Other Labs have claimed that bacterial interactions in poly-microbial UTIs change (increase) the tolerance of organisms to drugs. To support their claim, they concentrate the urine samples by centrifugation (not recommended or accepted by infectious disease specialists) and resuspend in a growth medium followed by aliquoting into plates that contain different concentrations of drugs. It is a well-known fact in microbiology that concentrating the organisms causes damage to their cell walls which will lead to inaccurate AST results. The pooled-AST method can only report 57% of uropathogens because they depend on retrieving the live organism.
Other Labs’ PCR
Their results do not match their claim because:
Only 4 of the 9 antibiotic classes in their data show any significant change of tolerance in pooled testing.
The small volume of growth medium added to the concentrated pooled organisms does not represent the actual matrix (urine) where organisms are present. It cannot be concluded that their results match actual clinical situations.
In their data there is indication that some organisms can be inhibited better than usual as a result of pooled AST method, but they highlight the opposite results and claim that their method is compliant with antibiotic stewardship efforts.
Pooled susceptibility can only detect viable organisms and will miss any slow grower or unculturable causative agent of UTI (ex. Ureaplasma, Mycoplasma)
There is no outside validation of this claim and in total only 2 scientific papers can be found on the subject.
Adding Pooled AST significantly increases turn-around times which leads to prescription of broad-spectrum antibiotics and therefore lack of contribution to stewardship efforts.
Our innovative assay validation approach enables us to report actual CFU/mL values for bacteria using our PCR methodology.
Our panel spans the detection of bacterial, fungal, and viral pathogens in one assay.
The Promus UTI-PCR molecular UTI panel detects >90% of these uropathogens and their resistance markers as compared to the pooled-AST method which only can report 57% of uropathogens.
Promus’ panel detects UTI co-infections and poly-microbial infections much more efficiently than pooled AST. Pooled-AST damages cells in the process and does not reflect the correct composition of bacteria.
Promus’ real-time PCR UTI panel delivers both identification and resistance results on the same day whereas Pooled-AST method may take more than 72 hours.
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Promus Diagnostics is a high-complexity CAP-Accredited & CLIA-Certified laboratory that utilizes a team of experts and state-of-the-art technology to deliver accurate and timely results. Our proprietary Promus Pathway is a revolutionary new testing platform that allows for rapid turnaround with a high degree of precision while maintaining customary reporting methodologies for more useful results.