Unveiling antimicrobial resistance in Chilean fertilized soils: a One Health perspective on environmental AMR surveillance.

Antimicrobial resistance (AMR) poses a significant threat to humans and animals as well as the environment. Within agricultural settings, the utilization of antimicrobial agents in animal husbandry can lead to the emergence of antimicrobial resistance. In Chile, the widespread use of animal-derived organic amendments, including manure and compost, requires an examination of the potential emergence of AMR resulting from their application. The aim of this research was to identify and compare AMR genes found in fertilized soils and manure in Los Andes city, Chile. Soil samples were collected from an agricultural field, comprising unamended soils, amended soils, and manure used for crop fertilization. The selected genes (n = 28) included genes associated with resistance to beta-lactams, tetracyclines, sulfonamides, polymyxins, macrolides, quinolones, aminoglycosides, as well as mobile genetic elements and multidrug resistance genes. Twenty genes were successfully identified in the samples. Tetracycline resistance genes displayed the highest prevalence, followed by MGE and sulfonamides, while quinolone resistance genes were comparatively less abundant. Notably, blaOXA, sulA, tetO, tetW, tetM, aac (6) ib., and intI1, exhibited higher frequencies in unamended soils, indicating their potential persistence within the soil microbiome and contribution to the perpetuation of AMR over time. Given the complex nature of AMR, it is crucial to adopt an integrated surveillance framework that embraces the One Health approach, involving multiple sectors, to effectively address this challenge. This study represents the first investigation of antimicrobial resistance genes in agricultural soils in Chile, shedding light on the presence and dynamics of AMR in this context.

One Welfare: Assessing the Effects of Drought and the COVID-19 Pandemic on Farmers' Well-Being and Their Perception of Goats' Welfare.

Considering the interconnections between human well-being, animal welfare, and the environment, this study aimed to investigate the impacts of drought and the COVID-19 pandemic on small-scale goat farmers' well-being and their perception of goats' welfare following the One Welfare framework. Using a telephone survey, close-ended questions, and Likert scales, we assessed the impacts of drought and the COVID-19 pandemic on human well-being and animal welfare in the Coquimbo region of Chile. The DASS-21 questionnaire was used to evaluate farmers' mental health. Goat farmers perceived the scarcity of water and food for animals as factors that negatively affected animal productivity and welfare and caused an increase in farmers' stress levels. Farmers who had not been visited by a veterinarian showed higher levels of stress than those who received one visit during the year (M = 10 vs. 2, p = 0.025). Additionally, farmers who perceived better welfare of their animals showed lower levels of depression (rs = -0.17, p = 0.048), anxiety (rs = -0.21, p = 0.016), and stress (rs = -0.33, p < 0.001). These findings emphasize the importance of addressing farmers' mental health and veterinary support as crucial aspects to ensure both goat welfare and farm productivity.

Identification of Coxiella burnetii in Tank Raw Cow Milk: First Findings from Chile.

Coxiella burnetii causes Q fever, an important zoonotic disease, and exposure is mainly associated with inhalation of contaminated aerosols. In South America, no systematic studies have been carried out. In Chile, the only official record of Q fever has been an outbreak of occupational context occurring in 1998 with eight confirmed human cases, all workers in the Agriculture and Livestock Service. Recently, in 2017 a Q fever outbreak was reported from dairy farm workers in two regions in southern Chile. This study determined the presence of C. burnetii in bulk tank milk samples from dairy farms obtained during this outbreak. A duplex real time quantitative PCR assay with primers and probes targeting two different gene sequences, IS1111 and com1, was used for diagnosis. C. burnetii was detected in 2 of 105 samples analyzed (2.1%). These results pose a potential public health risk as the milk from these farms was sold to the local human population. This is the first report on detecting C. burnetii in raw tank milk samples in Chile.

Optimization of florfenicol dose against Piscirickettsia salmonis in Salmo salar through PK/PD studies.

Salmonid Rickettsial Septicemia (SRS) is the disease of greatest economic importance in the Chilean salmon farming industry, causing high mortality in fish during the final stage of their productive cycle at sea. Since current, commercially available vaccines have not demonstrated the expected efficacy levels, antimicrobials, most commonly florfenicol, are still the main resource for the treatment and control of this pathogen. The aim of this study was to determine the most appropriate single dose of florfenicol, administered through medicated feed, for the treatment of Piscirickettsia salmonis (P. salmonis), using pharmacokinetic/pharmacodynamic (PK/PD) models. Previously, Minimum Inhibitory Concentrations (MICs) of florfenicol were determined for 87 P. salmonis isolates in order to define the epidemiological cut-off point (COWT). The most commonly observed MIC was 0.125 µg mL-1 (83.7%). The COWT value was 0.25 µg mL-1 with a standard deviation of 0.47 log2 µg mL-1 and 0.36 log2 µg mL-1, for Normalized resistance interpretation (NRI) method and ECOFFinder method, respectively. A MIC of 1 µg mL-1 was considered the pharmacodynamic value (PD) to define PK/PD indices. Three doses of florfenicol were evaluated in fish farmed under controlled conditions. For each dose, 150 fish were used and blood plasma samples were collected at different time points (0-48 hours). PK parameters were obtained from curves representing plasma concentrations as a function of time. The results of Monte Carlo simulation indicate that at a dose of 20 mg/Kg l.w. of florfenicol, administered orally as medicated feed, there is 100% probability (PTA) of achieving the desired efficacy (AUC0-24h/MIC>125). According to these results, we suggest that at the indicated dose, the PK/PD cut-off point for florfenicol versus P. salmonis could be 2 µg mL-1 (PTA = 99%). In order to assess the indicated dose in Atlantic salmon, fish were inoculated with P. salmonis LF-89 strain and then treated with the optimized dose of florfenicol, 20 mg/Kg bw for 15 days.

Corynebacterium pseudotuberculosis Infection in Patagonian Huemul ( Hippocamelus bisulcus ).

Corynebacterium pseudotuberculosis is an intracellular bacteria and the etiologic agent of caseous lymphadenitis in domestic and wildlife species. We report C. pseudotuberculosis infection in Patagonian huemul ( Hippocamelus bisulcus ) from the Cerro Castillo National Reserve, Region of Aysen, Chile. Subcutaneous abscesses in the abdominal and pectoral regions from two animals were sampled and bacteriologic isolation was performed. In both cases, we isolated a C. pseudotuberculosis strain belonging to the ovine genotype. In addition, one isolate was resistant to ciprofloxacin and streptomycin. We report that H. bisulcus is a susceptible species to this bacterium, which is transmitted by direct or indirect contact with domestic sheep ( Ovis aries ) and which represents a potential conservation threat to populations of H. bisulcus . Additional research and prevention efforts should be addressed.

Genetic and phenotypic evidence of the Salmonella enterica serotype Enteritidis human-animal interface in Chile.

Salmonella enterica serotype Enteritidis is a worldwide zoonotic agent that has been recognized as a very important food-borne bacterial pathogen, mainly associated with consumption of poultry products. The aim of this work was to determine genotypic and phenotypic evidence of S. Enteritidis transmission among seabirds, poultry and humans in Chile. Genotyping was performed using PCR-based virulotyping, pulse-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Pathogenicity-associated phenotypes were determined with survival to free radicals, acidic pH, starvation, antimicrobial resistance, and survival within human dendritic cells. As result of PCR and PFGE assays, some isolates from the three hosts showed identical genotypic patterns, and through MLST it was determined that all of them belong to sequence type 11. Phenotypic assays show diversity of bacterial responses among isolates. When results were analyzed according to bacterial host, statistical differences were identified in starvation and dendritic cells survival assays. In addition, isolates from seabirds showed the highest rates of resistance to gentamycin, tetracycline, and ampicillin. Overall, the very close genetic and phenotypic traits shown by isolates from humans, poultry, and seabirds suggest the inter-species transmission of S. Enteritidis bacteria between hosts, likely through anthropogenic environmental contamination that determines infection of seabirds with bacteria that are potentially pathogenic for other susceptible organism, including humans.

Serotype-associated polymorphisms in a partial rpoB gene sequence of Salmonella enterica.

Salmonella enterica is a zoonotic bacterium with more than 2500 serotypes, which affect a wide range of hosts and produce diverse clinical outcomes. Strain identification usually involves costly and time-demanding procedures. This paper describes the sequencing of a rpoB hypervariable gene segment (847 bp) that allows identification of serotypes in S. enterica strains isolated from several hosts. The nucleotide similarity values among S. enterica serotypes ranged from 98.23% to 99.88%, with potential usefulness for devising a simple one-step sequencing as a first approach for identification of S. enterica strains. In conclusion, the analysis of polymorphisms in the partial rpoB sequence can discriminate S. enterica strains at the subspecies level.

Identification of diverse Salmonella serotypes, virulotypes, and antimicrobial resistance phenotypes in waterfowl from Chile.

Salmonella enterica is a pathogen with a wide host-range that presents great concern in developed and developing countries. To determine and characterize Salmonella strains found in Chile's waterfowl, we sampled 758 birds along 2000 km of the Chilean coast. In this sample, 46 isolates from 10 serotypes were detected, several with multidrug resistance phenotypes and different combinations of virulence-associated genes (virulotypes). These results suggest that Salmonella infection in waterfowl in Chile could have impacts on public and animal health.