Active Microbiological Surveillance for Contrasting Multi-Drug-Resistant Pathogens: Comparison Between a Multiplex...

Area of Science:

• Clinical Microbiology
• Molecular Diagnostics
• Infectious Diseases

Background:

• Multi-drug-resistant (MDR) microorganisms, including beta-lactam-resistant Gram-negative bacteria and vancomycin-resistant enterococci, present a significant healthcare challenge.
• Culture methods for detecting MDR pathogens in surveillance swabs are reliable but suffer from long turnaround times and low sensitivity.
• Molecular techniques offer reduced time-to-result and precise identification of resistance genes, improving diagnostic capabilities.

Purpose of the Study:

• To evaluate the performance of two molecular assays, Allplex Entero-DR and Entero-DR Plus, for detecting key antimicrobial resistance genes directly from rectal swabs.
• To compare the diagnostic accuracy of these molecular assays against conventional culture-based methods for MDR pathogen surveillance.
• To assess the prevalence of specific resistance genes and identify the presence of Acinetobacter spp. and Pseudomonas aeruginosa spp. in the study population.

Main Methods:

• Evaluation of Allplex Entero-DR and Entero-DR Plus molecular kits using 300 rectal swabs collected during routine surveillance.
• Detection targets included genes for extended-spectrum beta-lactamases (ESBL), carbapenem resistance, and vancomycin resistance.
• Identification of Acinetobacter spp. and Pseudomonas aeruginosa spp. was also performed, with results compared to culture-based methods.

Main Results:

• The Allplex™ assay demonstrated high sensitivity (100%) and negative predictive value (100%), with 62.6% of samples testing positive for at least one target.
• Prevalence of blaCTX-M and van genes was high, alongside evidence of double-carbapenemase genes and metallo-beta-lactamase-producing strains.
• Limited data were obtained for carbapenem-resistant P. aeruginosa and Acinetobacter spp., suggesting a need for further investigation with larger sample sizes and respiratory samples.

Conclusions:

• Combining conventional and molecular diagnostic methods is crucial for effective investigation of MDR pathogens.
• The optimal diagnostic strategy should consider the epidemiological context and prevalence of resistance mechanisms.
• Molecular screening, due to its high negative predictive value, can effectively rule out negative samples in high-risk settings.