Colistin and Carbapenem Resistance in Gram-Negative Bacteria: An Emergent Threat

The rise of Gram-negative bacteria that resist both colistin and carbapenem antibiotics creates serious problems for clinical laboratories and patient treatment. This research examined how effectively automated laboratory systems can identify these developing resistance patterns in medically important Gram-negative bacteria. Researchers conducted a forward-looking observational study in hospitals throughout Erbil, Iraq from November 2024 to March 2025, studying 350 clinical samples taken from patients between 1 and 90 years old. Specimens included urine (295), swabs (17), blood (16), stool (14), and sputum (8) samples. Bacterial identification and antimicrobial susceptibility testing were performed using automated systems. Seven Gram-negative bacterial species were identified, with Escherichia coli predominating (183 isolates, 52.3%). Alarming carbapenem resistance emergence was detected, particularly in Klebsiella pneumoniae (48.10% imipenem, 37.97% meropenem resistance). Most critically, emerging colistin resistance was documented in typically susceptible organisms: Escherichia coli (1.64%), Klebsiella pneumoniae (3.80%), and Pseudomonas aeruginosa (6.67%), representing a dangerous evolutionary step toward pan-drug resistance. Female patients showed significantly higher infection rates (65.43% vs 34.57%, p=0.0222). The emergence of colistin resistance in previously susceptible Gram-negative bacteria, combined with extremely high carbapenem resistance rates, signals a critical evolution toward untreatable infections. This emerging resistance pattern demands immediate intervention through enhanced surveillance, antimicrobial stewardship, and infection control measures to prevent widespread dissemination of pan-drug resistant organisms.