Thermophilic Campylobacter in turkeys in Germany : Epidemiology, genotyping and antimicrobial sensitivity studies

Poultry remains an important vehicle for pathogens, leading to human food borne disease all over the world. Campylobacter infection in commercial broilers and turkeys represents a challenge for all persons involved in poultry food production chain. Studying the colonization and genetic diversity along with the antimicrobial resistance of Campylobacter jejuni in commercial poultry rearing is a matter of concern. The findings of this thesis clearly indicate that age and -possible- sex have an influence on the onset of colonization and prevalence of thermophilic Campylobacter in fattening turkey farms. Drinking water can be considered as primary source for flock infection. Additionally, multiplex PCR used for detection of thermophilic Campylobacter DNA which was directly extracted from faecal and environmental samples was developed and evaluated (Chapter 2). The assessment of the genetic diversity of a Campylobacter population is critical for the understanding of the epidemiology of this bacterium and consequently this information has to be used to reduce disease burden. Hence, a part of this study was conducted to investigate the dynamic of flock colonization and genetic diversity in Campylobacter isolates using different genotyping tools. The performance of established flaA genotyping, multilocus sequencing typing (MLST) and DNA microarray typing assay based on the ArrayTube™ technology was evaluated using C. jejuni isolates that proved to be genetically stable in their flaA genes. It was shown that different typing methods are useful to determine the genetic heterogeneity of C. jejuni isolated from turkey during the rearing process. The degree of relatedness was varying depending upon the typing method used. DNA microarray technique based on whole genome information had the highest discriminatory power compared to the other molecular typing methods assessed here. The ATTM microarray system is also relatively cheap, when hands-on-time, necessary equipment, and costs of material are considered. This investigation demonstrated changing of C. jejuni in turkeys and the coexistence of different genotypes during turkey rearing for the first time (Chapter 3). A recent concern is the emergence of antibiotic resistance in C. jejuni isolated from turkeys in particular of those antibiotics used to treat human illness. Monitoring the progress of this resistance becomes a growing public health issue. The third part of this study was conducted to provide information about the resistance of C. jejuni isolated from turkeys by investigating the genes for ciprofloxacin, tetracycline and erythromycin resistance. All isolates were fully susceptible to chloramphenicol and gentamicin. The isolates were highly resistant to sulphonamides, metronidazole, ciprofloxacin, naladixic acid, and tetracycline. The isolates were sensitive to streptomycin, erythromycin, neomycin, and amoxicillin. Multidrug resistance was detected. Replacement of the Thr-86→Ile of the gyrA gene, and a tet(O) gene were the main resistance mechanisms for fluoroquinolones and tetracycline resistance, respectively, while no point mutation in the 23S rRNA gene was found that could be responsible for macrolide resistance. The present study provides sufficient data suggesting that the PCR-RFLP and MAMA-PCR are simple and rapid methods for the detection of ciprofloxacin resistance in C. jejuni. These methods seem to be suitable to serve as possible alternative methods for routine detection of mutations without the need for sequencing. To our knowledge, this is the first study providing sufficient data on the current status of the antimicrobial susceptibility to C. jejuni isolated from turkey farms in different regions in Germany (Chapter 4). During the trail to isolate Campylobacter from caecal content of female turkey at 16th week of age Two Gram negative, micro-aerophilic, non-motile and non-spore-forming coccoid bacteria were isolated. The biochemical reaction profiles (API 20 E and API 20 NE) typed both strains as Ochrobactrum anthropi. On the basis of 16S rRNA gene and recA gene sequence similarities the strains were identified as Ochrobactrum anthropi and Ochrobactrum pecoris, respectively. Both strains were highly resistant against beta-lactam antibiotics, chloramphenicol and sulphonamides but variable in susceptibility to ciprofloxacin, gentamicin and tetracycline. This is the first time that Ochrobactrum species were isolated from an avian host (Chapter 5).