Distribution, antibacterial resistance, biofilm formation, and risk factors associated with carbapenemase-producing gram-negative bacteria in ICU patients.

Gram-negative bacteria are major contributors to intensive care unit (ICU)-acquired infections, further complicated by biofilm formation, multidrug resistance (MDR), and carbapenemase production. This study, conducted in Uttar Pradesh, India (2022-2023), assessed the distribution, antibacterial resistance profiles, biofilm formation, and risk factors associated with carbapenemase-producing organisms (CPOs) in ICU patients. A total of 321 g-negative bacteria (GNB) isolates were recovered from 311 clinical samples. Bacterial identification, antibacterial susceptibility testing, biofilm detection, and PCR-based carbapenemase gene analysis were performed. Clinical and demographic variables were evaluated to determine factors associated with CPO infections and outcomes. The predominant pathogens were Pseudomonas aeruginosa 109 (34%), Klebsiella pneumoniae 77 (24%), and Escherichia coli 53 (16.5%). High resistance rates were observed for β-lactams and fluoroquinolones, whereas carbapenems, aminoglycosides, and polymyxins remained largely effective. Biofilm formation was noted in Acinetobacter baumannii 23 (74.2%), K. pneumoniae 56 (72.7%), P. aeruginosa 74 (67.9%), and E. coli 34 (64.1%). The most prevalent carbapenemase genes were blaNDM-1 28 (45.9%), blaOXA-48 14 (23%), and blaVIM 7 (11.5%), with co-existence in 13 isolates (21.3%). CPO infections occurred in 61/311 patients (19.6%). Significant risk factors included male sex (42; 68.9%), age > 40 years (43; 70.5%), ICU stay > 7 days (46; 75.4%), urinary catheterization (41; 67.2%), venous catheterization (37; 60.7%), and mechanical ventilation (40; 65.6%). Mortality was higher in CPO-infected patients (23; 37.7%) than in non-CPO cases (52; 20.8%). Biofilm formation and carbapenemase genes are key drivers of MDR-GNB in ICUs. CPO infections are strongly linked to invasive device use and increased mortality, underscoring the need for robust antibacterial stewardship and infection control practices.