Detection and Identification of Microorganisms Flashcards
Limit of Detection
Lower limit of detection. The lowest target concentration that can be detected 95% of the time in a test assay.
True Negative
Lack of amplification of the target.
Homologous Extrinsic
A PCR template with primer-binding sites matching test targets and a nontarget insert.
Heterologous Extrinsic
Nontarget templates added to a sample before amplification to ensure proper sample purification and amplification.
Heterologous Intrinsic
Nontarget templates naturally occurring in a sample used to ensure proper sample purification and amplification.
False Positive
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.
Validation
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.
ITS
Internal Transcribed Spacer. Conserved elements found in regions separating the ribosomal RNA genes. Used for typing yeast and mold.
Cytopathic effect
CPE. Changes in the cell due to viral infection, such as lysis, growth, or growth inhibition.
Viral Load
The quantified amount of virus in a specimen.
-static
Antimicrobial agent that inhibits microbial growth.
-cidal
Antimicrobial agent that kills organisms outright.
Antimicrobial Agents
Antibiotic. A substance that kills or inhibits the growth of bacteria.
Susceptibility Testing
Measures the minimum inhibitory concentration of an antimicrobial agent.
MIC
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.
MIC
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.
Transposon
A fragment of DNA with the capacity to move from one genetic location to another.
Susceptibility Testing
Detection of resistance to given antimicrobial agents by the ability to grow in the presence of the agent.
MIC
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.
Nosocomial
The spread of pathogenic organisms within a hospital.
Iatrogenic
The spread of pathogenic organisms from the actions of a physician.
Locus-specific RFLP
RFLP performed with PCR amplification with gene-specific primers.
Arbitrary Primer PCR
Random amplified polymorphic DNA assay. A modified PCR using short (10 bases) oligonucleotides of random sequences to prime DNA amplification all over the genome.
Ribotyping
They typing of microorganisms using restriction fragment polymorphisms in ribosomal RNA genes.
Locus-specific RFLP
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.
ERIC
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.
ERIC
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.
BOX
Repetitive sequences that are 45-59bp long.
Spa Typing
Uses spa gene to identify MRSA.
Coa Typing
Uses coa gene to identify S. aureus.
Spa Typing
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.
Coa Typing
Uses coa gene to identify MRSA. Tandem repeat elements in the 3’ coding region of the Staphylococcus aureus coagulus gene, coa, analyzed by PFGE.
Reproducible
Yielding the same results on repeating testing of the same organism or strain.
Typing Capacity
Ability of a test to identify the target organism.
