Antibiotic resistance genes (ARGs) in the gastrointestinal microbiome of wild seabirds: the first detection of mecA in seabirds in South America

Ana Carolina Ewbank, Carlos Sacristán, Samira Costa-Silva, Marzia Antonelli, Janaina R. Lorenço, Cristiane K. M. Kolesnikovas, José Luiz Catão-Dias, Fernando Esperón Fajardo

Antibiotic resistance genes (ARGs) are considered environmental contaminants and anthropization indicators. We evaluated the degree of human interference in the marine ecosystem through the presence, identification and quantification of selected plasmid-mediated ARGs: with expected detection frequency (tet, aadA, str, sul, cat, erm); livestock and/or human health care use (qnrB, qnrS and blaTEM); and Public Health impact (mcr-1 and mecA), present in the gastrointestinal microbiome (enema samples) of wild seabirds upon admission in a rehabilitation center, Brazil. We evaluated 34 birds, divided into three groups according with the species: Larus dominicanus (Group A/n=14), Spheniscus magellanicus (Group B/n=11), and Other species (Thalassarche chlororhynchus, Macronectes giganteus, Sula leucogaster, Sula sula, Phalacrocorax brasilianus, and Sterna hirundinacea; Group C/n=9). All ARGs were detected and quantified by real-time PCRs. Group A presented a higher percentage of positives (?50%) for tetQ, sulII and blaTEM, Group B for tetQ, and Group C for qnrB. Among all genes, blaTEM presented the highest gene load percentage (mean values) in all groups. mecA, a gene of Public Health concern was detected in Group A. Multiresistant microbiomes (resistance to 3 or more antimicrobial classes) were observed in all groups: A (n=6), B (n=5) and C (n=3). Herein we report the detection of a high load and diversity of ARGs, including the first description of the mecA gene in seabirds in South America, commonly associated with Methicillin-resistant Staphylococcus aureus (MRSA), a relevant cause of nosocomial infections worldwide. Ongoing studies will assess if there are significant differences between biological and behavioral parameters (i.e., feeding behavior and migration).

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