Correlation of Phenotypic Resistance Profiles with Molecular Findings for Comprehensive Characterization

Abstract

Background: Antimicrobial resistance (AMR) poses a critical global health challenge. While phenotypic methods provide direct evidence of drug resistance, molecular approaches offer insights into the underlying genetic determinants. Correlating these approaches provides a comprehensive characterization that enhances diagnostic accuracy and guides therapeutic decisions.

Material and Methods: A total of clinical bacterial isolates were evaluated using standard phenotypic susceptibility testing methods such as disk diffusion and minimum inhibitory concentration assays. Molecular characterization was performed using PCR and sequencing to detect resistance genes. Inclusion criteria were culture-positive isolates, while contaminants and duplicates were excluded.

Results: Phenotypic resistance was observed across multiple drug classes, including β-lactams and fluoroquinolones. Molecular assays identified genes such as blaCTX-M, blaTEM, and gyrA mutations. Correlation analysis showed strong agreement between extended-spectrum β-lactamase (ESBL) phenotypes and blaCTX-M gene presence, while discrepancies were noted in quinolone resistance, suggesting additional non-genetic mechanisms.

Conclusion: Correlating phenotypic and molecular findings enhances the reliability of AMR detection. While molecular methods confirm resistance determinants, phenotypic assays capture the functional expression of resistance. A combined approach is essential for robust surveillance, clinical management, and targeted infection control policies