Thinking outside the box: Association of antimicrobial resistance with climate warming in Europe - A 30 country observational study.

The association of antimicrobial resistance (AMR) with climatic factors gained higher attention since resistance increased with increasing local temperatures in the USA. We aimed to investigate whether the explanatory strength of climatic factors holds true in a region encompassing diverse healthcare systems, like Europe. In particular, we determined whether exposure to temporal climate warming is associated with an increase in AMR prevalence for clinically relevant pathogens. A 30-country cross-sectional study was conducted. The six-year prevalence of carbapenem-resistant Pseudomonas aeruginosa (CRPA), Klebsiella pneumoniae (CRKP), Multiresistant Escherichia coli (MREC), and Methicillin-resistant Staphylococcus aureus (MRSA) was determined based on > 900 k clinical isolates. Bi- and multivariate analysis were performed to identify associations with climatic variables using healthcare and socio-economic confounders. CRPA was significantly associated with the warm-season change in temperature, which, alongside corruption perception, explained 78% of total CRPA variance. Accordingly, a 0.5 °C increase of year-wise temperature change (exposition) resulted in a 1.02-fold increase (p = 0.035) in CRPA prevalence (outcome). For a given country, exposition status doubled the odds of outcome attainment compared to non-exposition (OR = 2.03, 95%-CI [1.03-3.99]). Moreover, we found significant associations of CRKP, MREC, and MRSA with the warm-season mean temperature, which had a higher contribution to MRSA variance explanation than outpatient antimicrobial drug use. We identified a novel association between AMR and climatic factors in Europe, which reveals two aspects: climatic factors significantly contribute to the explanation of AMR in different types of healthcare systems, while climate change (i.e. warming) might increase AMR transmission, in particular CRPA.