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Diagnostic Micro Exam 1 > Diagnostic Micro > Flashcards

Diagnostic Micro Flashcards

0
Q

Gram stains are important because

A

It gives the relative abundance - double checks that everything grew

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1
Q

Diagnostic Microbiology is focused on the study of what?

A

Bacterial pathogens

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2
Q

What is purulence?

A

Pus

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3
Q

How are gram stains used as a diagnostic tool from a primary sample?

A

Confirm physician suspicion of etiology of infection
Aid in correct antibiotic selection
Screen adequacy of specimen
Identify cellular components & debris of inflammation
Presumptive diagnosis

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4
Q

What are some examples of primary cultures?

A

Smears from swabs
Smears from thick liquids
Smears from thick mucoid material
Smears from thin fluids

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5
Q

What is the cytospin used for?

A

Thin fluids with low cellularity

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6
Q

What does the cytospin do?

A

Maximize cell recovery from a liquid & deposit the sediment on a slide

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7
Q

How do you make a smear from a plate?

A

Emulsify material in a drop of water on a slide

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8
Q

What does PMN stand for?

A

Poly morphonuclear leukocytes

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9
Q

What is an example of contaminatin of a sample?

A

Epithelial cells

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10
Q

What is quality control?

A

When known positive & negatives are stained

Direct gram stain from primary sample better match what grows on the plates - internal control

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11
Q

Is there a larger peptidoglycan layer in gram-positive or gram-negative bacteria?

A

Gram-positive

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12
Q

Do endotoxins stain gram positive or negative?

A

Gram-negative

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13
Q

The peptidoglycan layer consists of what two alternating peptides?

A

NAG & NAM

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14
Q

The NAG & NAM chains are cross-linked to form a thick network of what?

A

Peptide bridge connected to the tetra-peptides on the NAM

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15
Q

What are two special acids that are part of gram-positive cell walls?

A

Teichoic acid & lipo-techoic acid

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16
Q

Are gram-negative cell walls thick or thin?

A

Thin

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17
Q

What type lipid is an endotoxin?

A

Lipid A

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18
Q

What is endotoxin responsible for?

A

Producing fever & shock in patients infected with gram-negative bacteria

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19
Q

What is the outer membrane of gram-negative bacteria a barrier to?

A

Hydrophobic compounds

20
Q

What does the outer membrane do?

A

It is a sieve

Allows water soluble molecules to enter through porins

21
Q

What are porins & what do they do?

A

Protein lined channels

Provides attachment sites that enhance attachment to host cells

22
Q

What gets released and becomes endotoxins?

A

Lipopolysaccharides

23
Q

What is chromosomal DNA?

A

One circular supercoiled ds DNA

24
Q

What are plasmid (extrachromosomal) DNA?

A

Non-essential circular supercoiled DNA fragments - low or high copy
Copied to daughter cells & spread by conjugation

25
Q

What are three mobile genetic elements present in bacterial DNA?

A

Insertion sequences
Transposons
Cassettes

26
Q

What are insertion sequences?

A

Short DNA that code for transposase

They may jump into a gene & activate or inactivate it

27
Q

What are transposons?

A

Longer pieces of DNA that are mobile & have more genes

An example is antibiotic resistance

28
Q

What are cassettes?

A

More sophisticated DNA inserts with multiple genes & regulatory elements

29
Q

How big is a bacterial chromosome?

A

2.8 Mb

30
Q

What is he size of a plasmid?

A

˜5 Kb

31
Q

What is the size of an insertion sequence?

A

1000 bp

32
Q

What is the size of an SCC cassette in MRSA?

A

20.9 to 66.0 kb

33
Q

What are three types of genome change?

A

Antibiotic resistance
Mutations
Genetic recombination

34
Q

How does the genome change to spread antibiotic resistance?

A

Acquisition of plasmids & other forms of mobile genetic elements that spread the antibiotic resistance

35
Q

What are the types of mutations that causes genome change?

A

Point - one base
Frameshift - disrupts amino acid sequence
Deletions
Insertions from mobile elements

36
Q

Where is the genome change caused by genetic mutation?

A

Between 2 DNA molecules

37
Q

What are the three mechanisms of gene transfer?

A

Transformation
Transduction
Conjugation

38
Q

What is transformation?

A

Uptake & incorporation of naked DNA from the environment

Cells must be competent to take it up

39
Q

What is transduction?

A

Transfer of genes by bacteriophage

Genes are incorporated into genome - lysogengy

40
Q

What is conjugation?

A

DNA from a donor strain integrates into the genome

41
Q

Which mechanism admires the naked form?

A

Transformation

42
Q

Which mechanism has conjugal visits?

A

Conjugated

43
Q

Which mechanism duct tapes viruses into the bacteria?

A

Transduction

44
Q

What does eukaryote mean?

A

True nucleus

45
Q

What is the structure of chromosomes in eukaryotic cells?

A

Linear complexed with histones & proteins

46
Q

What are present in extrachromosomal DNA?

A

Mitochondria & chloroplasts

47
Q

Eukaryotic have what components that are not present in prokaryotic cells?

A

Membrane bound organelles

Endoplasmic reticulum

Diagnostic Micro Exam 1 (6 decks)

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