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Advisor(s)
Abstract(s)
Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens that can cause serious
diseases in humans, including bloody diarrhoea and kidney failure. Ruminants, such as cattle,
are considered the main reservoirs and source of STEC. Human infection can occur through
contaminated food and water, or direct contact with infected animals. STEC antimicrobialresistance
(AMR) is increasingly frequent in patients with serious disease. It is necessary to
understand the epidemiology, the emergence, and the prevalence of AMR in STEC isolated from
cattle to investigate how resistance spreads from ruminants to humans. Thus, susceptibility tests
were performed on 55 STEC strains belonging to 29 serogroups. The strains were isolated from
healthy dairy cattle faeces (cows and heifers) in the North of Portugal. Antibiotic susceptibility
testing (AST) was performed by disc diffusion method following European Committee on
Antimicrobial Susceptibility Testing (EUCAST, 2020) and Clinical and Laboratory Standards
Institute (CLSI, 2020). The antibiotics used included penicillins (ampicillin; amoxicillin-clavulanic
acid), cephalosporins (ceftazidime; cefotaxime; cefoxitin; cephalothin), carbapenems (imipenem;
meropenem), aminoglycosides (kanamycin), phenicol (chloramphenicol), sulphonamides/
trimethoprim (trimethoprim-sulfamethoxazole), fluoroquinolones (moxifloxacin; levofloxacin) and
tetracyclines (tetracycline; tigecycline). Results reveal low level of resistance among the isolates
tested. However, five (9%) STEC isolates were resistant to one antibiotic, and three (5,5%) to
three or more antibiotic classes (multidrug resistance-MDR). The MDR strains were resistant to
trimethoprim-sulfamethoxazole, tetracycline and other antibiotics commonly used to treat
gastroenteritis. Two strains MDR belonged to O91 serogroup and were founded in heifers in the
same farm. O91 is an important serogroup to public health surveillance, as it is commonly
associated with contamination of products from animal origin, and it has been isolated from
patients with severe gastrointestinal disease. Overall, the AMR did not seem to be widely spread
in STEC isolates from cattle; but serotype O91 might be of special concern as two O91-multidrug
resistance profiles have been identified.
Description
Keywords
E. coli
Pedagogical Context
Citation
Andressa Ballem, Gonçalo Almeida, Carina Almeida, Conceição Fernandes, Maria José Saavedra (2021). Antibiotic resistance profile among Shiga toxin-producing Escherichia coli isolated from dairy cattle. In Dare2Change- Innovation-Driven Agrifood Business. Porto
Publisher
Iseki-Food Association