SUMMARYA collection of 85 strains of Streptococcus faecium and unclassified group D streptococci isolated from canned hams and pig intestines was typed serologically. Seventy-seven of the isolates, which included two motile strains, were distributed amongst 15 types and 4 subtypes. The distribution of types was widespread, the same type being isolated from several different countries.

SUMMARY: Streptococci and lactobacilli were isolated from the faeces and caecal contents of experimental pigs receiving various diets. Fifty‐seven strains of streptococci and forty‐one (representative of 220) lactobacilli were examined physiologically and serologically. Lactobacillus acidophilus and L. fermenti predominated among the lactobacilli, while the largest group of streptococci resembled the ‘unclassified’ strains of Barnes & Ingram (1955) and Barnes, Ingram & Ingram (1956) from bacon factory premises, pig faeces and canned hams.

The presence of a thermolabile inhibitor of coagulase-positive staphylococci in milk was confirmed. Starter streptococci significantly suppressed the multiplication of staphylococci in milk not only by their acid production but also by some other competitive effect.Cheesemaking trials showed that staphylococci multiplied considerably more rapidly in 'slow' or 'sweet' cheese, where the starter was inhibited by phage, than in normal cheese. Little decrease in numbers occurred in 'sweet' cheese even after 18 months, in contrast to the rapid decline in the normal cheese.Staphylococci subjected in the laboratory to sublethal heat treatments had a prolonged lag phase on all media and their % recovery on selective media was significantly lower than on optimal non-selective media. It is suggested that the low survival rate of the staphylococci in cheese made from milks heated at sublethal temperatures is due to the lag in recovery of heat-shocked cells and their inability to multiply in the unfavourable cheese curd.

SummaryThe occurrence of coagulase-positive staphylococci in 954 samples of raw or heat-treated market milk and in 910 samples of cheese of different varieties, taken at 40 cheese factories or farms in England and Wales was determined. Only 9% of the cheeses contained more than 500 000 staphylococci/g, and these were all made from raw milk. All but the mildest of the heat treatments used were effective in greatly reducing the numbers of staphylococci present in milk and usually resulted in cheese virtually free from staphylococci. The effect of sublethal heat treatment on multiplication of these organisms in cheese curd is discussed.