SIST EN ISO 6888-1:1999
(Main)Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) - Part 1: Technique using Baird-Parker agar medium (ISO 6888-1:1999)
Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other species) - Part 1: Technique using Baird-Parker agar medium (ISO 6888-1:1999)
This part of ISO 6888 specifies a horizontal method for the enumeration of coagulase-positive staphylococci in
products intended for human consumption or feeding of animals, by counting of colonies obtained on a solid
medium (Baird-Parker medium) after aerobic incubation at 35 °C or 37 °C.
Mikrobiologie von Lebensmitteln und Futtermitteln - Horizontales Verfahren für die Zählung von koagulase-positiven Staphylokokken (Staphylococcus aureus und andere Spezies) - Teil 1: Verfahren mit Baird Parker Agar (ISO 6888-1:1999)
Dieser Teil von ISO 6888 legt ein horizontales Verfahren für die Zählung von koagulase-positiven Staphylokokken in Lebensmitteln und Futtermitteln fest. Die nach aerober Inkubation bei 35° C oder 37° C auf einem festen Medium (Baird-Parker-Agar) erhaltenen Kolonien werden gezählt und bestätigt.
Microbiologie des aliments - Méthode horizontale pour le dénombrement des staphylocoques a coagulase positive (Staphylococcus aureus et autres especes) - Partie 1: Technique utilisant le milieu gélosé de Baird-Parker (ISO 6888-1:1999)
La présente partie de l'ISO 6888 spécifie une méthode horizontale pour le dénombrement des staphylocoques à coagulase positive dans les produits destinés à la consommation humaine ou à l'alimentation animale, par comptage des colonies obtenues sur milieu solide (milieu de Baird-Parker) après incubation en aérobiose à 35°C ou 37°C.
Mikrobiologija živil in krmil - Horizontalna metoda za štetje koagulazno pozitivnih stafilokokov (Staphylococcus aureus in drugih vrst) - 1. del: Tehnika uporabe Baird-Parkerjevega agarja (ISO 6888-1:1999)
Ta del standarda ISO 6888 določa horizontalno metodo za ugotavljanje števila koagulazno pozitivnih stafilokokov v izdelkih, namenjenih za prehrano ljudi ali krmljenje živali, s štetjem kolonij, pridobljenih na trdnem mediju (Baird-Parkerjev medij) po aerobni inkubaciji pri 35 °C ali 37 °C.
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 6888-1:1999
01-december-1999
Mikrobiologija živil in krmil - Horizontalna metoda za štetje koagulazno pozitivnih
stafilokokov (Staphylococcus aureus in drugih vrst) - 1. del: Tehnika uporabe
Baird-Parkerjevega agarja (ISO 6888-1:1999)
Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of
coagulase-positive staphylococci (Staphylococcus aureus and other species) - Part 1:
Technique using Baird-Parker agar medium (ISO 6888-1:1999)
Mikrobiologie von Lebensmitteln und Futtermitteln - Horizontales Verfahren für die
Zählung von koagulase-positiven Staphylokokken (Staphylococcus aureus und andere
Spezies) - Teil 1: Verfahren mit Baird Parker Agar (ISO 6888-1:1999)
Microbiologie des aliments - Méthode horizontale pour le dénombrement des
staphylocoques a coagulase positive (Staphylococcus aureus et autres especes) - Partie
1: Technique utilisant le milieu gélosé de Baird-Parker (ISO 6888-1:1999)
Ta slovenski standard je istoveten z: EN ISO 6888-1:1999
ICS:
07.100.30 Mikrobiologija živil Food microbiology
SIST EN ISO 6888-1:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 6888-1:1999
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SIST EN ISO 6888-1:1999
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SIST EN ISO 6888-1:1999
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SIST EN ISO 6888-1:1999
INTERNATIONAL ISO
STANDARD 6888-1
First edition
1999-02-15
Microbiology of food and animal feeding
stuffs — Horizontal method for the
enumeration of coagulase-positive
staphylococci (Staphylococcus aureus
and other species) —
Part 1:
Technique using Baird-Parker agar medium
Microbiologie des aliments — Méthode horizontale pour le dénombrement
des staphylocoques à coagulase positive (Staphylococcus aureus et autres
espèces) —
Partie 1: Technique utilisant le milieu gélosé de Baird-Parker
A
Reference number
ISO 6888-1:1999(E)
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SIST EN ISO 6888-1:1999
ISO 6888-1:1999(E)
Contents
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Principle.2
5 Diluent and culture media.2
6 Apparatus and glassware .5
7 Sampling.6
8 Preparation of test sample.6
9 Procedure .6
10 Expression of results .8
11 Precision.10
12 Test report .10
Bibliography.11
© ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
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SIST EN ISO 6888-1:1999
© ISO
ISO 6888-1:1999(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 6888-1 was prepared by Technical Committee ISO/TC 34, Agricultural food products,
Subcommittee SC 9, Microbiology.
This first edition of ISO 6888-1, together with ISO 6888-2, cancels and replaces ISO 6888:1983, which has been
technically revised.
ISO 6888 consists of the following parts, under the general title Microbiology of food and animal feeding stuffs —
Horizontal method for the enumeration of coagulase-positive staphylococci (Staphylococcus aureus and other
species):
Part 1: Technique using Baird-Parker agar medium
Part 2: Technique using rabbit plasma fibrinogen agar medium
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SIST EN ISO 6888-1:1999
© ISO
ISO 6888-1:1999(E)
0 Introduction
0.1 Because of the large variety of food and feed products, this horizontal method may not be appropriate in every
detail for certain products. In this case, different methods, which are specific to these products, may be used if
absolutely necessary for justified technical reasons. Nevertheless, every attempt should be made to apply this
horizontal method as far as possible.
When this part of ISO 6888 is next reviewed, account will be taken of all information then available regarding the
extent to which this horizontal method has been followed and the reasons for deviations from this method in the
case of particular products.
The harmonization of test methods cannot be immediate and, for certain group of products, International Standards
and/or national standards may already exist that do not comply with this horizontal method. It is hoped that when
such standards are reviewed they will be changed to comply with this part of ISO 6888 so that eventually the only
remaining departures from this horizontal method will be those necessary for well-established technical reasons.
0.2 ISO 6888 describes two horizontal methods (part 1 and part 2) for the enumeration of coagulase-positive
staphylococci among which enterotoxinogenic strains are encountered. It is mainly concerned with Staphylococcus
aureus, but also with S. intermedius and certain strains of S. hyicus.
In the general case, use part 1 of ISO 6888. However, it is preferable to use the procedure described in part 2 (see
reference [1]) only for foodstuffs (such as cheeses made from raw milk and certain raw meat products) likely to be
contaminated by:
staphylococci forming atypical colonies on a Baird-Parker agar medium;
background flora which can obscure the colonies being sought.
0.3 For the purposes of this part of ISO 6888, the confirmation of staphylococci is based on a positive coagulase
reaction, but it is reconized that some strains of Staphylococcus aureus give weakly positive coagulase reactions.
These latter strains may be confused with other bacteria but they may be distinguished from such other bacteria by
the use of additional tests not included in this part of ISO 6888, such as the sensitivity to lysostaphin, the production
of haemolysin, of thermostable nuclease and of acid from mannitol (see reference [2]).
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SIST EN ISO 6888-1:1999
INTERNATIONAL STANDARD © ISO ISO 6888-1:1999(E)
Microbiology of food and animal feeding stuffs — Horizontal
method for the enumeration of coagulase-positive staphylococci
(Staphylococcus aureus and other species) —
Part 1:
Technique using Baird-Parker agar medium
1 Scope
This part of ISO 6888 specifies a horizontal method for the enumeration of coagulase-positive staphylococci in
products intended for human consumption or feeding of animals, by counting of colonies obtained on a solid
medium (Baird-Parker medium) after aerobic incubation at 35 °C or 37 °C.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 6888. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 6888 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 6887-1, Microbiology of food and animal feeding stuffs — Rules for the preparation of the test sample, of initial
suspension and of decimal dilutions for microbiological examination — Part 1: General rules for the preparation of
the initial suspension and of decimal dilutions.
ISO 7218, Microbiology of food and animal feeding stuffs — General rules for microbiological examination.
3 Terms and definitions
For the purposes of this part of ISO 6888, the following terms and definitions apply.
3.1
coagulase-positive staphylococci
bacteria which form typical and/or atypical colonies on the surface of a selective culture medium and which show a
positive coagulase reaction when the test is performed following the method specified in this part of ISO 6888
3.2
enumeration of the coagulase-positive staphylococci
determination of the number of coagulase-postive staphylococci found per millilitre or per gram of sample when the
test is carried out according to the method specified in this part of ISO 6888
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SIST EN ISO 6888-1:1999
© ISO
ISO 6888-1:1999(E)
4 Principle
4.1 Inoculation of the surface of a solid selective culture medium, using duplicate plates, with a specified quantity
of the test sample if the product is liquid, or with a specified quantity of the initial suspension in the case of other
products.
Inoculation, under the same conditions, using decimal dilutions of the test sample or of the initial suspension, with
two plates per dilution.
1)
4.2 Aerobic incubation of the plates at 35 °C or 37 °C and examination after both 24 h and 48 h.
4.3 Calculation of the number of coagulase-positive staphylococci per millilitre, or per gram, of sample from the
number of typical and/or atypical colonies obtained on plates at dilution levels chosen so as to give a significant
result, and confirmed by a positive coagulase test result.
5 Diluent and culture media
5.1 General
For current laboratory practice, see ISO 7218.
5.2 Diluent
See ISO 6887-1 and the specific standard dealing with the product to be examined.
2)
5.3 Baird-Parker agar medium
NOTE Commercially available media may be used. In such cases, the manufacturer's instructions should be followed
carefully.
5.3.1 Base medium
5.3.1.1 Composition
Pancreatic digest of casein 10,0 g
Yeast extract 1,0 g
Meat extract 5,0 g
Sodium pyruvate 10,0 g
L-Glycine 12,0 g
Lithium chloride 5,0 g
1)
Agar 12 g to 22 g
Water, to a final volume of 1 000 ml
1) Depending on the gel strength of the agar.
5.3.1.2 Preparation
Dissolve the components or the dehydrated complete base in the water by boiling.
If necessary, adjust the pH so that after sterilization it is 7,2 ± 0,2 at 25 °C.
The temperature is agreed between the interested parties and is indicated in the test report.
1)
2) The agar medium is that of Baird-Parker (see reference [3]) with the addition of sulfamezathine (see reference [4]) if the
presence of Proteus is suspected.
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SIST EN ISO 6888-1:1999
© ISO
ISO 6888-1:1999(E)
Transfer the medium in quantities of 100 ml to flasks or bottles (6.5) of appropriate capacity.
Sterilize the medium for 15 min at 121 °C.
5.3.2 Solutions
5.3.2.1 Potassium tellurite solution
5.3.2.1.1 Composition
1)
Potassium tellurite (K TeO ) 1,0 g
2 3
Water 100 ml
1) It is recommended to ensure beforehand that the
potassium tellurite available is suitable for this test (see
5.3.2.1.2).
5.3.2.1.2 Preparation
Dissolve the potassium tellurite completely in the water with minimal heating.
The solid should be readily soluble. If a white insoluble material is present in the water, discard the powder.
Sterilize by filtration using 0,22 μm pore size membranes.
The solution may be stored at the maximum for one month at +3 °C – 2 °C.
Discard the solution if a white precipitate forms.
5.3.2.2 Egg yolk emulsion (concentration approximately 20 % or according to the manufacturer's instructions)
NOTE If a commercial preparation is available, it should be used.
Use fresh hen eggs with intact shells. Clean the eggs with a brush using a liquid detergent. Rinse them under
running water, then disinfect the shells either by immersing them in ethanol (70 % volume fraction) for 30 s and
allowing them to dry in the air, or by spraying them with alcohol followed by flame sterilization.
Proceeding under aseptic conditions, break each egg and separate the yolk from its white by repeated transfer of
the yolk from one half of the shell to the other. Place the yolks in a sterile flask (6.5) and add four times their volume
of sterile water. Mix thoroughly. Heat the mixture in the water bath (6.4) set at 47 °C for 2 h and leave for 18 h to
24 h at +3 °C ± 2 °C to allow a precipitate to form. Aseptically collect the supernatant liquid into a fresh sterile flask
for use.
The emulsion may be stored at +3 °C ± 2 °C for a maximum of 72 h.
5.3.2.3 Sulfamezathine (sulfamethazine, sulfadimidine) solution
NOTE This is to be used only if Proteus species are suspected in the test sample.
5.3.2.3.1 Composition
Sulfamezathine 0,2 g
Sodium hydroxide solution, c(NaOH) = 0,1 mol/l 10 ml
Water 90 ml
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ISO 6888-1:1999(E)
5.3.2.3.2 Preparation
Dissolve the sulfamezathine in the sodium hydroxide solution.
Dilute to 100 ml with the water.
Sterilize by filtration using 0,22 μm pore size membranes.
The solution may be stored at the maximum for one month at +3 °C ± 2 °C.
5.3.3 Complete medium
5.3.3.1 Composition
Base medium (5.3.1) 100 ml
Potassium tellurite solution (5.3.2.1) 1,0 ml
Egg-yolk emulsion (5.3.2.2) 5,0 ml
Sulfamezathine solution (5.3.2.3) (if necessary) 2,5 ml
5.3.3.2 Preparation
Melt the base medium, then cool it to approximately 47 °C by means of the water bath (6.4).
Add, under aseptic conditons, the two
...
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