Antimicrobial resistance patterns of WHO priority pathogens isolated in hospitalized patients in Japan: A tertiary centre observational study

Background: After issuing the "Global action plan on antimicrobial resistance" in 2015, the World Health Organization (WHO) established a priority pathogens list for supporting research and development of novel antimicrobials. We conducted a comprehensive analysis of the WHO priority organisms in a Japanese tertiary hospital to apprehend the local AMR epidemiology Methods Data were obtained from electrical medical records in Osaka University Hospital between January 2010 and March 2021. The critical, high, and medium "priority pathogens list" categories of the WHO were used to compare results between the early (2010–2015) and late (2016–2021) phases. Results Out of 52,130 culture-positive specimens, a total of 9,872 (18.9%) contained WHO priority isolates. In comparison to early phases, late phases were likely to have higher rates of carbapenem resistance in Pseudomonas aeruginosa (15.7% vs 25.0%, P < 0.001), 3rd generation cephalosporin resistance in Escherichia coli (11.5% vs 17.8%, P < 0.001) as well as Klebsiella pneumoniae (1.6% vs 4.4%, P < 0.001), and ampicillin resistance in Haemophilus influenzae (2.4% vs 3.9%, P < 0.001). After 2015, however, the proportion of methicillin-resistant and vancomycin-intermediate Staphylococcus aureus was low. In this study, in-hospital mortality was comparable among patients with resistance to the three WHO priority pathogen types: critical (5.9%), high (3.9%), and medium (3.8%), and no significant change was observed between two phases in each category. However, significant interactions for in-hospital mortality were observed in subgroup analyses between “critical priority” AMR and the presence of comorbid conditions, such as chronic kidney disease or diabetes mellitus. Conclusions To implement better antimicrobial stewardship policies and practices, local priority pathogens and "high-risk" patients for in-hospital death need to be acknowledged and evaluated periodically.