00:01
Okay, so this question is asking, what is the purpose of bacterial isolation and why is it necessary for medical diagnosis? so let's say we have two different bacteria here.
00:09
Okay, one's pathogenic.
00:11
That's the red one and one is non -pathogenic.
00:12
That's the green one.
00:14
On a diagnostic test, the pathogenic bacteria will give you, say, positive positive tests, whereas the non -pathogenic test will give you a negative, negative test.
00:24
But when you have a mixed culture, so they're not pure, what you can get is basically something like this.
00:34
A positive negative, right? or sometimes the test is positive, sometimes the test is negative.
00:40
You have this because you have a mixed culture.
00:42
And so in that case, the result is, diagnostically is inconclusive.
00:48
So it doesn't help you in terms of trying to figure out what the patient has.
00:52
So for this reason, we isolated bacteria so that we can get consistent testing results that can only be attributed to each, to only one bacteria at a time.
01:10
Okay? so the next clear of questions is asking about differential and selective media.
01:14
So i just picked two media, which is both selective and differential.
01:17
So one is called emb, eocene, methylene blue auger.
01:22
So eocene, methylene blue auger.
01:31
This is selective for gram negatives because eocene and methylene blue too, but eocene mostly inhibits gram positive bacteria.
01:40
Okay? so only grab negative bacteria will grow.
01:43
That's how it's selective.
01:45
It's differential because it could differentiate between bacteria that can ferment lactose or cannot ferment lactose...