Article history Dairy farming is an important social and economic activity in the Midwest region of Santa Catarina State, Brazil. However, despite technological advances in the productive chain, mastitis is still considered the main disease of dairy herds, due its high economic impact. Bacterial pathogens are the main cause of this disease and failures in the treatment of clinical cases are attributed in part to the antimicrobial resistance of these pathogens. As an alternative, in vitro antimicrobial susceptibility tests of strains isolated from bovine mastitis cases have been carried out; the information generated contributes to strategic treatment measures, and also to the control of microorganism resistance. Therefore, the aims of the present study were to evaluate the etiology and in vitro antimicrobial susceptibility profiles of bacterial strains isolated from cases of bovine mastitis in dairy herds from the Midwest region of Santa Catarina State, Brazil. For this purpose, 345 milk samples were collected from 70 herds located in 16 different municipalities. The main pathogens isolated were: staphylococci (55.9%), streptococci (34.8%), Corynebacterium spp. (7.8%) and Escherichia coli (1.4%). The resistance rates of staphylococcus strains to ampicillin and to gentamicin were lower (24.9%) and higher (33%), respectively, than those obtained in other Brazilian studies. The resistance profiles of streptococcus strains were similar to those described in the literature, while Corynebacterium spp., showed high resistance rates to tetracycline (85.2%). Moreover, a considerable prevalence of staphylococcus (27.5%) and streptococcus (11.7%) multiresistant strains was verified. These data reinforce the need for regional characterization of microorganisms.

The consumption of raw milk cheese has been growing worldwide with S. aureus and E. coli been the leading agents in food poisoning. The present work aims to evaluate the microbiological quality of raw milk cheeses commercialized in Brazil, regarding microbiology safety and enterotoxin gene presence. Forty-three raw milk cheeses samples from five different suppliers were analyzed. Counting and identification of S. aureus, E. coli and Salmonella spp were performed according to BAM from the FDA. Further S. aureus identification was performed by the cydB and Salmonella spp by the invA gene. S. aureus toxin genes (sea, seb, sec, see, ses, seh and sei) and E. coli gene LT, STa, Stb, stx1, stx2, eae, rmpA, wabG, mrkD, kfu, mcgA, fimH and uge were analysed. From the 43 samples analyzed, 18 presented S. aureus with two isolates positive for the tst gene, two for the sec gene, two for the seh gene and four for the sei gene. Thirty-five E. coli and seven. Salmonella spp isolates were obtained. E. coli isolates harbored sta and stx2 genes. The results revealed that raw milk cheeses sold can cause harm consumer's health and highlights the importance of adoption good hygienic-sanitary practices and consumers awareness.

The aim of this study was to investigate the presence of virulence and antimicrobial resistance genes and clonal profile of Enterobacteriaceae isolated from calves, cows, feeding buckets and the milk bucket. A a total of 31 Enterobacteriaceae isolates from calves (6), milk bucket (6), feeding buckets (6) and from cows' rectum (13) were used. The presence of LT, STa, STb, STx1, STx2, eae, rmpA, wabG, mrkD, kfu, mcgA, fimH and uge as well as the antimicrobial resistance genes: AmpC MOX, FOX, MIR, ACT, DHA, ACC, CTX-M-1, CTX-M2, TEM KPC and MCR-1 and SH were evaluated by PCR. The LT toxin gene were detected in five isolates (16.1%) and the mrkD gene was detected in three isolates (9.0%). The CTX-M-1 gene was detected in 13 isolates (41.9%), CTX-M-2 in five isolates (16.1%) and ACC-M in four isolates (12.9%). Most of the isolates obtained demonstrated, resistance to cephalothin (87.5%), ampicillin, (87.5%) and streptomycin (84.3%) with multidrug resistance observed in all isolates. Isolates from bucket and cow's rectum, calves and milk bucket, calf and cow's rectum shared the same pulsotypes. These findings may suggest that enterobacteria carring virulence and resistance genes may persist in the environment and became a reservoir of these genes.

Bovine mastitis is one of the main causes of economic damage in dairy farms. Therefore, the control and prevention of microorganisms involved in this disease, mainly Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae, are essential. One of the most important steps for the prevention of the disease is the use of antiseptic products before and after the milking process to avoid bacteria from infecting the udder of the animal. Currently, the most used antiseptic product in dairy farms is iodine-based, and organic dairy farms, which follow several strict regulations, including the use of natural products whenever possible, are often forced to adopt non-natural antiseptic products, such as iodine-based ones, because of the lack of natural alternatives. Propolis, a natural substance produced by honeybees, has been extensively studied for its various properties, one of which is antimicrobial activity. Therefore, a new natural antiseptic product containing 1% propolis in 10% hydroalcoholic solution for the pre-dipping, and 10% glycerol solution added with 0.2% citronella oil for the post-dipping was analyzed for its capacity to reduce bacteria in vivo in order to prevent bovine mastitis, allowing its use on organic dairy farms. A total of 128 samples were analyzed in terms of bacterial growth for Enterobacteriaceae and Staphylococcus spp. using the spreadplate technique. The reduction in the bacterial concentration after the application of the products was compared between two antiseptic solutions, an iodine-based solution as the control and a propolis-based one as the natural alternative. The results obtained show a similar efficiency for both products in terms of total bacterial reduction, indicating considerable antimicrobial activity against bacteria most commonly associated with bovine mastitis. Molecular analysis was carried out for the identification of Streptococcus agalactiae; the PCR results were negative for the presence of S. agalactiae in all samples, indicating that the animals most likely did not have any form of the disease. The efficiency of the natural antiseptic was satisfactory, indicating an important find facilitating organic milk production worldwide, showcasing a natural antiseptic solution with efficient antimicrobial activity.