Antimicrobial resistance (AMR) is a serious global health threat and extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales are a major contributor. This study aimed to gain a deeper insight into the AMR burden of wild animals. In total, 1595 fecal samples were collected by two systematic searches in Mecklenburg-Western Pomerania, north-east Germany. Samples were screened for ESBL-carrying Escherichia (E.) coli and isolates found were further analyzed using antimicrobial susceptibility testing and whole-genome sequencing. We found an estimated prevalence of 1.2% ESBL-producing E. coli in wild boar and 1.1% in wild ruminants. CTX-M-1 was the most abundant CTX-M type. We also examined fecal samples from wild boar and wild ruminants using shotgun metagenomics to gain insight into the resistome in wild animals. The latter revealed significantly lower normalized counts for AMR genes in wildlife samples compared to farm animals. The AMR gene levels were lower in wild ruminants than in wild boar. In conclusion, our study revealed a low prevalence of ESBL-producing E. coli and a low overall AMR gene burden in wild boar and wild ruminants, probably due to the secluded location of the search area.

The objectives of this study were to ascertain the fecal ESBL/AmpC-E. coli prevalence and to detect risk factors for their occurrence in young pre-weaned calves and their dams on large dairy farms in Germany. From 2018–2019 we investigated 2816 individual fecal samples from pre-weaned dairy calves and their dams, representing seventy-two farms (mean = 667 milking cows) from eight German federal states. To assess possible risk factors associated with ESBL/AmpC-E. coli prevalence in calves and dams, a questionnaire was performed, collecting management data. We observed an ESBL/AmpC-E. coli prevalence of 63.5% (95% CI: 57.4–69.5) among the sampled calves and 18.0% (95% CI: 12.5–23.5) among the dams. On all farms, at least one positive sample was obtained. To date, this is the highest ESBL/AmpC-E. coli prevalence observed in dairy herds in Europe. Feeding with waste milk was identified as a significant risk factor for a high prevalence of ESBL/AmpC-E. coli in calves. Many calves at large dairies in Germany are fed with waste milk due to the large amounts generated as a result of antibiotic dry-off routines and mastitis treatment with antibiotics. Other notable risk factors for high ESBL/AmpC-E. coli in calves were the general fitness/health of dams and calves, and the quality of farm hygiene. Taken together, these findings suggest that new or improved approaches to animal health management, for example, antibiotic dry cow management (selective dry cow therapy) and mastitis treatment (high self-recovery), as well as farm hygiene, should be researched and implemented.

Antimicrobial resistance (AMR) is a serious global health threat with extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales as the most critical ones. Studies on AMR in wild birds imply a possible dissemination function and indicate their potential role as sentinel animals. This study aimed to gain a deeper insight into the AMR burden of wild waterfowl by sampling semi-wild mallard ducks used as sentinels and to identify if AMR bacteria could be recommended to be added to the pathogens of public health risks to be screened for. In total, 376 cloacal and pooled fecal samples were collected from the sentinel plant over a period of two years. Samples were screened for ESBL-carrying E. coli and isolates found further analyzed using antimicrobial susceptibility testing and whole-genome sequencing. Over the sampling period, 4.26% (16/376) of the samples were positive for ESBL-producing E. coli. Bla_CTX-M-1 and bla_CTX-M-32 were the most abundant CTX-M types. Although none of the top global sequence types (ST) could be detected, poultry-derived ST115 and non-poultry-related STs were found and could be followed over time. The current study revealed low cases of ESBL-producing E. coli in semi-wild mallard ducks, which proves the suitability of sentinel surveillance for AMR detection in water-associated wildlife.

Background: The high susceptibility of AD patients to microbial skin infections has been attributed to a deficient antimicrobial peptide (AMP) expression, which is contradicted by a growing amount of recent studies clearly demonstrating that AMP expression is not impaired in lesional skin of AD patients. The reasons for the high susceptibility of AD patients to microbial infections are still unknown.Methods: The influence of self‐DNA on the antimicrobial activity of RNase 7, LL‐37, and hBD2 has been investigated using antibacterial and antiviral assays. The amount of self‐DNA on skin has been analyzed by skin rinsings and subsequent quantification using dsDNA assays. DNA source was identified by qPCR.Results: Complex formation of the AMPs with self‐DNA significantly impaired their antibacterial activity againstStaphylococcus aureusand their antiviral activity againstHSV‐1. The inhibition of the antibacterial activity was dependent on the DNA concentration but not on the length of the DNA molecules. Of note, we detected significant higher amounts of cell‐free self‐DNA in skin rinses taken from lesional AD skin compared to skin rinses from non‐lesional skin and from normal skin of healthy donors. Consequently, rinse solution from AD lesional skin prevented antibacterial activity of LL‐37.Conclusion: Our study indicates that extracellular self‐DNA is released in considerable amounts in AD skin lesions and AMP‐self‐DNA‐complex formation leads to a significant loss of antibacterial and antiviral activity in atopic dermatitis. Studies on strategies to reduce the amount of extracellular DNA in AD are needed to identify possible methods relevant in clinical settings.

Epidermal keratinocytes are a major source of antimicrobial peptides and proteins. RNase 7 (R7) exhibits antimicrobial and immunomodulatory activities and is upregulated in the lesional skin of atopic dermatitis and psoriasis patients. Here, we performed mRNA microarray analysis to study the influence of R7 on gene expression in human keratinocytes. R7 induced several genes encoding proteins potentially involved in skin integrity and inflammation, including IL-24. Since IL-24 is involved in the pathogenesis of inflammatory skin diseases and since it is induced by IL-6, we further characterized the effect of R7 on IL-6 and IL-24 expression and secretion. R7 increased the release of the cytokines IL-6 and IL-24 by keratinocytes. Using a function-blocking antibody against IL-6 we showed that the R7-induced IL-24 secretion was triggered by IL-6. IL-6 released from R7-stimulated keratinocytes induced STAT3 signaling in target keratinocytes, suggesting a potential pathway resulting in IL-24 induction. Pre-stimulation with IL-17 or IFN-γ, cytokines involved in the pathogenesis of psoriasis, further enhanced R7-induced IL-6 secretion. R7 increased IL-6 secretion mainly from undifferentiated keratinocytes, suggesting that in the epidermis, R7 released from the stratum granulosum may induce expression and secretion of cytokines from basal undifferentiated keratinocytes. In conclusion, our data show that R7 enhances the release of IL-6 in undifferentiated primary keratinocytes, which may have consequences for skin inflammation, defense against pathogens, and wound healing.