The pathogen Campylobacter fetus (CF) is classified into two subspecies, Campylobacter fetus subspecies fetus (CFF) and Campylobacter fetus subspecies venerealis (CFV). Even though CFF and CFV are genetically closely related, they exhibit differences in their host adaptation; CFF inhabits the gastrointestinal tract of both humans and several animal species, while classical CFV is specific to the bovine genital tract and is of particular concern with respect to international bovine trade regulation. Traditionally, differentiation between the two subspecies has been achieved using a limited number of biochemical tests but more rapid and definitive genetic methods of discrimination are desired. A recent study suggested that the presence of a genomic island only in CFV could discriminate between the two sub- species but this hypothesis could not be confirmed on a collection of isolates originating in Canada. To identify alternative gene targets that would support accurate subspecies discrimination, this study has applied several approaches including suppression subtractive hybridization and whole genome sequencing supplemented with optical mapping. A subtractive hybridization screen, using a well-characterized CFV isolate recovered during routine screening of bulls in an Artificial Insemination center in western Canada and that lacked much of the genomic island and a typical Canadian CFF isolate, yielded 50 clones; characterization of these clones by hybridization screening against selected CF isolates and by nucleotide sequence BLAST analysis identified three potentially CFV-specific clones that contained inserts originating from a second genomic island. Further screening using a larger CF sample set found that only Clone #35 was truly CFV-specific. Optical maps (NcoI digest) of the Canadian CFF and CFV isolates used for the subtractive hybridization showed that certain regions of these genomes were quite distinct from those of two reference strains. Whole genome sequencing of these two isolates identified two target genes (PICFV5_ORF548 and CFF_Feature #3) that appear to be selectively retained in the two subspecies. Screening of a collection of CF isolates by PCRs targeting these three loci (SSH_Clone #35, PICFV5_ORF548 and CFF_Feature #3) supported their use for subspecies discrimination. This work demonstrates the complex genomic diversity associated with these CF subtypes and the challenge posed by their discrimination using limited genetic loci.

Food-borne illness is a significant burden both with regard to public health and financially. Efforts to reduce the level of food-borne illness continue to concentrate on the full food supply chain with particular regard given to Campylobacter, the most commonly reported zoonosis and the greatest burden to public health. The focus of this research is domestic food safety practises, where there is no regulation. Food safety is reliant on people’s knowledge or awareness, their ability to adopt safe food handling practises and for the correct behaviours to achieve this, to be routine. The elicitation of awareness and perceptions with regard to food safety are problematic due to the complexities of human nature, including the presence of several forms of bias, such as social desirability bias and optimistic bias. The research was designed in order to try to minimise such biases, whilst further understanding influences on food safety preparation behaviour. Food safety preparation behaviours and kitchen hygiene were investigated between people who had campylobacteriosis in comparison to people who had not had food poisoning. Whilst no difference was noted in the kitchen hygiene between the two groups, significant differences were noted in self-reported food preparation behaviours. Optimistic bias was exhibited by both groups but when tested again after six months had elapsed, the group who had not had food poisoning increased their optimism, introducing a significant difference in optimistic bias between the two groups. Awareness of a number of unsafe food behaviours was explored for individuals and groups of people using a method developed as part of the research. This method of hazard awareness uses video as a stimulus, creating an interactive survey, combined with attitudinal and demographic data. Changes were made to perceptions of knowledge and risk following the hazard perception challenge, with the number of hazards missed, influencing this movement in perception. The risk perception of unsafe food handling behaviours was examined using a novel technique Best-Worst Scaling, in order to identify relative risks. This technique, in conjunction with latent class modelling, demonstrated a difference in perceptions between food safety experts and members of the general public. However, these differences are nuanced and demonstrate that heterogeneity exists both within and across the groups. Taken together, these findings have extended the research on domestic food safety behaviour and risk perceptions. It has done so by developing and testing novel methods to elicit relative risk perceptions and hazard perception with regard to food safety behaviours. The results provide valuable evidence for stakeholders particularly with regard to the novel methods used in identifying the heterogeneity and influences of food safety behaviour between groups of people. It also provides important tools for stakeholders, risk managers and communicators to use in future research, communication and education.

Membros termofílicos do gênero Campylobacter são reconhecidos como importantes enteropatógenos para o ser humano e animais. A grande diversidade ecológica destes microorganismos em diferentes habitats tais como: água, animais e alimentos predispõem ao aparecimento de novos fatores de virulência. Este trabalho teve por objetivo detectar os genes codificantes da Toxina Distensiva Citoletal (CDT) por meio da técnica de PCR, pesquisar a atividade de hemolisinas e a influência de soluções quelantes e de íons nesta atividade. Foram utilizadas 45 amostras de C. jejuni de origem avícolas para pesquisa de atividade hemolítica, cultivadas em Caldo Triptona de Soja (TSB). Após o crescimento bacteriano, as amostras foram semeadas em Ágar tríptico de soja (TSA) contendo 5% de sangue de ovino, equino e bovino, sendo cada sangue testado isoladamente. Para verificar a influência de agentes quelantes e solução de íons na atividade hemolítica, as amostras de C. jejuni foram cultivadas em TSB contendo separadamente os quelantes EDTA, ácido acético, soluções de íons CaCl2 , MgCl2 e FeCl3, em atmosfera de microaerofilia. Quanto à atividade de hemolisina de Campylobacter jejuni em placas de TSA – sangue, foi possível observar que houve hemólises em 48,89% das amostras quando utilizado sangue eqüino, em 40% em sangue de bovino e em 31,11% quando de ovino. Quanto à influência de agentes quelantes e íons em caldo TSB na atividade de hemolisinas em amostras de Campylobacter jejuni semeadas em placas de TSA – sangue ovino, foi observada atividade hemolítica em 26,67% quando utilizado CaCl2, 15,55% (FeCl3), 22,22% (EDTA), 11,11% (MgCl2) e apenas 2,22% (ácido acético). No tocante à atividade hemolítica, o TSA - sangue bovino apresentou 15,55% (CaCl2), 24,44% (FeCl3), 26,26% (EDTA), 20% (MgCl2) e 11,11% (ácido acético). A atividade hemolítica para o sangue equino foi de 24,44% (CaCl2), 22,22% (FeCl3), 28,89% (EDTA), 28,89% (MgCl2) e 8,89% (ácido acético). Para detecção dos genes cdtA, cdtB e cdtC através da técnica da Reação da Polimerase em Cadeia (PCR), foram utilizadas 119 amostras de C. jejuni de origem avícolas. Foi possível observar que 38% possuíam os três genes, e foram identificados somente os genes cdtA e cdtC em 19% do total de amostras, sendo que o gene cdtB foi encontrado em 14%, o gene cdtC foi observado em 12%, os genes cdtA e cdtB em somente 1%, os genes cdtB e cdtC em 1% e para cdtA em 1%. Observou-se que os resultados são dignos de atenção, pois demonstraram em amostras avícolas a presença de estirpes de C. jejuni com potencial virulento. A atividade hemolítica apresentou significativo aumento quando utilizado sangue de origem equina. A mesma foi diminuída quando utilizados agentes quelantes ou íons, nos três tipos de sangue. / Thermophilic members of the Campylobacter genus are recognized as important enteropathogenics for humans and also for other animals. The great diversity of ecological habitats in different organisms such as water, food, and animals may promote new virulence factors. This study aimed at detecting the distending cytolethal toxin (CDT) encoding genes by PCR, studying the activity of hemolysin and also the influence of chelation solutions and ions. A total of 45 samples of C. jejuni from poultry origin, grown in Tryptone Soy Broth (TSB) were used for investigating hemolytic activity. After bacterial growth, samples were plated on Tryptic Soy Agar (TSA) containing 5% sheep, equine or bovine blood, being each blood tested individually. In order to check the influence of chelation agents and ions solution on the hemolytic activity, samples of C. jejuni strains were grown in TSB containing chelation agents individually: EDTA, acetic acid, CaCl2 ion, MgCl2 and FeCl3 solutions, all in microaerophilic atmosphere. Regarding the detection of Campylobacter jejuni hemolysin activity on TSA plates, blood hemolysis were observed in 48.89 % of samples when equine blood was used; in 40% of samples when bovine blood was used and in 31.11 % when the blood used was of sheep origin. The influence of ions and chelation agents in hemolysin activity in TSB when Campylobacter jejuni was plated on TSA with sheep blood can be described as: hemolytic activity was observed at 26.67% of samples when CaCl2 was used, at 15.55 % for FeCl3, 22 22 % for EDTA, 11.11 % for MgCl2 and only 2.22% when acetic acid was used. The hemolytic activity detected when bovine blood - TSA was used indicated 15.55% for CaCl2, 24.44% for FeCl3, 26.26 % for EDTA, 20 % for MgCl2 and 11.11% for acetic acid. In terms of the hemolytic activity when equine blood was used, the results indicated 24.44% for CaCl2, 22.22 % for FeCl3, 28.89 % for EDTA, 28.89 % for MgCl2 and 8.89% for acetic acid. Finally, regarding the detection of cdtA, cdtB and cdtC through PCR, 119 samples of C. jejuni from poultry origin were used. The results indicated that all three genes were present in 38 % of the samples, whereas only two genes were identified in 19 % of samples, while the cdtB gene was singly found in 14%, the cdtC gene was independently observed in 12%, cdtA and cdtB genes together were found in 1% of the samples; the cdtB and cdtC genes associated were detected in 1%, while cdtA alone answered for 1% of detections. The results also showed the presence of C. jejuni strains with virulence potential. The hemolytic activity increased significantly when blood of equine origin was used, and that this activity was reduced when ions or chelating agents were used in combination with the three types of blood cells.

Campylobacter (C.) spp. und Yersinia (Y.) enterocolitica sind in Deutschland nach den Salmonellen die häufigsten Erreger der Enteritis infectiosa. Das Schwein wird als Reservoirtier für C. coli und Y. enterocolitica Bioserovar 4/O:3 angesehen. Da diese Infektionen beim Schwein zumeist klinisch inapparent verlaufen, sind sie bei der Schlachttier- und Fleischuntersuchung nicht feststellbar. Die Erreger können somit unerkannt in die Lebensmittelkette gelangen. In dieser Arbeit sollte ein Beitrag zur Epidemiologie dieser Erreger geleistet werden. Dazu wurden Prävalenzdaten in Betrieben und zum Schlachtzeitpunkt erhoben, Eintragungsquellen gesucht und genotypische Vergleiche durchgeführt. Im Zeitraum von Mai 2002 bis März 2004 wurden in vier verschiedenen Betrieben Verlaufsuntersuchungen zum Vorkommen dieser beiden Erreger durchgeführt. Dafür wurden Schweine von ihrer Geburt bis zur ihrer Schlachtung verfolgt. In drei dieser vier Betriebe wurden die Schweine konventionell, in einem ökologisch gehalten. Für die Untersuchungen wurden jeweils 100 Ferkel drei Tage nach ihrer Geburt mit einer Ohrmarke gekennzeichnet. Zu diesem Zeitpunkt erfolgte eine erste Kotprobenentnahme mittels eines sterilen Tupfers. Die Tiere mit den Marken 1-40 wurden auf Campylobacter spp. und Y. enterocolitica, die mit den Nummern 41-100 nur auf Y. enterocolitica untersucht. Eine zweite Untersuchung der Ferkel erfolgte kurz vor dem Absetzen. An diesen beiden Terminen wurden auch die Muttersauen beprobt. Nur in dem Ökobetrieb war eine Sauenuntersuchung aufgrund der Haltungsform nicht möglich. Weitere Untersuchungen wurden kurz vor dem Ausstallen aus dem Läuferstall, im Maststall und auf dem Schlachthof durchgeführt. Für den Nachweis von Y. enterocolitica wurden die Proben in ITC angereichert und auf CIN-Agar ausgestrichen. Bolton-Bouillon und mCCD-Agar wurden für die Anzucht der Campylobacter-Keime genutzt. Wie zu erwarten war, konnten hohe Prävalenzen (bis zu 100%) von C. coli nachgewiesen werden. Vor allem kurz vor dem Absetzen wurde der Erreger häufig isoliert. Aber es gab auch einen Betrieb, wo der Nachweis nur im Maststall und nur bei sehr wenigen Tieren gelang. Nicht nur in den Betrieben, sondern auch auf dem Schlachthof waren hohe Prävalenzen festzustellen. Vor allem aus dem Kot und aus den Tonsillen konnte der Erreger häufig isoliert werden. Auch die Schlachttierkörperoberfläche war häufig stark kontaminiert. Nach der Kühlung jedoch konnte der Erreger nur bei 3 von 443 (0,7%) untersuchten Tieren nachgewiesen werden. Zu bemerken ist, dass es sich hierbei nicht um C.coli, sondern um C. jejuni handelte. Auch aus einigen Umgebungsproben der Betriebe konnte C. coli isoliert werden. Die Genotypen dieser Isolate wurden mit den Genotypen zeitgleich isolierter Schweinestämme verglichen. Als Methode hierfür wurde die AFLP (Amplified Fragment Length Polymorphism) genutzt. Dabei konnte eine enge Verwandtschaft von Schweine- und Umgebungsproben beobachtet werden. In zwei der vier Betriebe konnte Y. enterocolitica aus Kotproben isoliert werden. Der Nachweis gelang aber nur im Maststall. Hier konnten im Kot sehr hohe Prävalenzen (bis zu 65,4%) nachgewiesen werden. Sauen, Ferkel und Läufer wurden immer als negativ getestet. Zum Schlachtzeitpunkt gelang die Isolierung sehr häufig aus den Tonsillen, im Kot war der Erreger zu diesem Zeitpunkt kaum noch nachzuweisen. Alle Isolate gehörten dem humanpathogenen Bioserovar 4/O:3 an, nur eines wurde als 3/O:9 identifiziert. Aus den 458 untersuchten Umgebungsproben konnte Y. enterocolitica nicht isoliert werden. Des Weiteren wurde mittels einer PCR untersucht, ob die isolierten Yersinien ein Virulenzplasmid beherbergen. Dieses ist notwendig, um eine volle Pathogenität auszubilden. Von insgesamt 263 isolierten Stämmen konnten 236 Stämme (89,7%) als plasmidtragend identifiziert werden. Auffallend war hierbei, dass 110 von 111 Stämmen (99,1%), die im Maststall isoliert wurden, das Plasmid besaßen. Im Gegensatz dazu konnte bei den Schlachthofisolaten das Plasmid nur bei 126 von 152 Stämmen (82,9%) nachgewiesen werden. Einige Isolate eines Betriebes wurden mit Hilfe der PFGE (Pulsed Field Gel Electrophoresis) unter Nutzung des Restriktionsenzyms NotI genotypisiert. Wie in der Literatur beschrieben, war innerhalb eines Bestandes auch nur ein Genotyp zu finden. Auch die Isolate aus Kot und Tonsillen waren klonal. Ebenso waren plasmidtragende nicht von plasmidlosen Stämmen zu unterscheiden. Auch wenn fast alle Herden stark mit Campylobacter spp. belastet sind, scheint aus Sicht des Verbraucherschutzes eine Bekämpfung auf Bestandsebene nicht notwendig zu sein, da die Kühlung des Schlachtkörpers den sauerstoff- und austrocknungsempfindlichen Erreger offensichtlich sehr effektiv zurückdrängt. Anders verhält es sich bei den Yersinien. Obwohl im Schweinefleisch nur relativ selten der Erreger nachweisbar ist, so sind Schlachtnebenprodukte oft stark belastet. Vor allem durch Kreuzkontaminationen im Küchenbereich der privaten Haushalte geht vom Fleisch und von den Nebenprodukten eine nicht zu unterschätzende Gefahr aus. Da über die Epidemoiologie des Erregers auf Bestandsebene noch relativ wenig bekannt ist, kann er momentan nur auf Schlachthofebene durch Einhaltung einer strikten Hygiene in seiner Ausbreitung begrenzt werden. Auf Bestandsebene scheint die Einführung von Monitoringprogrammen sinnvoll, um stark belastete Herden zu erkennen, diese möglichst am Schluss zu schlachten und somit das Lebensmittel Schweinefleisch sicherer zu machen.

This study investigates the analyses and clustering of Campylobacter spp., Listeria monocytogenes and Shiga toxin-producing Escherichia coli (STEC) at Livsmedelsverket. Livsmedelsverket is a control authority in Sweden. They work with eating habits, what food contains and safe food and good drinking water, where outbreak investigations of the above-mentioned bacterial types is a part of the work. For the investigations Livsmedelsverket uses a pipeline that is written in the programming language Python. The purpose of this project is to add identification of virulence genes and analysis of the STEC bacterium to the script. But also to develop the existing method to be able to cluster more isolates without losing information, enable the user to adjust parameters in the pipeline and write an ethical analysis to the work that is done. Our study shows the analysis and clustering of the three different types of bacteria, clustering of the samples from the analysis, both adaptively and statically, and that it can determine serotype, sequence type and virulence genes. We therefore conclude that STEC can be added to outbreak investigations at Livsmedelsverkets in-house pipeline. The clustering method has also been modified to be able to use more of the information given from the samples with the restriction of having lower accuracy.

The traditional method for the diagnosis of bovine genital campylobacteriosis is the culture and identification of the causative organism, Campylobacter fetus subsp. venerealis (Cfv) from the genital tract. This approach is considered relatively insensitive due to the fragility of the bacteria, their specific nutritional and atmospheric requirements and their being easily overgrown by commensal bacteria. The identification of isolates is also problematic due to the limited biochemical activity of the bacteria. With the rapid advances made in the molecular field, assays have become more robust and cost-effective making them feasible for the diagnostic laboratory. The potential speed, sensitivity and specificity offered by these assays provide attractive alternatives for the identification of pathogens which are notoriously difficult to identify. The first part of this investigation was concerned with the implementation and evaluation of a polymerase chain reaction (PCR) assay for the direct detection of C. fetus in bovine preputial specimens. The specificity of a published C. fetus-specific primer pair was established by testing C. fetus reference and field isolates in addition to a collection of other Campylobacter species and organisms which may encountered in the genital tract of cattle. All C. fetus isolates tested yielded a single PCR amplicon of approximately 750 bp. No amplicons were generated when any of the other non-C. fetus isolates were tested. Following minor modifications to the assay, the sensitivity of the assay was determined using spiked Weybridge medium. A detection limit of 615 Cfv/mR Weybridge medium (or 6,15 cell equivalents per PCR assay) was obtained. Preputial material collected and submitted for laboratory testing may often be contaminated with faeces, urine, semen and/or blood. All of these components are known to be potential PCR inhibitors and the influence of each, on the sensitivity of the PCR assay, was subsequently evaluated. Faeces were identified as a potent inhibitor and contamination of specimens with as little as 1% (w/v) faeces reduced the sensitivity of the assay. Concentrations of up to 50% (v/v) of blood, urine and semen had no effect on the sensitivity of the assay. Preputial specimens, collected in Weybridge medium, were subsequently pooled and spiked and used to establish the sensitivity of both the PCR and culture methods as well as determine the influence of time on the sensitivity of the assays. Testing was carried out in triplicate on samples collected from different herds which were ascertained to be free of Cfv based on the use of specific selection criteria. The detection limit of the culture method was found to be better than that achieved using PCR only immediately after the samples were spiked. The detection limit of the culture method decreased with time whilst the detection limit of the PCR assay remain unchanged up to 72 hours post-inoculation. Ensuing field evaluation involved the testing of 212 clinical samples using both the culture method and the optimized PCR assay. Of the samples tested 4,2% were found to be positive using the PCR assay, whilst only 3,8% were found to be positive by culture. Based upon this evaluation the analytical specificity of the PCR assay was calculated to be 99% and the analytical sensitivity, 85,7%. The second part of this investigation was concerned with the subspeciation of C. fetus isolates. Currently the only test recommended by the Office International des Epizooties (OIE) for the subspeciation of isolates, is tolerance to 1% glycine. Doubts over the reliability of this test have led to alternative or supplementary tests being sought. Within the context of this investigation a collection of 40 South African field isolates were subspeciated using a previously described subspecies-specific primer set as well as the traditional 1% glycine tolerance phenotyping test. Additionally, other phenotyping tests (selenite reduction, growth at 42 °C and susceptibility to metronidazole and cefoperazone) were evaluated to determine their suitability for use as an aid in the subspeciation of C. fetus isolates. None of the field isolates yielded a Cfv-specific subspecies PCR amplicon using the published primer set suggesting that all of the isolates were Campylobacter fetus subsp. fetus (Cff). Based on tolerance to 1% glycine however, only 6 isolates were identified as Cff (glycine tolerant), whilst the remainder were classified as Cfv. The results of the ‘sensitive’ hydrogen sulphide test indicated that the Cfv isolates were specifically Cfv biovar intermedius. The lack of agreement between the PCR and the phenotyping subspeciation results concur with the findings reported by other researchers. It is consequently concluded that the published VenSF/VenSR subspecies-primer set is unsuitable for the subspeciation of South African field isolates. / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted

During the last two or three years, the three largest hospitals in Stockton (St. Joseph’s, Dameron and San Joaquin General Hospitals) have modified their procedures to include the search for Campylobacter. On the other hand, the incidence of Yersinia in California is unknown, as most clinical laboratories do not specifically culture for it. There have been only a few reports of Yersinia in this state (personal communication of Dennis Ferrero, Director of the San Joaquin County Public Health Laboratory). This study has a threefold purpose: to investigate the incidences of Campylobacter and Yersinia, especially in relation to the incidence of Salmonella and Shigella, to study the biochemical and antibiogram characteristics of enteric isolates, particularly the “newer” pathogens, and to review the state of routine culture methods and assess their adequacy.

Campylobacter fetus subsp. venerealis ist der Erreger der bovinen genitalen Campylobacteriose, einer anzeigepflichtigen Tierseuche. Er hat sein natürliches Reservoir im Präputialsack klinisch gesunder Bullen und ist in der Lage, Aborte zu verursachen (enzooti-scher Abort). Davon abzutrennen sind Infektionen mit C. fetus subsp. fetus, welcher natürlicherweise im Intestinaltrakt des Rindes auftritt und ebenfalls Aborte auszulösen vermag (spo-radischer Abort). Während C. fetus subsp. venerealis einen ausgeprägten Tropismus für die Genitalschleimhaut des Rindes aufweist, handelt es sich bei der Subspezies fetus um einen Zoonoseerreger, der beim Menschen schwerwiegende Erkrankungen mit zumeist septikämischen Charakter verursachen kann. Die Übertragung von C. fetus subsp. venerealis erfolgt hauptsächlich durch den natürlichen Deckakt, es besteht aber auch die Gefahr der Verbreitung durch künstliche Besamung, da klinisch gesunde Bullen den Erreger im Samen enthalten können. Die Unterschiede in der Epidemiologie und die klinische Bedeutung der beiden C. fetus-Subspezies erfordern eine exakte Identifizierung und Differenzierung. Der erste Teil der Untersuchung befasst sich daher mit den Möglichkeiten des molekularen Erregernachweises. Im zweiten Teil wurden 50 Isolate aus den vergangenen fünf Jahren mit molekularen Methoden auf ihre genetische Ähnlichkeit untersucht. Eine Abgrenzung durch traditionelle mikrobiologische Methoden ist sehr problematisch, da sie im Wesentlichen auf nur zwei Reaktionen beruht: die Glycin-Toleranz und die Na-Selenit-Reduktion, wobei neueste Untersuchungen unter standardisierten Bedingungen nur die Glycin-Toleranz als eindeutig charakterische Reaktion für beide Subspezies übrigließe. Aus diesem Grunde wurden PCR-Untersuchungen zur Identifizierung und Differenzierung beider C. fetus-Subspezies eingeführt. In einem ersten Schritt wurde Campylobacter fetus spezifisch nachgewiesen. Danach erfolgte die Differenzierung der Subspezie durch eine weitere PCR, in der nur bei Vorliegen der DNS von C. fetus subsp. venerealis ein Amplikon erhalten wurde. Insgesamt wurden 103 C. fetus-Isolate untersucht, einschließlich der Typenstämme von C. fetus subsp. fetus und C. fetus subsp. venerealis. Auf Grund der Ergebnisse des Gly-cintoleranztests konnten 81 C. fetus subsp. venerealis (Glycin intolerant) und 22 C. fetus subsp. fetus (Glycin tolerant) identifiziert werden. Die Ergebnisse des Glycintoleranztests und der PCR stimmten bei allen 103 C. fetus Isolaten überein. Versuche zum Direktnachweis von C. fetus subsp. venerealis aus Bullensperma durch Anwendung von fünf unterschiedlichen DNS-Extraktionsmethoden waren in ihren Ergebnissen hinsichtlich ihrer Sensitivität nicht zufrieden stellend (104 KbE/ml). Daraus ergibt sich zwingend, dass die Kultivierung des Erregers vor seiner phäno- und genotypischen Charakterisierung weiterhin unverzichtbar bleibt. Durch Untersuchungen mittels PFGE wurde gezeigt, dass die Campylobacter fetus subsp. venerealis-Population, die in Deutschland vorkommt, genetisch nicht einheitlich ist. Eine strenge Gruppierung nach geografischen Regionen war nicht möglich. Innerhalb größerer Gruppen genetisch ähnlicher Stämme fielen Isolate mit identischen Mustern auf, was auf gemeinsame Infektionsquellen hindeutet. Die ERIC-PCR sollte in der vorliegenden Arbeit als zweite Methode der Analyse des Gesamtgenoms zur weiteren Stützung der Ergebnisse der Makrorestriktionsanalyse beitragen. Die Analysen mittels ERIC-PCR machte ein hohes Maß an Heterogenität innerhalb der einzelnen Spezies sichtbar, lässt jedoch keine Assoziation zwischen Bandenprofilen und einer Zuordnung zum Krankheitsbild oder zur geographischen Herkunft zu.

Schweine im Bestand und auf dem Schlachthof, Schlachttierkörper und Lebern sowie Hackfleisch vom Schwein und Schweinefleisch aus dem Handel wurden auf das Vorkommen von thermophilen Campylobacter spp. untersucht. Zusätzlich wurden Putenkarkassen auf einem Putenschlachthof und Hähnchen- und Putenfleischerzeugnisse aus dem Handel mit in die Untersuchung einbezogen. Die in den Proben gefundenen Campylobacter-Isolate wurden zuerst phänotypisch charakterisiert, anschließend erfolgte eine genotypische Feindifferenzierung durch zwei molekularbiologische Fingerprintingmethoden (AFLP-Typisierung und FLA-Typing). Durch den Vergleich der Isolate untereinander und mit humanen Campylobacter-Isolaten sollten epidemiologische Zusammenhänge geklärt und die Bedeutung von Geflügel- und Schweinefleisch als Infektionsquelle für den Menschen aufgezeigt werden. / Faeces of pigs at the farm and the slaughterhouse, pig carcasses, livers, minced meat and porc from retail were investigated for the occurence of thermophilic Campylobacter spp. Turkey carcasses at a turkey slaughterhouse and chicken and turkey products from retail were also included in this investigation. First the Campylobacter isolates found in the samples were characterized phenotypically, afterwards they were typed with two molecularbiological fingerprinting methods (AFLP- and FLA-Typing). The comparison of the isolates with human isolates should give answers to epidemiological questions and the importance of poultry and porc as a source of infection for humans.

Avian pathogenic Escherichia. coli (APEC) and Campylobacter are pathogenic threats to poultry and human health, respectively. In this study, the prevalence of these pathogens in Mississippi broilers and their antimicrobial resistance (AMR) properties were investigated, and a multidrug-resistant APEC strain (APEC-O2-MS1170) was further explored by whole-genome sequencing (WGS). The efficacy of in ovo injection of Lactobacillus in reducing the APEC in broilers was evaluated. Results revealed a high prevalence of APEC and Campylobacter in broilers and broiler products. A lot of isolates were resistant to antibiotics of different sorts. Moreover, the in ovo administration of Lactobacillus did not reduce the incidence of APEC. The WGS of APEC-O2-MS1170 revealed its detailed AMR and virulence properties and alerted a potential zoonotic risk. In conclusion, the Lactobacillus did not reduce the incidence of APEC in broilers, and the prevalence and AMR of APEC and Campylobacter are still challenges faced by the poultry industry.