Fig. 1. Counts of S. aureus (n=293; black bars) and E. coli (n=297; white bars) in New
Zealand raw milk, as percentages of samples that contained colony numbers ranging
from b1 to >1000 cfu/ml, in 50 cfu/ml increments.
Table 3
Estimates of numbers of bacterial pathogens contained within positive samples according
to a modified MPN method and Table 2.
Bacteria Number of positive
(%) samples
Volume (ml) in which
1 cfu was contained
(according to MPN and Table 2)
Campylobacter 1 (0.34%) 21
Non-pathogenic
E. coli O157:H7
1 30a
1 (1.01%) 21
1 4
Listeria spp.b 2 (0.68%) 21
L. innocua 8 (4.07%) 21
4 4
L. monocytogenes 2 (0.68%) 4
a In relation to Table 2, this is an unusual MPN outcome. It is attributable to an initial
positive rapid screening result (performed on a 25 ml enrichment) subsequently being
confirmed as a negative result, while the 10 ml sample was tested and resulted in a
positive.
b Not identified to the species level