Carbapenem-Resistant Enterobacterales in Indian ICU Patients: Molecular Insights, Risk Factors, and Clinical Impact

Carbapenem-resistant Enterobacterales (CRE) pose a critical threat in intensive care units (ICUs) due to rapid transmission potential and limited treatment options. The study aimed to determine the incidence of intestinal CRE colonization among ICU patients, characterize the isolates phenotypically and genotypically and identify associated risk factors. This cross-sectional study was conducted in a tertiary care hospital in North India and included 236 ICU patients. Clinical, demographic, lifestyle, and dietary data were collected through standardizedv questionnaires and medical records. CRE isolates were identified using standard microbiological techniques and characterized for resistance genes. CRE colonization was detected in 69.07% of patients. <i>Escherichia coli</i> (74.15%) and <i>Klebsiella pneumoniae</i> (21.61%) were the predominant species, with a significant rise in <i>K. pneumoniae</i> colonization during ICU stays (<i>p</i> = 0.049), suggesting nosocomial transmission. Asthma emerged as a novel independent risk factor (<i>p</i> = 0.023, 100% colonization). Other significant associations included non-vegetarian diet (<i>p</i> = 0.02), prolonged ICU stay (<i>p</i> = 0.010), and prior broad-spectrum antibiotic use (<i>p</i> = 0.028). Molecular analysis showed 84% of CRE isolates harbored the bla_NDM-1 gene, while bla_IMP was absent. CRE colonization was significantly associated with higher mortality (38.0% vs. 23.3%, <i>p</i> = 0.026). The study reveals a high prevalence of intestinal CRE colonization among ICU patients and highlights key modifiable risk factors and regional resistance patterns. Routine rectal screening, stringent infection control, and robust antimicrobial stewardship are urgently needed to limit CRE spread. A deeper understanding of colonization dynamics is essential to improving outcomes in critically ill patients.