NFB Flashcards
Which P. aeruginosa pathogenicity factor?
This exacerbates nosocomial pneumonia due to its suppression of cilia and damage to oxygenated tissue
Pyocyanin
Non-motile NFB
Acinetobacter
NFB with lavender-green colour and ammonia odour
Stenotrophomonas maltophilia
The one feature shared by all NFBs
Inability to ferment sugars
NFB that is increasingly isolated in UTIs, endocarditis, meningitis, cellulitis, peritonitis (dialysis)
Acinetobacter spp.
Why is Hugh-Leifson O/F media better for displaying carbohydrate utilization by NFBs?
Increased carbohydrate to protein ratio (5:1 rather than 2:1)
Diffusible yellow-green and fluorescent pigment produced by the fluorescent pseudomonads
PYOVERDIN
How is indole extracted in the indole production test?
1 mL xylene + 15 drops Ehrlich’s solution
P. aeruginosa infection that would more likely be seen in an immunocompetent individual?
Otitis externa (swimmer’s ear)
Suspect B. cepacia if:
Glucose = ? ONPG = ? Lysine = ? Oxidase = ?
Glucose = non-fermenter (NEG) ONPG = POS Lysine = POS Oxidase = weakly POS
This trauma often results in P. aeruginosa infections and subsequent extensive damage due to exotoxin A and other factors.
BURN
B. cepacia - growth on cetrimide?
NG;
But will grow in Povidone-iodine and other disinfectants
Grape odour
Pseudomonas aeruginosa
A special agar plate that can be used to detect pyoverdine using UV light
Pseudomonas F agar
Decarboxylase test for NFBs - why is base control purple (grey-purple, turbid)?
No fermentation step
3 initial clues from PRIMARY plates that may be indicative of NFB over Enterobacteriaceae
- Growth on BAP better than MAC
- Oxidase POS
- Pigmented
A 2-step enzymatic test requiring the organism to produce BOTH a dihydrolase AND a decarboxylase
The base will be greyish-purple turbid rather than yellow turbid if the isolate is an NFB
Moeller’s test for arginine
Causes dissolution of elastic lamina of blood vessels
Elastase
This NFB’s sources of infection include:
- contaminated medications
- disinfectants (povidone-iodine)
- water
- contaminated equipment
Burkholderia cepacia complex
Keratitis due to this organism is a medical emergency
P. aeruginosa
How does the Leifson flagellar stain work?
Alcoholic solution of a rosaniline dye
Alcohol evaporates, dye precipitates and coats the flagella
2 NFB that produce pyoverdine
- P. aeruginosa
- P. fluorescens
Purpose of Hugh-Leifson media?
Determine mode of glucose utilization for NFBs
Strongly oxidase POS and grow well on MAC
Pseudomonas
P. aeruginosa is notoriously resistant to many cephalosporins. However, this third-generation cephem is usually suitable.
CEFTAZIDIME
These polysaccharide polymers result in very mucoid, difficult to eradicat strains of P. aeruginosa.
ALGINATES
Most of the NFBs are “S” to this ABX; B. cepacia is “R”. For this reason it can be incorporated into media selective for B. cepacia e.g. PCM and OFPBL.
POLYMYXIN
In this stain procedure, a rosaniline dye is prepared in alcohol. As the alcohol evaporates, the dye precipitates and coats the flagella, making them visible by light micorscopy.
LEIFSON
In the Entner-Douderoff pathway, weak acids and __ are generated.
WATER
To detect ______ in NFBs:
- Use a richer source of tryptophan in the substrate
- Extract the product with xylene
- Test with Ehrlich’s reagent
Indole
Slime-like pathogenic substance
Alginates
Overlapping phenotypic and genotypic characteristics has made both taxonomy
and identification difficult
Burkholderia cepacia complex
2 NFBs that are oxidase NEG
- Stenotrophomonas maltophilia
- Acinetobacter spp.