Comparison between automated system and PCR-based method for identification and antimicrobial susceptibility profile...

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Enterococci are a growing cause of hospital-acquired infections globally.
• Accurate identification and susceptibility testing are crucial for effective treatment.
• Current automated systems may require enhancement for reliable Enterococcus spp. identification.

Purpose of the Study:

• To compare the performance of an automated MicroScan system, PCR-based assays, and disk diffusion for identifying Enterococcus species.
• To evaluate the accuracy of these methods in determining antimicrobial susceptibility profiles.
• To assess the utility of PCR for detecting specific antibiotic resistance genes in Enterococcus isolates.

Main Methods:

• Evaluated 30 clinical Enterococcus spp. isolates.
• Utilized MicroScan system and PCR for species identification.
• Employed PCR for detecting vancomycin, gentamicin, tetracycline, and erythromycin resistance genes.
• Performed antimicrobial susceptibility testing using automated system and disk diffusion.

Main Results:

• General agreement between PCR and automated identification was 90.0% (27/30), with 100% agreement for E. faecium and E. faecalis.
• Higher resistance rates observed in E. faecium compared to E. faecalis.
• Prevalence of resistance: erythromycin (86.7%), vancomycin (80.0%), tetracycline (43.3%), and gentamicin (33.3%).
• PCR detected the van(A) gene in all vancomycin-resistant enterococci.
• Disk diffusion and automated methods showed >80% category agreement for most antibiotics.

Conclusions:

• PCR is a reliable method for identifying clinically relevant enterococci and detecting resistance genes.
• Automated systems demonstrate good overall agreement but require improvement for certain Enterococcus species.
• The high prevalence of antibiotic resistance underscores the need for continuous monitoring and improved diagnostic tools.