

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Resistance• Killed at 55oc in 1 hour• High resistance to chemical agents• Resistance to quaternary ammonium compounds.• Resistant to Hexachlorophenes.• Grows also in antiseptic bottles.• Dettol as Cetrimide as selective medium.• Sensitive to acids ,silver salts, beta glutaraldehyde.

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Prevention and Control

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• Pseudomonas 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 leukaemia, 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. 16

Prevention and Control