Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and lateral flow immunochromatography for rapid identification of β-lactamase-gene-harboring Enterobacterales in urine specimens: Performance and cost-benefit analyses

In this single-center prospective study, we evaluated the performance to the MALDI-ToF MS based method in conjunction with lateral flow immunochromatographic (LFIC) in urine specimens for rapid diagnosis of bacterial Urinary Tract Infection (UTI) and detection of carbapenemase and/or extended-spectrum β- lactamase (ESBL) enzymes produced by the involved bacteria, compared to standard culture, and antimicrobial susceptibility testing/genotypic resistance markers characterization performed on culture-grown colonies. In addition, a cost-benefit analysis comparing this approach against standard procedures was conducted. A total of 324 urines were included in the study, of which 288 (88.9 %) yielded concordant results by the MALDI-ToF MS and conventional culture (Kappa agreement, 0.82; P<0.001). Direct LFIC testing could be carried out in 249/324 urines. Bacterial species carrying β-lactam genotypic resistance markers were identified in 35 urines (35 CTX-M and 2 OXA-48). Two ESBL-producing Escherichia coli were missed by LFIC (Kappa agreement with standard procedures of 0.96; P<0.001). The cost-benefit analysis indicated that our novel approach resulted in an improvement of clinical outcomes (less need of outpatient care) with a marginal incremental cost (€2.59).