Pseudomonas

Non-fermentative gram-negative bacilli (part 2)

Genus Pseudomonas

accounts for the largest percentage of all non-fermenters isoloated from clinical specimens

Pseudomonas

• Gram-negative bacilli or cocobacilli

• Strictly aerobic

• Motile (polar flagella)

• (+) Oxidase except P. luteola and P. oryzihabitans

Pseudomonas

• (+) Catalase

• Grows on MAC Agar

• Oxidizer of carbohydrates

Pseudomonas aeruginosa

secretes or produces pigments, which is one of the identifying characteristics of

• Pyocyanine

• Pyoverdin

• Pyorubin

• Pyomelanin

what does Pseudomonas aeruginosa secretes or produce?

Pseudomonas aeruginosa

• Most clinically isolated species

• Survives in nature and hospitals

Pseudomonas aeruginosa

• Opportunistic pathogen

• Can cause community or hospital acquired infections

• It will cause a disease or sickness to your patient, especially if the host’s immune system is immunocompromised

Pseudomonas aeruginosa

• Causes nosocomial infection

• Rarely part of the normal flora of healthy humans

found in the environment, in soil, water, and plants

what is the habitat or reservoir of Pseudomonas aeruginosa

Pseudomonas aeruginosa

• Survives well in domestic environments such as in hot tubs, whirlpools, contact lens solutions

• In the hospital environment, it will dwell in the sink, shower, respiratory equipment

• Folliculitis

• Otitis externa

• Infection following trauma

• Osteomyelitis

• Endocarditis

• Respirtaory infection in cystic fibrosis px - In IV drug users

• The infection is due to the disruption of the protection provided by the skin; trauma

Community-acquired infections of Pseudomonas aeruginosa

• Bacteremia

• Urinary Tract Infection

Hospital-acquired infections of Pseudomonas aeruginosa

• Exotoxin A

• Endotoxin (Lipopolysaccharide)

• Proteolytic enzymes

• Alginate

• Pili

• Motility (flagella)

Virulence factors of Pseudomonas aeruginosa

Pseudomonas aeruginosa

has several exotoxins, such as proteases, hemolysines, lecithinase, elastase, and deoxyribonucleases

exotoxin A

The most important exotoxin of Pseudomonas aeruginosa is ____. Functions similar to diphtheria toxin by blocking protein synthesis, which kills the host cells

Proteolytic enzymes and hemolysines

capable of destroying cells and tissues

pili

On the bacteria surface, the ____ mediate attachment of the organism to host cells

Alginate

It is a polysaccharide polymer, and when there is overproduction of ____, it causes mucoid colonies and production of biofilm, therefore contributing to the infection potential of patients with cystic fibrosis. ____ will also allow the organism to inhibit phagocytosis

PYOVERDIN

• Yellow-green pigment

• Water-soluble

• NOT Chloroform extractable

• Fluoresces under short-wavelength ultraviolet light

PYOCYANIN

• Blue phenazine pigment

• Water-soluble

• Chloroform extractable

• Combining with pyoverdin produces the characteristic green color

• No other non-fermentative gram-negative bacillus produces this

PYOCYANIN

Its presence can be used to specifically identify P. aeruginosa

PYOCYANIN

Produces reactive oxygen species which causes damage to cells

PYOCYANIN

• The reactive oxygen species are also bacteriocidal to the organism

• In order to protect itself from destruction, the organism produces the enzyme catalase

PYORUBIN

a red pigment

PYOMELANIN

a brown or black pigment

• ECTHYMA GANGRENOSUM

• JACUZZI / HOT TUB SYNDROME

• NAIL INFECTION

P. aeruginosa can cause several conditions such as:

ECTHYMA GANGRENOSUM

P. aeruginosa may invade and destroy the walls of the subcutaneous blood vessels, resulting in the formation of cutaneous papules that become black and necrotic

JACUZZI / HOT TUB SYNDROME

In swimmers and divers, a necrotizing rash develops in users in recreational facilities that are infected with P. aeruginosa

NAIL INFECTION

• The artificial nails, the nail beds become infected with the organism

• Can cause a greenish discoloration on the nail bed

• GRAM STAINING

• CULTURE

• BIOCHEMICAL TESTS

LABORATORY DIAGNOSIS of Pseudomonas aeruginosa

Gram-negative bacilli or cocobacilli

GRAM STAINING of Pseudomonas aeruginosa

CULTURE for Pseudomonas aeruginosa

Colonies usually grow well on most routine laboratory media

CULTURE for Pseudomonas aeruginosa

On MAC agar, you will see colorless colonies since your organism is a non-lactose fermenter

CULTURE for Pseudomonas aeruginosa

On Sheep Blood Agar, P. aeruginosa colonies are beta-hemolytic

• Produce flat spreading colonies

• Produce fruity grape-like odor caused by the presence of 2-aminoacetophenone

BIOCHEMICAL TESTS for Pseudomonas aeruginosa

• (+) Arginine dihydrolase

• (+) Citrate and Oxidase

BIOCHEMICAL TESTS for Pseudomonas aeruginosa

• Dentrification of nitrates and nitrites

• Grows at 42 deg C

• Acetamide utilization

cetramide agar

A very specific agar for Pseudomonas aueroginosa is

Cetramide agar

a selective and differential medium for the identification of Pseudomonas aeruginosa

Cetramide

acts as a detergent and inhibits most bacteria

Cetramide

Also enhance the production of the pigments

Alkaline slant over alkaline butt, no gas, no hydrogen sulfide

what is the result of the Triple Sugar Iron for Pseudomonas aeruginosa

SUSCEPTIBLE and RESISTANT

ANTIMICROBIAL SUSCEPTIBILITY TESTING for Pseudomonas aeruginosa

SUSCEPTIBLE

Aminoglycosides, piperacillin and ticarcillin, 3rd and 4th generation cephalosporins (Ceftazidime and Cefeprime), carbapenems (except entrapenem) and the fluoroquinolones

RESISTANT

Innately resistant to penicillin, ampicillin, 1st and 2nd generation cephalosporins, trimethoprim-sulfamethoxazole (SXT), Chloramphenicol and tetracyclines, tigecycline, entrapenem, nitrofurantonin

Pseudomonas Fluorescent Group

Produces pyoverdin

Pseudomonas Fluorescent Group

• Pseudomonas aeruginosa

• Pseudomonas fluorescens

• Pseudomonas putida

• Pseudomonas veronii

• Pseudomonas monteilii

• Pseudomonas mosselii

Pseudomonas Non-fluorescent Group

• Pseudomonas stutzeri

• Pseudomonas mendocina

• Pseudomonas alcaligenes

• Pseudomonas pseudoalcaligenes

• Pseudomonas luteola

• Pseudomonas oryzihabitans

42 deg Celsius

In the fluorescent pseudomonas group, only P. aeruginosa grows at

Oxidize Xylose

P. montelii can be distinguished from P. putida by its inability to

P. putida

In Gelatin Liquefied, both can be distinguished from Pseudomonas fluorescens by their inability to liquefy gelatin.

P. fluorescens

Under gelatin liquefied, only ____ is positive

Arginine dihydrolase

For non-fluorescent group, P. stutzeri can be differentiated from P. mendocina by the ____ because (+) mendocina while (-) stutzeri

P. stutzeri

____ can grow in anaerobic environment in nitrate-containing media, which then differentiates it from other Pseudomonas

P. putida and P. fluorescens

both rarely causes clinical disease due to being of low virulence. But there are reported cases of UTI, post-surgical abscesses, emphyma, septic arthritis and other wound infections

P. putida and P. fluorescens

Both produce pyoverdin, but neither produces pyocyanin or grows at 42 deg C

P. putida and P. fluorescens

both cannot reduce nitrate to nitrogen gas, but they can produce acid from Xylose

P. putida

Gelatin hydrolysis negative

P. fluorescens

Gelatin hydrolysis positive

P. putida

has been associated with catheter-related sepsis in patients with cancer

Pseudomonas oryzihabitans

(-) Oxidase

Pseudomonas oryzihabitans

Found in Japanese rice paddies and has been isolated from hospital drains and respiratory therapy equipment

Pseudomonas oryzihabitans

This organism has been isolated from the eye of one patient with post-operative endophthalmitis

Pseudomonas luteola

(-) Oxidase

Pseudomonas luteola

Recovered as the only isolated from a case of prosthetic valve endocarditis and subdiaphragmatic abscess and multiple brain abscess in a child

Pseudomonas luteola

Can be differentiated from oryzihabitans by the ONPG test (Onitrophenyl-beta-D-galactopyranoside) and esculin hydrolysis