Claudia Hess

ObjectivesThe objective of this study was to evaluate the antimicrobial resistance profiles and toxinotypes of Clostridium perfringens strains isolated from various poultry species in Austria and to determine the prevalence of strains associated with necrotic enteritis or other infections.MethodsOut of 117 archived strains of C. perfringens, 82 were isolated from layer chickens, 14 from turkeys, and the remaining strains were obtained from various types of poultry, including chicken breeders, geese, quails, and ostriches. The strains were isolated from different poultry showing various clinical signs. Isolates underwent antimicrobial susceptibility testing, and following the DNA extraction, multiplex PCR was performed for toxinotyping.ResultsThe findings from the antimicrobial susceptibility tests demonstrated that 86% of the samples were susceptible to amoxicillin, 85% to ampicillin, 97% to doxycycline, 96% to enrofloxacin, and 80% to tylosin. Importantly, all samples showed resistance to sulfamethoxazole-trimethoprim. Among the 117 strains analysed, ninety-five (76.6%) were classified as type D, seventeen (14.6%) as type B, five (4%) as type A, and three (2.4%) as type C. The results of this research indicate that the most common strain of C. perfringens among Austrian poultry species is type D.ConclusionsThe findings imply that type D can lead to infections in poultry, thereby affecting their health, even if it is typically not linked to necrotic enteritis. Given its high prevalence in poultry and its occurrence in humans, it is recommended that strains of C. perfringens type D be regularly monitored.

Broiler birds as compared to layers are more susceptible to avian colibacillosis.An aerosol challenge using an ilux2-APEC effectively evaluates disease pathogenesis.The ilux2-APEC persistently colonized the bursa of Fabricius after aerosol exposure.

Avian pathogenic Escherichia coli (APEC) infections in poultry adversely affect health and production, with public health implications. This study assessed the potential of bioluminescence imaging for real-time, noninvasive tracking of microbial progression in 12-day-old chicken embryos inoculated with an APEC strain or its derivatives integrated either with luxABCDE or ilux2 operon. Eggs were imaged daily for bioluminescence detection, with dead embryos sampled immediately and survivors killed at 5 days post inoculation (dpi). The eggs were opened, and egg contents were imaged for bioluminescence. Yolks were sampled for E. coli isolation and quantification. Results showed lethality rates of 100%, 93.3% and 80% in embryos inoculated with native strain, luxABCDE or ilux2, respectively. Bioluminescence analysis showed increased bioluminescence signal strength over time preceding embryo death. Surviving embryos exhibited a sequential reduction in signal strength. A strong positive correlation was found between bioluminescence signal intensity in ovo and ex ovo, with ilux2-APEC infected eggs showing a higher luminoscore than luxABCDE-APEC. The E. coli load in yolks of APEC-inoculated eggs showed a positive trend over time. Overall, bioluminescence imaging of ilux2 operon labelled bacteria enabled more efficient real-time detection and monitoring of E. coli in ovo. Multiple imaging sessions on the same embryo throughout the experiment allow precise monitoring of infection progression without sequential culling. This offers a controlled platform for evaluating antimicrobial treatments' efficacy in an in ovo model that closely resembles in vivo environment in chickens. It also bears the potential to study other pathogens' infection patterns, especially those pose risks to public health.

Staphylococcus species are widespread in poultry environments and can cause various infections, often when the host’s defences are compromised. This manuscript reports on a co-infection of chickens with Staphylococcus lentus and Staphylococcus aureus associated with an outbreak of arthritis, synovitis, and osteomyelitis in an organic broiler breeder flock in Austria. Clinically, the affected flock showed weakness, lethargy, lameness, and increased mortality. Post-mortem examinations identified purulent arthritis and femoral head necrosis. Bacteriological analysis using MALDI-TOF MS identified both S. aureus and S. lentus in the affected joints. Antibiotic resistance testing revealed significant resistance, particularly in S. lentus. Histological analysis showed severe inflammation and bacterial colonies in the joints. While S. aureus is a common pathogen in poultry, S. lentus is less frequently reported. This study emphasises the need for detailed bacterial characterisation in outbreaks to better understand the role of less common pathogens like S. lentus. Further research is necessary to elucidate the impact of S. lentus on poultry health and its role in causing arthritis and synovitis, highlighting the importance of comprehensive investigation in such outbreaks.

Anti-microbial peptides provide a powerful toolkit for combating multidrug resistance. Combating eukaryotic pathogens is complicated because the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria (EPB), symbionts of entomopathogenic–nematode species, release a series of non-ribosomal templated anti-microbial peptides. Some may be potential drug candidates. The ability of an entomopathogenic–nematode/entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product. This explains that those gene complexes that are responsible for the biosynthesis of different non-ribosomal templated anti-microbial protective peptides (including those that are potently capable of inactivating the protist mammalian pathogen Leishmania donovanii and the gallinaceous bird pathogen Histomonas meleagridis) are co-regulated. Our approach is based on comparative anti-microbial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated anti-microbial peptides that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourage us to forecast that the recently discovered “easy-PACId” research strategy is suitable for constructing entomopathogenic-bacterium (EPB) strains producing and releasing single, harmless, non-ribosomal templated anti-microbial peptides with considerable drug, (probiotic)-candidate potential.

Antimicrobial peptides provide a powerful toolkit for combating multidrug resistance. Combatting eukaryotic pathogens is complicated by the fact, the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria, (symbionts of entomopathogenic nematode species), release a series of non-ribosomal templated antimicrobial peptides, some may be potential drug candidates. The ability of an entomopathogenic nematode /entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product, explaining that those gene complexes which are responsible for the biosynthesis of different non-ribosomal templated antimicrobial protective peptides (including those which are potently capable to inactivate the protist mammalian -pathogen Leishmania and the gallinaceous bird pathogen Histomonas) are co-regulated. Our approach is based on comparative antimicrobial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated antimicrobial peptides, that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourages us to forecast that the recently discovered “easy-PACId” research strategy is suitable for constructing EPB strains producing and releasing single, harmless, non-ribosomal templated antimicrobial peptides with considerable drug, (probiotic) -candidate potential.

Salmonellosis caused by non-typhoidal Salmonella serovars is the second most frequently reported zoonotic disease in humans in the EU. The transmission of these agents is mainly via contaminated food of animal origin.

Controlling infectious diseases is vital for poultry health and diagnostic methods are an indispensable feature to resolve disease etiologies and the impact of infectious agents on the host. Although the basic principles of disease diagnostics have not changed, the spectrum of poultry diseases constantly expanded, with the identification of new pathogens and improved knowledge on epidemiology and disease pathogenesis. In parallel, new technologies have been devised to identify and characterize infectious agents, but classical methods remain crucial, especially the isolation of pathogens and their further characterization in functional assays and studies. This review aims to highlight certain aspects of diagnosing infectious poultry pathogens, from the farm via the diagnostic laboratory and back, in order to close the circle. By this, the current knowledge will be summarized and future developments will be discussed in the context of applied state-of-the-art techniques. Overall, a common challenge is the increasing demand for infrastructure, skills and expertise. Divided into separate chapters, reflecting different disciplines, daily work implies the need to closely link technologies and human expertise in order to improve bird health, the production economy and to implement future intervention strategies for disease prevention.