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Biomedical subjects

K Dierick

Publications and source records attributed to K Dierick.

4 recordsLinked to original sources

Quantitative risk assessment of Campylobacter spp. in poultry based meat preparations as one of the factors to support the development of risk-based microbiological criteria in Belgium.

The objective of this study was to do an exercise in risk assessment on Campylobacter spp. for poultry based meat preparations in Belgium. This risk assessment was undertaken on the demand of the competent national authorities as one of the supportive factors to define risk-based microbiological criteria. The quantitative risk assessment model follows a retail to table approach and is divided in different modules. The contamination of raw chicken meat products (CMPs) was represented by a normal distribution of the natural logarithm of the concentration of Campylobacter spp. (ln[Camp]) in raw CMPs based on data from surveillance programs in Belgium. To analyse the relative impact of reducing the risk of campylobacteriosis associated with a decrease in the Campylobacter contamination level in these types of food products, the model was run for different means and standard deviations of the normal distribution of the ln[Camp] in raw CMPs. The limitation in data for the local situation in Belgium and on this particular product and more precisely the semi-quantitative nature of concentration of Campylobacter spp. due to presence/absence testing, was identified as an important information gap. Also the knowledge on the dose-response relationship of Campylobacter spp. was limited, and therefore three different approaches of dose-response modelling were compared. Two approaches (1 and 2), derived from the same study, showed that the reduction of the mean of the distribution representing the ln[Camp] in raw CMPs is the best approach to reduce the risk of Campylobacter spp. in CMPs. However, for the simulated exposure and approach 3 it was observed that the reduction of the standard deviation is the most appropriate technique to lower the risk of campylobacteriosis. Since the dose-response models used in approach 1 and 2 are based on limited data and the reduction of the mean corresponds with a complete shift of the contamination level of raw CMPs, demanding high efforts from the poultry industry, it is proposed to lower the standard deviation of the concentration of Campylobacter spp. in raw CMPs. This proposal corresponds with the elimination of the products that are highly contaminated. Simulation showed that eating raw chicken meat products can give rise to exposures that are 10(10) times higher than when the product is heated, indicating that campaigns are important to inform consumers about the necessity of an appropriate heat treatment of these type of food products.

Animals↗

Survey of the contamination of foodstuffs of animal origin by Shiga toxin producing Escherichia coli serotype O157:H7 in Belgium from 1999 to 2003.

A survey of the prevalence of Shiga toxin-producing Escherichia coli (STEC) of O157 serotype in foodstuffs of animal origin (beef, veal, pork, chicken, fish) from 1999 to 2003 in Belgium was performed. STEC strains were only isolated from beef with a prevalence of 0.73%. This percentage is low in comparison with the prevalence in other countries. Among the 76 isolated STEC O157 strains, 75% belonged to the serotype O157:H7 and 25% to the serotype O157 non H7. Moreover, the most frequent pathotype was eae stx2 ehxA (74%).

Animals↗

Interlaboratory study comparing the microbiological potency of spiramycins I, II and III.

An interlaboratory study has been performed to determine the relative potencies of spiramycins (SPMs) I, II and III by diffusion or/and turbidimetric assays with Bacillus subtilis or Staphylococcus aureus as the test organisms. Six laboratories from three countries participated. Experimental procedures were according to the European Pharmacopoeia, 3rd ed. The activity of SPM I is markedly higher than that of SPM II and III. By diffusion, the activities of SPM II and III relative to SPM I were found to be 57 and 72%, respectively. The interlaboratory relative standard deviations (RSD) varied from 3.6 to 16.3%. By turbidimetry, the activities of SPM II and III relative to SPM I were found to be 45 and 52%, respectively. The interlaboratory RSD values varied from 2.6 to 7.7%. The results of the study were analyzed according to the ISO 5725-2 guidelines to determine the repeatability, the between-laboratory and the reproducibility variances of both methods.

Aminoglycosides↗

Neomycin: microbiological assay or liquid chromatography?

In a multicentre study involving six laboratories, a microbiological assay was performed on three neomycin samples containing respectively, 0.12, 2.1 and 11% (m/m) of neomycin C, as well on a pure neomycin C sample. The potency was determined according to the European Pharmacopoeia method but using a neomycin B base standard. The relative standard deviations between laboratories (RSD) on the potencies varied from 4.8 to 50%, depending on the sample examined. The RSD increased with the neomycin C content of the samples and the highest RSD values were observed for the pure neomycin C sample. The activity of neomycin C relative to neomycin B was found to be 62% by diffusion (RSD:41%) and 56% by turbidimetry (RSD: 50%). This confirmed that the presence of neomycin C in a neomycin sample influences the reproducibility of the microbiological assay. T estimate the influence of this effect on official standard, their composition was verified by liquid chromatography. The neomycin C base content of the standards varied between 0.4 and 5.8% (m/m). Based on the results obtained and on formerly published reports discussing problems encountered with microbiological assay of neomycin, it is proposed to introduce liquid chromatography in official monographs to replace microbiological assay.

Anti-Bacterial Agents↗