Fuente: Microorganisms - Revista científica (MDPI) Microorganisms, Vol. 14, Pages 523: Phenotypic Antimicrobial Resistance Profiles and Provisional Epidemiological Cut-Off Values of Edwardsiella anguillarum Isolated from Farmed Nile Tilapia (Oreochromis niloticus) in Brazil, with Exploratory Data on Edwardsiella tarda
Microorganisms doi: 10.3390/microorganisms14030523
Authors:
Natália Amoroso Ferrari
Vittória Cueva Segura da Silva
Pamela Giovana Turini
Julia Faria de Souza
Raffaella Menegueti Mainardi
Mayza Brandão da Silva
Alene Santos Souza
Gabriel Diogo Guimarães
Maisa Fabiana Menck-Costa
Marco Rozas-Serri
Mariene Miyoko Natori
Renata Galetti
Ulisses de Padua Pereira

Antimicrobial resistance in bacteria associated with aquaculture, such as Edwardsiella spp., represents an emerging challenge because of their relevance to fish health and their potential impact on animal, environmental, and human health. In this study, we primarily investigated the antimicrobial susceptibility profiles of Edwardsiella anguillarum isolated from farmed Nile tilapia (Oreochromis niloticus) in Brazil. Based on our findings, herein, we propose provisional local epidemiological cut-off values (pECVs) using the normalized resistance interpretation method, with data for Edwardsiella tarda included as an exploratory context. Fifty isolates (31 E. anguillarum and 19 E. tarda) collected between 2017 and 2025 were tested against 28 antibacterial agents using the disk diffusion method. Based on the pECVs, isolates were classified as wild type (WT) or non-WT (NWT), and the multiple antibiotic resistance (MAR) index was calculated. Most E. anguillarum isolates remained susceptible to several classes, although NWT and multidrug-resistant profiles were detected with a MAR index of 0.68, suggesting selective pressure in intensive tilapia farming systems. These findings support the use of local, species-specific pECVs for resistance surveillance in aquaculture, highlighting the importance of continuous antimicrobial resistance monitoring in aquaculture from a One Health perspective.