Sensibilidade antimicrobiana de patógenos causadores de mastite em vacas na região Centro-Oeste Paulista
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Data
2023-08-24
Autores
Amato, Beatriz Pinheiro [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A mastite gera prejuízos econômicos em rebanho leiteiros e interfere nos processos industriais de laticínios. O uso indiscriminado de antibióticos para tratar a doença agrava a resistência a tais medicamentos, sendo imprescindível a identificação do agente causador para o sucesso do tratamento. O objetivo do presente estudo foi isolar bactérias causadoras de mastite bovina em amostras de leite obtidas em propriedades leiteiras localizadas no Centro-Oeste Paulista e avaliar sua resistência frente aos antimicrobianos comumente utilizados em seu tratamento. Analisaram-se amostras de leite de 80 vacas com mastite clínica ou subclínica. As amostras foram inoculadas em Ágar Sangue e Ágar MacConkey e incubadas a 37 ºC/24 h. As colônias isoladas passaram por identificação morfo-tintorial (coloração de Gram) e bioquímica. Para a determinação da espécie, as amostras de leite também foram analisas por espectrometria de massa (MALDI-TOF MS). Os microrganismos identificados foram submetidos ao teste de sensibilidade aos antimicrobianos em placa de Ágar Müeller-Hinton (35 °C/24 h) com discos contendo Gentamicina (10 μg), Amoxicilina + Clavulanato (20 μg + 10 μg), Tetraciclina (30 μg) e Oxacilina (1 μg). Em 87,5% das amostras houve crescimento de bactérias Gram-positivas, com prevalência de Staphylococcus aureus (54,3%) e 21,2% das amostras apresentaram colônias de bactérias Gram-negativas, com o predomínio de Escherichia coli (18,6%). A resistência para oxacilina ocorreu em 48,6% das bactérias Gram-positivas e em 100% das bactérias Gram-negativas isoladas e, para tetraciclinas, a resistência foi de 12,8% e 29,4% respectivamente. Dentre as bactérias Gram-positivas, 11,4% apresentaram resistência para gentamicina e amoxacilina e clavulanato. As bactérias Gram-negativas apresentaram 5,9% de resistência para amoxacilina e clavulanato e nenhuma resistência frente à gentamicina. Concluiu-se que houve alta incidência de bactérias Gram-positivas causadoras de mastite na região e alta incidência de resistência a oxacilina entre os microrganismos isolados.
Mastitis causes economic losses in dairy herds and interferes in the industrial processes of dairy products. The indiscriminate use of antibiotics for its treatment leads to the worsening of resistance to these drugs, making the correct identification of the causative agent essential for the success of the treatment. The aim of the present study was to characterize the bacteria that cause bovine mastitis in milk samples obtained from dairy farms located in the Midwest of São Paulo and to assess whether there is resistance to the antimicrobials commonly used in the treatment of the disease. Milk samples from 80 cows with clinical or subclinical mastitis were analyzed. The samples were inoculated onto Blood Agar and MacConkey Agar and incubated at 37 °C/24 h. The colonies were identified by morpho-tinctorial identification (Gram staining) and biochemical tests. To determine the species level, the samples were also analyzed by mass spectrometry technique (MALDI-TOF MS). Subsequently, their antimicrobial susceptibility was tested on a Müeller-Hinton Agar plate (35 °C/24 h) with discs containing the antimicrobials Gentamicin (10 μg), Amoxicillin + Clavulanate (20 μg + 10 μg), Tetracycline (30 μg) and Oxacillin (1 μg). 87.5% of the samples had the growth of Gram-positive bacteria, with prevalence of Staphylococcus aureus (54.3%) and 21.2% of the samples showed colonies of Gram-negative bacteria, with predominance of Escherichia coli (18.6%). Resistance to oxacillin had an incidence of 48.6% for Gram-positive and 100% for Gram-negative and 12.8% and 29.4% for tetracyclines, respectively. Gram-positive bacteria showed 11.4% of resistance for gentamicin and for amoxacillin and clavulanate. Gram-negative bacterium showed 11.4% of resistance for amoxacillin and clavulanate and no resistance for gentamicin. It was concluded that there was a high incidence of Gram-positive bacteria causing mastitis in the region and a high incidence of resistance of the isolates to oxacillin.
Mastitis causes economic losses in dairy herds and interferes in the industrial processes of dairy products. The indiscriminate use of antibiotics for its treatment leads to the worsening of resistance to these drugs, making the correct identification of the causative agent essential for the success of the treatment. The aim of the present study was to characterize the bacteria that cause bovine mastitis in milk samples obtained from dairy farms located in the Midwest of São Paulo and to assess whether there is resistance to the antimicrobials commonly used in the treatment of the disease. Milk samples from 80 cows with clinical or subclinical mastitis were analyzed. The samples were inoculated onto Blood Agar and MacConkey Agar and incubated at 37 °C/24 h. The colonies were identified by morpho-tinctorial identification (Gram staining) and biochemical tests. To determine the species level, the samples were also analyzed by mass spectrometry technique (MALDI-TOF MS). Subsequently, their antimicrobial susceptibility was tested on a Müeller-Hinton Agar plate (35 °C/24 h) with discs containing the antimicrobials Gentamicin (10 μg), Amoxicillin + Clavulanate (20 μg + 10 μg), Tetracycline (30 μg) and Oxacillin (1 μg). 87.5% of the samples had the growth of Gram-positive bacteria, with prevalence of Staphylococcus aureus (54.3%) and 21.2% of the samples showed colonies of Gram-negative bacteria, with predominance of Escherichia coli (18.6%). Resistance to oxacillin had an incidence of 48.6% for Gram-positive and 100% for Gram-negative and 12.8% and 29.4% for tetracyclines, respectively. Gram-positive bacteria showed 11.4% of resistance for gentamicin and for amoxacillin and clavulanate. Gram-negative bacterium showed 11.4% of resistance for amoxacillin and clavulanate and no resistance for gentamicin. It was concluded that there was a high incidence of Gram-positive bacteria causing mastitis in the region and a high incidence of resistance of the isolates to oxacillin.
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Palavras-chave
Mastite, Bactérias, Antibióticos, Mastitis, Bacteria, Antibiotics