It is widely accepted that, in order to prevent and control antimicrobial resistance (AMR), surveillance systems across human, animal and environmental sectors need to be integrated, in a One Health approach. Currently, in Europe, there are surveillance networks established only for the human and food sector and, until now, there has been no organized effort to monitor AMR in bacterial pathogens derived from diseased animals in Europe. Since 2017, efforts to fill this gap have taken place by the European Antimicrobial Resistance Surveillance network in a veterinary medicine (EARS-Vet) initiative, included in the EU Joint Action on AMR and Healthcare-Associated Infections (EU-JAMRAI). EARS-Vet is designed to complement and integrate with existing European monitoring systems for AMR as well as constitute a European network of national monitoring systems. As Greece has no national AMR surveillance system for pathogens of animal origin currently in place, in the context of the development of EARS-Vet, an initiative took place for the organization of such a system by competent agencies and other stakeholders. In this article, the steps to organize a first AMR national surveillance network in Greece are presented and a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis is performed to present main characteristics of the approach implemented.

The first prospective surveillance of ESBL and colistin-resistant Escherichia coli recovered from sick pigs from a slaughterhouse in Central Greece aimed to investigate the spread of relevant genetic elements. In February 2021, 25 E. coli isolates were subjected to antimicrobial susceptibility testing using disk diffusion and broth microdilution techniques. PCR screening was conducted to identify ESBLs and mcr genes. Additional assays, encompassing mating-out procedures, molecular typing utilizing Pulsed-Field Gel Electrophoresis, multilocus sequence typing analysis, and plasmid typing, were also conducted. A 40% prevalence of ESBLs and an 80% prevalence of MCR-1 were identified, with a co-occurrence rate of 32%. The predominant ESBL identified was CTX-M-3, followed by SHV-12. Resistance to colistin, chloramphenicol, cotrimoxazol, and ciprofloxacin was detected in twenty (80%), fifteen (60%), twelve (48%), and four (16%) isolates, respectively. All bla_CTX-M-3 harboring plasmids were conjugative, belonging to the incompatibility group IncI1, and approximately 50 kb in size. Those carrying bla_SHV-12 were also conjugative, classified into incompatibility group IncI2, and approximately 70 kb in size. The mcr-1 genes were predominantly located on conjugative plasmids associated with the IncX4 incompatibility group. Molecular typing of the ten concurrent ESBL and MCR-1 producers revealed seven multilocus sequence types. The heterogeneous population of E. coli isolates carrying resistant genes on constant plasmids implies that the dissemination of resistance genes is likely facilitated by horizontal plasmid transfer.

In Greece, a National Monitoring Plan for Antimicrobial Resistance in sick bovine animals was launched (2021). We aimed at surveying the antimicrobial resistance profiles of 118 pathogenic Staphylococcus aureus isolates obtained from dairy cows >18 months with mastitis in the Region of Central Macedonia from 1st March to 31st July 2021, where 45% (Census 2020: 69.186/128.511) of dairy cows in Greece are concentrated. By using the disk diffusion method (according to the CLSI guidelines), we tested susceptibility of isolates to nine antimicrobials (penicillin, cefoxitin, cefquinome, gentamicin, tetracycline, marbofloxacin, erythromycin, clindamycin, enrofloxacin) selected following the marketing amounts of animal use in Greece. In the study, 62/11 Staphylococcus aureus isolates were found to be resistant 52,54% to penicillin; 57/118 were 48,31% resistant to erythromycin, 56/118 were resistant 47,46% to clindamycin; 29/118 were 24,58% resistant to tetracycline and cefquinome both, 27/118 were 22,88% resistant to cefoxitin, 20/118 were 16,95% resistant to gentamicin, 3/118 were 2,54% resistant to marbofloxacin and, 2/118 were 1,69% resistant to enrofloxacin. Regarding the surveillance on the antimicrobial resistance of the Staphylococcus aureus isolates, that cause mastitis in cattle (penicillin in combination with an aminoglycoside, is the most commonly applied therapeutic treatment scheme against mastitis in Greece), to the β-lactams (penicillin, cefoxitin) it is needed further investigation, under the ‘One Health’ approach in respect to the prudent use of antibiotics in staphylococcal infections in humans and in the veterinary medicine in Greece. However, it seems that several kinds of interventions at farm level led to the protection of quinolones. The study offers a thorough understanding of the antimicrobial resistance patterns among Staphylococcus aureus isolates. The significant resistance rates to various antibiotics highlight the need for responsible antibiotic usage and continuous monitoring of resistance trends. These insights are crucial in developing effective strategies to tackle the emergence and dissemination of resistant strains and ensuring better treatment and control of infections caused by this bacterium. The findings add valuable knowledge to our understanding of antibiotic resistance and its implications. Keywords: Antimicrobial Resistance; Staphylococcus aureus; mastitis; prudent use of antibiotics; One Health