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- High occurrence of multidrug-resistant Esche-richia colifrom Holstein-Friesian cattle in Northern Portugal: a One Health challengePublication . Quinteira, S.; Dias, A.B.; Pinho, L.; Brito, N.V.; Campos, Carla; Freitas, A.R.; Miranda, C.Escherichia coli is currently a leading pathogen for deaths associated with antimicrobial resistance (AMR). AMR related to food-producing animals is a public health risk requiring a One Health approach. Animals are major reservoirs of antibiotic resistant E. coli which can easily reach humans through the food chain, direct contact, or the environment. To analyze the AMR profiles of E. coli in fecal samples from Holstein-Friesian cattle, as information on AMR from dairy farming in Portugal is scarce. Samples (n=112) collected from 7 different farms at Northern Portugal were pooled during February-March 2023 based on age group (8 calves and 8 cows per farm). Characteristic E. coli colonies were selected from MacConkey Agar supplemented with or without antibiotics (4 µg/ml cefotaxime; 3 µg/ml colistin), for confirmation by MALDI-TOF mass spectrometry and antimicrobial susceptibility testing (AST), according to EUCAST/CLSI guidelines. ESBL phenotype were searched using the Double-Disk Synergy Test. Presumptive E. coli isolates (n=110) representing different farming production systems were obtained and 51 representatives were identified by MALDI-TOF and tested by AST. From both calves and cows, 95% and 63% of the E. coli isolates exhibited resistance to ≥1 antimicrobial classes and multidrug resistance (MDR, resistance to ≥3 antimicrobial classes), respectively. Isolates were mostly resistant to gentamycin (88%), ampicillin (72%), amoxicillin plus clavulanic acid (63%), tetracycline (63%) and cefotaxime (53%). Only two isolates showed susceptibility two all tested antibiotics. ESBL activity was observed in 21% of E. coli isolates. All analyzed pools were classified as MDR. This is one of the first studies on AMR rates of E. coli from dairy cattle in Northern Portugal. It reveals a high prevalence of MDR E. coli, which is a worrying finding and emphasize the need of a multisectoral One Health approach to minimize its impact.
- Dairy cattle and the iconic autochthonous cattle in northern Portugal are reservoirs of multidrug-resistant Escherichia coliPublication . Quinteira, Sandra; Dantas, Rui; Pinho, Luís; Campos, Carla; Freitas, Ana R.; Brito, Nuno V.; Miranda, Carla; Campos, CarlaAnimals destined for human consumption play a key role in potentially transmitting bacteria carrying antibiotic resistance genes. However, there is limited knowledge about the carriage of antibiotic-resistant bacteria in native breeds. We aimed to characterize the phenotypic profiles and antibiotic resistance genes in Escherichia coli isolated from bovines, including three native Portuguese bovine breeds. Forty-nine E. coli isolates were selected from 640 fecal samples pooled by age group (eight adult or eight calf samples) from each farm, representing both dairy cattle raised in intensive systems and meat cattle raised in extensive systems in Northern Portugal. The presumptive E. coli colonies plated onto MacConkey agar were confirmed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The antibiotic resistance profiles were screened by antimicrobial susceptibility testing (EUCAST/CLSI guidelines), and the antibiotic resistance genes by PCR. Most isolates showed resistance to ampicillin (69%), tetracycline (57%), gentamicin (55%), and trimethoprim + sulfamethoxazole (53%), with no resistance to imipenem. Resistance to at least one antibiotic was found in 92% of isolates, while 59% exhibited multidrug resistance. Most calf isolates, including those from native breeds, showed a multidrug-resistant phenotype. Among the adults, this was only observed in Holstein-Friesian and Barrosã cattle. None of the Holstein-Friesian isolates were susceptible to all the tested antibiotics. ESBL-producing E. coli was identified in 39% of isolates, including those from Holstein-Friesian calves and adults, Cachena calves and Minhota adults. The sul2 gene was detected in 69% of isolates, followed by blaCTX-M (45%), aac(3′)-IV (41%), and aac(6′)-Ib-cr (31%), with a higher prevalence in adults. This pioneering study highlights the concerning presence of multidrug-resistant E. coli in native Portuguese cattle breeds.