PCR Applications & Clinical Diagnostics Flashcards

For detection of tick-borne diseases such as Lyme disease in the US, which PCR specimen type is most clinically useful for direct pathogen detection?

Answer: Skin biopsy from the erythema migrans lesion

Skin biopsy from the erythema migrans rash has the highest PCR sensitivity for Borrelia burgdorferi detection during early Lyme disease.

Which PCR application is used to detect chromosomal translocations such as BCR-ABL fusion in chronic myeloid leukemia (CML)?

Answer: Reverse transcription PCR targeting the fusion transcript

RT-PCR targets the BCR-ABL mRNA fusion transcript produced by the Philadelphia chromosome translocation, providing a highly sensitive diagnostic and monitoring tool for CML.

In agricultural diagnostics, which PCR application is used by US regulatory agencies to verify the presence of approved genetically modified (GMO) crops?

Answer: Event-specific PCR targeting transgene insertion sites

Event-specific PCR amplifies the unique genomic junction between the inserted transgene and host plant DNA, providing definitive identification of a specific approved GMO event.

Which clinical PCR application is FDA-cleared and used to rapidly identify antimicrobial resistance genes (e.g., mecA for MRSA) directly from positive blood cultures?

Answer: Multiplex real-time PCR panels for bloodstream infection

FDA-cleared multiplex real-time PCR panels such as the FilmArray BCID can identify pathogens and resistance genes directly from blood culture bottles within one hour.

In veterinary diagnostics, which PCR application is used by USDA-approved laboratories to detect foot-and-mouth disease virus (FMDV) in suspect animal specimens?

Answer: Real-time RT-PCR for rapid confirmatory diagnosis

Real-time RT-PCR is the USDA-approved gold standard for rapid FMDV detection due to its high sensitivity, specificity, and ability to provide results within hours.

Which emerging PCR-based technology uses CRISPR-Cas systems coupled with PCR amplification to provide highly specific visual detection results for point-of-care infectious disease testing?

Answer: SHERLOCK (Specific High-sensitivity Enzymatic Reporter unLOCKing)

SHERLOCK combines isothermal amplification with CRISPR-Cas13 cleavage of a reporter molecule, generating a visible or fluorescent signal specific to the target nucleic acid.