Rapid commercial CTX-M diagnostics: Performance, limitations and clinical impact

Area of Science:

• Clinical microbiology
• Antimicrobial resistance
• Diagnostic technology

Background:

• CTX-M enzymes are the most prevalent extended-spectrum β-lactamases (ESBLs) in Enterobacterales, necessitating rapid detection for effective patient management.
• Timely identification of CTX-M-producing pathogens can significantly improve clinical outcomes in infected or colonized individuals.

Purpose of the Study:

• To review and assess commercially available rapid diagnostic tests for CTX-M enzymes and their genes.
• To discuss the clinical impact and implementation challenges of these rapid assays in routine laboratory settings.

Main Methods:

• Evaluation of lateral flow immunoassays for CTX-M protein detection.
• Analysis of microarrays, quantitative PCR, and loop-mediated isothermal amplification for blaCTX-M gene detection.
• Review of studies assessing the clinical utility of rapid CTX-M assays, particularly those used with positive blood cultures.

Main Results:

• Some rapid CTX-M assays, especially those analyzing positive blood cultures (e.g., Verigene, BioFire FilmArray, ePlex), offer advantages over standard methods by reducing time to effective therapy.
• Despite demonstrated benefits, widespread adoption is hindered by high costs and insufficient robust evidence of positive impact.
• Targeting specific patient subgroups, such as critically ill patients with Gram-negative positive blood cultures, may maximize the clinical utility of these assays.

Conclusions:

• Rapid CTX-M detection assays can enhance patient outcomes by enabling faster targeted therapy.
• Implementation strategies should focus on high-impact patient populations, like ICU patients with septic shock, to overcome adoption barriers.
• Integrating rapid testing with effective laboratory-clinician communication is crucial for optimizing patient management and improving outcomes.