THe DIFFERENCE
Problems with PCR based ABX gene detection:
- ABX genes are not specific to the infecting organism
- ABX genes may not be expressed phenotypically
- Pathogens or ABX genes detected can come from dead organism or contamination
- Other resistance genes may exist that the lab's PCR assay doesn't detect
- Can lead to incorrect initial treatment plan/ poor antibiotic stewardship
Problems with culture-based sensitivity:
- Long, 4-5 day process
- Slow growing organisms can be out competed on the plate
- Poly-microbial & low level infections harder to detect
- Can lead to incorrect initial treatment plan & poor antibiotic stewardship
Molecular AST Benefits:
- Highly specific pathogen/ polymicrobial infection detection
- Mimics culture sensitivity results in a recognizable format
- Reduce time to treatment: sensitivity results delivered within one day or less.
- Correctly identify phenotypic resistance of the infecting organism(s) every time
- Improve antibiotic stewardship
Why phenotypic antibiotic testing is important:
- Genotype does not always equal phenotype
- There is a 40% mismatch between genetic resistance and phenotypic resistance
- ex: If you always prescribe based on genetic markers alone, then 40% of the time it will be incorrect
