Injuries and bone fractures are the most frequent causes of admission at wildlife rescue centers. Wild birds are more susceptible to open fractures due to their anatomical structure, which can lead to osteomyelitis and necrosis. Antibiotic therapy in these cases is indispensable, but the increase of antimicrobial-resistant isolates in wildlife has become a significant concern in recent years. In this context, the likelihood of antibiotic failure and death of animals with infectious issues is high. This study aimed to isolate, identify, and assess the antimicrobial resistance pattern of bacteria in wounds and open fractures in wild birds. To this end, injured birds admitted to a wildlife rescue center were sampled, and bacterial isolation and identification were performed. Then, antimicrobial susceptibility testing was assessed according to the disk diffusion method. In total, 36 isolates were obtained from 26 different birds. The genera detected were Staphylococcus spp. (63.8%), Escherichia (13.9%), Bacillus (11.1%), Streptococcus (8.3%), and Micrococcus (2.8%). Among Staphylococcus isolates, S. lentus and S. aureus were the most frequent species. Antimicrobial resistance was detected in 82.6% of the isolates, among which clindamycin resistance stood out, and 31.6% of resistant isolates were considered multidrug-resistant. Results from this study highlight the escalating scope of antimicrobial resistance in wildlife. This level of resistance poses a dual concern for wildlife: firstly, the risk of therapeutic failure in species of significant environmental value, and, secondly, the circulation of resistant bacteria in ecosystems.

The Campylobacter prevalence in free-ranging broiler flocks is usually higher than in conventional flocks, and effective interventions for this production type are needed. This study aimed to investigate the on-farm Campylobacter-reducing effect of feeding three feed additives or a water additive to broilers from hatching to slaughter. Newly hatched Ranger Gold broilers (n = 140) were randomly placed into five cages (n = 28/cage) within a flock of 6,000 broilers. The broilers had access to outdoor areas after day 36. Three groups received one of the following feed additives: 2 % (w/w) Biochar Charcoal Feed Granules for Poultry, 0.125 % Original XPC™ (Saccharomyces cerevisiae fermentate), or 15 % oat hulls. One group received organic acids added to water (Selko®pH E 0.2 % (v/v)), and one group was fed standard feed pellets and water (control). Half of the broilers were sacrificed on day 36 and the rest on day 56 for enumeration and isolation of Campylobacter in cecal contents by culturing. Air samples were collected weekly, and water and boot sock samples were also collected on days 4, 36, and 59 and analyzed for Campylobacter. A selection of the obtained Campylobacter isolates (n = 43) was whole-genome-sequenced. For the three successive flocks tested, all broilers became Campylobacter-positive before access to the outdoors on day 36. Adding biochar in the feed resulted in 0.70 log₁₀ CFU/g lower C. jejuni than the control group on day 59. The addition of organic acids in water resulted in 0.62 log₁₀ CFU/g lower C. jejuni than the control group on day 36. There was a noticeable difference in dominant sequence types (ST) between day 36 (ST52 and ST475) and day 59 (ST45). STs were genetically similar across rotations, indicating transmission of isolates between successive flocks or from the outdoor environment. High variability was seen between calls for further testing to confirm the demonstrated effect.

Escherichia coli carrying IncK-bla_CMY-2 plasmids mediating resistance to extended-spectrum cephalosporins (ESC) has been frequently described in food-producing animals and in humans. This study aimed to characterize IncK-bla_CMY-2-positive ESC-resistant E. coli isolates from poultry production systems in Denmark, Finland, and Germany, as well as from Danish human blood infections, and further compare their plasmids. Whole-genome sequencing (Illumina) of all isolates (n = 46) confirmed the presence of the bla_CMY-2 gene. Minimum inhibitory concentration (MIC) testing revealed a resistant phenotype to cefotaxime as well as resistance to ≥3 antibiotic classes. Conjugative transfer of the bla_CMY-2 gene confirmed the resistance being on mobile plasmids. Pangenome analysis showed only one-third of the genes being in the core with the remainder being in the large accessory gene pool. Single nucleotide polymorphism (SNP) analysis on sequence type (ST) 429 and 1286 isolates showed between 0–60 and 13–90 SNP differences, respectively, indicating vertical transmission of closely related clones in the poultry production, including among Danish, Finnish, and German ST429 isolates. A comparison of 22 ST429 isolates from this study with 80 ST429 isolates in Enterobase revealed the widespread geographical occurrence of related isolates associated with poultry production. Long-read sequencing of a representative subset of isolates (n = 28) allowed further characterization and comparison of the IncK-bla_CMY-2 plasmids with publicly available plasmid sequences. This analysis revealed the presence of highly similar plasmids in ESC-resistant E. coli from Denmark, Finland, and Germany pointing to the existence of common sources. Moreover, the analysis presented evidence of global plasmid transmission and evolution. Lastly, our results indicate that IncK-bla_CMY-2 plasmids and their carriers had been circulating in the Danish production chain with an associated risk of spreading to humans, as exemplified by the similarity of the clinical ST429 isolate to poultry isolates. Its persistence may be driven by co-selection since most IncK-bla_CMY-2 plasmids harbor resistance factors to drugs used in veterinary medicine.

Campylobacter, a leading cause of foodborne illnesses in the EU, presents significant challenges in free-range broilers due to their limited biosecurity and increased environmental exposure. IceGun® is a device designed to spray slurry ice on poultry carcasses to enhance chilling, and its effectiveness in reducing Campylobacter was evaluated in a Danish slaughterhouse specialising in free-range broilers. In each of four trials, forty carcasses from a Campylobacter-positive flock were randomly selected, and half were subjected to air chilling and slurry ice treatment, while the other half received only air chilling. Neck and leg skin samples were collected after chilling and analysed for Campylobacter. Selected Campylobacter isolates (n = 90) were whole-genome sequenced to assess genetic diversity. Additionally, the carcasses were packaged in modified atmosphere packaging (MAP), refrigerated over the shelf life period, and analysed for microbiological, chemical, and sensory parameters. Of the four flocks tested, slurry ice application significantly reduced Campylobacter concentrations on neck skin by 0.44 log₁₀ CFU/g, while effects on leg skin were less pronounced. Slurry ice treatment accelerated chilling without affecting product quality during the shelf life period under MAP and refrigeration. Genomic analyses revealed substantial genetic diversity among the isolates, with nine predominant sequence types (STs), including ST-52, associated with human infections. Some STs were present beyond the defined shelf life, suggesting resilience under refrigeration and MAP. Antibiotic resistance profiling showed a low prevalence of resistance genes among the isolates. The study highlights the dual benefits of slurry ice technology in improving food safety without compromising product quality in free-range broiler processing.