[Antibiotic residues in bovine udders passed for consumption and meats containing milk-gland tissues (author's transl)]

Residues of identifiable antibiotics were found to be present in approximately 8.1 per cent of 999 bovine udders. In order to form an opinion on the consequences to consumers, the extent to which using milk-gland tissues results in the presence of detectable antibiotic residues in meats, was studied. For this purpose, 797 samples of meats were examined for antibiotic residues during the period from August to December 1976. The samples came from all over the country. Having been screened, the positive samples were examined by high-voltage electrophoresis on agar gel. The number of samples found to contain antibiotic residues could not be neglected. The results of these studies show that incorporating udder tissues in meats and meat-containing products is not acceptable without closer examination. It is doubted whether the decision to pass udders as fit for human consumption after palpation, incision and inspection is a correct procedure.

[Studies on the Microbiological Quality of Mammary Gland Tissues (author's transl)]

During the period from August to December 1976, 239 bovine udders were examined for their microbiological quality. Counts were made of the total number of aerobes, anaerobes, Enterobacteriaceae, coliform micro-organisms and staphylococci positive for coagulas and DNA-ase. The udders were examined for the presence or absence of Salmonella, E. coli and haemolytic streptococci. In addition, the Enterobacteriaceae were identified. The udders examined were from animals brought up for slaughter from all over the country. The studies were designed to examine whether udders are suited as raw material for products to be consumed by human individuals. The number of pathogenic bacteria isolated was found to be considerable and the average bacterial counts were rather high. The studies showed that the bacterial content of mammary-gland tissues has an adverse effect on the quality of raw meats made from these tissues so that they are not aceptable from the point of view of public health. Even when they are used as raw material for heated products, the risk of food poisoning caused by toxin produced by staphylococci cannot be entirely ruled out.

[An investigation into the presence of staphylococci in farm milk (author's transl)]

Two hundred bulk milk samples drawn from milk collected in cans, which came from cows at stable at 40 farms in the Food Inspection District Utrecht, were examined for Staphylococcus aureus, by means of Baird-Parker's medium. Cultures obtained were phage typed with international, bovine, and additional Dutch phage series. About 60% of the isolated strains were found to be of human origin and about 20% of bovine origin. Isolated strains appeared to be farm specific. Approximately 70% of the farms supplied bulk milk containing 0.08-1.3X10(4) coagulase and DNAse positive staphylococci/ml. The conclusion is inescapable that this type of bulk milk still represents a latent hazard for human health.

[Staphylococci in cheese made from raw milk. (author's transl)]

The presence of markedly varying numbers of coagulase-positive staphylococci per gram (less than 10(2) -- greater than 10(6)) of cheese made from raw milk is reported. In twenty cases, the strains isolated from the cheese were examined for their ability to produce toxins. Eight strains were found to produce toxin A, no toxin being isolated from cultures of the twelve other strains. In two cases, the studies were done because of food poisoning which had probably been caused by the cheese. The number of staphylococci was more than 10(6) in one case (cheese about four weeks old) and approximately 1.5 x 10(4) in another (matured cheese). Subsequent studies showed that rather large amount of enterotoxin A were present in the second cheese. The first cheese was not examined for the presence of toxin.

A new CoDNA-ase spot plate method for the detection of coagulase and DNA-ase activity of staphylococci

A new method for the determination of the coagulase and DNA-ase activity of staphylococci is described. The method enables the analyst to test large numbers of strains for this microorganism without the loss of time involved in the conventional technique.