Browsing by Author "Ballem, Andressa"
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- Antibiotic resistance profile among Shiga toxin-producing Escherichia coli isolated from dairy cattlePublication . Ballem, Andressa; Almeida, Gonçalo; Almeida, Carina; Fernandes, Conceição; Saavedra, Maria JoséShiga 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.
- Antibiotic resistance profile among Shiga toxin-producing Escherichia coli isolated from dairy cattlePublication . Ballem, Andressa; Almeida, Gonçalo; Almeida, Carina; Fernandes, Conceição; Saavedra, Maria JoséShiga 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.
- Antimicrobial activity against Staphylococcus aureus (MRSA and MSSA): bioactive compounds potencialPublication . Ballem, Andressa; Fernandes, Conceição; Zenão, S.; Gaspar, João; Carvalho, E.; Carvalho, J.A.; Aires, Alfredo; Rosa, Eduardo; Saavedra, Maria JoséHospital infections in diabetic patients are associated with Staphylococcus aureus, including S. aureus resistant to methicillin (MRSA). Besides their increase incidence, MRSA is considered one of the main pathogens causing nosocomial infections and, furthermore, many of these MRSA isolates are becoming multidrug resistant, constituting a public health problem. As a consequence, there is an increase for the search of alternatives to antibiotics, either by synthesis of new compounds or by the research for natural products with antibacterial properties. In this context, this work investigated the antibacterial effect of natural compounds present in plants (Urtica dioica L. and Lavandula angustifolia Mill) in several Gram-positive isolates, collected from diabetic foot ulcers, namely Staphylococcus aureus (MRSA and MSSA). Different plant extracts (extraction in ethanol, acetone and water) were tested and the antibacterial activity was evaluated by disk diffusion assay method, minimum inhibitory concentration (MICs), minimum bactericide concentration (MBC) and growth rate (µ). Spectrophotometry methods were used to assess the total phenolic content and HPLC-DAD/VIS method was used to identify and quantify the phytochemicals present in the plant extracts. Best antibacterial activity against both MRSA and MSSA was observed with the ethanolic extracts, reaching an effectiveness of 100%, in relation to the antibiotic gentamicin. For both plant extracts, the effect on bacterial growth rate was predominantly bacteriostatic. These findings indicate a potential of these plant extracts as a natural product with antimicrobial activity. Their use in formulations, alone or with synergistic effect with conventional antibiotics could be an alternative to limit the infections of these bacteria.
- Endangered bivalves as antimicrobial-resistant Escherichia coli and other species of the Enterobacteriaceae family.Publication . Saavedra, Maria José; Fernandes, Conceição; Ballem, Andressa; Varandas, SimoneFreshwater unionoids are one of the most threatened animal groups worldwide, suffering dramatic regressions globally. The freshwater pearl mussel Margaritifera margaritifera, currently listed as critically endangered in Europe, and Potomida littoralis, listed as endangered, are both present in the River Tua basin (Portugal). These aquatic long-lived organisms, responsible for important functions and vital ecosystem services [1], are sensitive to environmental changes, making them excellent bioindicators [2]. According to Grizzle & Brunner [3] mussels are capable of establishing symbiotic mutualistic or antagonistic relationships with bacteria. The inappropriate use of antibiotics has led to the emergence and spread of resistant bacteria, recognized today as a serious public health problem. Based in the concept of “One health”, the objective of this study was to examine the antibacterial resistance rates in Escherichia coli and other Enterobacteriaceae isolates obtained from water and the two freshwater bivalve species collected in the River Tua Basin.
- Endangered mussels as antimicrobial-resistant E. coli and other species (Enterobacteriaceae family) reservoirsPublication . Saavedra, Maria José; Fernandes, Conceição; Ballem, Andressa; Varandas, SimoneFreshwater unionoids are one of the most threatened animal groups worldwide, suffering dramatic regressions globally. The freshwater pearl mussel Margaritifera margaritifera, currently listed as critically endangered in Europe, and Potomida littoralis, listed as endangered, are both present in the River Tua basin (Portugal). The inappropriate use of antibiotics has led to the emergence and spread of resistant bacteria, recognized today as a serious public health problem. Based in the concept of “One health”, the objective of this study was to examine the antibacterial resistance rates in Escherichia coli and other Enterobacteriaceae isolates obtained from both bivalves collected in the River Tua Basin during the summer of 2018. Activity of 22 antibiotics was studied using disc diffusion (Kirby–Bauer) method. Multidrug resistant in E. coli and Enterobacteriaceae isolates was observed only from P. littoralis. Overall, results show that M. margaritifera inhabits more pristine sectors of river not subject to the development of multidrug resistance, unlike P. littoralis which, although does not tolerate high levels of contamination, is naturally found in lower stretches is subject to greater pressure and, as such, a greater probability of the appearance of multi-resistant organisms. The presence of E. coli in freshwater bivalves can represents serious public health problems once bacteria are one the most important biological contaminants in foodborne diseases. Given the conservation status of both studied species their protection against this silent/invisible enemy should be a priority, although work done with UnionidMussels fromNorthern Portugal showed that they had a great antimicrobial and antibiofilm activity.
- Etiology: the Genus BrucellaPublication . Saavedra, Maria José; Ballem, Andressa; Queiroga, Cristina; Fernandes, ConceiçãoBrucellosis is caused by bacteria of the Brucella species. Twelve species have been identified in the genus. In this chapter, we address the taxonomy and phylogenetic relationships of the presently recognised Brucella species and biovars, as well as Brucella morphology and metabolism and epidemiological features of the Brucella species. Brucella melitensis and B. ovis are the aetiological agents of small ruminant brucellosis. B. melitensis may infect both, goats and sheep, producing a disease mainly characterised by abortion, retained placenta and birth of weakened offspring, while B. ovis is pathogenic to sheep, inducing epididymitis and decreased fertility in males as main symptoms. B. melitensis is the main agent of zoonotic brucellosis, while B. ovis has lower zoonotic significance. Other Brucella species have negative impact on public health. Given the recent knowledge about the genus Brucella, it is worth describing the most relevant characteristics of the different species. Therefore, a short description of each species is presented.
- Freshwater bivalves as reservoirs of multiresistant bacteria: the case of two endangered species (Margaritifera margaritifera and Potomida littoralis)Publication . Varandas, Simone; Fernandes, Conceição; Ballem, Andressa; Teixeira, Amílcar; Saavedra, Maria JoséFreshwater bivalves (FB), responsible for important functions and vital ecosystem services are sensitive to environmental changes, making them excellent bioindicators
- Prevalence and serotypes of Shiga toxinproducing Escherichia coli (STEC) in dairy cattle from Northern PortugalPublication . Ballem, Andressa; Gonçalves, Soraia; Garcia-Meniño, Isidro; Flament-Simon, Saskia C.; Blanco, Jesús E.; Fernandes, Conceição; Saavedra, Maria José; Pinto, Carlos; Oliveira, Hugo; Blanco, Jorge; Almeida, Gonçalo; Almeida, CarinaThis is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The prevalence of Shiga toxin (Stx)-producing Escherichia coli (STEC) was determined by evaluating its presence in faecal samples from 155 heifers, and 254 dairy cows in 21 farms at North of Portugal sampled between December 2017 and June 2019. The prevalence of STEC in heifers (45%) was significantly higher than in lactating cows (16%) (p 0.05, Fisher exact test statistic value is 0.00001). A total of 133 STEC were isolated, 24 (13.8%) carried Shiga-toxin 1 (stx1) genes, 69 (39.7%) carried Shiga-toxin 2 (stx2) genes, and 40 (23%) carried both stx1 and stx2. Intimin (eae) virulence gene was detected in 29 (21.8%) of the isolates. STEC isolates belonged to 72 different O:H serotypes, comprising 40 O serogroups and 23 H types. The most frequent serotypes were O29:H12 (15%) and O113:H21 (5.2%), found in a large number of farms. Two isolates belonged to the highly virulent serotypes associated with human disease O157:H7 and O26:H11. Many other bovine STEC serotypes founded in this work belonged to serotypes previously described as pathogenic to humans. Thus, this study highlights the need for control strategies that can reduce STEC prevalence at the farm level and, thus, prevent food and environmental contamination.
- Prevalence of shigatoxigenic Escherichia coli in bovine cattle: a survey in the North Region of PortugalPublication . Ballem, Andressa; Gonçalves, Soraia; Ferreira, A.I.; Fernandes, Conceição; Saavedra, Maria José; Pinto, C.; Oliveira, H.; Almeida, Gonçalo; Almeida, CarinaShiga toxin-producing Escherichia coli (STEC) strains are food-borne pathogens that can be transmitted to humans through many different routes, but mainly through consumption of contaminated foods. STEC strains are characterized by the production of Shiga toxins (Stx) that are encoded by two genes stx1 and/or stx2. Each toxin can be subdivided into subtypes and, currently, there are three known subtypes for stx1 (stx1a, stx1c, and stx1d) and seven for stx2 (stx2a, stx2b, stx2c, stx2d, stx2e, stx2f, and stx2g). Others virulence factors, such the production of intimin protein, encoded by eae gene, are associated with severe outcomes of STEC-associated diseases. The most common STEC serotype implicated worldwide is E. coli O157:H7, but many other STEC strains are associated with severe human diseases. Ruminants, especially cattle, are a major reservoir for O157 and non-O157 STEC. Information on STEC prevalence in Portuguese dairy cattle is limited, so we analysed for the presence of STEC 329 faecal specimens collected from the rectum of healthy dairy cattle. The samples were collected from adult lactating cows (n=194) and from heifers (n=135) with ages among 6 to 18 months, between March and June 2019, at milk farms (n=17) in the North region of Portugal. After enrichment, in modified TSB with novobiocin, samples were analysed by real time PCR to detect the presence of stx1, stx2 and eae in accordance to ISO/TS 13136:2012(E). In addition, conventional PCR for the detection of sxt1 and stx2 gene subtypes was performed according to the guidelines of the VTEC European Union Reference
- Prevalence of shigatoxigenic Escherichia coli in bovine cattle: a survey in the North Region of PortugalPublication . Ballem, Andressa; Gonçalves, Soraia; Ferreira, A.I.; Fernandes, Conceição; Saavedra, Maria José; Pinto, C.; Oliveira, H.; Almeida, Gonçalo; Almeida, CarinaTo assess the prevalence of STEC in dairy cattle faeces in the North of Portugal and to determine the genetic pool of STEC virulence genes: stx1 and stx2 and eae.