This document discusses Pseudomonas spp., including: - It is a gram-negative, oxidase-positive bacillus that is an opportunistic pathogen. - It causes various infections like pulmonary infections, burn wound infections, UTIs, and eye infections. - It has several virulence factors and mechanisms of antibiotic resistance that make it challenging to treat. - Diagnosis involves culture, biochemical tests, and antibiotic susceptibility testing. Oxidase and oxidation-fermentation tests can help identify it.

1. Sharq Elneil College
School of Medical Laboratory
Sciences
Department of Microbiology
Medical Bacteriology course
Pseudomonas spp
U.Mahadi Hassan Mahmoud
mahadi2010sd@yahoo.com
Bsc, Msc, MIBMS Microbiology

2. Pseudomonas
1882 Carle Gessard, a chemist and
bacteriologist from Paris, France,

3. Classification of Bacteria
Gram Stain
Gram- Gram-
Positive Negative
Cocci Bacilli Cocci Bacilli

4. Gram-negatitive Bacilli
Oxidase Test
Oxidase positive Oxidase Negative
O/F
O/F
O+/F- O+/F+ O+/F+
Pseudomonadaceae Vibrionaceae Enterobacteriaceae

5. General characters:
 Not member of enterobacteriaceae.
 It is similar to them in diseases, saprophytes and
commensal in the intestine of human.
 Oxidase positive.
 Obligate aerobe.
 Does not ferment glucose.
 Large group of microorganisms, more than 200
spp, most of them are saprophytes. The most
important species according to infection is
P. aeruginosa.

6. Morphology & stain:
 Aerobic, opportunistic pathogen
 Gram-negative bacillus
 Flagella

8. Culture characters:
 Non-fastidious.
 Aerobic organism.
 Blood agar: Large irregular colonies surround by
zone of β-haemolysis.
 MacConkey agar: Pale yellow colonies (NLF),
Large irregular colonies.
 CLED: Green-blue colonies (NLF), large and
irregular.
 Nutrient agar: Produced pigmented colonies.

9. Culture characters:
 Different type of pigment:
 Pyocynin: blue-green, water soluble and need
peptone water as substrate.
 Pyoverdin: yellow-green, fluorescence (UV) and
need phosphate as substrate.
 pyorubin (red)
 Pyomelanin: brown, need 1% tyrosine in media.
Musty smell (grape like smell due to
aminoacetophenone).

10. On MacConkey : NLF

11. On MacConkey agar

12. Pseudomonas on Blood agar


14. On Nutrient agar
Name this pigment?

15. On Nutrient agar
Name this pigment?

16. Viability:
 It can grow & life in water with small
nutrient.
 Highly resistant to antimicrobial agents, but
sensitive to the group of aminoglycosides
(e.g.: Gentamicin, tobramycin).

17. Biochemical reaction:
 One of the inert microorganism.
 Cannot ferment glucose, but attack it by
oxidation.
 Oxidase test: +ve.
 Citrate utilization test: +ve.
 Motility test: +ve.
 Indole test: -ve.

18. Oxidase test
 Principle:
 Certain organism produce oxidase enzyme that
oxidize oxidase reagents to give purple colour.
 Methods:
 Filter paper method:
 Test requirements:
 Freshly prepared 1% Oxidase reagent (tetramethyl-p-
phenylene diamine).
 Filter paper.
 Wood stick or glass rods.
 Take a colonies and put it in filter paper, add drop of
oxidase reagents and examined for purple colour.
 Oxidase +ve like Neisseria and Pseudomonas.

20. Oxidation Fermentation
 Principle:
 The test depends on fermentation of carbohydrate on
anaerobic condition of oxidation of it in aerobic
condition.
 Media content:
 2 media each contain nutrition, sugar and bromothymol
blue. One of them closed from air by paraffin oil.
 Results:
 Oxidative ferment sugar on open tube (Yellow colour).
 Fermentative but anaerobically give yellow on closed
tube.
 Facultative anaerobic ferment CHO on both tube
(Yellow).
 Non oxidative- Non fermentative– give Blue colour on
both tube.

21. Attack sugers by Oxiation and Not
Fermentation

22. Results
There are three types of reactions possible
Reaction 1 Reaction 2 Reaction 3
Non-Saccharolytic O-/F Oxidative O+/F- Fermentative O+/F+
Alcaligenes faecalis Pseudomonas Enterobacteriaceae
Open & covered remain green Open turns yellow Both turn yellow

23. Biochemical reaction:
 Urease test: -ve.
 H2S production test: -ve.
 MR / VP test: -ve.
 KIA: Butt Slant H 2S Gas
Alkaline Alkaline - -
 O F test: Open tube Sealed tube
Y G

24. Virulance Factors

26. Pathogenicity:
 Pulmonary Infections
 Burn Wound Infections and other skin and soft
tissue infections (life threatening)
 UTI’s (especially catheterized)
 External Otitis (malignant OE, swimmer’s ear)
 Eye Infections and corneal ulceration via
contaminated contact lens cleaning fluids
 Pseudomonal Endocarditis

27. Pulmonary Infections
 Can range from asymptomatic colonization to
severe necrotizing bronchopneumonia
 Colonization is seen in patients with cystic
fibrosis, chronic lung disease, and neutropenia
 Mucoid strains are commonly isolated from
chronic pulmonary patients and are more difficult
to eradicate
 Predisposing conditions include previous
therapy with broad spectrum abx

28. Pseudomonas PNA

29. Ecthyma Gangrenosum
 Ecthyma gangrenosum is a well recognized
cutaneous manifestation of severe,
invasive infection by Pseudomonas
aeruginosa that is usually seen in
immunocompromised, burn patients, and
other critically ill patients

30. Echtyma Gangrenosum

31. Malignant Otitis Externa

32. Pseudomonas Keratitis and Corneal
Ulceration

33. Endocarditis

34. LAB- Diagnosis:
 Specimen: according to the side of infection
( swabs, blood, urine, sputum……etc).
 Direct Gram stain (same specimen).
 Culture & incubation.
 Colonial morphology.
 Indirect Gram stain.
 Biochemical reaction.

35. Antimicrobial Susceptibility testing
 Sensetive to:aminoglycosides (e.g.:
Gentamicin, tobramycin
 Inherently resistant to many abx
 Can mutate to more resistant strains
during therapy
 Combination of active abx generally
required for successful therapy

36. Mechanisms of Antibiotic Resistance
in Pseudomonas aeruginosa

37. 