The CLSI M47 2nd Edition (M47-Ed2), published in April 2022, sets international standards for the "vein-to-report" process of blood culturing to optimize pathogen recovery and minimize contamination. The guideline provides evidence-based recommendations on specimen collection, volume, bottle distribution, and laboratory processing. For more details, visit CLSI M47 - Principles and Procedures for Blood Cultures
CLSI M47 is a standard that provides guidelines for the identification of microorganisms using various laboratory methods. The standard, titled "Microbial Identification—Approved Guideline," was developed to provide a comprehensive framework for laboratories to identify microorganisms accurately and efficiently.
The Clinical and Laboratory Standards Institute (CLSI) is a globally recognized, non-profit organization that develops standards and guidelines for medical testing. CLSI M47 is the dedicated guideline focusing exclusively on used to identify bacteria and characterize their traits (e.g., virulence factors or antimicrobial resistance genes). clsi m47
A crucial recommendation: , as bacterial loads do not correlate with infection severity in the same way as viruses.
For ongoing testing, CLSI M47 mandates a three-tier QC system: The CLSI M47 2nd Edition (M47-Ed2), published in
A reference lab develops an in-house sequencing assay for culture-negative endocarditis. Under M47:
The guideline warns against "off-label" use without proper validation. For example, using a test validated only for culture isolates on a direct blood sample requires re-validation. A crucial recommendation: , as bacterial loads do
| Framework | Relationship to M47 | |-----------|----------------------| | | M47 provides the technical guidance to meet CLIA validation requirements for high-complexity testing. | | ISO 15189 | M47 complements ISO by offering method-specific validation protocols for molecular bacteriology. | | CAP Checklist | The College of American Pathologists explicitly cites M47 for molecular microbiology checklist items (MOL.31400, MOL.31500). | | FDA | For LDTs, M47 is the standard for analytical validation; for cleared assays, it guides verification. |
The shift from culture to molecular identification is irreversible. In sepsis, hours matter. In meningitis, minutes matter. CLSI M47 provides the rigorous, evidence-based framework that ensures these rapid tests deliver reliable results.
Note: Always ensure you have the current edition. As of my last update (late 2025), M47-Ed2 (2022) is the most recent. Verify with CLSI’s website.
Molecular methods bypass culture entirely, detecting bacterial DNA directly from clinical specimens (blood, cerebrospinal fluid, tissue) or from positive blood cultures. However, this speed introduces new challenges: