Burden of Carbapenemase-Producing Enterobacterales in Critical Care Settings: Insights from a Tunisian Intensive Care Unit

Background: This study aimed to determine the prevalence of carbapenem-resistant Enterobacterales (CRE), to characterize their molecular resistance mechanisms, and to assess associated clinical outcomes among intensive care unit (ICU) patients in Tunisia. Methods: A cross-sectional study was conducted from January to March 2025 in the ICU of Habib Thameur Hospital and included all patients with clinically significant CRE infections. Resistance determinants were identified using multiplex polymerase chain reaction with reverse dot blot hybridization. Results: Among 95 ICU admissions, 17 patients developed CRE infections, corresponding to an incidence density of 21.6 cases per 1,000 patient-days. All infections were hospital-acquired. The most frequent risk factors were the presence of central venous and urinary catheters (16 patients each) and mechanical ventilation (15 patients). Klebsiella pneumoniae predominated, accounting for 26 of 27 isolates, all of which were multidrug-resistant (MDR), with a median antibiotic resistance index of 1.00. The bla NDM and bla OXA-48 genes were detected in 81.5% and 77.8% of isolates, respectively, with 70.4% co-producing both carbapenemases. All K. pneumoniae isolates harbored bla SHV and/or bla CTX-M , while a single Escherichia coli isolate carried bla OXA-48 . Cluster analysis revealed strong associations between β-lactamase production and resistance to aminoglycosides and fluoroquinolones, suggesting co-selection of MDR strains. Empirical antimicrobial therapy was appropriate in only 47% of cases, and ICU mortality reached 82.4%. Conclusion: These findings highlight an alarmingly high burden of CRE infections in this ICU, driven mainly by K. pneumoniae co-producing NDM and OXA-48, and underscore the urgent need for strengthened infection control and antimicrobial stewardship strategies.