Challenges and opportunities by bridging human and animal surveillance to tackle antimicrobial resistance

Introduction: Antimicrobial resistance (AMR) requires a global and multidisciplinary approach to improve awareness, understand dynamics and find preventive solutions. In this framework we set up a one-health tailored pilot surveillance network to monitor occurrence of Escherichia coli ESBL in humans and food producing animals FPA, to investigate on dissemination paths of ESBL resistant E. coli in human healthcare units and to plan and develop educational modules for prudent use of antimicrobials in human and animals. With the project network in place we could promptly investigate on the emergence of the plasmid-mediated colistin resistance gene mcr-1 that has been recently reported in E. coli of both animal and human origin. Materials and Methods: According to objectives: i) we set up a cross-sectional study (2016-2017) by collecting representative E. coli ESBL+ isolates from human communities and FPA industrial holdings in six Italian Regions; ii) we searched for available data sources for descriptors and parameters to develop dynamic mathematical models to describe E. coli ESBL+ dissemination paths between health care units and iii) we explored the learning needs to tackle AMR so to identify knowledge gaps to be addressed by specific educational proposals. In this frame, colistin resistance was investigated among E. coli ESBL+ isolates from both animal and human sources. MIC was determined by broth microdilution method and interpreted according to EUCAST breakpoints. mcr-1 gene was detected by PCR and sequencing. Results: Halfway through the project 827 E. coli ESBL+ isolates (277 were from FPA) were collected. A post graduate course and a distance learning courses were identified to fulfill learning needs of clinicians, veterinarians and microbiologists. Few E. coli ESBL+ of human origin were tested for colistin resistance so far and found all susceptible. On the contrary among colistin resistant E. coli ESBL+ isolates of animal origin mcr-1 was detected in 5% of poultry and 10% of bovines and of swine isolates. Data from antimicrobial susceptibility test (AMS) of patients from a high geographical coverage and statistics from health care units is feeding and providing parameters for mathematic dynamic models. Conclusions: A challenge in a one-health-based surveillance of opportunistic bacteria is the different reference population that require a wide animal sample to detect the targeted human pathogens. So far, our experience recommends to stick on strong case definitions of both clinical cases and isolates to be included in the study. Although the data herein reported is preliminary the proportions of mcr-1 carriers E. coli ESBL+ detected in FPA represents a serious public health threat that requires strict surveillance.