Detection and Identification of Microorganisms

Question 1

Limit of Detection

Answer 1

Lower limit of detection. The lowest target concentration that can be detected 95% of the time in a test assay.

Question 2

True Negative

Answer 2

Lack of amplification of the target.

Question 3

Homologous Extrinsic

Answer 3

A PCR template with primer-binding sites matching test targets and a nontarget insert.

Question 4

Heterologous Extrinsic

Answer 4

Nontarget templates added to a sample before amplification to ensure proper sample purification and amplification.

Question 5

Heterologous Intrinsic

Answer 5

Nontarget templates naturally occurring in a sample used to ensure proper sample purification and amplification.

Question 6

False Positive

Answer 6

Results suggesting the presence of an analyte that is not in a test sample. The nucleic acid-based tests remain positive longer than culture assays. This is seen with the presence of dead or dying microorganisms when a patient is taking antimicrobial agents.

Question 7

Validation

Answer 7

Must be performed on new molecular-based tests that are brought into the laboratory. Controls must be tested, and the sensitivity, specificity, and reproducibility of the assay must be determined using reference materials.

Question 8

ITS

Answer 8

Internal Transcribed Spacer. Conserved elements found in regions separating the ribosomal RNA genes. Used for typing yeast and mold.

Question 9

Cytopathic effect

Answer 9

CPE. Changes in the cell due to viral infection, such as lysis, growth, or growth inhibition.

Question 10

Viral Load

Answer 10

The quantified amount of virus in a specimen.

Question 11

-static

Answer 11

Antimicrobial agent that inhibits microbial growth.

Question 12

-cidal

Answer 12

Antimicrobial agent that kills organisms outright.

Question 13

Antimicrobial Agents

Answer 13

Antibiotic. A substance that kills or inhibits the growth of bacteria.

Question 14

Susceptibility Testing

Answer 14

Measures the minimum inhibitory concentration of an antimicrobial agent.

Question 15

MIC

Answer 15

Minimum Inhibitory Concentration. The least amount of antimicrobial agent that inhibits the growth of an organism. An indication of susceptibility or resistance for a given organism and antimicrobial agent pair.

Question 16

MIC

Answer 16

Minimum Inhibitory Concentration. The least amount of antimicrobial agent that inhibits the growth of an organism. An indication of susceptibility or resistance for a given organism and antimicrobial agent pair.

Question 17

Transposon

Answer 17

A fragment of DNA with the capacity to move from one genetic location to another.

Question 18

Susceptibility Testing

Answer 18

Detection of resistance to given antimicrobial agents by the ability to grow in the presence of the agent.

Question 19

MIC

Answer 19

Minimum Inhibitory Concentration. The least amount of antimicrobial agent that inhibits the growth of an organism. An indication of susceptibility or resistance for a given organism and antimicrobial agent pair.

Question 20

Nosocomial

Answer 20

The spread of pathogenic organisms within a hospital.

Question 21

Iatrogenic

Answer 21

The spread of pathogenic organisms from the actions of a physician.

Question 22

Locus-specific RFLP

Answer 22

RFLP performed with PCR amplification with gene-specific primers.

Question 23

Arbitrary Primer PCR

Answer 23

Random amplified polymorphic DNA assay. A modified PCR using short (10 bases) oligonucleotides of random sequences to prime DNA amplification all over the genome.

Question 24

Ribotyping

Answer 24

They typing of microorganisms using restriction fragment polymorphisms in ribosomal RNA genes.

Question 25

Locus-specific RFLP

Answer 25

Detection of polymorphisms in restriction sites within designated regions or genes. RFLP performed with PCR amplification with gene-specific primers. Used for typing of microorganisms.

Question 26

ERIC

Answer 26

Enterobacterial Repetitive Intergenic Consensus. Sequences that are 126bp long found in bacterial species that are highly conserved, even though they are not in coding regions.

Question 27

ERIC

Answer 27

Enterobacterial Repetitive Intergenic Consensus. Sequences that are 126bp long found in bacterial species that are highly conserved, even though they are not in coding regions.

Question 28

BOX

Answer 28

Repetitive sequences that are 45-59bp long.

Question 29

Spa Typing

Answer 29

Uses spa gene to identify MRSA.

Question 30

Coa Typing

Answer 30

Uses coa gene to identify S. aureus.

Question 31

Spa Typing

Answer 31

Uses spa gene to identify MRSA. Tandem repeat elements in the 3’ coding region of the Staphylococcus aureus protein A gene, spa, analyzed by PFGE.

Question 32

Coa Typing

Answer 32

Uses coa gene to identify MRSA. Tandem repeat elements in the 3’ coding region of the Staphylococcus aureus coagulus gene, coa, analyzed by PFGE.

Question 33

Reproducible

Answer 33

Yielding the same results on repeating testing of the same organism or strain.

Question 34

Typing Capacity

Answer 34

Ability of a test to identify the target organism.