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To replace synthetic preservatives and expand green consumption, several essential oils have been tested in foods and food packaging due to their antimicrobial properties. This study aimed to analyze the synergistic antimicrobial action of a chitosan-gelatin based active biopolymers with the addition of essential oils (EOs). The antimicrobial agents were tested against foodborne microorganisms Staphylococcus aureus and Escherichia coli strains. The antibacterial activity of Thymus vulgaris, Ocimum basilicum, Origanum majorana, and the synergistic interactions among them were assessed according to the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the microdilution method. Chitosan-gelatin based active biopolymers were developed, and 23% (w/w) of each essential oil and combined oils were added. The antimicrobial effect of active films was measured using the disk diffusion method. Active films with the addition of essential oils have potential applications as active packaging agents, especially those that demonstrated inhibition zones. Combined EOs can be used to enhance the antimicrobial activity, ensuring reduced doses used in active packaging and decreasing the association with adverse sensory characteristics.

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We carried out a thorough genetic evaluation of Streptococcus dysgalactiae isolated from clinical bovine mastitis cases and performed a phylogenetic analysis to represent the evolutionary relationship between S. dysgalactiae sequences. A total of 35 S. dysgalactiae strains were isolated from cases of clinical mastitis identified at a large commercial dairy farm located near Ithaca, New York. Whole-genome sequencing identified twenty-six antibiotic resistance genes, four of which were acquired genes, in addition to fifty virulence genes. Multi-locus sequence typing detected three new sequence types (STs). We conclude that a high proportion of this microorganism carries multiple virulence determinants and resistance genes, and that this indicates its potential to cause mastitis. Eight different STs were identified, of which ST453 (n = 17) was the most prevalent and ST714, ST715, ST716 were novel STs.

Background Staphylococcus spp. are among the most isolated bacteria from cases of clinical and subclinical mastitis in dairy cattle. Also, Staphylococcus is commonly isolated from bovine mammary secretions, not exclusively from intramammary infections. The genus comprises bacteria capable to form biofilm, produce toxins and acquire multi-drug resistance. The aims of this work were to evaluate the genetic virulence and antimicrobial resistance features of Staphylococcus spp. isolated from bovine milk using whole genome sequencing, and build a phylogenetic tree with gene sequences of Staphylococcus spp. isolated from clinical mastitis and non-clinical fresh cows. Results The bacterial collection comprised 29 Staphylococcus strains isolated from clinical mastitis cases (n = 7) and milk samples collected from fresh cows (n = 22). Strains were identified as Staphylococcus aureus (n = 2), Staphylococcus chromogenes (n = 19), and Staphylococcus haemolyticus (n = 8). After sequences quality control, twenty-three strains had good quality of contigs to be included in the further analysis. Conclusions Ninety-four virulence genes were observed, including pvl, icaA, icaD and MMSCRAMS genes. We also detected important resistance genes as blaZ, ant(4), erm(B), fexA, lnu(D), tet(L) and tet(M). The phylogenetic tree related the species as expected and presented four clades.

Nowadays, consumers are increasingly looking for quality food, that is healthy, easy to prepare and easy to consume and, consequently, minimally processed foods have emerged as this alternative. The objective of this work was to evaluate the microbiological quality of 200 minimally processed fruits and vegetables samples. The samples were collected from products marketed in the state of São Paulo, Brazil, in order to determine the most probable number of thermotolerant coliforms (TC) and to detect the presence of Salmonella and Staphylococcus sp. For the Staphylococcus sp strains, the presence of genes related to the production of classical enterotoxins and biofilm was tested. Additionally, the production of enterotoxins and biofilm in vitro by the isolated Staphylococcus sp strains was evaluated. Among the 200 fruits and vegetables samples, 157 (78.5%) were out of the acceptable limits for thermotolerant coliforms. Furthermore, strains producing sed enterotoxin in vitro and strains producing biofilm on stainless steel and glass surfaces were found. Therefore, according to the obtained results, the analyzed products are improper for consumption, presenting contamination levels above law recommendation.