Resultado da pesquisa (2)
Termo utilizado na pesquisa Costa MM
#1 - (Online First) Serodetection of antibodies against bovine enzootic leukosis virus in confined Holstein cattle herds
Abstract in English:
The enzootic bovine leukosis (EBL) virus is the etiological agent of a permanent and incurable infection in cattle. The virus integrates into the host’s DNA and replicates continuously, primarily infecting B lymphocytes and negatively affecting the immune response of infected cattle. With oncogenic potential, the virus is responsible for the development of lymphomas in adult cattle; however, neoplasia is uncommon, occurring in approximately 2–5% of infected animals. Most seropositive cattle remain subclinical, which may lead to decreased immunity, particularly when associated with other diseases. This study aimed to estimate herd-level and within-herd seroprevalence of antibodies against EBL in confined dairy cow herds in the northern region of Rio Grande do Sul, Brazil. Four commercial farms using Free Stall or Compost Barn systems were selected by convenience, and all cows older than six months of age were sampled, totaling 750 animals. Serum samples were tested using a commercial blocking enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against EBL virus. Descriptive statistics were used to calculate herd-level and within-herd seroprevalences and their 95% confidence intervals (95% CI). All herds had at least one seropositive animal (herd-level prevalence: 100%). Within-herd seroprevalence varied across the four herds, ranging from 51% in the São Luiz Gonzaga herd to 65.2% in the Salvador das Missões herd, and the overall seroprevalence among all sampled cows was 55.1% (95% CI: 51.2–58.9). These results demonstrate a high level of EBL seropositivity among dairy cows in the four confined herds evaluated in this study in the northern region of Rio Grande do Sul and indicate similarities in management practices and seroprevalence across these farms.
Abstract in Portuguese:
O vírus da leucose enzoótica bovina (LEB) é o agente etiológico de uma infeção permanente e incurável nos bovinos. O vírus integra-se no DNA do hospedeiro e replica-se continuamente, infectando principalmente os linfócitos B e afetando negativamente a resposta imunitária dos animais infectados. Com potencial oncogênico, o vírus é responsável pelo desenvolvimento de linfomas em bovinos adultos; no entanto, a neoplasia é pouco frequente, ocorrendo em aproximadamente 2–5% dos animais infectados. A maioria dos bovinos soropositivos mantém-se assintomática, o que pode levar a uma diminuição da imunidade, sobretudo quando associada a outras doenças. Este estudo teve como objetivo estimar a soroprevalência de anticorpos contra o vírus da LEB em rebanhos leiteiros confinados na região norte do Rio Grande do Sul, Brasil, tanto a nível de rebanho como dentro de cada rebanho. Foram selecionadas quatro fazendas comerciais que utilizam sistemas de confinamento em “Free Stall” ou em “Compost Barn”, por conveniência, e foram amostrados todos os bovinos com mais de seis meses de idade, totalizando 750 animais. As amostras de soro foram testadas através de um ensaio de imunoabsorção enzimática (ELISA) de bloqueio comercial para detecção de anticorpos contra o vírus da LEB. Foram utilizadas estatísticas descritivas para calcular a soroprevalência ao nível do rebanho e dentro de cada rebanho, bem como os seus respetivos intervalos de confiança a 95% (IC 95%). Todos os rebanhos apresentaram pelo menos um animal soropositivo (prevalência ao nível do rebanho: 100%). A soroprevalência dentro de cada rebanho variou entre 51% no rebanho de São Luiz Gonzaga e 65,2% no rebanho de Salvador das Missões, e a soroprevalência global entre todas as vacas amostradas foi de 55,1% (IC 95%: 51,2–58,9). Estes resultados demonstram um elevado nível de soropositividade para o vírus da LEB entre vacas leiteiras nos quatro rebanhos confinados avaliados na região norte do Rio Grande do Sul e indicam similaridade de manejo e de soroprevalência entre as fazendas.
#2 - Antimicrobial activity of plant extracts and compounds over resistant Gram-negative isolates from domestic animals
Abstract in English:
Gram-negative bacteria present significant challenges due to their antimicrobial resistance. Members of the Enterobacterales order, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, pose the greatest risk to public health because of their numerous mechanisms of antimicrobial resistance. Therefore, this study aimed to evaluate the antimicrobial activity of crude ethanolic extracts (CEE) of Hymenaea martiana Hayne (jatobá), Commiphora leptophloeos (Mart.) Gillett (imburana), Ocimum campechianum Mill. (alfalvaca) and Morus nigra L. (amora miura), as well as the hexane and ethyl acetate fractions of the last one, against clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis obtained from domestic animals. Furthermore, three commercially available compounds – gallic acid (GA), p-Coumaric acid (p-CA), benzoic acid (BA) – and one conducting polymer (synthesized for the test), polypyrrole (Ppy), were also evaluated for their antimicrobial potential against these isolates. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts and compounds were determined. All E. coli and K. pneumoniae isolates were resistant to the tested extracts. The crude ethanolic extracts showed inhibitory activity against P. mirabilis isolates at concentrations of 3,125 µg/mL for H. martiana and 12,500 µg/mL for O. campechianum. However, C. leptophloeos, M. nigra, and their fractions (hexane and ethyl acetate), as well as GA, did not exhibit bactericidal activity against any of the pathogens. Benzoic acid demonstrated both inhibitory and bactericidal activity against all isolates, with pronounced bactericidal activity against two K. pneumoniae isolates (MBC of 2,000 µg/mL). p-Coumaric acid showed inhibitory activity against all isolates and bactericidal activity (MBC of 5,000 µg/mL) against 66.66% (4/6) of the isolates, proving effective against E. coli and K. pneumoniae. Polypyrrole exhibited the most potent antibacterial activity, inhibiting 100% of the isolates and showing bactericidal activity against 83.33% (5/6) of the clinical isolates tested. These results suggest that the tested extracts and compounds, particularly polypyrrole, may offer a viable alternative against multidrug-resistant microorganisms.
Abstract in Portuguese:
Gram-negative bacteria present significant challenges due to their antimicrobial resistance. Members of the Enterobacterales order, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, pose the greatest risk to public health because of their numerous mechanisms of antimicrobial resistance. Therefore, this study aimed to evaluate the antimicrobial activity of crude ethanolic extracts (CEE) of Hymenaea martiana Hayne (jatobá), Commiphora leptophloeos (Mart.) Gillett (imburana), Ocimum campechianum Mill. (alfalvaca) and Morus nigra L. (amora miura), as well as the hexane and ethyl acetate fractions of the last one, against clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis obtained from domestic animals. Furthermore, three commercially available compounds – gallic acid (GA), p-Coumaric acid (p-CA), benzoic acid (BA) – and one conducting polymer (synthesized for the test), polypyrrole (Ppy), were also evaluated for their antimicrobial potential against these isolates. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts and compounds were determined. All E. coli and K. pneumoniae isolates were resistant to the tested extracts. The crude ethanolic extracts showed inhibitory activity against P. mirabilis isolates at concentrations of 3,125 µg/mL for H. martiana and 12,500 µg/mL for O. campechianum. However, C. leptophloeos, M. nigra, and their fractions (hexane and ethyl acetate), as well as GA, did not exhibit bactericidal activity against any of the pathogens. Benzoic acid demonstrated both inhibitory and bactericidal activity against all isolates, with pronounced bactericidal activity against two K. pneumoniae isolates (MBC of 2,000 µg/mL). p-Coumaric acid showed inhibitory activity against all isolates and bactericidal activity (MBC of 5,000 µg/mL) against 66.66% (4/6) of the isolates, proving effective against E. coli and K. pneumoniae. Polypyrrole exhibited the most potent antibacterial activity, inhibiting 100% of the isolates and showing bactericidal activity against 83.33% (5/6) of the clinical isolates tested. These results suggest that the tested extracts and compounds, particularly polypyrrole, may offer a viable alternative against multidrug-resistant microorganisms.
