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Hochdorf, Switzerland

Muller A.,University of Zurich | Stephan R.,University of Zurich | Fricker-Feer C.,Hochdorf Nutritec AG | Lehner A.,University of Zurich
Journal of Food Protection | Year: 2013

In this study, 141 Cronobacter isolates that were collected based on a hygienic monitoring program performed in a powdered infant formula production facility in Switzerland between September 2011 and October 2012 were further characterized. Isolates were identified to the species level by molecular methods, and strains of Cronobacter sakazakii were further subtyped by applying PCR-based O-antigen serotyping, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). C. sakazakii was the most prevalent species identified (93.6%). Among this collection of isolates, representatives of all but one O-antigen serotype (serotype O5) were recognized. MLST analysis of 19 selected isolates revealed that most of the typeable isolates belonged to sequence type (ST) 4. Correlations between ST4 and serotype O2 and between ST83 and serotype O7 were observed. PFGE analysis revealed clusters with multiple isolates, including strains from samples collected at different time points and sampling sources. Generally, the observed heterogeneity among strains collected over the 13 months of the monitoring program was high, suggesting a constant flux among strains rather than a selection for persisting organisms. Copyright ©, International Association for Food Protection. Source

Brandl H.,University of Zurich | Fricker-Feer C.,Hochdorf Nutritec AG | Ziegler D.,Mabritec AG | Mandal J.,University of Zurich | And 2 more authors.
Journal of Dairy Science | Year: 2014

Airborne communities (mainly bacteria) were sampled and characterized (concentration levels and diversity) at 1 outdoor and 6 indoor sites within a Swiss dairy production facility. Air samples were collected on 2 sampling dates in different seasons, one in February and one in July 2012 using impaction bioaerosol samplers. After cultivation, isolates were identified by mass spectrometry (matrix-assisted laser desorption/ionization-time-of-flight) and molecular (sequencing of 16S rRNA and rpoB genes) methods. In general, total airborne particle loads and total bacterial counts were higher in winter than in summer, but remained constant within each indoor sampling site at both sampling times (February and July). Bacterial numbers were generally very low (<100cfu/m3 of air) during the different steps of milk powder production. Elevated bacterial concentrations (with mean values of 391±142 and 179±33cfu/m3 of air during winter and summer sampling, respectively; n=15) occurred mainly in the "logistics area," where products in closed tins are packed in secondary packaging material and prepared for shipping. However, total bacterial counts at the outdoor site varied, with a 5- to 6-fold higher concentration observed in winter compared with summer. Twenty-five gram-positive and gram-negative genera were identified as part of the airborne microflora, with Bacillus and Staphylococcus being the most frequent genera identified. Overall, the culturable microflora community showed a composition typical and representative for the specific location. Bacterial counts were highly correlated with total airborne particles in the size range 1 to 5μm, indicating that a simple surveillance system based upon counting of airborne particles could be implemented. The data generated in this study could be used to evaluate the effectiveness of the dairy plant's sanitation program and to identify potential sources of airborne contamination, resulting in increased food safety. © 2014 American Dairy Science Association. Source

Lehner A.,University of Zurich | Fricker-Feer C.,Hochdorf Nutritec AG | Gschwend K.,Hochdorf Nutritec AG | Stephan R.,University of Zurich
Archiv fur Lebensmittelhygiene | Year: 2010

Cronobacter spp. (former Enterobacter sakazakii) are occasional contaminants of powdered infant formula (PIF) and have been implicated in rare cases of neonatal infections. Surveys on the prevalence of these organisms and/or contamination routes during the processing of the infant formula are of importance to the manufacturers in order to reduce the level of contamination of these products. Increasing customer awareness on possible contamination of other milk powder based products intended for consumption by (older) infants posed the question about the presence of Enterobacteriaceae and especially Cronobacter spp. in products other than PIF e. g. milk concentrate (intermediate) and milk powder, both added to a variety of infant foods. It was the aim of this study to create data on the prevalence of Enterobacteriaceae and possible epidemiologic correlation of Cronobacter spp. in raw milk, milk concentrate and milk powder obtained from a Swiss milk powder production facility (2 production sites). A total of 100 raw milk samples, 91 milk concentrate samples and 172 milk powder samples were collected and tested for the presence of Enterobacteriaceae including Cronobacter spp. by cultural means. Subsets of isolates from each sample category were selected for further molecular identification and subtyping analysis. A variety of members of the Enterobacteriaceae family were observed in all types of samples, whereas Cronobacter spp. was isolated from milk powder only. Subtyping revealed a relatively high degree of heterogeneity among Cronobacter spp. isolates from both production sites suggesting continuous entry and dissemination of organisms from the production environment into the products. © M. & H. Schaper GmbH & Co. Source

Popp A.,University of Zurich | Fricker-Feer C.,Hochdorf Nutritec AG | Gschwend K.,Hochdorf Nutritec AG | Stephan R.,University of Zurich
Archiv fur Lebensmittelhygiene | Year: 2010

The family of Enterobacteriaceae is a useful indicator for hygiene conditions in food production facilities and food products. For powdered infant formula (PIF) the absence of Enterobacteriaceae in 100 g is required. Nevertheless, occasionally Enterobacteriaceae can be detected. A recent study concentrated on the occurrence of a specific foodborne pathogen out of the Enterobacteriaceae family, Cronobacter spp., in PIF manufacturing facilities in order to investigate clonal persistence and identify possible transmission routes. The aim of this study was to genotype isolates from frequently found other species within the family of Enterobateriaceae in order to elucidate and trace back transmission routes not only limited on Cronobacter spp. In total 216 isolates from three different species (Enterobacter (E.) cloacae, Klebsiella (K.) pneumoniae and Leclercia (L) adecarboxylata) were genotyped. The isolates originated from raw ingredients, environment and products of an infant formula processing plant. Restriction digest with Xbal revealed discriminative PFGE patterns consisting of 10-20 bands for all three species. Heat sensitive additives could be traced back as contamination source for products. Furthermore, the production environment was found as a reservoir for persisting strains. Showing analogy to the situation described for Cronobacter spp., especially E cloacae that can be found in the same niches as Cronobacter spp. but more frequently might therefore be used for hygiene monitoring along the processing chain. Certain genotypes of E cloacae, that are able to persist within the factory environment, might possess special properties as e. g. enhanced desiccation tolerance enabling them to survive the harsh environmental conditions. © M. & H. Schaper GmbH & Co. ISSN 0003-925X. Source

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