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Epidemiological analysis of the dynamic and diversity of Salmonella spp. in five German pig production clusters using pheno- and genotyping methods: An exploratory study

Niemann, J., Tietze, E., Ruddat, I., Fruth, A., Prager, R., Rabsch, W., Blaha, T., Münchhausen, C., Merle, R., Kreienbrock, L.
Veterinary microbiology 2015 v.176 no.1-2 pp. 190-195
Salmonella, biosecurity, epidemiological studies, feces, herds, minisatellite repeats, multilocus sequence typing, multiple-locus variable number tandem-repeat analysis, pulsed-field gel electrophoresis, swine production, tandem repeat sequences
An exploratory study in five conventional pig production clusters was carried out to investigate the dynamic and diversity of Salmonella spp. within different production stages and sample site categories (pooled feces, direct and non-direct environment). Observing two production cycles per production cluster, a total of 1276 samples were collected along the pig production chain. Following a microbiological examination via culture, 2246 subcultures were generated out of 285 Salmonella positive samples and analysed by pheno- and genotyping methods. Based on a combination of serotyping, MLVA (multiple-locus variable-number tandem repeat (VNTR) analysis), PFGE (pulse-field gel electrophoresis) and MLST (multilocus sequence typing), an amount of 22.3% Salmonella positive samples were characterized in clonal lineages and its variants.Within each production cluster, one main clonal lineage could be identified and persisted over both production cycles with a large diversity of variants and a wide distribution in sample site categories and production stages. Results underline the importance of biosecurity with emphasis on the environment to prevent persistence and circulation of Salmonella within herds. Furthermore, the combined implementation of MLVA, PFGE and MLST with conventional culture techniques for isolate classification could be successfully applied as an effective and valuable tool for identifying similar pattern of Salmonella occurrence within pig production clusters.