AS 4659.3:2015 – Guide to determining the equivalence of food microbiology test methods Part 3: Confirmation tests.
4.1 fleflnc the equkalence determination
The equkalence determination should be defined in terms of the following:
(a) The target organism’s genus. species. serotype. etc.
(h) The alternate method—precisely defined by refercncc to a publication, manufacturers instructions and any optional procedures employed or deviation from the published method.
(C) The rcfercnce method—including the specification of any optional steps.
(d) The steps of the mcthods that are to be compared.
4.2 flefinc the conditions of thr cquisaknce determination
The conditions of the equivalence determination should be defined in terms of the following:
(a) the laboratory where testing is performed.
(hi Controls observed by thc laboratory during testing, for xamplc, controls on thc environment of the laboratory, prevention of cross contamination, controls on media and reagents, calibration of equipment, etc. where these factors arc considered critical to the success of either method.
(c) The staff performing the tests (experience, qualifications. etc.).
(d) The starling and finishing dates of the tests.
(c) The batch numbers of media. rcagents, etc. used,
NOTE: This infonnaition is defined for thc purpose of reporting on the equivalence determination and recording factors which may have some hearing on the results obtained. These factors do not necessarily affect the veracity of the study.
43 Select test orsnisms
Fifty strains should he selected. These arc to include diversity in the strain selected. A minimum of 20 positive isolates and 20 closely related negative isolates should be selected. In addition, a minimum of 10 non-related strains should be tested.
The reference cultures prescribed in the Australia Standard method should be included. The other strains may be selected from the following list (in order of preference):
(a) Strains of the target organism isolated by the laboratory,
(b) Strains of the target organism isolated by reference laboratories or industry sources as representative.
(c) Strains of the target organism held by culture collections.
The identity of the strains chosen should be determined by appropriate means (e.g. biochemical, physiological, serological, molecular) before performing further work. Consultation with a reference laboratory or an expert may be necessary. The source and identity of the strains should be recorded.
NOTE: It is possible. by the selection of test strains, to bias the reulis of the study. Care should be taken to select representative strains which do not possess characteristics which arc likely to Icad to biased results being obtained.
4.4 Preparation of inuculum
The test strain inoculum should be such that at least equivalence in sensitivity to the reference method may be demonstrated. The strains chosen should be prepared as prescribed by the method being studied.
4.7Acceptance criteria
The alternatc method will only be accepted if B +C= 0.
NOTE:If B or C is greatcr than zero then equivalence of the alternate method has not becnadequately demonstrated.An explanation should be sought for the discrepancy. lIt may lie in thechoice of test organism, the performance of a critical step in the alternatc method or some otherfactor.Once the reason is determined,the procedure may be repeated,after redefining the testorganisms where necessary, to fulfil the requirement that B = 0.
The report should contain the following information:
(s)All details necessary for identification of sample types.
(b)Reference to this Standard (i.e. AS 4659.3) and other appropriate Australian
(c) Refcrence to the altcrnative method.
(d) Each step of the method above reported in full.(e)The results obtained.
(Date of testing.
(g)Any circumstances that may have influenced the result.