Methicillin-resistant Coagulase-Negative Staphylococci: key role in the maintenance and dissemination of antibiotic resistance in human, animal and environment interface

Ramzi Boubaker Elandoulsi ^a, Sana Dhaouadi ^a,c , Leila Soufi^a, Floriana Campanile ^b, Ameur Cherif ^a, Stefania Stefani ^b

^a University of Manouba, ISBST, BVBGR-LR11ES31, Biotechpole Sidi Thabet, Ariana, Tunisia ; ^b Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy ; ^c University of Tunis El Manar, Rommana City, Tunis, Tunisia

Antibiotic resistance is an issue that extends beyond human health and can only be tackled with a ‘one-health’ approach, which considers human and veterinary medicine in parallel and in the context of environmental factors. Besides S. aureus, other staphylococcal species, so-called coagulase-negative staphylococci (CNS), colonize frequently both animals and humans. They have been described to have rates of resistance to several different antimicrobial classes that surpass those of S. aureus, being considered reservoirs of antimicrobial resistance for other more pathogenic bacteria. Moreover, CNS were previously suggested to be themselves the origin of resistance genes that provide resistance to important antimicrobial classes like beta-lactams. There is a gap of knowledge and lack in data concerning antibiotic resistance transmission dynamic. Thus, our research will provide important data concerning the impact of antimicrobial drug misuse in environment, agriculture, and animals. The aims to i) isolate, identify and genetically characterize antibiotic resistant bacteria from environmental, animal and human sources; and ii) assess risk factors of transmission of antibiotic resistance genes in order to develop preventive measures and efficient control strategies. After sample collection in different “hot spots” (human, animals, and environment), isolation and identification of resistant bacteria, molecular, genomic, and metagenomic innovative methods have fulfilled. CNS from the three origins carried various resistance genes [mecA, blaZ, tet(K), erm(A), erm(B), msr(A)], suggesting an ongoing genetic exchange among CNS from the three niches. The mecA gene was detected in CNS (n=11) recovered from cows, manure, and humans, whereas the mecC gene (n=3) was only detected in CNS from cows and manure. Various staphylococcal cassette chromosome mec (SCCmec)– SCCmec type I (n=1), II (n=3), IV (n=2), V/VII (n=2) and untypeable (n=3) – and diverse pulsed-field gel electrophoresis (PFGE) patterns were observed in mecA-positive CNS. Otherwise, similar SCCmec types and PFGE patterns were found in meticillin-resistant CNS within different farms and origins, showing the potential of SCCmec interspecies exchange and circulation of the same clones of meticillin-resistant CNS in the human– animal–environment interface. This will allow minimizing resistance genes and/or bacteria transfer from environment to animals and between animals and humans and will contribute for the socioeconomic development of sustainable agriculture as well as animals and human welfare.

Keywords: CNS, Human–animal–environment interface, Clonal dissemination