Risk Factors Associated with Carriage of NDM-producing Enterobacterales: A Matched Case -Control Study.

BACKGROUND: Carbapenemase-producing Enterobacterales, particularly New Delhi metallo-β-lactamase (NDM) producers, are spreading rapidly in European hospitals despite reinforced control measures. Risk factors specifically associated with hospital carriage of NDM-producing Enterobacterales in France remain poorly defined. We aimed to identify factors independently associated with in-hospital NDM carriage. METHODS: We performed a retrospective, single centre, 1:2 matched case -control study at Avicenne University Hospital (Paris, France) over 2024. Cases were patients with NDM-producing Enterobacterales identified at least three days after admission. Each case was matched to two controls hospitalized in the same ward, during the same period, with a comparable length of stay and at least two negative rectal screenings. Clinical, demographic, and epidemiological variables were analyzed using conditional logistic regression. RESULTS: Seventy-two cases were matched to 144 controls. In multivariable analysis, NDM carriage was independently associated with a Charlson comorbidity index ≥5 (adjusted odds ratio [aOR] 2.84, 95% CI 1.30-6.19), prior surgery (aOR 2.92, 95% CI 1.47-8.44), endoscopic procedures during hospitalization (aOR 3.52, 95% CI 1.47-8.44), recent travel abroad (aOR 3.58, 95% CI 1.41-9.13), and hospitalization in two or more epidemic wards during the same year (aOR 5.85, 95% CI 1.84-18.55). CONCLUSION: Carriage of NDM-producing Enterobacterales results from the interplay between patient vulnerability, invasive procedures, international exposure, and intra-hospital transmission dynamics. These findings support targeted screening strategies and reinforced infection prevention measures for high-risk patients, particularly those undergoing invasive procedures or transferred between epidemic wards.