Schlüsselwort: methicillin-resistant Staphylococcus aureus

Microbiological-hygienic Investigations on a Pig (Hog) Raising farm in China in Consideration of Salmonella and Methicillin Resistant Staphylococcus aureus (MRSA) In this study data about the prevalence of Salmonella spp. in animal food and fecal samples on a Chinese pig farm was collected, and biotechnological treatments (composting and anaerobic fermentation in biogas plant) with a strong focus on hygienisation capacity were invastigated. Additionaly studies about the tenacity of a monophasic serovar of Salmonella Typhimurium DT120, isolated as dominating strain on the pig farm, were performed by the means of laboratory work. Furthermore the nasal colonization with methicillin-resistent Staphylococcus aureus (mrsa) of pigs was invastigated. Susceptibility testing for isolated strains of Salmonella spp. and mrsa to antimicrobial agents were examined in order to gain information about the situation of resistances of these pathogens on a farm level. There was a high prevalence for Salmonella spp. of 50.0% in all fecal pool samples, with 62.0% for samples of fattening pigs and 31.5% for samples of sows. As dominating strain a multiresistent monophasic variant of Salmonella Typhimurium DT120 was identified. In addition, with lower prevalence the serovar Salmonella Derby and sporadicly the serovar Senftenberg and Havana were found in fecal samples of sows. For nasal colonization of pigs with methicillin-resistent Staphylococcus aureus (mrsa) the prevalence found in this study was very high with around 90% in total, around 98% in fattening pigs and 77% in sows. All isolated strains of mrsa were multiresistent and belonged to the spa-type t899, SCCmec-type IVb and mlst ST2136, belonging to the clonal complex 9. The mesophilic (23°C to 26°C) anaerobic treatment (biogas plant) of animal wastes on the pig farm did not guarantee a sufficient hygienisation under modern microbiologic-hygienic aspects in accordance to the German Bio-Waste Ordinance (BioAbV, 2012) to achieve safe fertilizer for use in agriculture. In all samples of substrates and residues after anaerobic treatment diverse serovars of Salmonella spp. were detected. Additionally laboratory studies about the inactivation of the monophasic strain of Salmonella Typhimurium DT120 in pig slurry and residues of anaerobic fermentation during long time storage for 48 weeks at 10°C showed long survival times. A complete inactivation respectively a reduction over five log10 for tested Salmonella Typimurium DT120 was achieved in stored residues of anaerobic fermentation after 36 weeks respectively 20 weeks and in pig slurry after 48 weeks respectively 36 weeks. Half technical experiments of aerobic thermophilic treatment (composting) of pig manure with corn stalks was tested in small rotting Boxes (1m3) in a farm building under roof during winter in China. Results showed the possibility of using this technic as an adequate biotechnological treatment to achieve an improvement of hygienic conditions in organic wastes for safe use as fertilizer. The abilitiy of hygienisation through high temperature treatment in accordance with the German Bio-Waste Ordinance (BioAbV, 2012) was shown by the inactivation of the test organism Salmonella Senftenberg W775 H2S negative. In additional studies under laboratory conditions a complete inactivation respectively a reduction of five log10 for the monophasic Salmonella Typhimurium DT120 was achieved by a treatment of eighteen hours at 53°C, two hours at 60°C, and one hour at 70°C. For pig slurry results show the necessity of a treatment of eighteen hours at 50C° or four hours at 53C°.