Gernot Schmoock

Clostridium difficile Genotypes in Piglet Populations in Germany

ABSTRACT Clostridium difficile was isolated from 147 of 201 (73%) rectal swabs of piglets from 15 farms of Lower Saxony and North Rhine-Westphalia. In 14 farms, 14 to 100% (mean, 78%) of the animals tested were culture positive. The rate of isolation was 68% postpartum, increased to 94% in animals 2 to 14 days of age, and declined to 0% for animals 49 days of age and older. There was no link between isolation and antibiotic treatment or diarrhea of piglets. Strains were assigned to 10 PCR ribotypes, and up to 4 PCR ribotypes were found to be present at the same time on a farm. The closely related PCR ribotypes 078 (55%) and 126 (20%) were most frequently recovered and were present in 13 of the 14 positive farms. The comparison of multilocus VNTR (variable number of tandem repeats) analysis (MLVA) data from this study and previously published data on human, porcine, and bovine PCR ribotype 078 isolates from 5 European countries revealed genetic differences between strains of different geographic origin and confirmed the relatedness of human and porcine C. difficile isolates. This study demonstrated that the human-pathogenic PCR ribotypes 078 and 126 are predominant in piglets in Germany. The results suggest that presence of C. difficile is correlated with animal age but not with antibiotic treatment or clinical disease. MLVA indicated that strains of the same geographical origin are often genetically related and corroborated the hypothesis of a close epidemiological connection between human and porcine C. difficile isolates.

German Francisella tularensis isolates from European brown hares (Lepus europaeus)reveal genetic and phenotypic diversity

BackgroundTularemia is a zoonotic disease caused by Francisella tularensis that has been found in many different vertebrates. In Germany most human infections are caused by contact with infected European brown hares (Lepus europaeus). The aim of this study was to elucidate the epidemiology of tularemia in hares using phenotypic and genotypic characteristics of F. tularensis.ResultsCultivation of F. tularensis subsp. holarctica bacteria from organ material was successful in 31 of 52 hares that had a positive PCR result targeting the Ft-M19 locus. 17 isolates were sensitive to erythromycin and 14 were resistant. Analysis of VNTR loci (Ft-M3, Ft-M6 and Ft-M24), INDELs (Ftind33, Ftind38, Ftind49, RD23) and SNPs (B.17, B.18, B.19, and B.20) was shown to be useful to investigate the genetic relatedness of Francisella strains in this set of strains. The 14 erythromycin resistant isolates were assigned to clade B.I, and 16 erythromycin sensitive isolates to clade B.IV and one isolate was found to belong to clade B.II. MALDI-TOF mass spectrometry (MS) was useful to discriminate strains to the subspecies level.ConclusionsF. tularensis seems to be a re-emerging pathogen in Germany. The pathogen can easily be identified using PCR assays. Isolates can also be identified within one hour using MALDI-TOF MS in laboratories where specific PCR assays are not established. Further analysis of strains requires genotyping tools. The results from this study indicate a geographical segregation of the phylogenetic clade B.I and B.IV, where B.I strains localize primarily within eastern Germany and B.IV strains within western Germany. This phylogeographical pattern coincides with the distribution of biovar I (erythromycin sensitive) and biovar II (erythromycin resistance) strains. When time and costs are limiting parameters small numbers of isolates can be analysed using PCR assays combined with DNA sequencing with a focus on genetic loci that are most likely discriminatory among strains found in a specific area. In perspective, whole genome data will have to be investigated especially when terrorist attack strains need to be tracked to their genetic and geographical sources.

Presence of Clostridium difficile PCR ribotype clusters related to 033, 078 and 045 in diarrhoeic calves in Germany.

This study provides data on the distribution and relationship of C. difficile PCR ribotypes in diarrhoeic calves in Germany. C. difficile was isolated from 176 of 999 (17.6 %) faecal samples or swabs of diarrhoeic calves from 603 farms collected between January 2010 and August 2012 by eight federal laboratories of six states. Strains were assigned to 17 PCR ribotypes. PCR ribotypes 033 (57 %), 078 (17 %) and 045/FLI01 (closest match to 045 in the WEBRIBO database; 9 %) were found the most frequently. Nine per cent of all culture-positive tested animals shed more than one multiple locus variable number tandem repeat analysis (MLVA) or PCR ribotype. Eight PCR ribotypes with related profiles (including 033, 078 and 045/FLI01) representing 92 % of all isolates were grouped into three clusters. Molecular relatedness was supported by the absence of the MLVA locus A6Cd only in clustered strains and identical toxin gene profiles for strains within each cluster. Previously reported mulitilocus sequence typing analysis for PCR ribotypes that were also recovered in this study found identical sequence types and a tcdC deletion (Δ39 bp) for 033, 045, 078 and 126 (ST-11), confirming this clustering. A different geographical occurrence of PCR ribotypes was shown for cluster 033 (found more frequently in southern Germany) and 045 (found more frequently in northern Germany). This study showed that clusters of C. difficile PCR ribotypes related to 033, 078 and 045 are predominant in diarrhoeic calves in Germany. The high number of strains belonging to PCR ribotype 078 demonstrated that diarrhoeic calves are also potential reservoirs for human pathogenic C. difficile strains.

DNA microarray-based detection and identification of Burkholderia mallei, Burkholderia pseudomallei and Burkholderia spp.

We developed a rapid oligonucleotide microarray assay based on genetic markers for the accurate identification and differentiation of Burkholderia (B.) mallei and Burkholderia pseudomallei, the agents of glanders and melioidosis, respectively. These two agents were clearly identified using at least 4 independent genetic markers including 16S rRNA gene, fliC, motB and also by novel species-specific target genes, identified by in silico sequence analysis. Specific hybridization signal profiles allowed the detection and differentiation of up to 10 further Burkholderia spp., including the closely related species Burkholderia thailandensis and Burkholderia-like agents, such as Burkholderia cepacia, Burkholderia cenocepacia, Burkholderia vietnamiensis, Burkholderia ambifaria, and Burkholderia gladioli, which are often associated with cystic fibrosis (CF) lung disease. The assay was developed using the easy-to-handle and economical ArrayTube (AT) platform. A representative strain panel comprising 44 B. mallei, 32 B. pseudomallei isolates, and various Burkholderia type strains were examined to validate the test. Assay specificity was determined by examination of 40 non-Burkholderia strains.

Use of a Western blot technique for the serodiagnosis of glanders

BackgroundThe in vivo diagnosis of glanders relies on the highly sensitive complement fixation test (CFT). Frequently observed false positive results are troublesome for veterinary authorities and cause financial losses to animal owners. Consequently, there is an urgent need to develop a test with high specificity. Hence, a Western blot assay making use of a partly purified lipopolysaccaride (LPS) containing antigen of three Burkholderia mallei strains was developed. The test was validated investigating a comprehensive set of positive and negative sera obtained from horses and mules from endemic and non endemic areas.ResultsThe developed Western blot assay showed a markedly higher diagnostic specificity when compared to the prescribed CFT and therefore can be used as a confirmatory test. However, the CFT remains the test of choice for routine testing of glanders due to its high sensitivity, its feasibility using standard laboratory equipment and its worldwide distribution in diagnostic laboratories.ConclusionsThe CFT should be amended by the newly validated Western blot to increase the positive likelihood ratio of glanders serodiagnosis in non endemic areas or areas with low glanders prevalence. Its use for international trade of horses and mules should be implemented by the OIE.

Zoonotic Agents in Small Ruminants Kept on City Farms in Southern Germany

ABSTRACT Sheep and goats are popular examples of livestock kept on city farms. In these settings, close contacts between humans and animals frequently occur. Although it is widely accepted that small ruminants can carry numerous zoonotic agents, it is unknown which of these agents actually occur in sheep and goats on city farms in Germany. We sampled feces and nasal liquid of 48 animals (28 goats, 20 sheep) distributed in 7 city farms and on one activity playground in southern Germany. We found that 100% of the sampled sheep and 89.3% of the goats carried Shiga toxin-producing Escherichia coli (STEC). The presence of Staphylococcus spp. in 75% of both sheep and goats could be demonstrated. Campylobacter spp. were detected in 25% and 14.3% of the sheep and goats, respectively. Neither Salmonella spp. nor Coxiella burnetii was found. On the basis of these data, we propose a reasonable hygiene scheme to prevent transmission of zoonotic agents during city farm visits.

Prevalence of Coxiella burnetii in clinically healthy German sheep flocks

BackgroundCurrent epidemiological data on the situation of Coxiella (C.) burnetii infections in sheep are missing, making risk assessment and the implementation of counteractive measures difficult. Using the German state of Thuringia as a model example, the estimated sero-, and antigen prevalence of C. burnetii (10% and 25%, respectively) was assessed at flock level in 39/252 randomly selected clinically healthy sheep flocks with more than 100 ewes and unknown abortion rate.ResultsThe CHECKIT™ Q-fever Test Kit identified 11 (28%) antibody positive herds, whereas real-time PCR revealed the presence of C. burnetii DNA in 2 (5%) of the flocks. Multiple-locus variable number of tandem repeats analysis of 9 isolates obtained from one flock revealed identical profiles. All isolates contained the plasmid QpH1.ConclusionsThe results demonstrate that C. burnetii is present in clinically inconspicuous sheep flocks and sporadic flare-ups do occur as the notifications to the German animal disease reporting system show. Although C. burnetii infections are not a primary veterinary concern due to the lack of significant clinical impact on animal health (with the exception of goats), the eminent zoonotic risk for humans should not be underestimated. Therefore, strategies combining the interests of public and veterinary public health should include monitoring of flocks, the identification and culling of shedders as well as the administration of protective vaccines.

Comparative evaluation of eleven commercial DNA extraction kits for real-time PCR detection of Bacillus anthracis spores in spiked dairy samples.

Spores of Bacillus anthracis are highly resistant and can survive conditions used for food preservation. Sample size and complexity represent the major hurdles for pathogen detection in food-related settings. Eleven commercial DNA extraction kits were evaluated for detection of B. anthracis spores by quantitative real-time PCR (qPCR) in dairy products. DNA was extracted from serial dilutions of B. anthracis spores in milk powder, cream cheese, whole milk and buttermilk. Three kits (QIAamp DNA mini kit, Invisorb Food kit I and II) were determined to produce the lowest limit of detections (LODs) with equally good performance. These kits employed lysozyme and proteinase K treatments or proteinase K in combination with cethyltrimethylamonium bromide-mediated (CTAB) precipitation of cell debris for cell disruption and DNA release. The LODs for these three kits were determined as 10(2) spores/ml of distilled water, 10(3)s pores/20 mg of powdered milk and 10(4) spores/100 mg of cream cheese, respectively. Performance testing of the QIAamp DNA mini kit demonstrated a good reproducibility and appropriate detection limits from 10(3)/ml for butter milk, 10(4)/ml for whole milk and 10(4)/100 mg for low fat cream cheese. However, DNA extraction efficiency was strongly inhibited by cream cheese with higher fat contents with an increased LOD of 10(6)/100 mg spores. This study demonstrated that qPCR detection depends directly on the appropriate DNA extraction method for an individual food matrix and bacterial agent.

Coxiella burnetii and coinfections in Ixodes ricinus ticks in Central Germany.

A total of 1000 Ixodes ricinus ticks were collected in 2006 and 2007 in a forest region of Central Germany and investigated for Coxiella burnetii. The transposase element IS1111 and isocitrate dehydrogenase gene were targets of the real-time polymerase chain reaction. The pathogen was detected in 19 ticks (1.9%), and interestingly, in 10 of these samples, coinfections with Borrelia spp., spotted fever group rickettsiae, or Babesia spp. were present. Our study reports on C. burnetii infections in I. ricinus ticks in an area where cases of Q fever occur regularly and Dermacentor marginatus is not present. The broad spectrum of copathogens indicates interactions in transmission cycles and the possibility of coinfections in humans in areas where people are in close contact with infected ticks and domestic animals.

Cross-border molecular tracing of brucellosis in Europe

To assess the general impact of endemic countries on the re-emergence of brucellosis in non-endemic regions of the European Union, the genetic fingerprints of Brucella melitensis strains imported to Germany were compared to ovine strains from Turkey in a molecular epidemiological study. Genotyping of 66 Brucella strains (based on Multiple Locus of Variable number of tandem repeats Analysis) isolated from German travellers and Turkish immigrants living in Germany revealed epidemiological concordance with 20 sheep isolates originating from Eastern Anatolia, Turkey. In summary, cross-border molecular tracing confirmed brucellosis being a zoonosis of concern for European public health.