Deeper exploration of inflammatory cell populations in milk to monitor udder health in dairy cows

The present study explored the predictive values of milk leukocyte differentials (MLD) as a basis for improving the diagnosis of intramammary infections (IMIs) and subclinical mastitis. Quarter milk samples were collected for bacteriological analysis, quarter somatic cell count (qSCC), and MLD. The MLD were assessed using the cytospin technique, direct microscopic smears, and flow cytometry. The predictive values of each single leukocyte population and useful potential indices that could better reflect immune complexity were also calculated. Changes in the percentage of any leukocyte alone failed to substantially improve the predictive value of qSCC in diagnosing IMIs. Although certain parameters increased the area under the receiver operating characteristic curve (ROC curve) as a result of increased specificity values, a slight reduction in sensitivity was observed. The so-called CD8 complex was a unique parameter which improved both the sensitivity (78.79 %) and the specificity (80.77 %) in IMI diagnosis, resulting in the highest area under the ROC curve (0.87). To diagnose subclinical mastitis, the percentage of macrophages and the sum of the percentage PMNLs and T CD8+ cells divided by the percentage of macrophages showed the highest predictive values (sensitivity = 79.63, specificity = 73.68, and area under the ROC curve = 0.83) in the differentiation of the inflammatory condition status of cows. In conclusion, this study provides further insights into using T CD8+ lymphocytes in diagnosing bovine IMIs, combined with PMNLs and macrophages. The antidromic trend of macrophages vs. PMNLs and T CD8+ lymphocytes due to the increasing qSCCs was crucial to differentiating quarters under both inflammatory and non-inflammatory conditions.

Sensibilidade de bactérias causadoras de mastite bovinaaextratos de plantas nativas do cerrado / Sensitivity of bacteria causing bovine mastitis toextractsofnative plants of the cerrado / Sensibilidad de bacterias causantes de mastitis bovinaaextractos de plantas nativas en cerrado

A mastite bovina é a doença mais onerosa da produção leiteira e é caracterizadapelainflamação da glândula mamária. O tratamento da doença, sem o controle adequado, geramicrorganismos resistentes. Desta forma o uso de fitoterápicos tem se tornado uma fontedepesquisa como possível alternativa, como as plantas nativas do cerrado Dedaleiro (Lafoensiapacari), Jatobá (Hymenaea sp.) e Barbatimão (Stryphnodendron adstringens). No presentetrabalho, bactérias isoladas de vacas com mastite subclínica foram identificadas por testesbioquímicos. Posteriormente foram feitos testes de antibiograma e pesquisa por genesderesistência a antibióticos, por fim foi realizado o teste para avaliação da sensibilidadeaosextratos das plantas do cerrado. Foram identificados Staphylococcus aureus (S.aureus), Enterobacter sp. e Escherichia coli (E. coli). Entre os isolados de S. aureus, foramencontrados resistentes a meticilina (MARS), bem como resistentes à vancomicina (VARS). Foram encontrados isolados produtores de beta-lactamases de espectro extendido(ESBL)para Entreobacter sp. e E. coli. Os extratos, principalmente de Stryphnodendron adstringenseLafoensia pacari, são uma alternativa para a terapêutica antimicrobiana.(AU)

Bovine mastitis is the most costly disease of dairy production and is characterizedbyinflammation of the mammary gland. The treatment of the disease, without adequate control, generates resistant microorganisms. In this way, the use of herbal medicines has becomeasource of research as a possible alternative, such as the native plants of the cerrado Dedaleiro(Lafoensia pacari), Jatobá (Hymenaea sp.) and Barbatimão (Stryphnodendron adstringens). In the present work, bacteria isolated from cows with subclinical mastitis were identifiedthrough biochemical tests. Subsequently, antibiogram tests and research for antibioticresistance genes were carried out, finally the test was carried out to evaluate the sensitivitytoextracts of cerrado plants. Staphylococcus aureus (S.aureus), Enterobacter sp. andEscherichia coli (E. coli). Among the S. aureus isolates, methicillin resistant (MARS) as well as vancomycin resistant (VARS) were found. Extended spectrum beta-lactamases (ESBL)producing isolates were found for Entreobacter sp. and E. coli. The extracts, mainly from Stryphnodendron adstringens and Lafoensia pacari, are an alternative for antimicrobial therapy.(AU)

La mastitis bovina es la enfermedad más costosa de la producción lechera y se caracterizaporla inflamación de la glándula mamaria. El tratamiento de la enfermedad, sin uncontrol adecuado, genera microorganismos resistentes. De esta forma, el uso de fitoterápicos sehaconvertido en fuente de investigación como posible alternativa, como las plantas nativas del cerrado Dedaleiro (Lafoensia pacari), Jatobá (Hymenaea sp.) y Barbatimão (Stryphnodendronadstringens). En el presente trabajo se identificaron mediante pruebas bioquímicas bacteriasaisladas de vacas con mastitis subclínica. Posteriormente se realizaron pruebas deantibiograma e investigación de genes de resistencia a antibióticos, finalmente se realizólaprueba para evaluar la sensibilidad a extractos de plantas de cerrado. Staphylococcus aureus(S. aureus), Enterobacter sp. y Escherichia coli (E. coli). Entre los aislamientos de S. aureus, se encontraron resistentes a la meticilina (MARS) y resistentes a la vancomicina (VARS). Seencontraron aislamientos productores de betalactamasas de espectro extendido (ESBL) paraEntreobacter sp. y E. coli. Los extractos, principalmente de Stryphnodendron adstringensyLafoensia pacari, son una alternativa para la terapia antimicrobiana.(AU)

Efficacy assessment of an intramammary formulation based on soluble polypyrrole in cows with experimentally induced mastitis / Avaliação da eficácia de uma formulação intramamária à base de polipirrol solúvel em vacas com mastite experimentalmente induzida

Considerando a necessidade de terapias alternativas para a mastite bovina, uma inflamação, normalmente de causa infecciosa, de alta prevalência e de alto impacto econômico nas fazendas leiteiras, avaliou-se a eficácia antimicrobiana, in vivo, de uma formulação intramamária à base de polipirrol (PPy) solúvel, um polímero condutor promissor para aplicações biomédicas, especialmente como potente antibacteriano. Neste ensaio, quartos mamários de vacas holandesas sadias (n = 8) foram inoculados com Staphylococcus aureus e tratados, por via intramamária, com formulação experimental à base de PPy solúvel (5%) e com formulação comercial à base de sulfato de gentamicina. O efeito desses tratamentos foi avaliado com a realização de lactoculturas, da Contagem Bacteriana Total (TBC), da Contagem de Células Somáticas (SCC) e da análise da composição do leite das amostras obtidas de quartos mamários, em sete momentos experimentais. Avaliação hematológica dos animais também foi realizada. A aplicação intramamária de três doses da formulação experimental à base de PPy solúvel resultou em maiores log/mL da TBC e da SCC quando comparadas ao grupo controle positivo e ao grupo que recebeu sulfato de gentamicina. A administração da formulação experimental não induziu alterações na composição do leite e nos parâmetros hematológicos. Alguns fatores farmacocinéticos e farmacodinâmicos do PPy solúvel podem ser atribuídos a ineficácia antimicrobiana da pomada experimental. Outras pesquisas devem ser realizados em prol do desenvolvimento de formulações que permitam a atuação antibacteriana do PPy solúvel no ambiente intramamário de vacas leiteiras.

Given the need for alternative therapies for bovine mastitis, an infectious disease of high prevalence and significant economic impact in dairy farms, this study evaluated the in vivo antimicrobial efficacy of an intramammary formulation based on soluble polypyrrole (PPy), a promising conductive polymer for biomedical applications, especially as an effective antimicrobial agent. In this assay, mammary quarters of healthy Holstein Friesian cows (n = 8) were inoculated with Staphylococcus aureus and treated, via the intramammary route, with an experimental formulation based on soluble PPy (5%) and a commercial formulation based on gentamicin sulfate. The effect of these treatments was evaluated based on milk cultures, Total Bacterial Count (TBC), Somatic Cell Count (SCC), and milk composition analysis of mammary quarter samples in seven experimental moments. In addition, hematological evaluations of the animals were also performed. The intramammary application of three levels of the experimental formulation based on soluble PPy resulted in higher log/mL of the TBC and SCC compared to a positive control group and a group that received gentamicin sulfate. The experimental formulation did not induce changes in milk composition or in hematological parameters. Certain factors related to pharmacokinetics, such as the type of carrier used in the formulation and the pharmacodynamics of soluble PPy, may have contributed to the antimicrobial ineffectiveness of the experimental formulation. The results of this study neither define nor decrease the antimicrobial potential of soluble PPy. Further research is required to develop formulations that enable the antibacterial action of soluble PPy in the intramammary environment of dairy cows.

Commercial mastitis vaccines - effects on mastitis rates and somatic cell counts in Saanen goats

Background: Staphylococcus spp. are the most frequently isolated microorganisms in mastitis cases of small ruminants. The virulence factors of Staphylococcus spp. are critical in the treatment. Therefore, preventive medicine and mastitis control programs, especially herd vaccinations are of great importance in the prevention of mastitis. However, it is not always easy to obtain these vaccines under field conditions. This study, it was aimed to compare the effects of different commercial Staphylococcus spp. vaccines licensed for bovines and species-specific mastitis vaccines on mastitis rates and somatic cell count (SCC) on Saanen goats on field conditions. Materials, Methods & Results: The animal material consisted of 115 (230 udder halves) nulliparous Saanen goats. Goats were randomly grouped as bovine vaccine 1 (BV1 , n = 58), bovine vaccine 2 (BV2 , n = 58), small ruminant vaccine (SRV, n = 56), and control (n = 56). Vaccines were administered to goats in 2 doses according to the label regimen. First milk samples were collected between 0-5 days in milk (DIM) for microbiological analysis and 25-35 DIM for SCC. The other milk samples were collected at 25-35 (1st month) DIM, 60-65 (2nd month) DIM, 85-95 (3rd month) DIM, 115-125 (4th month) DIM, 145-155 (5th month) DIM for microbiological analysis and SCC. Non-aureus staphylococci (NAS) and Staphylococcus aureus were the most frequently isolated microorganism. It was found that the total mastitis rate decreased in vaccine groups compared to the control group. A significant difference was found only in the BV2 and SRV groups. The significant difference in S. aureus infection was found only in the SRV group. Mastitis vaccines used in this study decreased the NAS mastitis rate, but no significant difference was observed. It was found that the clinical mastitis incidence decreased in all vaccine groups compared to the control group, and a significant difference was found between the BV2 and SRV groups compared to the control group (P < 0.05). Somatic cell count was lower in the SRV and BV2 groups compared to the control group (P < 0.05). Discussion: In this study, compatible with the previous reports NAS and S. aureus were the most frequently isolated microorganism. The diversity of virulence factors of Staphylococcus spp. also plays an important role in its high incidence. In some countries, mastitis vaccines used in cows are also administered to small ruminants for reducing infection rates. Similarly, in this study, it was found that the mastitis rate decreased in all vaccine groups compared to the control group. A significant difference was found only in the BV2 and SRV groups. It is thought that the reason for the statistical difference may be due to the biofilm antigen in the BV2 and SRV. In addition, J5 strain in the BV2 is estimated to be effective in reducing the prevalence of gram-negative mastitis. It was observed that the infection rates decreased in the vaccine groups, especially due to S. aureus and NAS. Spontaneous treatment rates were very close to each other between the groups. The reason for the high rate of spontaneous treatment in this study can be explained by the fact that the animals were young and in their 1st lactation. SCC was lower in all vaccine groups compared to the control group. This situation is associated with the decrease in infection rates related to the use of vaccines. It was observed that SCC was lower in the vaccine groups. In addition, SCC was found to be lower in this study compared to similar studies. However, it is evident that the use of species-specific vaccines in the SRV group significantly reduced the rates of total S. aureus mastitis, subclinical NAS mastitis, and new infections by NAS compared to other vaccines. Furthermore, the species-specific vaccine significantly increased the rate of spontaneous treatment for S. aureus mastitis.

Impact of different search strategies on the results of a meta-analysis for mastitis in dairy cattle / Impacto de diferentes estratégias de busca sob os resultados de uma metanálise para a característica mastite em gado de leite

Poorly formulated search strategies can have great influences on the results of a meta-analysis, since it directly impacts the amount and adherence to the theme of the works used for study, therefore, the formulation of a consistent and functional search strategy is essential for the review system to achieve its goals. The objective of this work was to study the impact of different search strategies in a systematic review by performing a meta-analysis to estimate heritability for the mastitis trait in dairy cattle. Once the search strategies were defined, the searches carried out in the Web of science, Scopus, Scielo and Pubmed databases returned 921 studies from which, after going through the identification, selection, eligibility and inclusion processes, 25 studies were selected. Withdrawals from selected articles, 26 heritability estimates were used in the meta-analysis. A random effect model was used, with all analyzes performed by the R program, through the Metafor package. The estimates obtained through the combined statistics of studies for mastitis, presented values of low magnitude (0.05 and 0.06). The effects of search strategies have a significant impact on the meta-analysis estimates produced.

Estratégias de buscas mal formuladas podem apresentar grandes influências nos resultados de uma metanálise, uma vez que impacta diretamente na quantidade e aderência ao tema dos trabalhos utilizados para estudo, portanto, a formulação de uma estratégia de busca consistente e funcional é fundamental para que a revisão sistemática atinja seus objetivos. O objetivo deste trabalho foi estudar o impacto de diferentes estratégias de busca em uma revisão sistemática por meio da realização de uma metanálise para estimação de herdabilidade para a característica mastite em gado de leite. Uma vez definidas as estratégias de busca, as pesquisas realizadas nas bases de dados Web of science, Scopus, Scielo e Pubmed retornaram 921 estudos dos quais, após passarem pelos processos de identificação, seleção, elegibilidade e inclusão, 25 estudos foram selecionados. Retiradas dos artigos selecionados, 26 estimativas de herdabilidades foram utilizadas na realização da metanálise. Utilizou-se um modelo de efeito aleatório, sendo todas as análises realizadas pelo programa R, por meio do pacote Metafor. As estimativas obtidas através da estatística combinada de estudos para mastite, apresentou valores de baixa magnitude (0,05 e 0,06). Os efeitos das estratégias de busca têm impacto significativo nas estimativas de metanálise produzidas.

Real-time polymerase chain reaction for detection and enumeration of Staphylococcus aureus and Streptococccus agalactiae using different milk samplings

The objective of the present study was to evaluate the qPCR for detection and enumeration of Staphylococcus aureus and Streptococcus agalactiae using different milk samplings in comparison to the conventional microbiology. Four dairy herds with a history of subclinical mastitis caused by S. aureus and S. agalactiae were selected. Sampling approach included milk samples from bulk tank (BT), cow level (composite samples, CO), and mammary quarter level (MQ) from 785 lactating cows. Three consecutive monthly milk samplings were carried out, totaling 3347 MQ milk samples, 912 CO, and 12 from BT. All collected milk samples were subjected to conventional microbiology and qPCR for detection and enumeration of S. aureus and S. agalactiae. The qPCR showed 71.5% of diagnostic sensitivity for S. aureus isolated from MQ milk samples, 71.8% for CO, and 50% for BT milk samples compared with conventional microbiology methodology. Taken together, the diagnostic sensitivity for S. agalactiae isolated from MQ milk samples was 90.2, 87.7 for CO, and 90.9% for BT milk samples. In general, the qPCR methodology enabled the detection of S. aureus and S. agalactiae, regardless of the type of milk sampling. The direct use of milk samples to estimate the counting of S. aureus by qPCR demonstrated lower sensitivity than the counting of S. agalactiae, which can be explained by the pathogen infection dynamics and differences in milk sample type.

Epidemiology of mastitis and interactions of environmental factors on udder health in the compost barn system / Epidemiologia da mastite e interações de fatores ambientais na saúde do úbere no sistema de Compost Barn

This study aimed to describe the epidemiological indexes of mastitis, milk quality and udder hygiene in the Compost Barn system, as well as to search for associations between isolated pathogens from milk with compost characteristics. Three dairy herds participated in the study, and the samples were collected during different periods on each farm. Individual milk samples were collected in duplicate for SCC analysis and microbiological culture. Environmental pathogens caused most cases of clinical mastitis on farm 2, and contagious pathogens caused the most cases on farm 1. Bed moisture was not associated with the incidence of environmental pathogens. Most of the animals remained in good udder hygiene during the study. Poor udder hygiene contributed to the increased incidence of environmental pathogens in one of the farms. A higher number of animals with a hygiene score of ≥ 2 were observed during the warmer and rainfall periods. There was no association between hygiene scores and somatic cell counts. The results suggest that pathogens isolated from milk in animals confined in Compost Barn under tropical climate are like other confinement systems adopted elsewhere. The year period influenced the udder hygiene score, reinforcing the importance of bed management throughout the year.

O objetivo deste estudo foi descrever os índices epidemiológicos da mastite, da qualidade do leite e da higiene do úbere em animais confinados no sistema Compost Barn, bem como buscar associações entre patógenos isolados do leite e características do composto. Três rebanhos leiteiros participaram do estudo e as amostras foram coletadas em diferentes períodos em cada fazenda. Amostras individuais de leite foram coletadas em duplicata para análise de CCS e cultura microbiológica. Patógenos ambientais causaram a maioria dos casos de mastite clínica na fazenda 2, e na fazenda 1 a maioria dos casos foi em decorrência de patógenos contagiosos. Amostras de material da cama foram coletadas em duas fazendas para análise da densidade bacteriana e da umidade. A umidade da cama permaneceu dentro da faixa de controle durante o estudo e não foi associada à incidência de patógenos ambientais. A maioria dos animais permaneceu com boa higiene de úbere durante o estudo. A falta de higiene do úbere contribuiu para o aumento da incidência de patógenos ambientais em uma das fazendas. Durante o período mais quente e mais chuvoso, um número maior de animais com escore de sujidade ≥2 foi observado em todos os rebanhos. Não houve associação entre escore de sujidade e contagem de células somáticas em qualquer uma das três fazendas. Os resultados indicam que o perfil de patógenos isolados do leite em animais confinados em Compost Barn sob clima tropical é semelhante a outros sistemas de confinamento adotados em outros lugares. O período do ano influenciou o escore de higiene do úbere, o que reforça a importância do manejo da cama ao longo do ano.

Genetic diversity and antimicrobial susceptibility of Staphylococcus aureus isolated from bovine mastitis in Minas Gerais, Brazil / Diversidade genética e susceptibilidade a antimicrobianos em Staphylococcus aureus isoladas de mastite bovina em Minas Gerais, Brasil

This study evaluated the genetic diversity and antimicrobial susceptibility of Staphylococcus aureus isolates from dairy cows in Minas Gerais, Brazil. Thirty-seven isolates from five municipalities (8 herds) were genotyped using multi-locus sequence typing (MLST) and susceptibility to 12 antimicrobial agents was tested using the disk diffusion method. High resistance rates for penicillin [75.68% (28/37)], ampicillin [70.27% (26/37)], and tetracycline [70.27% (26/37)] were detected. Multidrug resistance was observed in seven [18.92% (7/37)] isolates, and two were suggestive of Methicillin-resistant Staphylococcus aureus (MRSA). Among the 37 isolates, 33 novel sequence types (ST) and two known STs (ST126 and ST746) were identified in MLST. The clonal complexes more frequently observed were: CC97 [78.38%; (29/37)], CC1 [8.11%; (3/37)] and CC5 [5.40%; (2/37)]. Minimum­spanning tree (MST) analysis according to data from municipalities, herds, and resistance patterns for all isolates did not show any clustering pattern. However, the MST comparing all Brazilian S. aureus isolates deposited in the PubMLST database and from this study depicted an association between the genotype and strain origin (clinical sample). Isolates from this study that belong to CC97 were close to database isolates from milk and dairy products, while those that belong to CC1 and CC5 were close to database isolates from human sources and the environment of dairy farms or industries. In conclusion, our results showed a high rate of resistance to penicillins and tetracyclines and great genetic diversity among the S. aureus isolates from bovine mastitis genotyped in the present study.

Este estudo teve como objetivo avaliar a diversidade genética e a suscetibilidade a antimicrobianos de cepas de Staphylococcus aureus isoladas de vacas leiteiras em Minas Gerais, Brasil. Trinta e sete cepas provenientes de cinco municípios (oito rebanhos) foram genotipadas usando a técnica multi-locus sequence typing (MLST) e a suscetibilidade a 12 antimicrobianos foi avaliada pelo método de difusão em disco. Foram detectadas altas taxas de resistência para penicilina [75,68% (28/37)], ampicilina [70,27% (26/37)] e tetraciclina [70,27% (26/37)] entre os isolados. A multirresistência foi observada em sete [18,92% (7/37)] isolados e dois foram classificados como sugestivos de Staphylococcus aureus resistente à meticilina (MRSA). Entre os 37 isolados, 33 novos sequence types (ST) e dois STs conhecidos (ST126 e ST746) foram identificados pelo MLST. Os complexos clonais mais frequentemente observados foram: CC97 [78,38%; (29/37)], CC1 [8,11%; (3/37)] e CC5 [5,40%; (2/37)]. Foi construída uma minimum­spanning tree (MSTs) com todos isolados estudados e esta não mostrou padrão de agrupamento quando comparada com dados epidemiológicos como municípios e rebanho, do qual foi isolado, e perfis de resistência a antimicrobianos. Uma segunda MST foi construída comparando os isolados deste estudo e todas as cepas de S. aureus depositadas no banco de dados PubMLST provenientes do Brasil, que mostrou associação entre o genótipo, STs e a origem da cepa. Foi possível observar entre os isolados do estudo que, aqueles que pertenciam ao CC97, eram geneticamente mais próximos das cepas depositadas no PubMLST isoladas de leite e de produtos lácteos, enquanto aqueles que pertenciam aos CC1 e CC5 estavam mais próximos a cepas isoladas de humanos ou do ambiente de fazendas e indústrias de laticínios. Em conclusão, nossos resultados mostraram um alto índice de resistência às penicilinas e tetraciclinas e grande diversidade genética entre as cepas de S. aureus isoladas de casos de mastite bovina.

Prediction of health disorders in dairy cows monitored with collar based on binary logistic analysis / Previsão de distúrbios de saúde em vacas leiteiras monitoradas com base em coleira sobre análise logística binária

The objective of this study was to analyze data on physical activity and rumination time monitored via collars at the farm coupled with milk yield recorded by the rotary milking system to predict cows based on several disorders using the binary Logistic regression conducted with R software. Data for metritis (n=60), mastitis (n=98), lameness (n=35), and digestive disorders (n=52) were collected from 1,618 healthy cows used to construct the prediction model. To verify the feasibility and adaptability of the proposed method, we analyzed data of cows in the same herd (herd 1) not used to construct the model, and cows in another herd (herd 2) with data recorded by the same type of automated system, and led to detection of 75.0%, 64.2%, 74.2%, and 76.9% animals in herd 1 correctly predicted to suffer from metritis, mastitis, lameness, and digestive disorders, respectively. For cows in herd 2, 66.6%, 58.8%, 80.7%, and 71.4% were correctly predicted for metritis, mastitis, lameness, and digestive disorders, respectively. Compared with traditional clinical diagnoses by farm personnel, the algorithm developed allowed for earlier prediction of cows with a disorder.

Os objetivos deste estudo foram analisar dados sobre a atividade física e o tempo de ruminação monitorados através de coleiras na fazenda junto com a produção de leite registrada pelo sistema rotativo de ordenha para prever vacas com base em vários distúrbios utilizando o software de regressão logística binária realizado com o software R. Dados para metrite (n=60), mastite (n=98), manqueira (n=35) e distúrbios digestivos (n=52) foram coletados de 1.618 vacas saudáveis foram usados para construir o modelo de previsão. Para verificar a viabilidade e adaptabilidade do método proposto, analisamos os dados de vacas do mesmo rebanho (rebanho 1) não utilizadas para construir o modelo, e vacas de outro rebanho (rebanho 2) com dados registrados pelo mesmo tipo de sistema automatizado, e levamos à detecção de 75,0%, 64,2%, 74,2%, e 76,9% de animais do rebanho 1 previstos corretamente para sofrer de metrite, mastite, manqueira e distúrbios digestivos, respectivamente. Para as vacas do rebanho 2, 66,6%, 58,8%, 80,7% e 71,4% foram previstos corretamente para metrite, mastite, manqueira e distúrbios digestivos, respectivamente. Em comparação com os diagnósticos clínicos tradicionais feitos pelo pessoal da fazenda, o algoritmo desenvolvido permitiu a previsão antecipada de vacas com um distúrbio.

Identification of key genes in bovine mammary epithelial cells challenged with Escherichia coli and Staphylococcus aureus by integrated bioinformatics analysis

This study integrated four microarray datasets by Robust Rank Aggregation (RRA) method to identify the differentially expressed genes (DEG) in bovine mammary epithelial (BME) cells in response to Escherichia coli and Staphylococcus aureus infection. Furthermore, the GO function and KEGG pathway enrichment analysis of the integrated DEG were performed. Finally, the protein-protein interaction (PPI) network was constructed. A total of 72 integrated DEG were identified from the four datasets. The most significantly enriched terms within the integrated DEG were mainly involved in the immune response. The PPI network of DEG was constructed with 53 nodes. Seventeen genes, which constitute a significant module, were identified as hub genes. Among them, CD40, CXCL6, and NFKBIZ were further screened as the key genes and have the potential to become biomarkers of E. coli and S. aureus mastitis, considering the specificity of biomarkers for diseases. The identified key genes and pathways in this study can assist in the search for biomarkers for mastitis diagnosis and disease resistance breeding.

Genetic diversity and antimicrobial susceptibility of Staphylococcus aureus isolated from bovine mastitis in Minas Gerais, Brazil / Diversidade genética e susceptibilidade a antimicrobianos em Staphylococcus aureus isoladas de mastite bovina em Minas Gerais, Brasil

ABSTRACT: This study evaluated the genetic diversity and antimicrobial susceptibility of Staphylococcus aureus isolates from dairy cows in Minas Gerais, Brazil. Thirty-seven isolates from five municipalities (8 herds) were genotyped using multi-locus sequence typing (MLST) and susceptibility to 12 antimicrobial agents was tested using the disk diffusion method. High resistance rates for penicillin [75.68% (28/37)], ampicillin [70.27% (26/37)], and tetracycline [70.27% (26/37)] were detected. Multidrug resistance was observed in seven [18.92% (7/37)] isolates, and two were suggestive of Methicillin-resistant Staphylococcus aureus (MRSA). Among the 37 isolates, 33 novel sequence types (ST) and two known STs (ST126 and ST746) were identified in MLST. The clonal complexes more frequently observed were: CC97 [78.38%; (29/37)], CC1 [8.11%; (3/37)] and CC5 [5.40%; (2/37)]. Minimum‐spanning tree (MST) analysis according to data from municipalities, herds, and resistance patterns for all isolates did not show any clustering pattern. However, the MST comparing all Brazilian S. aureus isolates deposited in the PubMLST database and from this study depicted an association between the genotype and strain origin (clinical sample). Isolates from this study that belong to CC97 were close to database isolates from milk and dairy products, while those that belong to CC1 and CC5 were close to database isolates from human sources and the environment of dairy farms or industries. In conclusion, our results showed a high rate of resistance to penicillins and tetracyclines and great genetic diversity among the S. aureus isolates from bovine mastitis genotyped in the present study.

RESUMO: Este estudo teve como objetivo avaliar a diversidade genética e a suscetibilidade a antimicrobianos de cepas de Staphylococcus aureus isoladas de vacas leiteiras em Minas Gerais, Brasil. Trinta e sete cepas provenientes de cinco municípios (oito rebanhos) foram genotipadas usando a técnica multi-locus sequence typing (MLST) e a suscetibilidade a 12 antimicrobianos foi avaliada pelo método de difusão em disco. Foram detectadas altas taxas de resistência para penicilina [75,68% (28/37)], ampicilina [70,27% (26/37)] e tetraciclina [70,27% (26/37)] entre os isolados. A multirresistência foi observada em sete [18,92% (7/37)] isolados e dois foram classificados como sugestivos de Staphylococcus aureus resistente à meticilina (MRSA). Entre os 37 isolados, 33 novos sequence types (ST) e dois STs conhecidos (ST126 e ST746) foram identificados pelo MLST. Os complexos clonais mais frequentemente observados foram: CC97 [78,38%; (29/37)], CC1 [8,11%; (3/37)] e CC5 [5,40%; (2/37)]. Foi construída uma minimum‐spanning tree (MSTs) com todos isolados estudados e esta não mostrou padrão de agrupamento quando comparada com dados epidemiológicos como municípios e rebanho, do qual foi isolado, e perfis de resistência a antimicrobianos. Uma segunda MST foi construída comparando os isolados deste estudo e todas as cepas de S. aureus depositadas no banco de dados PubMLST provenientes do Brasil, que mostrou associação entre o genótipo, STs e a origem da cepa. Foi possível observar entre os isolados do estudo que, aqueles que pertenciam ao CC97, eram geneticamente mais próximos das cepas depositadas no PubMLST isoladas de leite e de produtos lácteos, enquanto aqueles que pertenciam aos CC1 e CC5 estavam mais próximos a cepas isoladas de humanos ou do ambiente de fazendas e indústrias de laticínios. Em conclusão, nossos resultados mostraram um alto índice de resistência às penicilinas e tetraciclinas e grande diversidade genética entre as cepas de S. aureus isoladas de casos de mastite bovina.

Caudal vena cava thrombosis in cows

Background: Caudal vena cava thrombosis (CVCT) is a serious disease that affects cattle. Due to being commonly a fatal pathology, it causes economic losses for producers and national livestock. Thus, the present study describes the epidemiological, clinical, ultrasonographic imaging and pathological findings in 4 cattle with CVCT attended at the Veterinary Hospital (HV) of the Institute of Veterinary Medicine (IMV) of the Federal University of Pará (UFPA). Cases: The animals were crossbreds of the Gir x Holstein and Jersey x Holstein breeds, aged between 4 and 8 years old, raised in semi-extensive and intensive systems. The main clinical signs were pale mucous membranes, reluctance to move, markedly positive venous pulse, engorged jugular with positive stasis test, and serous to mucopurulent nasal exudation. The auscultation of the lung fields revealed tachypnea, silent areas, wheezing, and pleural friction, in addition to coughing, expiratory dyspnea, mouth breathing, and expiratory grunts. One animal had severe hemoptysis. The ultrasound examination performed on a bovine revealed a circular and dilated caudal vena cava in cross-section. Laboratory tests in 3 cattle revealed anemia, leukocytosis with neutrophil left shift, and increased liver enzymes. At necropsy, all cattle had thrombi in the hepatic segment of the caudal vena cava. In the lung, multiple abscesses and areas of parenchymal consolidation, crateriform areas, as well as thrombi in the arteries were observed. Pleural effusion and ascites were seen in all cattle. Clotted blood was seen in the trachea, bronchi, and on rumen contents of an animal. Histopathological alterations seen in the liver were centrilobular hepatocytes with frequent intensely eosinophilic cytoplasm, and pyknotic, karyorrhexic, or absent nuclei and cell borders barely distinguishable. In the lung were nodular and random formations, with a thick wall of mature connective tissue and a central area full of cellular debris, necrotic cells, and intact and degenerated neutrophils (abscesses). Discussion: The set of diagnostic tools that include epidemiology, clinical signs and clinical examinations, ultrasound, necropsy, and histopathology were efficient in the diagnosis of CVCT. The possible causes that led the animals to develop CVCT were diffuse septic pododermatitis in the medial nail of the right pelvic limb associated with traumatic reticuloabomasitis and liver abscesses. In 1 cow, it was not possible to establish the probable cause of CVCT, but for the other cattle in the present study, the probable causes are in agreement with studies that have shown that this disease can occur as a sequel to several septic conditions such as jugular phlebitis, mastitis, hoof rot, enteritis, pneumonia, traumatic reticulopericarditis, acidosis and rumen laminitis, as well as omphalophlebitis in calves. The tachypnea, serous to purulent nasal exudation, pulmonary wheezing, pleural friction, coughing, and expiratory dyspnea, usually with open mouth breathing and expiratory grunts evidenced in the animals of this study, occurred as a result of embolic abscess pneumonia. The presence of multiple lung abscesses, areas of parenchymal consolidation, crateriform foci, and thrombi in the pulmonary arteries and chronic suppurative pneumonia, found at necropsy of the animals in the present study, are related to the development of a thrombus in the caudal vena cava that detaches and embolizes and lodges in the pulmonary arteries. The histopathological findings in 1 cow are compatible with lesions found at necropsy and draw attention to embolic pneumonia and liver lesions, which, are related to thrombi in pulmonary arteries and abscesses formed from CVCT, as well as venous stasis exerted in the return circulation.

Economic and production aspects ofmilking management in dairy farming / Aspectos econômicos e produtivos do manejo de ordenha na pecuária leiteira

The Brazilian dairy sector is important for the world agricultural production; however, it presents problems in production efficiency and milk quality, since the occurrence of mastitis in the herds can reach 47%. The present study analyzed data from a rural property with 100 lactating cows in a semi-intensive breeding system, which did not adopt adequate hygiene management for milking processes. Corrective measures were proposed, such as daily strip cup test, biweekly California Mastitis Test, formation of a new milking line, and daily pre dipping and post dipping and cleaning of teat cups. Milk samples from 10 animals with positive clinical mastitis, 10 animals with positive subclinical mastitis, and from the cooling tank were collected at one day before and 90 days after the implementation of the proposed measures and sent to a laboratory for analysis of somatic cell counting (SCC) and total bacteria counting (TBC). An increase of 17% in milk production and decreases of 64% and 40% in clinical and subclinical mastitis, respectively, were found after 90 days, with a consequent decrease in SCC and TBC. The milking duration after this period denoted an adaptation of the employees to the new procedures. The production financial yield was calculated based on the implementation costs of the adopted adequations and increases in milk production, representing a profitability increase of 10.4%. The implemented adequations were efficient for the control of mastitis and increase in milk yield and quality, resulting in a positive economic return.(AU)

O setor lácteo brasileiro possui grande relevância na produção agrícola mundial e apesar disso, ainda são encontra-dos problemas na eficiência produtiva e na qualidade do leite, onde a prevalência de mastite nos rebanhos pode chegar a 47%. Neste estudo, foram analisados dados de uma propriedade rural com 100 vacas lactantes e sistema de criação semi-intensivo, que não adotava manejo higiênico adequado na ordenha. Foram propostas medidas de correção como execução diária do teste da caneca telada e teste quinzenal do CMT, formação de nova linha de ordenha, adoção diária do pré dipping e pós dipping e higienização das teteiras. Foram coletadas amostras de leite de 10 animais positivos para mastite clínica, 10positivos para mastite subclínica e do tanque de resfriamento um dia antes e 90 dias após a implementação das novas medidas e enviadas ao laboratório para análise da CCS e CBT. Após 90 dias, houve aumento na produção de leite em 17% e redução dos índices de mastite clínica e subclínica em 64% e 40%, respectivamente, com consequente diminuição dos valores de CCS e CBT. A duração da ordenha após esse período indicou adaptação dos colaboradores aos novos procedimentos instaurados. Por fim, calculou-se o rendimento financeiro da produção baseado nos custos de implantação das correções e no aumento da produção de leite, que reverteu-se em lucratividade 10,4% maior. Conclui-se que as adequações implementadas foram eficazes no con-trole de mastite e no aumento da produtividade dos animais e da qualidade do leite, resultando em retorno econômico positivo.(AU)

Termografia infravermelha aplicada ao diagnóstico de mastite subclínica / Infrared thermography applied in diagnosis of subclinical mastites

A mastite é uma doença inflamatória de alta incidência nos rebanhos leiteiros de todo o mundo, sendo responsável por grandes prejuízos econômicos na cadeia produtiva do leite. Existem diversos testes para a detecção da forma subclínica da doença, sendo os mais utilizados: a contagem de células somáticas (CCS) e o California Mastitis Test (CMT). No entanto, esses testes possuem algumas limitações práticas, como a interpretação subjetiva, o que pode resultar em diagnósticos falso-positivos. Diante desses aspectos, novas tecnologias vêm sendo estudadas para auxiliar o diagnóstico precoce da mastite subclínica, dentre as quais a termografia infravermelha (TIV), que é um método não invasivo de diagnóstico por imagem. Dessa forma, o objetivo desta revisão foi discutir sobre a técnica de termografia infravermelha e sua aplicabilidade no diagnóstico de mastite subclínica. A TIV tem sido empregada, com sucesso, em várias áreas da produção animal de precisão, inclusive no diagnóstico de mastite, sendo relatadas alterações térmicas na superfície do úbere antes do aparecimento dos sintomas clínicos e sua correlação com a CCS do leite. O uso dessa tecnologia se mostra promissor para a detecção do estado não saudável do úbere, mesmo na forma subclínica. Entretanto, mais estudos devem ser realizados para que se avalie a aplicabilidade da técnica em rebanhos comerciais.

Mastitis is an inflammatory disease of high incidence in dairy herds around the world, resulting in great economic losses in the milk production chain. There are several tests to detect the subclinical form of this disease, where the most applied are the somatic cell count (SCC) and the California Mastitis Test (CMT). However, due to their subjectivity, these tests can result in false-positive diagnoses. Therefore, new technologies have been studied for the early diagnosis of subclinical mastitis, including infrared thermography (IRT), which is a non-invasive diagnostic approach. Thus, this review aimed to discuss the infrared thermography technique and its applicability in the diagnosis of subclinical mastitis. The IRT has been successfully applied in numerous areas of precision animal production, including mastitis diagnosis, showing thermal alterations on the udder surface before the onset of clinical symptoms that are linked to milk SCC. Therefore, the use of this technology is a promising strategy to detect the unhealthy udder state, even in the subclinical form. However, further studies should be carried out to assess the applicability of this technique in commercial herds.

Prevalence and influence of clinical and subclinical mastitis in the service period of dairy cows in Tarumirim (MG) / Prevalência e influência da mastite clínica e subclínica no período de serviço de vacas leiteiras em Tarumirim (MG)

The objective was to assess the prevalence and influence of clinical and subclinical mastitis during the service period of cows in a herd in Tarumirim (MG), from October 2019 to May 2020. Around 65 Gir x Holstein and Guzerá x Holstein lactating crossbred cows were evaluated. Subclinical mastitis was diagnosed by means of the California Mastitis Test (CMT), and clinical mastitis, by means of the strip cup test and the animals' clinical signs. Pregnancy after calving was diagnosed by the rectal palpation method, with the aid of ultrasound. The time from calving to conception was considered as the service time. The prevalence rates of clinical and subclinical mastitis were 2.9 and 63.7%, respectively, throughout the experimental period. The mean service period was shorter (p<0.05) in healthy cows (63.1 days) than in cows with subclinical mastitis (88.5 days) and clinical mastitis (111.2 days). The service period increased by 30.9 days for each mammary quarter with clinical mastitis (p<0.05). With each increase in the degree and days of duration of clinical and subclinical mastitis, the service period rose by 25.4 and 6.5 days, and 8.5 and 0.6 days, respectively (p<0.05). Therefore, mastitis increases the service period of dairy cows. Good milking hygiene and animal handling practices should be adopted in order to reduce the prevalence of mastitis in the herd.(AU)

Objetivou-se avaliar a prevalência e influência da mastite clínica e subclínica no período de serviço de vacas em um rebanho de Tarumirim (MG), ao longo de outubro de 2019 a maio de 2020. Em torno de 65 vacas mestiças Gir x Holandês e Guzerá x Holandês em lactação foram avaliadas. A mastite subclínica foi diagnosticada por meio de California Mastitis Test(CMT) e a mastite clínica por meio do teste da caneca e sinais clínicos dos animais. O diagnóstico de gestação após o parto foi realizado pelo método de palpação retal, com auxílio de ultrassom. O tempo do parto até a concepção foi considerado como o tempo de serviço. As prevalências de mastite clínica e subclínica foram de 2,9 e 63,7%, respectivamente, ao longo do período experimental. O período de serviço médio foi menor (p<0,05) em vacas sadias (63,1 dias) que em vacas com mastite subclínica (88,5 dias) e clínica (111,2 dias). O período de serviço aumentou 30,9 dias a cada quarto mamário com mastite clínica (p<0,05). A cada aumento do grau e dias de duração da mastite clínica e subclínica, o período de serviço aumentou 25,4 e 6,5 dias e 8,5 e 0,6 dias, respectivamente (p<0,05). Portanto, a mastite aumenta o período de serviço de vacas leiteiras. Boas práticas de higiene de ordenha e manejo dos animais devem ser adotadas para reduzir a prevalência de mastite no rebanho.(AU)

Training, development, and evaluation of on-farm culturing as a technical resource to reduce the use of antimicrobials in dairy herds in the Midwest Region of Santa Catarina State, Brazil / Capacitação, implementação e avaliação da cultura de leite na fazenda como recurso técnico voltado ao uso reduzido de antimicrobianos em rebanhos leiteiros no meio oeste catarinense

On-farm culturing is a technology booming in Brazil. It is based on the microbiological diagnosis of milk samples collected from clinical cases of bovine mastitis, on the farm where the animals are handled, quickly, simply, and at an affordable cost. With this resource, after 24 h of incubation, the isolated microorganisms are classified as gram positive or gram negative, helping to make decisions regarding the therapy of the animals. Considering the relevance of the Midwestern region of Santa Catarina State in the national dairy production scenario, the objectives of the study were: 1) to promote the technical training of the farmers in three dairy farms located in Treze Tílias-SC, 2) to assist in the implementation and evaluation of on-farm culturing as technological resource viewing the reduced use of antimicrobials in herds. In addition to the rapid acceptance by the farmers and their efficient training, with the use of the technology, there was a 45-50% reduction in the use of antimicrobials in dairy herds. This result demonstrated a significant effect on animal health, and determines an important cost reduction for farmers, as presented in detail in this manuscript.

A cultura de leite na fazenda (do inglês On farm culturing) é uma tecnologia em franca expansão no Brasil. Fundamenta-se no diagnóstico microbiológico de amostras de leite colhidas de casos clínicos de mastite bovina, na própria fazenda onde são manejados os animais, de forma rápida, simples e com custo acessível. Com este recurso, após 24 horas de incubação, os micro-organismos isolados são classificados em Gram-positivos ou Gram-negativos, auxiliando na tomada de decisões quanto à terapia dos animais. Considerando a relevância da região meio oeste catarinense no cenário nacional de produção leiteira, o objetivo do presente estudo foi promover a capacitação técnica dos produtores em três propriedades localizadas em Treze Tílias-SC, e auxiliar na implementação e avaliação da cultura de leite na fazenda como recurso tecnológico voltado ao uso reduzido de antimicrobianos nos rebanhos. Além da rápida aceitação pelos produtores e eficiente capacitação dos mesmos, verificou-se, com o emprego da tecnologia, redução de 45% a 50% do uso de antimicrobianos nos rebanhos. Este resultado, além de demonstrar significativo impacto em saúde animal, determinou importante redução de custos aos produtores, como apresentado detalhadamente no presente artigo.

Training, development, and evaluation of on-farm culturing as a technical resource to reduce the use of antimicrobials in dairy herds in the Midwest Region of Santa Catarina State, Brazil / Capacitação, implementação e avaliação da cultura de leite na fazenda como recurso técnico voltado ao uso reduzido de antimicrobianos em rebanhos leiteiros no meio oeste catarinense

On-farm culturing is a technology booming in Brazil. It is based on the microbiological diagnosis of milk samples collected from clinical cases of bovine mastitis, on the farm where the animals are handled, quickly, simply, and at an affordable cost. With this resource, after 24 h of incubation, the isolated microorganisms are classified as gram positive or gram negative, helping to make decisions regarding the therapy of the animals. Considering the relevance of the Midwestern region of Santa Catarina State in the national dairy production scenario, the objectives of the study were: 1) to promote the technical training of the farmers in three dairy farms located in Treze Tílias-SC, 2) to assist in the implementation and evaluation of on-farm culturing as technological resource viewing the reduced use of antimicrobials in herds. In addition to the rapid acceptance by the farmers and their efficient training, with the use of the technology, there was a 45-50% reduction in the use of antimicrobials in dairy herds. This result demonstrated a significant effect on animal health, and determines an important cost reduction for farmers, as presented in detail in this manuscript.(AU)

A cultura de leite na fazenda (do inglês On farm culturing) é uma tecnologia em franca expansão no Brasil. Fundamenta-se no diagnóstico microbiológico de amostras de leite colhidas de casos clínicos de mastite bovina, na própria fazenda onde são manejados os animais, de forma rápida, simples e com custo acessível. Com este recurso, após 24 horas de incubação, os micro-organismos isolados são classificados em Gram-positivos ou Gram-negativos, auxiliando na tomada de decisões quanto à terapia dos animais. Considerando a relevância da região meio oeste catarinense no cenário nacional de produção leiteira, o objetivo do presente estudo foi promover a capacitação técnica dos produtores em três propriedades localizadas em Treze Tílias-SC, e auxiliar na implementação e avaliação da cultura de leite na fazenda como recurso tecnológico voltado ao uso reduzido de antimicrobianos nos rebanhos. Além da rápida aceitação pelos produtores e eficiente capacitação dos mesmos, verificou-se, com o emprego da tecnologia, redução de 45% a 50% do uso de antimicrobianos nos rebanhos. Este resultado, além de demonstrar significativo impacto em saúde animal, determinou importante redução de custos aos produtores, como apresentado detalhadamente no presente artigo.(AU)

Influence of microclimate on ketosis, mastitis and diseases of cow reproductive organs

This study investigated the influence of the farm microclimate parameters in different seasons on the incidence of ketosis, foot diseases, reproductive diseases, and mastitis in three dairy farms of North Kazakhstan. Microclimate parameters were recorded in four seasons: summer, autumn, winter, and spring. The average temperature was 1.2 °C above the established norm in summer and 1.7 °C below the established norm in winter. The humidity was below the norm by 9.7% and 1.6% in summer and autumn, respectively, and above the norm by 9.6 % and 6.6 % in winter and spring, respectively. The airflow was 0.1 m/s lower than the norm in summer, winter, and spring. The general illumination was 3.8 and 2.6 LUX lower than the norm in winter and spring, respectively. The average morbidity (cumulative incidence of all four diseases) was 63.8% (highest) in the winter, followed by spring (60.0%). Average morbidity was considerably less in summer and autumn at 46.7% and 37.1%, respectively. Study results indicate that minor deviations in microclimate parameters from the norms, particularly in winter and spring, can considerably impact the disease incidence on dairy farms in Kazakhstan. The farm management should strive to maintain microclimate conditions on the farm as close to the norm as possible during different seasons to avoid losses from livestock morbidity.

Mastitis in cattle due to Mycobacteroides abscessus - case report / [Mastite bovina por Mycobacteroides abscessus - relato de caso]

Mastitis is considered the main disease that affects dairy cattle worldwide, and it is caused mainly by Staphylococcus aureus and environmental Streptococcus spp. Eventually, nonconventional pathogens, as rapidly growing mycobacteria (RGM), may also cause chronic mastitis, which will not be responsive to antibiotic treatments. Diagnosis of mastitis caused by RGM is a difficult task, and most of time this agent may be misdiagnosed. Here we describe a case of clinical mastitis caused by the RGM Mycobacteroides abscessus in a cow from Southern Brazil, confirmed by microbiological and molecular characterization. Our results reinforce the necessity of a detailed laboratorial identification of the agent and to include this agent in differential diagnosis of chronical clinical mastitis nonresponsive to treatment.

A mastite é considerada uma das principais doenças que afetam rebanhos leiteiros ao redor do mundo e é causada principalmente por Staphylococcus aureus e Streptococcus spp. ambientais. Eventualmente, patógenos não convencionais, como Mycobacterium de crescimento rápido (RGM), podem também causar mastite crônica, a qual não respondera ao tratamento com antimicrobianos. O diagnóstico de mastite causada por RGM é uma tarefa difícil, e a maioria das vezes esse agente pode ser subdiagnosticado. Neste relato, descreveu-se um caso de mastite clínica em uma vaca, no sul do Brasil, causada por RGM Mycobacteroides abscessus, confirmado por caracterização microbiológica e molecular. Os resultados reforçam a necessidade de um diagnóstico laboratorial detalhado para a identificação do agente e a inclusão deste como diagnóstico diferencial no reconhecimento de mastite crônica não responsiva ao tratamento.

Biofilm production by Staphylococcus spp. isolated from bovine mastitis in dairy herds in state of Acre, Brazil and its implications / Produção de biofilme por Staphylococcus spp. isolados de mastite bovina, em rebanhos leiteiros do estado do Acre, Brasil, e suas implicações

This study aimed to identify the Staphylococcus species responsible for bovine mastitis in dairy herds in northern Brazil, to investigate the capacity of biofilm production, and to analyze the association of biofilm production with multiresistance and intensity of California Mastitis Tests (CMT) reactions that can make treatment more difficult and cause misdiagnoses, respectively. Milk samples were collected from 23 dairy farms located in five municipalities in the state of Acre. A total of 339 crossbred cows were tested by CMT, with 109 animals (229 udder ceilings) reacting to the test. After bacterial isolation in blood agar, the catalase-positive and gram-positive cocci were submitted for identification by MALDI-TOF MS. Of 103 strains identified as staphylococci, Staphylococcus chromogenes (58.3%) and Staphylococcus aureus (19.4%) were the most prevalent species. Biofilm production was quantitatively evaluated using a microplate adherence test. Among the Staphylococcus strains, 71.8% were biofilm producers. Most strains of S. chromogenes (68.3%) had the capacity to produce biofilms, ranging from weak (43.3%), moderate (13.3%), and strong (11.7%) producers. Among S. aureus strains, 50% were non-biofilm producers, and none were strong producers. Our data showed an association between biofilm production capacity and multidrug resistance. In addition, there was a reduction in the response to the CMT test, which can mask the diagnosis.

O presente estudo teve como objetivos identificar as espécies de estafilococos envolvidas com mastite em rebanhos leiteiros no norte do Brasil, investigar a capacidade de produção de biofilme e analisar a associação da produção de biofilme com multirresistência e intensidade de reações de CMT que podem dificultar o tratamento e causar erros de diagnósticos, respectivamente. Amostras de leite foram coletadas em 23 propriedades leiteiras, situadas em cinco municípios do estado do Acre. Um total de 339 vacas mestiças foram testadas pelo CMT, sendo detectados 109 animais (229 tetos) reagentes ao teste. Após isolamento em ágar sangue, os cocos Gram positivos produtores de catalase foram submetidos à identificação por MALDI TOF MS. Um total de 103 estirpes foram identificadas como estafilococos, sendo mais prevalentes as espécies Staphylococcus chromogenes (58,3%) e S. aureus (19,4%). A produção de biofilme foi avaliada quantitativamente pelo teste de aderência em microplaca. Dentre todas as amostras de estafilococos, 71,8% foram produtoras de biofilme. A maioria das amostras de S. chromogenes (68,3%) apresentou capacidade de produzir biofilme, variando de fraco (43,3%), moderado (13,3%) a forte (11,7%) produtor. Entre as amostras de S. aureus, 50% não foram produtoras e nenhuma foi produtora forte. Essa capacidade de produção de biofilme mostrou-se associada à multirresistência a antimicrobianos, além de diminuir a intensidade no teste CMT, podendo mascarar o diagnóstico.