Publications (67) View all
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Article: Multiple-Locus Variable-Number Tandem Repeats Analysis in Genotyping Yersinia enterocolitica Strains from Human and Porcine Origin.
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ABSTRACT: Sporadic and epidemiologically linked Yersinia enterocolitica strains (n=379) that originated from fecal samples of human patients, tonsil or fecal samples of pigs collected at slaughterhouses and pork samples collected at meat stores were genotyped using multiple-locus variable-number tandem repeats analysis (MLVA) with six loci V2A, V4, V5, V6, V7 and V9. In total 312 different MLVA types were found. Similar types were detected i) in fecal samples of clinical human patients over two to three consecutive years, ii) between samples originating from humans and pigs and iii) in pigs that originated from the same farms. Among porcine strains, we found farm-specific MLVA profiles. One to four number variations in tandem repeat numbers of VNTR loci V2A, V5, V6 and V7 were observed within a farm. MLVA was applicable for serotypes O:3, O:5,27 and O:9 and appeared to be a highly discriminating tool in distinguishing both sporadic and outbreak-related strains. In long-term use, interpreting the results became more challenging due to variations in more discriminating loci as was observed in strains originating from pig farms. Additionally, we encountered unexpectedly short V2A VNTR fragments and sequenced these. According to the sequencing results, updated guidelines for interpreting the V2A VNTR results were aggregated.Journal of clinical microbiology 05/2013; · 4.16 Impact Factor -
Article: Characteristics of Yersinia enterocolitica biotype 1A strains isolated from patients and asymptomatic carriers.
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ABSTRACT: Yersinia enterocolitica biotype 1A strains are frequently isolated from the environment, foods, and animals, and also from humans with yersiniosis. There are controversial reports on the pathogenicity of biotype 1A strains. In this study, 811 fecal samples from asymptomatic humans from Switzerland were studied for the presence of Y. enterocolitica. Nine (1.1 %) of the 811 samples were positive for Y. enterocolitica 1A. These strains were compared with 12 Y. enterocolitica 1A strains from Swiss patients with diarrhea isolated in the same year. Almost all (20/21) Y. enterocolitica 1A strains carried the ystB gene, seven strains carried the hreP gene, and none carried the ail, ystA, myfA, yadA, or virF genes. Most (17/21) Y. enterocolitica 1A strains belonged to two major clusters, A and B, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Strains of cluster B were only isolated from humans with diarrhea; however, ystB and hreP genes were detected in strains from both clinical and non-clinical samples and from strains of clusters A and B. Using ribotyping, six restriction patterns among biotype 1A strains were obtained with HindIII enzyme. The most common ribotype (RT I) was found in strains isolated from humans with and without diarrhea. All biotype 1A strains had a unique NotI profile by pulsed-field gel electrophoresis (PFGE), showing a very high genetic diversity. In this study, Y. enterocolitica 1A strains from clinical and non-clinical samples could not be clearly differentiated from each other. More research is needed in order to prove that biotype 1A strains are a primary cause for human yersiniosis and not only a secondary finding.European Journal of Clinical Microbiology 01/2013; · 2.86 Impact Factor -
Article: Pathogenic Yersinia enterocolitica O:3 isolated from a hunted wild alpine ibex.
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ABSTRACT: Occurrence of Yersinia spp. in wild ruminants was studied and the strains were characterized to get more information on the epidemiology of enteropathogenic Yersinia in the wildlife. In total, faecal samples of 77 red deer, 60 chamois, 55 roe deer and 27 alpine ibex were collected during 3 months of the hunting season in 2011. The most frequently identified species was Y. enterocolitica found in 13%, 10%, 4% and 2% of roe deer, red deer, alpine ibex and chamois, respectively. Interestingly, one Y. enterocolitica O:3 strain, isolated from an alpine ibex, carried the important virulence genes located on the virulence plasmid (yadA and virF) and in the chromosome (ail, hreP, myfA and ystA). Most of the Y. enterocolitica strains belonged to biotype 1A of which 14 were ystB positive. Further studies are needed to clarify the importance of alpine ibex as a reservoir of pathogenic Y. enterocolitica.Epidemiology and Infection 06/2012; · 2.84 Impact Factor -
Article: High number of Yersinia enterocolitica 4/O:3 in cold-stored modified atmosphere-packed pig cheek meat.
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ABSTRACT: Yersinia enterocolitica is a psychrotrophic, facultative anaerobic zoonotic bacterium belonging to family Enterobacteriaceae and it can be transmitted from pigs to humans through pork. The growth of bacteria belonging to Enterobacteriaceae and aerobic spoilage bacteria is usually effectively restricted by 20% or more CO(2) enriched atmosphere at refrigerated temperatures. In this study, 40 samples of meat strips from pig cheek (musculus masseter) and 40 samples from hind leg (m. semimembranosus) muscles were packaged in modified atmosphere (MA) (30% CO(2)/70% O(2)) and stored at 6°C for 12d. Twenty naturally contaminated samples per muscle type were studied on days 1 and 13. Violet red bile glucose (VRBG) and de Man Rogosa Sharpe (MRS) agar plates were used for enumeration of Enterobacteriaceae including Y. enterocolitica and lactic acid bacteria, respectively. During the 12-d storage at 6°C in MA, the mean number of bacteria on pork strips of cheek meat was increasing from 1.6 to 4.5 log cfu/g and from 3.1 to 7.2 log cfu/g on VRBG and MRS agar plates, respectively. Most of the oxidase-negative isolates on VRBG plates, which were isolated from the cheek meat samples after 12-d cold storage in MA, were identified as Y. enterocolitica 4/O:3. The mean number of this pathogen was 4.1 log cfu/g varying between 2.3 and 5.4 log cfu/g. The pH of the cheek meat and leg meat was measured on days 1 and 13, and it remained high (pH>6) in most cheek meat samples during the storage. No Y. enterocolitica 4/O:3 was isolated from meat strips of hind leg. This study shows that cheek meat of slaughter pigs is contaminated with Y. enterocolitica 4/O:3 and that this pathogen can grow well on raw pork packaged in MA at 6°C even in the presence of high number of lactic acid bacteria.International journal of food microbiology 04/2012; 155(1-2):69-72. · 3.01 Impact Factor -
Article: Detection and characterization of Shiga toxin-producing Escherichia coli in faeces and lymphatic tissue of free-ranging deer.
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ABSTRACT: SUMMARYShiga toxin-producing Escherichia coli (STEC) have led to outbreaks worldwide and are considered emerging pathogens. Infections by STEC in humans have been reported after consumption of mainly beef, but also deer. This study investigated the occurrence of STEC in deer in Germany. The virulence genes eae, e-hlyA and saa, the stx subtypes, pulsed-field gel electrophoresis (PFGE) patterns and serovars were studied. In total, 120 samples of 60 animals were screened by real-time polymerase chain reaction (PCR). The PCR results showed a high detection rate of stx genes (83%). Mainly faecal samples, but also some lymphatic tissue samples, tested stx-positive. All isolates carried stx2, were eae-negative and carried e-hlyA in 38% and saa in 9% of samples. Serovars (O88:[H8], O174:[H8], O146:H28) associated with human diseases were also identified. In some animals, isolates from lymphatic tissue and faecal samples showed undistinguishable PFGE patterns. The examined deer were shown to be relevant reservoirs of STEC with subtype stx2b predominating.Epidemiology and Infection 02/2012; · 2.84 Impact Factor
