P. Cremonesi

Detection of enterotoxigenic Staphylococcus aureus isolates in raw milk cheese

Aim:u2002 To develop an easy, rapid and efficient DNA extraction procedure for Staphylococcus aureus detection with a low number of steps and removing completely the PCR inhibitors, applicable to raw milk cheese samples, and to compare phenotypical and genotypical method to detect Staph. aureus isolates and staphylococcal enterotoxins (SEs) production.

Development of DNA Extraction and PCR Amplification Protocols for Detection of Mycoplasma bovis Directly from Milk Samples

Cremonesi, P., Vimercati, C., Pisoni, G., Perez, G., Miranda Ribera, A., Castiglioni, B., Luzzana, M., Ruffo, G. and Moroni, P., 2007. Development of DNA extraction and PCR amplification protocols for detection of Mycoplasma bovis directly from milk samples. Veterinary Research Communications, 31(Suppl. 1), 225–227

Enzymatic reactions for the determination of sugars in food samples using the differential pH technique.

All ATP coupled reactions, when performed at neutral or moderately alkaline pH, produce an acidification of the reaction mixture. The detection of small pH changes--0.1 mpH (1 mpH = 10(-3) pH)--in a constant buffering capacity solution makes it possible to quantify, over a wide concentration range (1-1500 mmol L(-1)), various analytes with very high precision and accuracy. Glucose, fructose, glycerol and gluconic acid can be analysed in less than 1 min with a single step reaction. Wine samples were analysed using the hexokinase reaction for glucose + fructose (sugars undergoing fermentation) and compared against an established method, showing excellent performance over the whole range of concentrations (R = 0.9994). Increased sensitivity in some applications can be obtained by cycling reactions, e.g. a kinase reaction followed by a phosphatase reaction. in a one step analysis, as required for lactulose assay in milk, a useful indicator of heat treatment damage. A sensitivity well below 0.1 mmol L(-1) in the original milk sample has been demonstrated.

Identification of Enterotoxin Genes in Staphylococcus aureus Isolates from Bovine and Caprine Milk

Among the main microorganisms responsible for bovine, ovine and caprine mastitis, Staphylococcus aureus is important, not only with respect to the animal disease, but also because of its potential impact on public health and food safety. In fact, some Staphylococcus aureus strains can produce enterotoxins which could cause food poisoning through consumption of milk or dairy products, particularly cheeses manufactured with raw milk. Inasmuch as milk of infected animals is considered the main source of enterotoxigenic S. aureus of animal origin, the importance of an efficient screening process for the presence of enterotoxigenic strains is required. The aim of this study was to develop an assay using a multiplex PCR technique to verify the presence of genes encoding for classical (from A to D) and recently described (G, H, I, J, L) staphylococcal enterotoxins in Staphylococcus aureus strains isolated from bovine and caprine milk.

Analysis of genetic polymorphisms in Staphylococcus aureus strains isolated from bovine milk

C. Vimercati1, P. Cremonesi2, B. Castiglioni3, P. Boettcher3, M. Luzzana2, G. Ruffo1 and P. Moroni1,∗ 1Department of Animal Pathology, Hygiene and Veterinary Public Health, University of Milano, Italy; 2Department of Biomedical Sciences and Technologies, University of Milano, Italy; 3Institute of Agricultural Biology and Biotechnology, Italian National Research Council, Milano, Italy ∗Correspondence: E-mail: paolo.moroni@unimi.it