External Quality Assessment in Microbiology

External quality assessment (EQA) in microbiology is an independent evaluation of a laboratory's ability to correctly identify microorganisms and determine their antimicrobial susceptibility. Proficiency testing (interlaboratory comparison) programs in this field cover bacteriology, virology, mycology and parasitology. Regular participation is a requirement of GOST R ISO 15189-2024 (the Russian national adoption of ISO 15189) and a cornerstone of the fight against antimicrobial resistance.

The Importance of EQA for Microbiological Diagnostics

Microbiology holds a special place in laboratory medicine. The result depends not only on the equipment but also on staff expertise, the quality of culture media and correct interpretation. Misidentification of a pathogen or incorrect antimicrobial susceptibility results can lead to ineffective therapy and a worse prognosis.

Key objectives of EQA in microbiology:

With antimicrobial resistance (AMR) rising worldwide, the accuracy of microbiological testing is of strategic importance. The WHO lists AMR among the top ten threats to public health.

Confirming the accuracy of bacterial, fungal and viral identification
Assessing the correctness of antimicrobial susceptibility testing (AST)
Verifying the performance of automated identification systems (VITEK 2, MALDI-TOF)
Quality control of blood cultures and molecular pathogen detection
Detecting errors in the pre-analytical and analytical phases

Areas Covered

Bacteriology

Identification of gram-positive and gram-negative bacteria
Determination of the minimum inhibitory concentration (MIC)
Detection of resistance mechanisms: MRSA, ESBL, carbapenemases (KPC, NDM, OXA-48)
Pathogen typing for epidemiological surveillance

Mycology

Identification of yeasts and filamentous fungi
Antifungal susceptibility testing

Blood Cultures

Correct processing of positive blood cultures
Speed of pathogen identification from blood
AST accuracy for sepsis pathogens

Infectious Disease Serology

Detection of antibodies to pathogens: HIV, hepatitis B and C, syphilis, the TORCH panel
Confirmatory tests (Western blot, ELISA)

International EQA Programs for Microbiology

Provider	Program	Frequency	Focus
CAP	M47/M30 — Gram ± Bacteriology	3×/year	Bacterial identification, AST
CAP	V-BC — Blood Culture	2×/year	Blood cultures
UK NEQAS	Bacteriology, AST	6×/year	Antimicrobial resistance, identification
UK NEQAS	Mycology	4×/year	Mycology
INSTAND e.V.	Ringversuch 359 — MALDI-TOF	3×/year	Mass spectrometry-based identification
INSTAND e.V.	Microbiology, serology	2–4×/year	Bacteriology, virology, serology
Labquality	Microbiology	4–6×/year	Full range: from bacteriology to mycology

Programs for Molecular Pathogen Detection

QCMD: panels for PCR detection of respiratory viruses, HBV, HCV, HIV and MTB
INSTAND: proficiency testing rounds for PCR-based infection diagnostics (programs 348 and 357)
CAP: molecular identification, 16S/18S Sepsis Panel (MOL)

Compatibility with Microbiology Equipment

For automated identification systems (VITEK 2, MALDI-TOF), it is critical to participate in programs that support method-specific peer grouping. This makes it possible to verify that the mass spectrometer database or identification card updates are configured correctly.

Equipment	Manufacturer	Recommended EQA programs
VITEK 2 / VITEK MS	bioMérieux	CAP M47, UK NEQAS Bacteriology, INSTAND
BACTEC FX / FX40	BD	CAP V-BC, INSTAND, Labquality
MALDI Biotyper	Bruker	INSTAND 359 (MALDI-TOF), CAP M47
WASPLab	Copan	CAP Bacteriology, UK NEQAS
Phoenix M50	BD	CAP M47, UK NEQAS AST, INSTAND

Specifics of EQA in Microbiology

Unlike clinical chemistry and hematology, microbiology EQA is qualitative: what is assessed is not a numerical result but the correctness of identification and interpretation.

Types of Control Materials

Lyophilized strains: stable during transport, long shelf life
Simulated clinical specimens: as close as possible to real samples
Digital panels: images for assessing microscopy skills (Gram staining, colony morphology)

Assessment Criteria

Identification accuracy: agreement with the reference result down to species level
AST correctness: agreement of S/I/R categories (susceptible / intermediate / resistant) and of MIC values with reference values
Timeliness: turnaround time is an important indicator of clinical effectiveness

Practical Recommendations

Optimal Participation Strategy

1. Core set: CAP Bacteriology + UK NEQAS AST, providing international recognition and comprehensive assessment

2. For laboratories with MALDI-TOF: add INSTAND 359 to verify mass spectrometry-based identification

3. For molecular testing: QCMD + INSTAND for PCR panels of infectious agents

Working with Results

Analyze identification errors: confusion between related species (for example, S. pneumoniae vs S. mitis) indicates that the database needs updating
Discrepancies in AST results are a reason to review interpretation criteria (EUCAST vs CLSI)
Maintain a nonconformity database for trend analysis and staff training

Integration with the LIS

Configure the LIS microbiology module to record EQA rounds automatically
Create corrective action templates for common nonconformity categories
Ensure an audit trail, as required by ISO 15189 for document control

KombiMED's Comprehensive Approach

KombiMED supplies equipment for the complete microbiology workflow, from inoculation and incubation systems to automated identification systems (bioMérieux VITEK 2, Bruker MALDI Biotyper) and blood culture analyzers (BD BACTEC). We also arrange enrollment in international EQA programs tailored to your laboratory's configuration.

Our specialists can help you:

Request a consultation on external quality assessment programs for your microbiology laboratory.

Select EQA programs for bacteriology, mycology and molecular detection
Arrange the supply of control strains in compliance with biosafety requirements
Prepare your laboratory for GOST R ISO 15189-2024 accreditation for microbiological testing