Diagnostic characteristics of the Rapid ESBL NP® test directly on urine samples in patients with a urinary tract infection

Abstract

AIM: To determine the suitability of the Rapid ESBL NP test for the rapid detection of extended spectrum beta-lactamase (ESBL) in clinical urine samples of patients with a urinary tract infection. BACKGROUND: The rise of antibiotic resistance in Gram-negative bacteria threatens successful treatment of infections, increasing the need for last-resort antibiotics, and consequently the risk of overtreatment. Rationalising the use of these last-resort antibiotics can be done using rapid diagnostics for the detection of ESBL, such as the Rapid ESBL NP® test, which can determine ESBL-activity within one hour. METHODS: A total of 218 urine samples were collected from two Dutch hospitals, of which 67 contained ESBL-producing bacteria, 101 contained non ESBL-producing bacteria and 50 were negative controls. Culture-based techniques and the Rapid ESBL NP® test were used to confirm the presence of ESBL-producing bacteria. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated with 95% confidence intervals. RESULTS: The Rapid ESBL NP® test gave 16 (7.3%) non-interpretable results. After excluding these non-interpretable results, the test had a sensitivity, specificity, PPV and NPV of 96.8% (95%CI: 89.0-99.6), 100% (97.4-100.0), 100.0% (94.1-100.0) and 98.6% (94.7-99.6), respectively. When non-interpretable tests were seen as negative, these values became 91.0% (95%CI: 81.5-96.6), 100% (97.6-100.0), 100% (94.1-100.0) and 96.2% (92.1-98.2), respectively. CONCLUSIONS: The Rapid ESBL NP® test can be a suitable screening tool for ESBL-producing bacteria in clinical urine samples while awaiting the more accurate culture-based results and further antimicrobial susceptibility pattern, ensuring more accurate initial prescription of last-resort antibiotics.

Keywords

• Rapid diagnostics
• ESBL
• urinary tract infection