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Publications & Studies
Our testing methodologies are backed by peer-reviewed research — much of it authored by our own scientific leadership.
Eight papers published in 2025 examine the same clinical question: does PCR-based diagnosis of complicated UTI outperform conventional culture and sensitivity testing? Five draw on the multicenter randomized trial NCT06996301.
The randomized trial
The core evidence base — a multicenter, randomized, investigator-blinded trial (NCT06996301) and its secondary analyses.
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Why PCR Improves Outcomes: Faster Antibiotics, Better Choices
How PCR-guided management changes clinical symptom resolution in complicated UTI, and what mediates the benefit.
The strongest patient-outcome paper in the set. It doesn't just show PCR works — it shows why: roughly three-quarters of the benefit comes from starting the right antibiotic sooner.
Key findings
- Median time to first antibiotic: 20 h (IQR 12–36) vs. 52 h (IQR 30–66), p < 0.001
- Appropriate antibiotic chosen: 83.4% (161/193) vs. 62.1% (105/169), p < 0.001
- Complete clinical cure: 74.1% (143/193) vs. 62.7% (106/169), p = 0.020
- Partial cure (≥50% symptom reduction): 83.4% vs. 71.6%, p = 0.014
- Adjusted odds ratio for cure 1.95 (95% CI 1.12–3.39, p = 0.018)
- Approximately 74% of the benefit mediated through faster antibiotics and better initial choice
- Authors
- Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K.
- Trial
- NCT06996301 · 362 participants (PCR n = 193, culture n = 169)
Read the paper 10.3390/diagnostics15243107Full citation
Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K. Clinical Symptom Resolution Following PCR-Guided vs. Culture and Susceptibility-Guided Management of Complicated UTI: How Time-To-Antibiotic Start and Antibiotic Appropriateness Mediate the Benefit of Multiplex PCR—An Ad Hoc Analysis of NCT06996301. Diagnostics 2025, 15(24), 3107.
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Predicting Antibiotic Resistance from PCR: Genotype–Phenotype Concordance
Whether resistance genes detected by PCR reliably predict actual phenotypic resistance, and what that means for stewardship.
Establishes the scientific basis for acting on a PCR resistance result before susceptibility testing comes back.
Key findings
- blaCTX-M in E. coli: sensitivity 0.94 (95% CI 0.88–0.97), specificity 0.995 (95% CI 0.990–0.998), κ ≈ 0.93
- Median time to antibiotic: 20 h (PCR) vs. 52 h (culture)
- Treatment success: 88.1% vs. 78.1% — adjusted odds ratio 1.95 (95% CI 1.12–3.40, p = 0.018)
- 63% of the treatment-success benefit was mediated by earlier antibiotic initiation
- ROC AUC 0.62–0.81 for ΔCt predicting non-susceptibility
- Authors
- Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K.
- Trial
- NCT06996301 · PCR arm n = 193, culture arm n = 169
Read the paper 10.3390/diagnostics15232945Full citation
Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K. Genotype–Phenotype Concordance and Ct-Informed Predictive Rules for Antimicrobial Resistance in Adult Patients with Complicated Urinary Tract Infections: Clinical and Stewardship Implications from the NCT06996301 Trial. Diagnostics 2025, 15(23), 2945.
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Reading Bacterial Load from PCR: ΔCt Thresholds and Specimen Handling
Whether PCR signal tracks bacterial load, and what actually explains PCR-positive / culture-negative discordance.
Answers the most common objection to PCR — that it detects dead DNA. Most discordance turns out to be explained by specimen handling delay, not false positives.
Key findings
- PCR positivity 82–88% vs. culture 66–70% across all six sites
- ΔCt correlated strongly with bacterial load (Spearman ρ −0.64 to −0.75; Pearson r −0.75 to −0.83)
- Each 1-unit ΔCt change ≈ a 5.6–8.4-fold difference in CFU
- ROC AUC 0.78–0.84 for discriminating high bacterial load
- Processing delay cost ~0.048 log₁₀CFU per hour — time-dependent viability loss drives the discordance
- Collection method (catheter vs. clean-catch) did not materially affect the relationship
- Authors
- Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K.
- Trial
- NCT06996301 · 1,027 paired specimens across 6 sites
Read the paper 10.3390/diagnostics15232959Full citation
Priestly, I.P.; Chavez, R.; Derrick, D.; Huard, T.K. Semi-Quantitative ΔCt Thresholds for Bacteriuria and Pre-Analytic Drivers of PCR-Culture Discordance in Complicated UTI: An Analysis of NCT06996301. Diagnostics 2025, 15(23), 2959.
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What Culture Misses: Polymicrobial Infection, Resistance, and Treatment Failure
A secondary analysis of pathogen detection, resistance profiles, and their impact on clinical outcomes.
The clearest evidence that culture's blind spots have real consequences for patients. When culture missed a polymicrobial infection, treatment failed half again as often.
Key findings
- PCR identified polymicrobial infection in 43.52% of cases vs. 31.95% for culture (p = 0.033)
- Missed polymicrobial infection → clinical failure in 33.33% (14/42) vs. 22.22% (12/54) when both methods agreed (p = 0.041)
- PCR found additional pathogens in 54.44% (92/169) of culture-arm cases; failure 28.26% vs. 14.29% when culture missed pathogens (p = 0.015)
- When culture missed phenotypic resistance, failure hit 50% (16/42) vs. 13.22% (21/121) when both agreed (p = 0.001)
- Authors
- Kardjadj, M.; Chang, T.W.; Chavez, R.; Derrick, D.; Spangler, F.L.; Priestly, I.P.; Park, L.Y.; Huard, T.K.
- Design
- Multicenter, randomized, investigator-blinded
Read the paper 10.3390/microorganisms13040949Full citation
Kardjadj, M.; Chang, T.W.; Chavez, R.; Derrick, D.; Spangler, F.L.; Priestly, I.P.; Park, L.Y.; Huard, T.K. The clinical validity and utility of PCR compared to conventional culture and sensitivity testing for the management of complicated urinary tract infections in adults: A secondary (ad hoc) analysis of pathogen detection, resistance profiles, and impact on clinical outcomes. Microorganisms 2025, 13(4), 949.
The two-part clinical series
Published back-to-back in Diagnostic Microbiology and Infectious Disease. Part I covers outcomes and turnaround; Part II covers diagnostic agreement and antibiotic choice.
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PCR vs. Culture in Complicated UTI — Part I: Clinical Outcomes and Turnaround Time
Clinical outcomes, investigator satisfaction scores, and turnaround times when PCR replaces conventional culture and sensitivity testing for complicated UTI in adults.
- Authors
- Spangler, F.L.; Williams, C.; Aberger, M.E.; Wilson, B.A.; Ajib, K.; Gholami, S.S.; Goodwin, H.N.; Park, L.Y.; Kardjadj, M.; Derrick, D.; et al.
Read the paper PMID 39532029Full citation
Spangler, F.L.; Williams, C.; Aberger, M.E.; Wilson, B.A.; Ajib, K.; Gholami, S.S.; Goodwin, H.N.; Park, L.Y.; Kardjadj, M.; Derrick, D.; et al. Clinical utility of PCR compared to conventional culture and sensitivity testing for the management of complicated urinary tract infections in adults: Part I: Assessment of clinical outcomes, investigator satisfaction scores, and turnaround times. Diagn. Microbiol. Infect. Dis. 2025, 111, 116601.
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PCR vs. Culture in Complicated UTI — Part II: Diagnostic Concordance and Antibiotic Selection
How often PCR and culture agree, what drives the cases where they disagree, and whether PCR leads to better antimicrobial selection.
- Authors
- Spangler, F.L.; Williams, C.; Aberger, M.E.; Wilson, B.A.; Ajib, K.; Gholami, S.S.; Goodwin, H.N.; Park, L.Y.; Kardjadj, M.; Derrick, D.; et al.
Read the paper PMID 39671979Full citation
Spangler, F.L.; Williams, C.; Aberger, M.E.; Wilson, B.A.; Ajib, K.; Gholami, S.S.; Goodwin, H.N.; Park, L.Y.; Kardjadj, M.; Derrick, D.; et al. Clinical utility of PCR compared to conventional culture and sensitivity testing for management of complicated urinary tract infections in adults: Part II: Evaluation of diagnostic concordance, discordant results, and antimicrobial selection efficacy. Diagn. Microbiol. Infect. Dis. 2025, 111, 116646.
Reviews and commentary
Broader syntheses, including the paper addressing MolDX coverage criteria directly — the most useful one for practices in restricted states.
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PCR vs. Culture for Complicated UTI: Evidence Review and MolDX Coverage Criteria
A synthesis of real-world evidence, clinical trials, and meta-analyses examined specifically against Molecular Diagnostic Services (MolDX) program coverage criteria.
The most directly useful paper for practices in MolDX-restricted states, and the natural citation for our MolDX guidance work.
- Authors
- Aberger, M.E.; Wilson, B.A.; Chavez, R.
Read the paper reviewsinurology.comFull citation
Aberger, M.E.; Wilson, B.A.; Chavez, R. Evaluating the analytical validity and clinical utility and validity of polymerase chain reaction diagnostics vs culture and sensitivity methods in complicated urinary tract infection management: A comprehensive review of real-world evidence, clinical trials, and meta-analyses concerning molecular diagnostic services program coverage criteria. Rev. Urol. 2025, 24, 1–11.
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PCR in Complicated UTI: A Paradigm Shift in Diagnostics and Management
A commentary framing the shift from culture-based to molecular diagnosis in complicated UTI, published in the AUA's open-access journal.
- Authors
- Kardjadj, M.
Read the paper 10.1097/JU9.0000000000000353Full citation
Kardjadj, M. Clinical Utility of PCR in Complicated Urinary Tract Infections: A Paradigm Shift in Diagnostics and Management. JU Open Plus 2025, 3, e00114.
The science
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