Anthropogenic gradients shape Staphylococcus/Mammaliicoccus communities: Bacterial composition and resistance patterns as indicators of landscape hemeroby

Antimicrobial resistance (AMR) is one of the greatest challenges within the One Health continuum. Exploring transmission routes between health domains and determining their driving forces are key priorities for future research. This effort can be effectively supported by landscape epidemiology, a field of science that integrates methods from landscape ecology and epidemiology to unravel the complex interdependencies behind disease transmission. This exploratory study aimed to demonstrate that landscape diversity and the degree of hemeroby (anthropogenic impact) correlate with the composition of bacterial communities and their AMR profiles. To test this hypothesis, submandibular lymph nodes from Cervidae and Suidae were collected to detect Staphylococcus and Mammaliicoccus bacteria and characterise their AMR features using selective culture and the VITEK 2 Compact automated system. As a result, the bacterial community in the more natural landscape was more diverse, characterised by the dominance of Mammaliicoccus sciuri and pan-susceptible isolates of Staphylococcus hyicus, and it displayed a low-level, heterogeneous AMR profile. Within the more hemerobic landscape, the bacterial community was characterised by the dominance of Staphylococcus epidermidis, a human-adapted species, and the AMR profile showed signs of higher antimicrobial pressure from both public health and veterinary origins. Although this study was based on only two study sites and was therefore not suitable for drawing definite conclusions, the findings suggest that human impact manifests itself in both bacterial and AMR profiles. A high prevalence of mammaliicocci and a heterogeneous AMR profile appeared to be indicators of naturalness. Conversely, the dominance of a human-adapted bacterial species and the accumulation of AMR features characteristic of medical environments likely indicate higher degrees of hemeroby.