Prieto Lago, AlbertoLópez Novo, CynthiaDíaz Fernández, PabloDíaz Cao, José ManuelLópez-Lorenzo, GonzaloAnton, ClaudiaRemesar Alonso, SusanaGarcía-Dios, DavidLópez Sández, Ceferino ManuelPanadero Fontán, RosarioDíez Baños, PabloMorrondo Pelayo, María PatrocinioFernández Rodríguez, Gonzalo2024-01-252024-01-252022-01Prieto, A.; López-Novo, C.; Díaz, P.; Díaz-Cao, J.M.; López-Lorenzo, G.; Antón, C.; Remesar, S.; García-Dios, D.; López, C.; Panadero, R.; et al. Antimicrobial Susceptibility of Enterotoxigenic Escherichia coli from Diarrhoeic Neonatal Calves in Spain. Animals 2022, 12, 264. https://doi.org/ 10.3390/ani120302642076-2615http://hdl.handle.net/10347/31988Enterotoxigenic Escherichia coli (ETEC) is one of the major pathogens involved in neonatal calf diarrhoea (NCD) causing high economic losses in dairy farms. Antibiotic treatment is common in cases of systemic illness caused by NCD, but antimicrobial susceptibility tests (AST) are usually not performed. Thus, the aim of this study was to characterize the antimicrobial susceptibility of ETEC strains obtained from calves with diarrhoea between 2018–2020. Faecal samples (n = 420) were analyzed to detect the typical ETEC virulence factors F5 and STa. Positive samples were cultured to identify and isolate ETEC strains (n = 41) and ASTs were performed. Our results are alarming since ETEC strains resistant to three or more families of antimicrobials were detected in all isolates. Only four antibiotics (ceftiofur, cefoperazone, cefquinome and gentamicin) presented efficacy against more than 90% of the ETEC strains, while the other ten antibiotics were effective against less than 40% of the strains. In addition, a high number of strains were resistant to most first-line antimicrobials used in veterinary practice. For this reason, when ETEC infection is suspected, an AST must always be performed to select the most appropriate antimicrobial in each case and to avoid the emergence of new resistance mechanisms.eng© 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) licensehttp://creativecommons.org/licenses/by/4.0/Neonatal calf diarrhoeaEscherichia coliETECAntimicrobial susceptibilityjournal article10.3390/ani12030264open access