Lab 6: Microbiology Part 2 Flashcards
What is the purpose of HEAT FIXING while preparing a Gram stain?
Kills BACTERIA and cause BACTERIAL CELLS to adhere to the slide
What is the purpose of CRYSTAL VIOLET while preparing a Gram stain?
Stains PEPTIDOGLYCAN in BACTERIAL CELL WALL, especially thick layer in GRAM POSITIVE CELLS
What is the purpose of GRAM’S IODINE while preparing a Gram stain?
Involves application of a MORDANT, which forms an insoluble complex with the CRYSTAL VIOLET, fixing the stain in the CELL WALL
What is the purpose of ACETONE-ALCOHOL while preparing a Gram stain?
In GRAM POSITIVE CELLS, this will dehydrate the CELL, further trapping the CRYSTAL VIOLET-IODINE complex. In GRAM NEGATIVE CELLS this step dissolves the LIPOPOLYSACCHARIDE in the outer membrane and washes away excess stain from the surface of CELLS
What is the purpose of SAFRANIN while preparing a Gram stain?
Stains the thinner PEPTIDOGLYCAN coat of GRAM NEGATIVE CELLS pink
What general shape is seen in COCCI BACTERIA?
Round BACTERIA
What general shape is seen in BACILLI BACTERIA?
Rod BACTERIA
Define: ENTERIC
BACTERIA that live in the DIGESTIVE SYSTEM
Define: AEROBIC
BACTERIA that require O2
Define: ANAEROBIC
BACTERIA that don’t require O2
Define: PATHOGENIC
BACTERIA that cause disease
What could be concluded from a BAP (BLOOD AGAR PLATE) that has no visible colonies?
There is no BACTERIA present in the sample, or BACTERIA in the sample were killed
What could be concluded from a BAP that has colonies on it, no change to the media surrounding it?
y-hemolytic, non-hemolytic
What could be concluded from a BAP that has colonies on it, surrounding are has turned green?
a-hemolytic activity, partially hemolytic
What could be concluded from a BAP that has colonies on it, surrounding area has become transparent?
b-hemolytic activity, completely hemolytic
What could be concluded from a MAC (MACCONKEY AGAR PLATE) that has no colonies visible?
BACTERIA cannot grow in the presence of CRYSTAL VIOLET and bile salts; therefore BACTERIA are likely GRAM POSITIVE or NON-ENTERIC
What could be concluded from a MAC (MACCONKEY AGAR PLATE) that has colonies visible?
BACTERIAL growth not affected by CRYSTAL VIOLET and bile salts; therefore BACTERIA are GRAM NEGATIVE and ENTERIC
What could be concluded from a MAC (MACCONKEY AGAR PLATE) that has white colonies visible?
These GRAM NEGATIVE BACTERIA are also LACTOSE NEGATIVE. They cannot use LACTOSE and instead metabolize the PEPTONE in the media, forming ammonia and raising pH. Likely SALMONELLA or SHIGELLA
What could be concluded from a MAC (MACCONKEY AGAR PLATE) that has pink colonies visible?
These GRAM NEGATIVE BACTERIA are also LACTOSE POSITIVE. They use LACTOSE, produce acid, and activate the neutral red dye. Likely E COLI or KLEBSIELLA
True or false:
When interpreting a KIRBY-BAUER results table, the most effective ANTIBIOTIC will be the least sensitive
FALSE, other way around
Note: Sensitivity can be deducted by measuring the diameter of the clear zone around the ANTIBIOTIC
List 3 factors that should be considered when determining an ANTIBIOTIC to treat BACTERIAL INFECTIONS
- Allergies
- Other meds
- Cost
What is a BROAD SPECTRUM ANTIBIOTIC?
An ANTIBIOTIC that treats a wide range of BACTERIAL INFECTIONS
What is a NARROW SPECTRUM ANTIBIOTIC?
A specialized ANTIBIOTIC to treat a specific BACTERIA
If there is only a small zone of inhibition around the ANTIBIOTIC DISC, the BACTERIA is ________ to the ANTIBIOTIC.
Resistant
If there is a large zone of inhibition around the ANTIBIOTIC DISC, the BACTERIA is ________ to the ANTIBIOTIC.
Sensitive
The prefix STREPTO indicates what?
That the BACTERIA are arranged in a line
The prefix STAPHYLO indicates what?
That the BACTERIA are in a cluster
