62 research outputs found
Detection of tet(M) gene from raw milk by rapid DNA extraction followed by a two-step PCR with nested primers.
The likelihood that milk and milk products may act as a vehicle for antibiotic-resistant bacterial genes has become a concern to the food industry and a public health issue, and the demand for rapid tests has increased. The purity of DNA extracted from food samples is a key issue in the sensitivity and usefulness of biological analyses, such as PCR for pathogens and nonpathogens. A rapid, phenol-chloroform free method based on a modification of a sodium iodide DNA extraction, followed by a two-step PCR was developed for direct detection of the tet(M) gene in milk samples within a single working day. This study compares the proposed method with a traditional phenol solvent extraction method and with a commercial kit (QIAamp DNA blood mini kit, Qiagen). The three DNA extraction methods were used to ensure access to the tet(M) gene from 1 ml of raw milk, inoculated with a strain of Enterococcus faecalis, which carries the tet(M) gene. The proposed method, followed by a two-step PCR with nested primers specific for the tet(M) gene, was able to reach a detection limit below 10 CFU/ml in less than 4 h, including the two amplification cycles, thus outperforming in sensitivity and rapidity both the traditional and the commercial method
The relationship between S. aureus and branched-chain amino acids content in composite cow milk
The early diagnosis of mastitis is an essential factor for the prompt detection of the
animal for further actions. In fact, if not culled, infected cows must be segregated from the milking
herd and milked last, or milked with separate milking units. Besides microbiological analysis, the
somatic cell count (SCC) commonly used as predictor of intramammary infection, frequently lead
to a misclassification of milk samples. To overcome these limitations, more specific biomarkers
are continuously evaluated. The total amino acid content increases significantly in mastitic milk
compared to normal milk. S. aureus requires branched-chain amino acids (BCAAs—isoleucine,
leucine, and valine) for protein synthesis, branched-chain fatty acids synthesis, and environmental
adaptation by responding to their availability via transcriptional regulators. The increase of BCAAs
in composite milk has been postulated to be linked to mammary infection by S. aureus. The aim
of this work is to demonstrate, by a direct ion-pairing reversed-phase method, based on the use of
the evaporative light-scattering detector (IP-RP-HPLC-ELSD), applied to 65 composite cow milk
samples, a correlation between the concentration of isoleucine and leucine, and S. aureus load. The
correlation coe cient, r, was found to be 0.102 for SCC (p = 0.096), 0.622 for isoleucine (p < 0.0001),
0.586 for leucine (p < 0.0001), 0.013 for valine (p = 0.381), and 0.07 for tyrosine (p = 0.034), standing for
a positive correlation between S. aureus and isoleucine and leucine concentration. The link between
the content of BCAAs, isoleucine and leucine, and udder infection by S. aureus demonstrated with
our study has an important clinical value for the rapid diagnosis of S. aureus mastitis in cows.http://www.mdpi.com/journal/animalsam2020Paraclinical Science
Data for: FATE OF SELECTED PATHOGENS IN SPIKED «SALAME NOSTRANO» PRODUCED WITHOUT ADDED NITRATES FOLLOWING THE APPLICATION OF NONITTM TECHNOLOGY
GraphPad Prism file
Data for: FATE OF SELECTED PATHOGENS IN SPIKED «SALAME NOSTRANO» PRODUCED WITHOUT ADDED NITRATES FOLLOWING THE APPLICATION OF NONITTM TECHNOLOGY
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