  Citation: Plawi ´ nska-Czarnak, J.; Wódz, K.; Piechowicz, L.; Tokarska-Pietrzak, E.; Belkot, Z.; Bogdan, J.; Wi´ sniewski, J.; Kwieci ´ nski, P.; Kwieci´ nski, A.; Anusz, K. Wild Duck (Anas platyrhynchos) as a Source of Antibiotic-Resistant Salmonella enterica subsp. diarizonae O58—The First Report in Poland. Antibiotics 2022, 11, 530. https:// doi.org/10.3390/antibiotics11040530 Academic Editor: Jonathan Frye Received: 26 March 2022 Accepted: 14 April 2022 Published: 15 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). antibiotics Communication Wild Duck (Anas platyrhynchos) as a Source of Antibiotic-Resistant Salmonella enterica subsp. diarizonae O58—The First Report in Poland Joanna Plawi ´ nska-Czarnak 1, * , Karolina Wódz 2 , Lidia Piechowicz 3 , Ewa Tokarska-Pietrzak 3 , Zbigniew Belkot 4 , Janusz Bogdan 1 , Jan Wi´ sniewski 1 , Piotr Kwieci ´ nski 2 , Adam Kwieci ´ nski 2 and Krzysztof Anusz 1 1 Department of Food Hygiene and Public Health Protection, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; janusz_bogdan@sggw.edu.pl (J.B.); jan_wisniewski1@sggw.edu.pl (J.W.); krzysztof_anusz@sggw.edu.pl (K.A.) 2 Laboratory of Molecular Biology, Vet-Lab Brudzew, Turkowska 58c, 62-720 Brudzew, Poland; karolina.wodz@labbrudzew.pl (K.W.); vetlab@interia.pl (P.K.); kwiecinski@vetlabbrudzew.pl (A.K.) 3 Department of Medical Microbiology, Faculty of Medicine, Medical University of Gda´ nsk, D˛ ebowa 25, 80-204 Gda ´ nsk, Poland; lidiap@gumed.edu.pl (L.P.); etok@gumed.edu.pl (E.T.-P.) 4 Department of Food Hygiene of Animal Origin, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-950 Lublin, Poland; zbigniew.belkot@up.lublin.pl * Correspondence: joanna_plawinska_czarnak@sggw.edu.pl Abstract: The “One Health” approach increasingly demonstrates the global spread of pathogenic microorganisms and their antimicrobial resistance in the environment, both in animals and humans. Salmonella enterica subsp. diarizonae is nowadays very often isolated from cold-blooded reptiles to a lesser extent from sheep, but unfortunately more and more often from humans. However, there are a few studies describing the isolation of Salmonella enterica subsp. diarizonae from migratory wild birds. The mallard duck (Anas platyrhynchos), a wild animal that traverses the continent of Eurasia, can be an excellent indicator of the spread of intestinal microbes as well as their resistance to antibiotics. This is the first report of the Salmonella enterica subsp. diarizonae detection in Poland in a migrating mallard duck. This research presented the identification difficulties associated with the isolation of Salmonella enterica subsp. diarizonae using three different biochemical tests and advanced serology tests. At the same time, we detected very high antimicrobial resistance in the isolated strain. By using the minimum inhibitory concentration (MIC) method, it was found that the isolated strain of S. enterica subsp. diarizonae has high antibiotic resistance against 14 of the 33 tested antimicrobials agents. The resistance genes that have been identified in S. enterica subsp. diarizonae include aadA, strA/strB, and bla TEM . Keywords: Salmonella enterica subsp. diarizonae; antibiotic-resistant Salmonella; wild duck 1. Introduction Salmonellosis is an important cause of water-borne [1] and food-borne epidemics in humans. In the European Union, salmonellosis is the second most frequently reported human gastrointestinal infection right after campylobacteriosis. In 2021 a total of 90,105 hu- man salmonellosis cases were reported by EU EFSA [2]. People contract Salmonella not only from animal origin foods but also from eating contaminated vegetables and fruits or from their pets. Now there are more and more reports of human diseases caused by Salmonella enterica subsp. diarizonae [3]. Salmonella enterica subsp. diarizonae is a subspecies IIIb of six within Salmonella enterica spp. It is most often described as a Gram-negative rod infecting cold-blooded animals, including reptiles kept as pets [4,5]. However, Salmonella enterica subsp. diarizonae was also isolated in Norway and Switzerland from sheep [6,7] and Greece [8]. Chatzopoulos et al. showed that Salmonella enterica subsp. diarizonae is an opportunistic gastrointestinal pathogen in lamb [9]. Antibiotics 2022, 11, 530. https://doi.org/10.3390/antibiotics11040530 https://www.mdpi.com/journal/antibiotics