Elaine Maria Seles Dorneles

Escherichia coli is a versatile pathogen that causes bovine mastitis and acts as a reservoir of virulence and antimicrobial resistance genes, causing risks to both animal and public health. This study characterized 83 E. coli isolates from milk samples of cows with clinical (n = 19) or subclinical mastitis (n = 33) and fecal samples from lactating cows (n=31) in Brazil. The isolates were evaluated for phylogenetic group, antimicrobial susceptibility, extended-spectrum β-lactamase (ESBL), plasmid-mediated colistin resistance (mcr), O157 genotype, and biofilm formation. Phylogenetic classification revealed predominance of phylogroups A and B1. Antimicrobial susceptibility testing showed resistance to phenicols (38.6%), β-lactams (27.7%), polymyxins (20.5%), and tetracyclines (20.5%), with multidrug resistance (MDR) observed in 20.5% of isolates, most frequently among clinical mastitis and fecal strains. ESBL production was detected in 47.4% of the isolates evaluated, often concomitant with MDR. All isolates tested negative for the mcr genes, despite 20.5% being colistin-resistant, and were also negative for the O157 antigen. Biofilm formation was widespread, observed in 79.5% of the isolates. These results demonstrated the circulation of diverse antimicrobial-resistant profiles of E. coli strains in Brazilian dairy farms. Taken together, the coexistence of multidrug resistance, ESBL production, and biofilm-forming ability among isolates from mastitic milk and bovine feces indicates that antimicrobial-resistant E. coli strains are present in both clinical and intestinal reservoirs within dairy herds. Furthermore, the detection of colistin-resistant isolates lacking the investigated mcr genes suggests the involvement of alternative resistance mechanisms that warrant further investigation.

Escherichia coli is a versatile pathogen that causes bovine mastitis and acts as a reservoir of virulence and antimicrobial resistance genes, causing risks to both animal and public health. This study characterized 83 E. coli isolates from milk samples of cows with clinical (n = 19) or subclinical mastitis (n = 33) and fecal samples from lactating cows (n=31) in Brazil. The isolates were evaluated for phylogenetic group, antimicrobial susceptibility, extended-spectrum β-lactamase (ESBL), plasmid-mediated colistin resistance (mcr), O157 genotype, and biofilm formation. Phylogenetic classification revealed predominance of phylogroups A and B1. Antimicrobial susceptibility testing showed resistance to phenicols (38.6%), β-lactams (27.7%), polymyxins (20.5%), and tetracyclines (20.5%), with multidrug resistance (MDR) observed in 20.5% of isolates, most frequently among clinical mastitis and fecal strains. ESBL production was detected in 47.4% of the isolates evaluated, often concomitant with MDR. All isolates tested negative for the mcr genes, despite 20.5% being colistin-resistant, and were also negative for the O157 antigen. Biofilm formation was widespread, observed in 79.5% of the isolates. These results demonstrated the circulation of diverse antimicrobial-resistant profiles of E. coli strains in Brazilian dairy farms. Taken together, the coexistence of multidrug resistance, ESBL production, and biofilm-forming ability among isolates from mastitic milk and bovine feces indicates that antimicrobial-resistant E. coli strains are present in both clinical and intestinal reservoirs within dairy herds. Furthermore, the detection of colistin-resistant isolates lacking the investigated mcr genes suggests the involvement of alternative resistance mechanisms that warrant further investigation.

Este trabalho avaliou o impacto de concursos de qualidade do leite realizado pela Emater-MG em parceria com a Rede LeiteInova como ação extensionista na microrregião do Serro-MG. Comparou-se resultados globais de análises laboratoriais de 44 produtores de Queijo Minas Artesanal (QMA) participantes do 1º concurso (2024) e de 27 produtores de QMA e 26 produtores que comercializam leite à laticínios participantes do 2º concurso (2025). Comparou-se também os resultados de 14 produtores que participaram de ambos eventos. Considerou-se os índices de qualidade da IN 76/2018 e da Portaria 146/1996 do MAPA como referência. Os resultados mostraram uma redução da CCS global de 736,48×10³ CS/mL para 370,11×10³ CS/mL e redução de proporção de amostras positivas para estafilococos coagulase-positiva de 71,43% para 0% entre os produtores participantes de ambos concursos. Os demais parâmetros como gordura, proteína, lactose e sólidos mantiveram-se dentro dos padrões, no geral. No entanto, houve um aumento nas contagens de coliformes totais, o que ressalta a necessidade de aprimorar as práticas de higiene de ordenha. Conclui-se que os concursos de qualidade do leite servem como diagnóstico situacional aos extensionistas, incentivam a melhoria da qualidade do leite e promovem o desenvolvimento sustentável da cadeia produtiva na microrregião do Serro-MG.

This study investigated the relationship between uterine inflammation, microbiological composition, and housing conditions in dairy cows managed in compost-bedded pack barn (CBP) systems. A total of 312 cows from 20 herds were clinically evaluated 3–45 days postpartum, and two endometrial samples were collected, one for cytology and other for bacterial isolation using microbiological culture followed by MALDI-TOF MS. Bedding material was analyzed for physicochemical properties, including moisture, pH, temperature, and organic matter. The optimal threshold for diagnosing subclinical endometritis was determined at the point where the decrease in Akaike Information Criteria (AIC) began to plateau, as identified by linear regression analysis. Subclinical endometritis was diagnosed at a polymorphonuclear cells (PMN) cutoff of 8.3 %. No bedding physicochemical characteristic were significantly associated with PMN levels by means of a linear model, indicating that CBP systems — under appropriate management conditions — do not inherently increase uterine inflammatory risk. Microbiological analysis revealed a diverse uterine microbiota typical of the postpartum period. Four bacterial genera showed significant associations with inflammation in the mixed-effects model: Prevotella and Arthrobacter were positively associated with PMN counts, whereas Enterococcus and Histophilus showed negative association. These findings highlight the complexity of the postpartum uterine ecosystem and emphasize the value of integrating microbiological profiling with cytological evaluation. Establishing a PMN threshold of 8.3 % provides a practical diagnostic reference for herds housed in CB systems. Further studies are needed to clarify the functional roles of non-classical taxa in uterine health.

This study estimated the self-reported prevalence of accidental exposure and its associated risk factors related to the S19 and RB51 vaccine strains, as well as occupational brucellosis among veterinarians registered at the Secretaria de Estado da Agricultura, Abastecimento e Desenvolvimento Rural (SEAGRI) in the Distrito Federal (DF), Brazil. Data were collected through an online questionnaire, with one hundred and seven (107) participants included in the census. Accidental exposure to the S19 vaccine was reported by 22.43% (24/107) of the respondents, whereas the prevalence of self-reported occupational brucellosis cases was 8.41% (9/107), 55.56% (5/9) of which were attributed to S19 exposure. Multivariate logistic regression models for vaccine exposure and self-reported brucellosis by veterinarians were tested, but no significant results were obtained for any variable selected by the purposeful selection algorithm. Although risk factors associated with these outcomes were not identified in the studied population, the present study contributes significantly to the formulation of public policies aimed at disease prevention and control, as well as improvements in health education for these veterinarians.

Brucellosis is a zoonotic bacterial infection of significant concern for veterinary and public health. Following the recent identification of a novel Brucella species in bats, this study aimed to screen bat samples captured from regions encompassed by the Pesquisa Ecológica de Longa Dura¸c˜ao with high bat diversity. Two field campaigns were conducted in April and October 2023 in each study site: Vereda de Perua¸cu, Vereda de Pedras, and a Private Natural Heritage Reserve. Mist nets were used to capture bats, which were then evaluated for species, sex and age. Oral and rectal swabs were collected, placed in Stuart transport medium, and stored at -80°C. Samples were processed in a Biosafety Level 3 laboratory for Brucella spp. isolation. Swabs were eluted in phosphate-buffered saline and incubated in trypticase soy broth with Farrell selective supplement. After 7 days at 37°C under 5% CO2, aliquots were plated on trypticase soy agar and incubated under the same conditions. Bacterial growth was monitored, and up to five colonies per sample were selected for biochemical analysis. Suggestive colonies were inactivated, stored, and subjected to DNA extraction using the guanidinium thiocyanate method. All DNA samples were tested for Brucella spp. using conventional PCR (bcsp31), qPCR (IS711), and Multiplex PCR (Bruce-ladder and AMOS). A total of 96 swabs each, oral and rectal, were collected from 99 individuals representing 13 species, including 69 males and 30 females, with 95 adults and 4 young animals. From four adult males (Artibeus cinereus, Molossops temminckii, Gardnerycteris crenulatum, and Glossophaga soricina) colonies suggestive of Brucella were isolated and tested positive in both conventional (bcsp31) and qPCR, confirming that the colonies belong to the genus Brucella. However, no match was observed in multiplex PCR with known Brucella species. These findings highlight to bats as hosts and potential wild reservoirs of Brucella spp.

A compost-bedded pack barn (CBP) is a high-density housing system for dairy cattle, characterized by a communal resting area composed of an organic bed mixed with animal excrement, which aims to compost organic material with permanent antimicrobial activity. The CBP system was designed to promote animal welfare, however, despite its growing adoption in Brazil, information concerning the role of CBP system in the transmission of diseases is still limited. One of these diseases is bovine brucellosis, transmitted among cattle mainly through contact with fetal tissues and contaminated surfaces. Thus, con- sidering the increasing use of CBP and its possible role in the transmission of brucellosis in cattle, this study aimed to evaluate the presence of brucellosis in CBP beds and dairy cows during the transition period kept in CBP environments in Brazil. Three hundred and fourteen (314) animals housed in CPB was sampled from 20 dairy farms, localized in the states of Goi´as [1/20 (5.0%)] and Minas Gerais [19/20 (95.0%)]. Brucella spp. DNA was prospected through PCR in samples of vaginal swabs and uterine cytology of cows until 30 days post-partum, as well as in samples of the beds of the barns where these cows were housed. Serological tests (Rose Bengal and mercaptoethanol tests) were also performed for all animals. A total of 13 [13/20 (65.0%)] farms showed at least one animal positive for brucellosis in the serological or PCR tests. Brucella spp. DNA was also found in the material of CPB beds of three of these farms. These findings suggest that the CBP beds can be a source of Brucella abortus for healthy animals, creating favorable conditions for the dissemination of the pathogen and its transmission among confined animals.