Applications of Molecular Diagnostics

CLINICAL MICRIOBIOLOGY

what is nucleic acid hybridization?

lab technique where single-stranded DNA/RNA bind together through complementary base pairing

what is a southern blot technique?

a hybridization technique where DNA is digested with restriction enzymes and separated on an agarose gel and transferred to a membrane → useful for detecting specific genes but is time-consuming

what is a northern blot technique?

same as the southern blot technique but for RNA

what is the gen-probe accuprobe system?

a rapid DNA probe test to identify specific ribosomal rRNA

what is the nucleic acid amplification test (NAAT)?

a tool that detects tiny amounts of genetic material (pathogens) and copies it many times so it can be easily identified (PCR)?

what is a cepheid geneXpert system used for?

single/multiplex real-time PCR which makes it good for screening/confirmation of a specific causative agent

what is a biomerieux biofire system used for?

rapid identification when causative agent could be one of many causing similar symptoms

what is a signal amplification technique?

amplify the detection signal of a probe bound to a target molecule rather than copying the target DNA/RNA

what is pyrosequencing?

targets the 16s RNA and used to determine antimicrobial resistance gene types

what is metagenomics?

sequences everything and generates a profile of the source → arrange sequences into databases for comparisons

what are the limitations of molecular diagnostics?

1. presence of an organism doesn’t always mean causation

2. does not indicate live/dead organisms

3. no information regarding antibiotic sensitivity (still have to grow/test for antibiotics)

4. extreme sensitivity to contamination

what is a maldi-tof used for?

to analyze fragile molecules/compounds without breaking them apart (laser) which allows for rapid/cheap identification of suspected pathogens → extremely useful for slow-growing organisms

what is antigenic detection testing?

rapid testing methods for certain pathogens by finding specific proteins from a virus/disease marker

what is a bacterial / parasite antigen test used for?

a simple, fast method used to detect certain antigens that is commonly used in stool (for Giardia and Cryptosporidium)

what is latex agglutination testing used for?

very popular/easy antigenic detection method performed on colonies for presence/absence determination