NON-FERMENTING GRAM NEGATIVE BACILLI Flashcards
(13 cards)
What is the criteria for classifying NFGNB?
What are the types of flagella that exist?
- Presence or absence of motility
- Type of flagella
- Fluorescent pigment production (Fluorescent group & Non-fluorescent group)
Flagella can be:
* Polar
*bipolar
*petrichous
Discuss PSEUDOMONAS and it’s characteristics
*Gram negative
*Motile (Polar Flagellation)
*Aerobic
*Water Soluble (GREEN) Pigment production common
*Widely found in soil, water, plants and animals
*More than 200 species
* oxidase positive
Discuss pyoverdine Q
FLUORESCENT PSEUDOMONAS obtains its fluorescents due to pyoverdine
* a white to blue-green pigment
* a water-soluble pigment
* fluoresces at 400-nm
* Pigment production is enhanced in media with a high phosphate concentration
What are the 3 members of the Flurorescent pseudomonas group? Which is most prevalent?
P. aeruginosa
P. fluorescence
P. putida
Disucss the characteristics of P. aeruginosa
*Widely distributed in natures
*Normal flora of intestine & skin
*Common in hospital environment
*Primary nosocomial pathogen
*Gram negative rod
*0.6 by 2 micron
*Unipolar flagellation (motile)
*Singles, pairs & short chains
*Capsulated
*Pili in Clinical strains
What are the Characteristics of P. AERUGINOSA CULTURE (PRACTICAL)
Which pigments does it produce?
*Grows readily on many media
*Smooth & round colonies usually
*Multiple colony types on one plate possible
*Fluorescent greenish colour
*Sweet odour or
*Grape-like odour
*Taco-like odour
*Obligate aerobe
*Grows Best at 37OC - 42OC
*Some strains are Beta haemolytic (Beta haemolysin)
*Oxidase positive (as all aerobic bacteria)
*Ferment glucose, no other CHO
Produces Water soluble pigments:
Pyocyanin,
Pyoverdine,
Pyorubin,
Pyomelanin
What is the pathogenesis of p.aeruginosa?
*Inhibits protein synthesis by inactivation of EF2
*EF2 Is required for elongation of nascent polypeptide chain on ribosome
*Toxin catalyzes rxn btw adenin-diphosphate-ribose (ADPR) & EF2 to form ADPR-EF2 complex (inactive)
*Leads to cell/tissue death ? Apoptosis
*Exotoxin mode of action similar to that of
Corynebacterium diphtheriae
In a diagrammatic form describe the virulence determinants of p.aeruginosa Q
Diagram includes:
flagellum (motility)
pillus (attachment)
alginate (CF isolates) antiphagocytic
Endotoxin (shock)
Other products: toxin A, hemolysin, phospholipase C, pigments, proteases, exoenzyme S & leukocidinT
In a tabular form describe the virulence determinants of p.aeruginosa Q
Category Types
1. Adhesion: Fimbriae (N-methyl-phenylalanine pili), Polysaccharide capsule (Glycocalyx), Alginate slime (biofilm)
2. Invasins: Elastase, Alkaline protease, Heamolysins (Phospholipase, Lecithinase), Cytotoxins (Leucocidins), Siderophores & Siderophore Uptake System, Pyocyanin diffusible pigment
3. Motility/ Chemotaxis Flagella
4. Toxins Exoenzyme S (Exoenzyme A), LPS
5. Defense against serum bacterial action: Slime layer, Capsules, LPS, Protease enzymes
6. Defense against immune response: Capsules, Slime layer, Protease enzyme
7. Genetic attributes: Genetic exchange (Transduction & Conjugation), Inherent natural drug resistance, R-factor & Drug resistance plasmids
8. Ecologic criteria: Adaptability to minimal nutritional requirements, Metabolic diversity
Widespread occurrence in a variety of habitat
What disease are caused by P.aeruginosa?
*Endocarditis
*Respiratory infections
*Bacteraemia
*CNS Infections
*ENT Infections especially Otitis external
*Ocular infections
*Bone & Joint Infections
*UTI
*GIT Infections
*Skin & soft tissues infections
Wounds,
Pyoderma
Dermatitis
What risk factors of P.aeruginosa?
*Cystic fibrosis
*Burns
*Cancers
*Prolonged hospital admission
* Intensive care unit admission
*Organ transplant
*Drug addiction
*Tracheostomy
*Indwelling catheter
*Swimmer’s ear
weeping cutaneous wound
How can P.aeruginosa be diagnosed?
Specimen: depends on infection type
*Culture media:
Blood agar
Eosin methylthionine blue agar
*Incubation aerobically at 42OC
Laboratory identification
Cultural characteristics
Fruity odour,
pigmentation,
fluorescence
*Gram staining
*Oxidase test
*Non-lactose fermenter
On blood or chocolate agar appear as large colonies with
metallic sheen, mucoid, rough. or pigmented (pyocyanin) and often
beta-hemolytic
CONTROL & TREATMENT
*Proper cleaning & sanitation
*Disinfection
*Topical wound treatment with antimicrobial agents: Silver
sulphadiazine
*Surgical debriment
*Rx with anti-pseudomonas drugs: Gentamycin, carbapenem
*Rx review with AST result
