One of the problems of the ISO system is that membership of technical committees sometimes leaves few outside the committees with enough expertise and gravitas to criticise their work. Such experts may carry undue ISO influence into other committees, national bodies, professional organisations, and as technical assessors for inspection bodies.
Standarisation to ISO methods enforced by the cartel brings the potential for lack of competition between methods that stifles the emergence of superior methodology.
The Spanish paper below describes an assessment of one ISO method. It is for those with highly specialist expertise to critically evaluate competing methods such as this. However, this paper shows the standards of sensitivity and specificity that might be expected in diagnostic veterinary pathology. The standards achievable and that these authors consider adequate are in the 80-90% range. For the paperwork that is inspected, any failure is a non-compliance.
Why do inspectors expect higher standards from the paperwork kept by the personnel than the tests themselves are capable of delivering? Do they think this can improve on the shortcomings of the tests?
It only makes sense if you’ve caught the same obsession.
The ISO 6579:2002/Amd 1:2007 (ISO) standard has been the bacteriological standard method used in the European Union for the detection of Salmonella spp. in pig mesenteric lymph nodes (MLN), but there are no published estimates of the diagnostic sensitivity (Se) of the method in this matrix. Here, the Se of the ISO (SeISO) was estimated on 675 samples selected from two populations with different Salmonella prevalences (14 farms with a ≥20% prevalence and 13 farms with a <20% prevalence) and through the use of latent-class models in concert with Bayesian inference, assuming 100% ISO specificity, and an invA-based PCR as the second diagnostic method. The SeISO was estimated to be close to 87%, while the sensitivity of the PCR reached up to 83.6% and its specificity was 97.4%. Interestingly, the bacteriological reanalysis of 33 potential false-negative (PCR-positive) samples allowed isolation of 19 (57.5%) new Salmonella strains, improving the overall diagnostic accuracy of the bacteriology. Considering the usual limitations of bacteriology regarding Se, these results support the adequacy of the ISO for the detection of Salmonella spp. from MLN and also that of the PCR-based method as an alternative or complementary (screening) test for the diagnosis of pig salmonellosis, particularly considering the cost and time benefits of the molecular procedure.