The consumption of ready-to-eat fresh vegetables has increased significantly in the recent decades. So far, no data are available on the bacteriological burden and the prevalence of foodborne pathogens in ready-to-eat lettuce, fresh-cut fruit, and sprouts on the Swiss market. This study was based on investigations carried out during 2 months of the summer season in 2011. Samples of 142 salads, 64 fresh-cut fruit, and 27 sprouts were included in this study. Escherichia coli, an indicator microorganism for fecal contamination, was only found in 5 lettuce samples, with amounts ranging between 2 and 3 log CFU/g. No Salmonella spp. were detected from any of the 233 samples analyzed in this study, and a low occurrence was found for contamination with L. monocytogenes, Shiga toxin-producing E. coli, enteropathogenic E. coli, and Cronobacter. From the results of the present study, we conclude that even in a country where the use of chlorine solutions to sanitize fruits and vegetables in the fresh-cut industry is not allowed, it is possible to produce ready-to-eat lettuce, fresh-cut fruit, and sprouts with high microbiological standards. Strict maintenance of good practices of hygiene at preharvest, harvest, and postharvest levels is of central importance to ensure both public health protection and product quality.

A total of 52 Shiga toxin-producing Escherichia coli (STEC) strains, isolated from fecal samples of six ibex, 12 chamois, 15 roe deer, and 19 red deer were further characterized by subtyping the stx genes, examining strains for the top nine serogroups and testing for the presence of eae and ehxA. Eleven of the 52 strains belonged to one of the top nine STEC O groups (O26, O45, O91, O103, O111, O113, O121, O145, and O157). Eight STEC strains were of serogroup O145, two strains of serogroup O113, and one strain of serogroup O157. None of the strains harbored stx2a, stx2e, or stx2f. Stx2b (24 strains) and stx1c (21 strains) were the most frequently detected stx subtypes, occurring alone or in combination with another stx subtype. Eight strains harbored stx2g, five strains stx2d, three strains stx1a, two strains stx2c, and one strain stx1d. Stx2g and stx1d were detected in strains not harboring any other stx subtype. The eae and ehxA genes were detected in two and 24 STEC strains, respectively. Considering both, the serogroups and the virulence factors, the majority of the STEC strains isolated from red deer, roe deer, chamois, and ibex do not show the typical patterns of highly pathogenic STEC strains. To assess the potential pathogenicity of STEC for humans, strain isolation and characterization is therefore of central importance. A total of 52 Shiga toxin-producing Escherichia coli (STEC) strains, isolated from fecal samples of six ibex, 12 chamois, 15 roe deer, and 19 red deer were further characterized by subtyping the stx genes, examining strains for the top nine serogroups and testing for the presence of eae and ehxA. Eleven of the 52 strains belonged to one of the top nine STEC O groups (O26, O45, O91, O103, O111, O113, O121, O145, and O157). Eight STEC strains were of serogroup O145, two strains of serogroup O113, and one strain of serogroup O157. None of the strains harbored stx2a, stx2e, or stx2f. Stx2b (24 strains) and stx1c (21 strains) were the most frequently detected stx subtypes, occurring alone or in combination with another stx subtype. Eight strains harbored stx2g, five strains stx2d, three strains stx1a, two strains stx2c, and one strain stx1d. Stx2g and stx1d were detected in strains not harboring any other stx subtype. The eae and ehxA genes were detected in two and 24 STEC strains, respectively. Considering both, the serogroups and the virulence factors, the majority of the STEC strains isolated from red deer, roe deer, chamois, and ibex do not show the typical patterns of highly pathogenic STEC strains. To assess the potential pathogenicity of STEC for humans, strain isolation and characterization is therefore of central importance.

23 24Yersinia enterocolitica biotype 1A strains are frequently isolated from the environment, foods 25 and animals but also from humans with yersiniosis. There are controversial reports on the 26 pathogenicity of biotype 1A strains. In this study, 811 fecal samples from asymptomatic 27 humans from Switzerland were studied for the presence of Y. enterocolitica. Nine (

The aim of this study was to compare the virulence characteristics and phylogenetic features of enteroaggregative Escherichia coli (EAEC) strains from adults with and without diarrhoea and to search for associations between the analysed genes and carrier or diarrhoeagenic strains, respectively. Faecal samples of 487 healthy humans were screened for EAEC strains and compared with isolates from diarrhoeal patients. Virulence and virulence-associated gene typing, serotyping, multilocus sequence typing and antibiotic susceptibility testing were performed for characterization of the isolates. Characteristics significantly linked to carrier strains or to diarrhoeagenic strains were determined. From 487 stool samples, 24 EAEC strains were obtained. Comparison with strains originating from diseased persons showed a statistically significant association of the genes sat (P50.002) and agg3C (P50.0139) with the carrier strains, and of pCVD432 (P50.0001), aap (P50.003), aggR (P50.0048) and air (P50.031) with the diarrhoeagenic strains. Our study indicates that a certain subset of EAEC is unrelated to diarrhoea, for which sat and agg3C may be markers. Our results further suggest that diarrhoeagenic EAEC strains are distinguishable from carrier strains and suggest that, in addition to well-established markers such as pCVD432 and aggR, aap and air may be useful additional markers to define EAEC as an aetiological agent of diarrhoea in adults. INTRODUCTIONEnteroaggregative Escherichia coli (EAEC) infection is a common cause of diarrhoea worldwide and is frequently seen as an aetiological agent of persistent paediatric diarrhoea in developing as well as in industrialized countries (Huang et al., 2006). In industrialized countries, EAEC has been described as a cause of diarrhoeal illness in individuals with immune deficiency syndrome and in travellers visiting less developed areas of the world (Kaur et al., 2010). EAEC is becoming increasingly recognized as a major cause of sporadic diarrhoea in otherwise healthy adults and children in industrialized countries. As well as sporadic cases, outbreaks of EAEC-caused diarrhoea that include foodborne outbreaks have been described (Smith et al., 1997;Morabito et al., 1998;Scavia et al., 2008). The outbreak of Shiga toxin-producing EAEC in northern Germany in 2011, with related cases in 15 other countries, received international attention, afflicting some 3000 people and causing over 800 cases of haemolytic uraemic syndrome and 46 deaths (Rasko et al., 2011). This outbreak revealed the alarming capability of this pathogen to genetically recombine, resulting in a phenotype of devastating proportions (Mellmann et al., 2011).Because EAEC can persist in recovered or subclinical cases (Huang et al., 2003) and thereby contribute to cryptic dissemination, its detection and prediction of its virulence and pandemic potential are of challenging importance. EAEC are traditionally defined by their ability to adhere to HEp-2 cells in culture in a so-called 'stacked-brick' aggregative formation (Natar...

The aim of this study was to determine the effect of saliva composition on caries lesion development independently of the flow rate of unstimulated whole saliva (UWS) and other caries-related variables such as lesion progression time, oral hygiene level, and fluoride exposure. We hypothesized that this could be done by developing experimental root caries under carefully controlled conditions in situ in test subjects with UWS flow rates within a narrow window of normalcy. Fifteen female and 5 male subjects (66 ± 6 years) were selected for the study according to their UWS flow rates between 0.2 and 0.4 ml/min. All subjects developed experimental root caries lesions during a 62-day period in which UWS as well as stimulated whole saliva (SWS) were repeatedly collected and analysed for flow rate, pH, buffer capacity, inorganic, and organic composition. Caries lesion development was determined by quantitative microradiography. The mean UWS flow rate was 0.30 ± 0.05 ml/min. Significant negative correlations were obtained between UWS total phosphate concentration and mineral loss (ΔZ; r_s = –0.72, p < 0.001) and UWS total protein concentration and ΔZ (r_s = –0.70, p < 0.01). SWS and its constituents had only limited or no effect on ΔZ. Qualitative UWS protein analysis (SDS-PAGE) revealed that subjects with low ΔZ values had broader and more stained amylase bands than subjects with high ΔZ values. These findings were confirmed quantitatively by HPLC. We conclude that, within a group of subjects with normal UWS flow rates, the UWS composition was more important for caries lesion development than the SWS composition. Furthermore, high UWS concentrations of phosphate, protein, and amylase were caries-protective.