ISO 21703:2019

INTERNATIONAL ISO
STANDARD 21703
First edition
2019-01
Surface active agents — Microbiology
— Microbiological test methods for
liquid hand dishwashing
Agents de surface — Microbiologie — Méthodes d’essai
microbiologique pour les détergents liquides de lavage de vaisselle
à la main
Reference number
©
ISO 2019
© ISO 2019
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Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Diluents and culture media . 2
5.1 General . 2
5.2 Neutralizing diluent and diluents . 2
5.2.1 General. 2
5.2.2 Neutralizing diluent: Fluid casein digest — soy lecithin — polysorbate 20
medium (SCDLP 20 broth) . 3
5.2.3 Diluent for the bacterial suspension (Tryptone sodium chloride solution) . 3
5.3 Culture medium for counting . 3
5.3.1 General. 3
5.3.2 Soybean-casein digest agar medium (SCDA) or tryptic soy agar (TSA) . 3
5.3.3 Other medium for counting . 4
5.4 Culture medium for detection . 4
5.4.1 General. 4
5.4.2 Enrichment broth: Eugon LT 100 broth . 5
5.5 Culture media for isolation and identification . 5
5.5.1 MacConkey agar medium . 5
5.5.2 Levine eosin-methylene blue agar medium (EMB agar medium) . 6
5.5.3 Cetrimide agar medium . 6
5.5.4 Pseudomonas agar medium for detection of pyocyanin (Pseudomonas agar P) . 7
6 Apparatus and glassware . 7
7 Strains of microorganisms . 7
8 Handling of the product and laboratory samples . 8
9 Procedure. 8
9.1 General recommendation . 8
9.2 Preparation of the initial suspension . 8
9.3 Enumeration methods . 8
9.3.1 Dilutions for enumeration . 8
9.3.2 Plate-count methods . 8
10 Method for detection and identification .11
10.1 Enrichment .11
10.2 Isolation .11
10.3 Detection of aerobic mesophilic bacteria .11
10.4 Detection and Identification of Escherichia coli .11
10.4.1 General.11
10.4.2 Gram’s stain .11
10.4.3 Culture on Levine eosin-methylene blue agar medium (EMB agar medium) .11
10.4.4 Expression of results .12
10.5 Detection and identification of Pseudomonas aeruginosa .12
10.5.1 General.12
10.5.2 Gram’s stain .12
10.5.3 Oxidase test .12
10.5.4 Culture on Pseudomonas agar medium for detection of pyocyanin .12
10.5.5 Expression of results .12
11 Neutralization of the antimicrobial properties of the product .13
11.1 General .13
11.2 Preparation of inoculum .13
11.3 Suitability of counting methods .13
11.3.1 Principle .13
11.3.2 Suitability test of the pour-plate method .13
11.3.3 Suitability of the surface spread method .13
11.3.4 Suitability of the membrane filtration method .14
11.4 Suitability of the detection method .14
11.4.1 Procedure .14
11.4.2 Interpretation .14
12 Test report .15
Annex A (informative) Neutralizers of antimicrobial activity of preservatives and rinsing
liquids .16
Annex B (informative) Other culture media .17
Bibliography .19
iv © ISO 2019 – All rights reserved

Foreword
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INTERNATIONAL STANDARD ISO 217
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