Disease Occurrence in- and the Transferal of Zoonotic Agents by North American Feedlot Cattle

Macrolide resistance in Mannheimia haemolytica isolates associated with bovine respiratory disease from the German national resistance monitoring program GERM-Vet 2009 to 2020

Data collected from the German national resistance monitoring program GERM-Vet showed slowly increasing prevalence of macrolide resistance among bovine respiratory disease (BRD)-associated Pasteurellacae from cattle over the last decade. The focus of this study was to analyze the genetic basis of antimicrobial resistance (AMR) and the prevalence of multidrug-resistance (MDR)-mediating integrative and conjugative elements (ICEs) in 13 German BRD-associated Mannheimia haemolytica isolates collected between 2009 and 2020 via whole-genome sequencing. Antimicrobial susceptibility testing (AST) was performed via broth microdilution according to the recommendations of the Clinical and Laboratory Standards Institute for the macrolides erythromycin, tilmicosin, tulathromycin, gamithromycin, tildipirosin, and tylosin as well as 25 other antimicrobial agents. All isolates either had elevated MICs or were resistant to at least one of the macrolides tested. Analysis of whole-genome sequences obtained by hybrid assembly of Illumina MiSeq and Oxford Nanopore MinION reads revealed the presence of seven novel Tn7406-like ICEs, designated Tn7694, and Tn7724- Tn7729. These ICEs harbored the antimicrobial resistance genes erm(T), mef (C), mph(G), floR, catA3, aad(3")(9), aph(3')-Ia, aac(3)-IIa, strA, strB, tet(Y), and sul2 in different combinations. In addition, mutational changes conferring resistance to macrolides, nalidixic acid or streptomycin, respectively, were detected among the M. haemolytica isolates. In addition, four isolates carried a 4,613-bp plasmid with the β-lactamase gene blaROB - 1. The detection of the macrolide resistance genes erm(T), mef (C), and mph(G) together with other resistance genes on MDR-mediating ICEs in bovine M. haemolytica may explain the occurrence of therapeutic failure when treating BRD with regularly used antimicrobial agents, such as phenicols, penicillins, tetracyclines, or macrolides. Finally, pathogen identification and subsequent AST is essential to ensure the efficacy of the antimicrobial agents applied to control BRD in cattle.

Frequency and Molecular Identification of Cryptosporidium in Adult Prim'Holstein Dairy Cattle Farms in the North of France

Cryptosporidium apicomplexan protozoa are ubiquitous intracellular agents affecting humans and animals. In particular, bovine cryptosporidiosis is recognized as endemic worldwide. However, epidemiological investigations remain limited in France regarding the burden of these parasites in cattle. To improve our understanding of the epidemiology of cryptosporidiosis, the main aim of this study was to determine the frequency and the genetic diversity of Cryptosporidium in adult Prim'Holstein dairy cattle farms in the north of France. Fecal specimens were collected from 1454 non-diarrheic and non-pregnant animals (nulli-, primi-, or multiparous) throughout 20 farms in an area of 110 km around Lille. For Cryptosporidium species identification, nested PCR followed by sequence and phylogenetic analyses were used. The overall frequency of Cryptosporidium spp. in-fection was 30.00% (C.I. 95%: 12.83-54.33) in farms and 0.89% (C.I. 95%: 0.498-1.57) at the individual level. In primi- or multiparous cows, only C. andersoni was found. C. ryanae, C. bovis/xiaoi and C. andersoni were detected in heifers. The phylogenetic tree confirmed that analyzed sequences were grouped with known reference sequences reported in dairy cattle. Further studies on the cumulative prevalence, risks factors and pathogenicity are needed to give a more accurate assessment of the impact of Cryptosporidium infection in dairy cattle in France.

Effect of Antimicrobial Use in Conventional Versus Natural Cattle Feedlots on the Microbiome and Resistome

Antimicrobial use (AMU) in the livestock industry has been associated with increased levels of antimicrobial resistance. Recently, there has been an increase in the number of "natural" feedlots in the beef cattle sector that raise cattle without antibiotics. Shotgun metagenomics was employed to characterize the impact of AMU in feedlot cattle on the microbiome, resistome, and mobilome. Sequenced fecal samples identified a decline (q < 0.01) in the genera Methanobrevibacter and Treponema in the microbiome of naturally vs. conventionally raised feedlot cattle, but this difference was not (q > 0.05) observed in catch basin samples. No differences (q > 0.05) were found in the class-level resistome between feedlot practices. In fecal samples, decreases from conventional to natural (q < 0.05) were noted in reads for the antimicrobial-resistant genes (ARGs) mefA, tet40, tetO, tetQ, and tetW. Plasmid-associated ARGs were more common in feces from conventional than natural feedlot cattle. Interestingly, more chromosomal- than plasmid-associated macrolide resistance genes were observed in both natural and conventional feedlots, suggesting that they were more stably conserved than the predominately plasmid-associated tetracycline resistance genes. This study suggests that generationally selected resistomes through decades of AMU persist even after AMU ceases in natural production systems.

The leptospiral OmpA-like protein (Loa22) is a surface-exposed antigen that elicits bactericidal antibody against heterologous Leptospira

Leptospirosis is the most widespread zoonosis, affecting over 1 million humans each year, with more than 60,000 deaths worldwide. Leptospirosis poses a significant health threat to dogs, horses, cattle, and wildlife. The disease may be self-limiting or progress to a life-threatening multi-system disorder affecting the kidneys, liver, and lungs. Currently, bacterin vaccine formulations that consist of one or more laboratory-cultivated strains are used for prevention. However, the antibody response elicited by these vaccines is directed primarily at lipopolysaccharide and is generally serovar-specific. The development of broadly protective subunit vaccines for veterinary and human applications would be a significant step forward in efforts to combat this emerging and antigenically variable pathogen. This study assessed the properties and potential utility of the Leptospira Loa22 (Leptospira OmpA-like 22 kDa protein) protein as a vaccine antigen. Loa22 is a virulence factor that is predicted to transverse the outer membrane and present its N-terminal domain on the cell surface. This report demonstrates that diverse Leptospira strains express Loa22 in vitro and that the protein is antigenic during infection in dogs. Immunoblot and size exclusion chromatography revealed that Loa22 exists in monomeric and trimeric forms. Immunization of rats with recombinant Loa22 elicited bactericidal antibodies against diverse Leptospira strains. The immunodominant bactericidal epitopes were localized within the N-terminal domain using protein-blocking bactericidal assays. This study supports the utility of Loa22, or subfragments thereof, in developing a multivalent chimeric subunit vaccine to prevent leptospirosis and sheds new light on the cellular localization of Loa22.

Brucella-infected abdominal aortic aneurysm: management strategies for an uncommon aneurysm

Objective

The occurrence of Brucella-induced abdominal aortic aneurysms is an exceedingly rare phenomenon, yet it stands as one of the most severe complications within this context. The combined utilization of serological testing and imaging diagnostics has been validated as an effective approach for the identification of Brucella-induced abdominal aortic aneurysms. Presently, the predominant therapeutic strategies encompass antibiotic treatment and surgical intervention. Nonetheless, ongoing controversies persist concerning the establishment of diagnostic criteria, the optimal timing and selection of antibiotic regimens, and the nuanced decision between open surgical procedures and endovascular interventions. Through a meticulous analysis of cases originating from our institution as well as a comprehensive review of previously documented instances, we aim to engage in a detailed discourse on the salient diagnostic and therapeutic facets surrounding Brucella-induced abdominal aortic aneurysms.

Methods

We conducted a retrospective summary of three cases involving Brucella-induced abdominal aortic aneurysms treated within our institution. Furthermore, we performed a comprehensive PubMed search, without imposing restrictions on language or publication year, to identify pertinent literature pertaining to Brucella-induced abdominal aortic aneurysms. The selection criteria primarily focused on case reports delineating occurrences of abdominal aortic aneurysms attributed to Brucella infection.

Results

We present three distinct cases of Brucella-induced abdominal aortic aneurysms managed at our institution, providing comprehensive insights into the employed diagnostic and therapeutic approaches. Additionally, over the past five decades, a total of 24 cases in 23 publications of Brucella-induced abdominal aortic aneurysms have been reported on PubMed. The earliest report dates back to 1976.

Conclusion

Our analysis suggests that Brucella-induced abdominal aortic aneurysm is characterized by a remarkably low incidence but is associated with a substantial risk of life-threatening complications. The integration of serological and imaging assessments assumes pivotal importance in facilitating prompt diagnosis of this condition. The prompt initiation of targeted antibiotic therapy is recommended, and the selection of appropriate surgical strategies should be guided by considerations including aneurysm dimensions and morphological attributes. The timely identification and intervention carry utmost significance in retarding disease advancement and ameliorating unfavorable clinical outcomes.