Guide for medical professionals: European standards for disinfection and antisepsis in the medical area

According to SR EN 14885:2022 - Part II: Spectrum of microbial activity

3. Spectrum of microbial activity

Disinfectant products exhibit different levels of antimicrobial activity. Understanding these categories helps you select the right product for each clinical situation.

3.1. Bactericidal activity (mandatory for all products)

Bactericidal activity is the minimum requirement for all disinfectant products in the medical area (except for those exclusively claiming activity against Legionella, or fungicidal or sporicidal activity).

Performance criteria:

•             Logarithmic reduction: ≥ 5.0 log for most applications

•             Logarithmic reduction: ≥ 3.0 log for hygienic hand wash products

•             Suspension tests (Phase 2/1): EN 13727

•             Practical application tests (Phase 2/2): varies by application (EN 1499, EN 1500, EN 12791, EN 14561, EN 16615, EN 16616, EN 17387)

Standard test organisms:

•             Staphylococcus aureus ATCC 6538 (Gram-positive bacterium)

•             Pseudomonas aeruginosa ATCC 15442 (Gram-negative bacterium)

•             Enterococcus hirae ATCC 10541 (resistant Gram-positive bacterium)

•             Escherichia coli K12 NCTC 10538 (for hand hygiene products)

•             Enterococcus faecium ATCC 6057 (for chemo-thermal processes at temperatures ≥ 40°C)

3.2. Yeasticidal activity (mandatory for all products)

Yeasticidal activity (against yeasts) is also a minimum requirement for all disinfectant products in the medical area (except for those exclusively claiming activity against Legionella, or fungicidal or sporicidal activity).

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 log for most applications

•             Logarithmic reduction: ≥ 2.0 log for hygienic hand wash products

•             Suspension tests (Phase 2/1): EN 13624

•             Practical application tests (Phase 2/2): varies by application (EN 14562, EN 16615, EN 16616, EN 17387)

Standard test organism:

•             Candida albicans ATCC 10231

3.3. Fungicidal activity (optional)

Fungicidal activity covers both yeasts (Candida) and fungi (Aspergillus). It is an optional requirement, necessary for certain specific applications.

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 log

•             Suspension tests (Phase 2/1): EN 13624

•             Practical application tests (Phase 2/2): EN 14562, EN 16616, EN 17387

Standard test organisms:

•             Candida albicans ATCC 10231 (yeasts)

•             Aspergillus brasiliensis ATCC 16404 (fungi - formerly called Aspergillus niger)

Note: Activity against fungal spores is not considered relevant for hand hygiene and hand surgery products.

3.4. Tuberculocidal and mycobactericidal activity (optional)

These activities are relevant for applications where there is a risk of contamination with mycobacteria.

Tuberculocidal activity (lower level):

Testing against a single representative organism for tuberculosis.

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 log

•             Suspension test (Phase 2/1): EN 14348

•             Practical application test (Phase 2/2): EN 14563, EN 16616

Test organism:

•             Mycobacterium terrae ATCC 15755

Full mycobactericidal activity (higher level):

Testing against two mycobacterial species.

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 log (≥ 7.0 log for textiles with EN 16616)

•             Suspension test (Phase 2/1): EN 14348

•             Practical application test (Phase 2/2): EN 14563, EN 16616

Test organisms:

•             Mycobacterium terrae ATCC 15755

•             Mycobacterium avium ATCC 15769

Applicability: EN 14348 can be used for products intended for hygienic hand rub and wash, surface and textile disinfection, with the adaptation of contact times according to the principles of EN 13727 and EN 13624.

Note: Mycobactericidal activity is not considered relevant for surgical hand disinfection.

3.5. Virucidal activity - three levels

The standard defines three distinct levels of virucidal activity, depending on the spectrum of viruses covered:

1. Virucidal activity against enveloped viruses (easiest level)

Represents the minimum level of antiviral protection, covering lipid-enveloped viruses (more sensitive to disinfectants).

Covers: ALL enveloped viruses, including:

•             Coronavirus (SARS-CoV-2, MERS-CoV)

•             Influenza virus

•             HIV (human immunodeficiency virus)

•             Hepatitis B and C virus

•             Herpes simplex virus

•             Varicella-zoster virus

•             Cytomegalovirus

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 lg (≥ 2.0 lg for hygienic wash products with a maximum concentration of 50%)

•             Suspension test (Phase 2/1): EN 14476

•             Practical application tests (Phase 2/2): EN 16777, EN 17111

Test organisms:

•             Vaccinia virus, Ankara strain (MVA) ATCC VR-1508 or Elstree strain ATCC VR-1549

2. Limited spectrum virucidal activity

Intermediate level of protection, covering enveloped viruses plus the most important non-enveloped viruses for the medical field.

Performance criteria:

•             Log reduction: ≥ 4.0 lg

•             Suspension test (Phase 2/1): EN 14476

•             Practical application tests (Phase 2/2): EN 16777

Test organisms:

•             Adenovirus type 5, strain Adenoid 75, ATCC VR-5

•             Murine norovirus, strain S99 Berlin

3. General virucidal activity (highest level)

Highest level of antiviral protection, covering all types of viruses, including the most resistant ones.

Covers: ALL viruses (enveloped and non-enveloped), including:

Performance criteria:

•             Log reduction: ≥ 4.0 lg

•             Suspension test (Phase 2/1): EN 14476

•             Practical application tests (Phase 2/2): EN 16777, EN 17111

Test viruses:

•             Poliovirus type 1, LSc-2ab (for suspension tests only)

•             Adenovirus type 5, strain Adenoid 75, ATCC VR-5

•             Murine norovirus, strain S99 Berlin

Important note: Poliovirus is not used in surface tests (Phase 2/2) due to drying issues.

Special considerations for virucidal activity:

For chemo-thermal processes (temperatures ≥ 40°C):

Thermo-resistant viruses are used:

•             Murine parvovirus (minute virus of mice), Crawford strain, ATCC VR-1346

For hygienic handwash products:

Due to the method of application, these products can only be tested at a maximum concentration of 50% (62.5% in EN 14476). For this reason:

•             They can only have virucidal activity against enveloped viruses

•             The minimum log reduction is 2.0 lg (instead of the standard 4.0 lg)

3.6. Sporicidal activity - two levels

Sporicidal activity is the most difficult to achieve because bacterial spores are extremely resistant to disinfectants.

1. Sporicidal activity against Clostridioides difficile

A specific level for the control of C. difficile infections, a major cause of antibiotic-associated diarrhea in hospital settings.

Performance criteria:

•             Log reduction: ≥ 4.0 lg

•             Suspension test (Phase 2/1): EN 17126

•             Contact time: Maximum 15 minutes for patient-contact surfaces

Test organism:

•             Clostridioides difficile spores NCTC 13366 (formerly Clostridium difficile)

2. General sporicidal activity

A wider level of protection against various types of bacterial spores.

Covers:

•             C. difficile spores (see above)

•             PLUS spores of:

–            Bacillus subtilis ATCC 6633

–            Bacillus cereus CIP 105151

Performance criteria:

•             Logarithmic reduction: ≥ 4.0 lg

•             Suspension test (Phase 2/1): EN 17126

•             No practical application tests (Phase 2/2) specific for sporicidal activity

Applications:

•             Surface disinfection: maximum contact time 60 minutes (15 minutes for surfaces in contact with the patient)

•             Instrument disinfection: maximum contact time 60 minutes, temperature 20-70°C

•             Textile disinfection: maximum contact time 60 minutes, temperature 20-80°C

Important note: Sporicidal activity is tested only in Phase 2/1 (suspension). There are currently no specific Phase 2/2 standards for sporicidal activity, although these may be developed in the future.

3.7. Summary of activity spectra

The next article in the series presents the practical application of this knowledge: concrete clinical scenarios, special aspects regarding chemo-thermal disinfection, airborne room surface disinfection, as well as the mandatory information on the label.

Information document based on SR EN 14885:2022. This material is for educational purposes and does not replace consultation of the official standard.

Bibliography:

ASRO (2022). SR EN 14885:2022 – Chemical disinfectants and antiseptics – Application of European Standards for chemical disinfectants and antiseptics.

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