Chilean aquaculture mainly produces salmonids and molluscs. Salmonid production has been questioned by its excessive use of antimicrobials. This study aimed to investigate the bacterial microbiota composition of Mytilus spp. cultivated near salmonid farms and to determine the minimum inhibitory concentration (MIC) to florfenicol and oxytetracycline of its culturable bacteria. Seven Mytilus farming sites classified according to their proximity to salmon farms as close (CSF) or distant (DSF) were sampled in two years. We analyzed Mytilus microbiota composition through culture-independent methods, and isolated culturable bacteria, and identified those isolates with MIC values ≥ 64 μg mL^-1 to florfenicol or oxytetracycline. Results revealed that the alpha diversity was affected by sampling year but not by Mytilus farming site location or its interaction. Nevertheless, in 2018, we observed a significant negative correlation between the alpha diversity of Mytilus microbiota in each farm sites and the tonnes of florfenicol reported for each phytosanitary management area. We detected significant differences in beta diversity and relative abundance of specific bacterial taxa in Mytilus microbiota depending on the proximity to salmon farms and years. A higher proportion of isolates with MIC values ≥ 64 μg mL^-1 to both antibiotics was detected in 2019 compared to 2018, but not significant differences were detected according to Mytilus farming site location. However, in 2019, isolates from CSF sites showed higher MIC values for both antibiotics than those from DSF. Bacterial genera corresponding to isolates with MIC values ≥ 64 μg mL^-1 represented a low proportion of Mytilus microbiota identified with the culture-independent approach, reflecting the need to implement new methodologies in the study of antimicrobial resistance. These results suggest that the proximity to salmonid farms and sampling year influence the Mytilus microbiota and MIC values of their bacterial isolates; however, other environmental variables should be considered in further studies.

Antimicrobial resistance (AMR) is a growing global health concern for both animal and public health, and collaborative strategies are needed to combat the threat. The level of awareness and funding for policies focused on reducing AMR varies between countries. The aim of this study was to compare the integrated surveillance systems for AMR in high and low–middle economies of the Asia-Pacific Economic Cooperation and determine whether there was any improvement from 2015 to 2018. We conducted a survey with a group of 21 countries at different development levels. Associations between the economic development level and the questions of AMR awareness and funding were established using Fisher’s exact test. Improvements were identified where countries established public policies for integrated surveillance of AMR. High economies showed greater advancement in several topics related to AMR than low–middle economies. The survey revealed that there is a better understanding surrounding the implications of the emergence of AMR in human medicine than in veterinary medicine, agriculture, and food production. Our results show that countries enhanced overall AMR surveillance over the 4-year-period; however, more research is needed concerning these advances, especially in low–middle economies and the food production sector.

Background: The microbiota‒gut‒brain axis modulates pigs’ stress response, behavior, and overall welfare. Stressful management practices can disrupt gut microbiota (GM), negatively impacting pigs' health and welfare. This study evaluated how the quality of human handling influences stress-related physiological responses, productive performance, and gut microbiota (GM) composition in pigs during the nursery phase. Results: Female pigs (n= 36, 21 days old) were randomly assigned to three experimental groups (12 pigs/group, four pens per treatment): positive human handling (PHH), negative human handling (NHH), and a control group (CG). The PHH group experienced gentle tactile interactions, whereas the NHH group was subjected to chronic intermittent stress through acute stressors, and the CG group received minimal handling for routine practices. Hair cortisol concentrations were measured as an indicator of chronic stress (days 15 and 64). Productive performance was assessed through body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed conversion (FC). Fecal samples were collected at baseline (T0, day 16), mid-study (T1, day 37), and end of the study (T2, day 65) and analyzed using 16S rRNA gene amplicon sequencing to assess GM changes over time. Pigs in the PHH group showed a significant reduction in cortisol levels from baseline to post-treatment (P < 0.0001), while no significant changes were observed in the NHH group (P = 0.26). A smaller but significant decrease was also detected in the CG group (P = 0.001). PHH pigs had higher BW (P = 0.0009) and ADG (P = 0.03) during the later growth phase compared to NHH pigs. At T2, PHH pigs exhibited greater diversity and richness compared to NHH pigs, indicating a restorative effect on GM composition. Differential abundance analyses identified four bacterial genera that distinguished treatment groups: Blautia , Megasphaera , and Subdoligranulum were enriched in PHH pigs, while Terrisporobacter was enriched in NHH pigs. Additionally, bacterial interaction networks exhibited the least complex network in the NHH group, with ecological associations primarily involving Clostridium and Terrisporobacter . Conclusions: The quality of human handling influenced stress physiology, performance, and gut microbiota in pigs. Positive handling reduced cortisol levels, improved growth, and promoted microbial diversity, while negative handling was linked to decreased performance and reduced microbial network complexity. These results highlight the potential of positive interactions to enhance welfare and productivity, and identify specific bacterial genera as potential biomarkers differentiating negative and positive handling conditions.