EXERCISE 10 Flashcards
Most important pathogens that are water-borne
Vibrio cholerae & Salmonella enterica
COLIFORMS:
- oxygen level
- type of bacteria
- spore forming?
- shape
aerobic to facultative anaerobe
gram - bacteria
non-spore forming
rod-shaped
What kind of bacteria are coliforms
enteric (exist in intenstines of animals)
the KEY fecal coliform of interest
Escherichia coli
What is the test used for coliform?
MPN technique (most probable number technique)
Significance of MPN
estimating population of microorganisms in samples with very low counts
What are the 3 steps in MPN technique
- Presumptive MPN
- Confirmatory MPN
- Completed Test
What is the media used in PRESUMPTIVE MPN
LAURYL SULFATE TRYPTOSE BROTH with inverted Durham Tubes
What are the indications for positive tubes in presumptive mpn?
turbidity and gas production in DURHAM TUBE
what does turbidity denote in presumptive mpn?
there are microorganisms that can FERMENT LACTOSE but may not be coliforms
What medium is used in confirmatory mpn?
Brilliant Green Lactose Bile Broth
What kind of tubes are present in BGLBB?
Durham tubes too
How much from each positive tube of presumptive MPN will be transferred to BGLBB?
only a loppful
What are the indications for positive tubes in confirmatory mpn?
turbidity and acid production thru bubbles w/ or w/o yellowing
what does turbidity denote in confirmatory mpn?
microorganisms are indeed coliforms
