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 Impa

Clinical success in treating complicated urinary tract infections (cUTIs) depends on accurate pathogen detection, given the common occurrence of polymicrobial infections and antimicrobial resistance. This multicenter, randomized, investigator-blinded study compared polymerase chain reaction (PCR)-based diagnostics to conventional culture and sensitivity (C&S) testing in guiding the treatment of cUTIs. PCR identified polymicrobial infections in 43.52% of cases, a significantly higher rate than that observed with C&S (31.95%, <i>p</i> = 0.033). Patients in the C&S arms with undetected polymicrobial infections had a significantly higher clinical failure rate (33.33%, 14/42, <i>p</i> = 0.041) compared to those with concordant polymicrobial infection identification by both methods (22.22%, 12/54). PCR also detected additional pathogens in 54.44% (92/169) of cases in the C&S arm, where clinical failure was significantly higher when C&S missed pathogens (28.26% vs. 14.29%, <i>p</i> = 0.015). Similarly, when C&S failed to detect phenotypic resistance (compared to PCR), clinical failure occurred in 50% (16/42) of cases, compared to 13.22% (21/121, <i>p</i> = 0.001) when resistance detection was concordant (PCR and C&S). To further illustrate the clinical impact, patient-level case analyses are included to demonstrate how PCR-guided therapy improved pathogen detection and enabled more appropriate antimicrobial selection compared to C&S. These findings highlight the limitations of C&S in detecting polymicrobial infections, antimicrobial resistance, and hetero-resistance due to its limited clonal analysis, supporting the integration of PCR for more accurate diagnostics and optimized cUTI management.