Biomedical subjects

E Bartelt

Publications and source records attributed to E Bartelt.

3 recordsLinked to original sources

PubMed2006

Comparison of different sampling techniques and enumeration methods for the isolation and quantification of Campylobacter spp. in raw retail chicken legs.

Comparable quantitative data of Campylobacter spp. on chicken products are a major data lack for quantitative risk assessment approaches. The objective of this study was to compare two different sampling techniques for the isolation and enumeration of Campylobacter spp. in chicken and to evaluate a suitable enumeration method comparing the most probable number (MPN) technique to the direct plating method. For this, 90 packages containing at least two raw chicken legs were examined for the comparison of sampling techniques, rinsing one leg and homogenizing 25 g of skin of the other leg of each package; both sample preparation types were examined by direct plating method and MPN technique in 40 out of 90 packages. Of the skin samples, 70% (63/90), and of the rinse samples, 77% (69/90), were Campylobacter-positive. Enumeration of Campylobacter spp. by direct plating revealed a median of log 4 cfu/leg surface in skin samples (S.D.=0.6) and a median of log 4.3 cfu/leg surface in rinse samples (S.D.=0.9) of the rinse samples; 73% (37/51) had higher numbers of Campylobacter spp. than the skin samples although the difference was not significant (p=0.08). The correlation coefficient of Campylobacter counts in skin and rinse samples was 0.43. The prevalence of Campylobacter spp. in rinse samples was 58% (23/40). In 5% (2/40) of the rinse samples, numbers of Campylobacter spp. could be detected only by the MPN technique due to the lower detection limit compared to the direct plating method. The MPN technique turned out to be unsuitable for the enumeration of Campylobacter spp. in skin samples because a layer formation on the top of the incubated MPN-tubes leads to irregular MPN results. Out of 80% (16/20) of the compared rinse samples, the direct plating detected higher numbers of Campylobacter spp., with a median count of log 4.2 cfu/leg surface (S.D.=1) compared the MPN technique where a median of log 4 cfu/leg surface (S.D.=1.1) was obtained. The difference was not significant (p=0.05). A highly positive correlation coefficient of 0.9 was observed between the direct plating and the MPN technique. Both sampling methods, rinsing the chicken leg and homogenizing the skin, are suitable for the detection and quantification of Campylobacter spp.; the direct plating method was superior to the MPN technique for enumerating Campylobacter spp. in raw chicken legs at retail level because enumeration is more rapid and less laborious.

Animals↗

PubMed2004

Analysis of gyrA mutations in quinolone-resistant and -susceptible Campylobacter jejuni isolates from retail poultry and human clinical isolates by non-radioactive single-strand conformation polymorphism analysis and DNA sequencing.

AIMS: The aims of this study were to characterize the molecular variations in the quinolone resistance-determining region (QRDR) of gyrA among quinolone-resistant and -susceptible Campylobacter jejuni isolates originating from foods of animal origin and human infections and to evaluate the suitability of the single-strand conformation polymorphism (SSCP) method as a screening method for molecular characterization of fluoroquinolone resistance. METHODS AND RESULTS: Alterations in QRDR of gyrA from 182 C. jejuni isolates were determined by nonradioisotopic SSCP analysis and direct sequencing. A total of 13 types of nucleic acid sequence combinations within the QRDR of the gyrA gene resulted in 11 different SSCP patterns. All nalidixic acid resistant strains possessed nucleotide substitution at either codon Thr-86 or Asp-90. Silent mutations were detected additionally. Thr-86 to Ile mutation was detected in all 139 ciprofloxacin resistant strains, which showed cross-resistance to nalidixic acid. CONCLUSIONS: The SSCP method is suitable for a molecular screening of quinolone resistant C. jejuni isolates and in combination with DNA sequencing suitable to detect genetic variations of the QRDR of gyrA. SIGNIFICANCE AND IMPACT OF STUDY: This study provides data of the genetic variations of the QRDR of gyrA from C. jejuni isolates of foods and human beings.

Animals↗

PubMed2004

[Monitoring and risk assessment of campylobacter infections].

The aim of a national study of a "Quantitative Risk Assessment of Campylobacter infections and broiler chicken" at the Federal Institute for Risk Assessment is to estimate the chicken meat associated risk of Campylobacteriosis in Germany by using probabilistic models. Furthermore, process parameters (modelling parameters) with the most vital impact on the risk of Campylobacteriosis due to chicken meat have to be elaborated to give recommendations for risk management options in the whole food chain. The outcome of Joint FAO/WHO Expert Consultations on Risk Assessment of Microbiological Hazards in Foods (JEMRA) with respect to Campylobacter spp. in broiler chickens are the baseline for the national approach. In addition, national studies from Canada, Denmark and The Netherlands have to be considered. Typical regional data with respect to the disease, to risk factors in Germany and to the qualitative and quantitative occurrence of Campylobacter in broiler chickens along the "farm-to-fork" continuum have to be collected and validated for elaboration of the four elements of a risk assessment. Data on the prevalence of the agent at different stages of the food chain given in available surveillance systems in Germany are limited with respect to their suitability as incoming parameters for the models. A monitoring programme, as required in the Directive 2003/99/EC on the monitoring of zoonoses and zoonotic agents, as well as coordinated programmes for the official food control authorities, could improve the data baseline for risk assessment studies for instance. To collect all necessary information on the quantitative load of Camylobacter in broiler chickens will go beyond the scope of any existing or future monitoring systems. Results can only be achieved by detailed studies. Beside this, regional data on production and processing of broiler chicken, consumption data and information on the behaviour of consumers in households when preparing broiler chicken products are relevant for assessing the final risk to the consumers. For some questions, especially with respect to the dose-response-relation, internationally used models have to be applied. The national study is embedded in a national epidemiological network of "Foodborne Infections in Germany" which is coordinated by the Robert-Koch-Institute and supported by the Federal Ministry of Education and Research (BMBF).

Animal Husbandry↗