Survival of Escherichia coli O157:H7 during the manufacture and ripening of Cacioricotta goat cheese.

The aim of this study was to assess the growth and survival of Escherichia coli O157:H7 during the manufacturing and ripening of Cacioricotta goat cheese. Goat milk was artificially contaminated with E. coli O157:H7 and the bacterial load was monitored from production up to 90 days of ripening. Goat milk was inoculated with 102 cfu ml-1 of E. coli O157:H7 and the bacterial count of the curd at time zero was 2.31 log10 cfu g-1. During the first day of ripening, the bacterial load has increased to 5.73 log10 cfu g-1 to more than 6.20 log10 cfu g-1 during the first week. The bacterial load remained constant up to 28 days and then slightly decreased until the end of ripening, with values of aw and pH of 0.88 and 5.41 respectively. The results of this study highlighted that E. coli O157:H7 is able to survive the manufacturing process and they suggest that the 90-day period of ripening alone is insufficient to remove E. coli O157:H7 in contaminated Cacioricotta goat cheese. Moreover, these results support the assumption that the presence of a low contamination of milk with E. coli O157:H7 could represent a potential source of infection and a threat to consumers.

Increased frequencies of both chromosome abnormalities and SCEs in two sheep flocks exposed to high dioxin levels during pasturage.

During the past four years several livestock farms (sheep, cattle and river buffalo) in the provinces of Naples and Caserta (southern Italy) have been unable to sell their milk and other dairy products due to the levels of dioxins (17 different types) present in the milk mass exceeding the value permitted [3 pg/g of fat, as human WHO 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin) equivalent]. While some farms, especially those showing relatively low levels of dioxins, have managed to reduce the dioxins in the milk below the permitted threshold by changing the diet, many, especially sheep farms, have failed to do so. Indeed, about 12,000 head of cattle, river buffaloes and sheep have so far been culled. In the present study, 34 and 42 sheep from two herds raised in the province of Naples (Acerra municipality) and where high levels of dioxins (50.65 and 39.51 pg/g of fat, respectively) were found in the milk mass, were cytogenetically investigated and compared with 20 sheep (control) raised 80 km away from the exposed area. Increases of both chromosome abnormalities (gap, chromosome and chromatid breaks) (17 and 8 times higher in the two exposed herds, respectively) and sister chromatid exchanges (SCEs) were found in both herds when compared with the control, and the differences were highly significant (P<0.001). No statistical differences were found when comparing the frequencies of aneuploid cells of exposed animals (16.4 and 17.8%) and control (17.9%). Furthermore, high levels of mortality and abnormal foetuses were recorded in one of the two farms when compared with the control.