CaV did not statistically differ from mCPC in terms of detection of Vv
from oysters using the MPN procedure (p = 0.371). However, up to
50.8% of putative Vv isolates on mCPC were confirmed by vvh probe
while only 47.2% of colonies recovered on CaV tested positive (Fig. 3).
It is noteworthy that 50% of the putative colonies obtained on mCPC
were not Vv. This percentage was higher than that seen by Staley et al.
(2013) and Macian et al. (2000) but much lower than that obtained by
Hoi et al. (1998). CaV showed even less specificity and only produced
about 2/3 of the isolates as mCPC. The MPN procedure requires only
one positive colony from a dilution for that dilution to be positive but
each dilution can have up to 3 positive colonies, thus accounting for
the difference in detected colonies and lack of difference in MPN. Previous
studies have analyzed the use of CaV to confirm results obtained on
other media (Cruz et al., 2013; Williams et al., 2011) but this is the first
study to analyze it as an alternative to mCPC. Although this study determined
that media do not significantly impact final results in terms of
MPN of Vv, it is important to highlight that mCPC yielded more Vv colonies
than did CaV and thus mCPC is preferred for this type of study.