Pseudomonas

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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

2. 2
Chapter NO # 06
 Soft tissue infections
 Sepsis
 Bone and joint infections
 Endocarditis
Health Problems with Cystic Fibrosis

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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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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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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