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Detection of Erysipelothrix rhusiopathiae in pigs condemmed during meat inspection because of skin and joint erysipelas From August 2003 to October, 2003 samples where taken from 20 pig carcasses with skin and joint erysipelas from two German abattoirs. A total of 648 samples was collected (per carcass: eight skin-, eight muscle-samples, 12 lymphnodes, four samples from the joints and both kidneys). All were examined for E. rhusiopathiae. A conventional method and a PCR based method where applied. Material and Method Prior to both applications the original samples were cultivated in Brain-Heart-Infusion broth. The genus Erysipelothrix was identified by Gram-staining, growth on solid blood media, ability to produce H2S and the presence of catalase reaction. Additionaly growth in gelatine, aeskulinhydrolysis, Voges-Proskauer-Reaktion, motility (20°C/37°C) and the utilisation of glucose where checked. To differentiate between E. rhusiopathiae and E. tonsillarum, production of acid from lactose was tested. Isolates identified by the conventional assay were additionally verified by PCR. The DNA was isolated using the cooking method. For the genus Erysipelothrix, the primers MO101/102 (MAKINO et al. 1994) where used. These primers yield a fragment of 407 bp. The species specific analysis was carried out using the primers ER01/02 (SHIMOJI et al. 1998), the result is a fragment with 937 bp. Results E. rhusiopathiae was isolated from 18 of the 20 carcasses. For one slaughtered animal with skin- and one with joint-erysipelas E. rhusiopathiae could not be detected. A total of 155 samples was positive for E. rhusiopathiae, the conventional method was more efficient (n=143). The efficiency of the PCR was lower (n=95). In 83 samples both methods showed positive results. All isolates could be verified with PCR. In animals with skin erysipelas, more samples were positive (27.2 %, n=489) than in animals with joint erysipelas (13.8 %, n=159). E. rhusiopathiae was isolated from animals with skin erysipelas in 50 % (n=16) of kidney samples, 43 % (n=174) of lymphnodes, 25.8 % (n=120) of skin samples, 15 % (n=1 20) of muscles and 3 % (n=59) of joints. Carcasses with joint erysipelas were positive in 30 % (joint samples, n=20), 15 % (skin samples, n=40) and 17 % (n=59) in samples of lymphnodes. Here, E. rhusiopathiae was not obtained from the muscle-samples. Discussion The PCR as carried out here was less effective compared to the conventional method. The results demonstrate that animals under suspicion of erysipelas (attachment 1, chapter IV, No. 7.1 FIHV) should indeed be condemned. The results of this study show, that the detection of E. rhusiopathiae depends on the type of the infection. Skin erysipelas had high detection levels in lymphnodes (Lymphonodi mandibulares and Lymphonodi cervicales superficiales dorsales) and in the kidneys, although there was not too much samples. Samples from animals with joint erysipelas had lower detection rates, with best results in the joints. For practical work, Lymphnodes, kidneys and skin are recommended for sampling. Because E. rhusiopathiae is frequently inactive in its biochemic reactions and because of 100 % matching with the conventional results, the analysis of the isolates by PCR might offer an opportunity for the verification of isolates. This way, a useful combination of primer specifity and sensitivity can be achieved. The AVVFIH gives only a vague guideline for the confirmation of isolates from potential cases of erysipelas. Consequently, this suggestion bears no contradiction to the legislation in force.