Phenotypic and Molecular Characterization of Multidrug Resistant Gram-Negative Organisms from Lower Respiratory Tract Infections: A Review
Keywords:
Multidrug resistance; Gram-negative bacteria; Lower respiratory tract infections; phenotypic characterization; Molecular characterization; Antimicrobial resistance genes and ESBL.Abstract
Lower respiratory tract infections (LRTIs) remain among the leading causes of morbidity and mortality worldwide, particularly in immunocompromised and hospitalized patients. The emergence of multidrug resistant (MDR) Gram-negative bacteria such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli has further complicated clinical management. Conventional phenotypic antimicrobial susceptibility testing (AST) provides essential guidance but fails to capture the complete resistance landscape. Molecular approaches, including PCR-based detection of resistance genes, offer greater precision in identifying extended-spectrum β-lactamases (ESBLs) and carbapenemases. This review synthesizes current evidence on phenotypic and molecular characterization of MDR Gram-negative bacteria in LRTIs, emphasizing their epidemiology, mechanisms of resistance, diagnostic approaches, and clinical implications.
