Carbapenem-resistant Acinetobacter baumannii carrier detection: a simple and efficient protocol

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical multidrug-resistant pathogen causing significant nosocomial infections.
• Standardized laboratory methods for CRAB carrier identification are lacking, hindering effective infection control strategies.
• WHO and CDC highlight CRAB as a major public health threat requiring urgent detection and management.

Purpose of the Study:

• To develop and validate a practical, sensitive, and specific protocol for detecting CRAB carriers from screening samples.
• To compare the performance of different selective agar media for CRAB isolation.
• To optimize sample enrichment time and identify the most accurate PCR-based methods for CRAB identification.

Main Methods:

• Evaluated three selective agar media: mSuperCARBA (SC), CHROMagar Acinetobacter (CaA), and modified CHROMagar Acinetobacter (mCaA) with meropenem.
• Assessed PCR for species-specific genes (gyrB, blaOXA-51) and carbapenemase genes (blaOXA-23, blaOXA-24, blaOXA-58).
• Conducted a prospective study using skin sampling with a 6-hour enrichment period, followed by plating on mCaA and PCR confirmation.

Main Results:

• Modified CHROMagar Acinetobacter (mCaA) demonstrated high specificity (97%) and sensitivity (98%) for CRAB detection.
• Skin sampling with a 6-hour enrichment achieved 98% sensitivity for CRAB carriage detection.
• PCR targeting gyrB (98% accuracy) and blaOXA-51 (99% accuracy) effectively differentiated CRAB from other species on mCaA.

Conclusions:

• A novel protocol combining skin sampling, short enrichment, mCaA selection, and PCR-based identification provides reliable and rapid CRAB carrier detection.
• This protocol achieves a 24-hour turnaround time, facilitating timely implementation of infection control measures.
• The developed method addresses the need for standardized and efficient CRAB screening in healthcare settings.