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
Bibliographic record
Abstract
Background: Rapid multiplex PCR assays promise faster and broader detection of uropathogens and resistance markers than conventional quantitative urine culture and susceptibility testing (C&S), but trial evidence linking PCR-guided management to patient-centered outcomes and the mechanisms of any benefit is limited. We performed an ad hoc analysis of the randomized, multicenter NCT06996301 trial to evaluate whether PCR-guided diagnostic management improves clinical symptom resolution in complicated urinary tract infection (cUTI) and to quantify mediation by time-to-antibiotic start and antibiotic appropriateness. Methods: Paired PCR and C&S were collected for all participants; treating investigators received and acted on randomized results from one diagnostic modality and remained blinded to the comparator. The modified intention-to-treat (Mod-ITT) cohort at end-of-study (EOS) included 362 participants (PCR n = 193; C&S n = 169). The primary outcome was complete clinical cure at EOS (absence of all baseline symptoms). Secondary outcomes included partial cure (≥50% symptom reduction) and per-symptom changes. We used mixed-effects logistic regression (site random intercept) to estimate associations, and causal mediation analysis with nonparametric bootstrap (B = 2000) to decompose PCR’s total effect into indirect effects via time-to-antibiotic (log-transformed) and antibiotic appropriateness (binary, adjudicated at EOS) for complete clinical cure and partial cure. Results: Median time-to-first antibiotic was substantially shorter in the PCR arm (20 h; IQR 12–36) than in the C&S arm (52 h; IQR 30–66; p < 0.001). Antibiotic appropriateness was higher after PCR-guided care (161/193; 83.4%) versus C&S (105/169; 62.1%; p < 0.001). Complete clinical cure occurred in 143/193 (74.1%) PCR versus 106/169 (62.7%) C&S (p = 0.020); partial cure in 161/193 (83.4%) versus 121/169 (71.6%; p = 0.014). In a total-effect mixed model (no mediators), PCR assignment was associated with higher odds of cure (adjusted OR 1.95; 95% CI 1.12–3.39; p = 0.018). In the mechanistic model including mediators, antibiotic appropriateness (OR 2.48; 95% CI 1.45–4.24; p = 0.001), and time-to-antibiotic (per 1 h, OR 0.95; 95% CI 0.926–0.975; p < 0.001) were independently predictive, while the direct arm effect was attenuated (OR 1.10; 95% CI 0.33–3.71). Mediation analysis estimated a statistically significant combined indirect effect (ACME) of 0.0648 (95% CI 0.0343–0.0977), ADE 0.0207 (95% CI −0.0282–0.0784), total effect 0.0796 (95% CI 0.0419–0.1225), and proportion mediated ≈ 74%. Both time-to-antibiotic and appropriateness contributed, with ACME_time ≈ 0.046 and ACME_appropriateness ≈ 0.019. Exploratory analysis using partial cure as the outcome confirmed the robustness and internal validity of the complete-cure findings. Conclusions: In this ad hoc analysis of a randomized trial, PCR-guided management of cUTI improved patient-centered symptom outcomes compared with culture-guided care. Most of the benefit was mediated through faster initiation of antibiotics and, to a lesser extent, increased probability of an appropriate initial antibiotic. These results support stewardship-integrated, rapid molecular diagnostics (used alongside culture) to shorten time-to-effective therapy and improve clinical outcomes in cUTI.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".