Diagnostic characteristics of the Rapid ESBL NP - test and ResistanceFinder 2SMART multiplex PCR for the detection of ESBL directly on urine samples - Research

Sep 28, 2026

Purpose determines diagnostic characteristics of the phenotypic Rapid ESBL NP test and a prototype ResistanceFinder 2SMART multiplex PCR for rapid ESBL detection directly in urine from patients with urinary tract infections. Methods evaluate both tests on direct urine samples and compare results with conventional urine cultures, calculating sensitivity, specificity, PPV and NPV with 95% confidence intervals. Results include high post-exclusion accuracy for Rapid ESBL NP and lower PPV for the PCR when positive gene detection defines positivity. Conclusion highlights high NPVs, suggests Rapid ESBL NP as a suitable screening tool while noting prospective validation needs and potential carbapenem overuse.

LanguageEnglish

CategoryHealthcare

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Abstract

Introduction

Materials and methods

Results

Conclusion

European Journal of Clinical Microbiology & Infectious Diseases (2025) 44:3021–3028 [https://doi.org/10.1007/s10096-025-05256-9](https://doi.org/10.1007/s10096-025-05256-9) RESEARCH Diagnostic characteristics of the Rapid ESBL NP ® test and ResistanceFinder 2SMART multiplex PCR for the detection of ESBL directly on urine samples Marit W. Bot1,2 · Jacky Flipse1,3 · Sabien L.M. Bongers1,2 · Chiara Giardino4 · Lieke E.K.W. Geraets4 · Antoinette A.T. P. Brink4 · Jacobien J. Hoogerwerf5,6 · Jaap ten Oever5,6 · Heiman F. L. Wertheim2,6 · Maurits P.A. van Meer1 Received: 27 June 2025 / Accepted: 20 August 2025 / Published online: 25 September 2025 © The Author(s) 2025 Abstract Purpose To determine the diagnostic characteristics of the phenotypic Rapid ESBL NP® test and a prototype version of the molecular ResistanceFinder 2SMART multiplex PCR for the rapid detection of ESBL in patients with urinary tract infections. Methods The Rapid ESBL NP® test and the ResistanceFinder 2SMART multiplex PCR were performed on direct urine samples (enterobacterales, ≥105 CFU/ml and ≥ 3 plusses of leukocytes in Gram stain) collected at Rijnstate and Radboudumcand compared to conventional urine cultures. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated with 95% confidence intervals. Results In total, 218 urine samples were collected, of which 66 contained ESBL-producing bacteria, 102 contained Gramnegative bacteria without ESBL production and 50 contained no clinically significant growth. The Rapid ESBL NP® test gave 16 (7.3%) non-interpretable results. After excluding the non-interpretable results, the test had a sensitivity, specificity, PPV and NPV of 96.8%(89.0-99.6), 100%(97.4–100), 100%(94.1–100) and 98.6%(94.7–99.6), respectively. Using detection ofCTX-M and VEB genes as positive, the ResistanceFinder 2SMART multiplex PCR had a sensitivity, specificity, PPV and NPV of 95.5%(87.3–99.1), 94.1%(89.1–97.3), 87.5%(78.8–93.0) and 98.0%(94.0-99.3), respectively. Conclusion The NPVs for both tests were high. However, the lower PPV of the ResistanceFinder2 SMART multiplex PCR could lead to increased overuse of carbapenems when implemented into clinical practice. The Rapid ESBL NP® test could be a suitable screening tool for ESBL-producing bacteria in clinical urine samples, ensuring more accurate prescription of antibiotics, though prospective validation is necessary first. Keywords Rapid diagnostics · Extended-spectrum beta lactamase · Urinary tract infection · Phenotypic detection · PCR Heiman F.L. Wertheim and Maurits P.A. van Meer have contributed equally to this work. 􀀍 Marit W. Bot [mbot@rijnstate.nl](mbot@rijnstate.nl) 1 Department of Medical Microbiology and Immunology, Rijnstate Hospital, Arnhem, the Netherlands 2 Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands 3 Laboratory for Medical Microbiology and Immunology, Dicoon, Elst, the Netherlands 4 PathoFinder B.V., Randwycksingel 45, Maastricht 6229 EG, Netherlands 5 Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands 6 Radboud Community for Infectious Diseases, Radboud University Medical Center, Nijmegen, the Netherlands Introduction Resistance to antibiotics, particularly in Gram-negative bacteria, is a major threat to patients as the subsequent failure to treat infections is a leading cause of death [1]. A large patient group affected by antibiotic resistant infections are those with (complicated) urinary tract infections (cUTI), defined in this study as having 1–2 species of enterobacterales, a CFU of at least 105/mL and 3–4 plusses of leukocytes in the Gram stain. In standard clinical practice, patients with an indication for hospital admission are treated empirically with a second-or third-generation cephalosporin based on regional antibiotic resistance prevalence. However, if a patient is suspected

FAQs

What is the purpose of comparing the Rapid ESBL NP test with the ResistanceFinder 2SMART multiplex PCR?

To determine diagnostic characteristics for rapid ESBL detection directly on urine samples from patients with urinary tract infections, using conventional urine cultures as the reference.

How were the tests performed and what samples were used?

Both tests were performed on direct urine samples with specified enterobacterales counts and leukocyte findings, collected at Rijnstate and Radboudumcand, then compared with routine urine cultures.

What were the key findings about sensitivity, specificity, PPV, and NPV?

After excluding non-interpretable Rapid ESBL NP results, sensitivity and specificity were very high with an NPV of 98.6%; for the PCR, NPV was high (98.0%) but PPV was lower, 87.5%, when CTX-M and VEB genes defined positivity.

What clinical implication is highlighted in the conclusion?

High NPVs support both tests, but the lower PPV of the ResistanceFinder 2SMART multiplex PCR could increase overuse of carbapenems, while the Rapid ESBL NP test may serve as a suitable screening tool pending prospective validation.

Sep 28, 2026

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