F. Vitale et al., DETECTION OF MYCOBACTERIUM-TUBERCULOSIS COMPLEX IN CATTLE BY PCR USING MILK, LYMPH-NODE ASPIRATES, AND NASAL SWABS, Journal of clinical microbiology, 36(4), 1998, pp. 1050-1055
The PCR technique was applied to the diagnosis of tuberculosis in live
cattle, and both skin-test-negative and skin-test-positive animals we
re studied, DNA was taken from various sources including specimens of
lymph node aspirates, milk, and nasal swabs, After slaughter and visua
l inspection, tissues such as lymph nodes, lungs, and udders from tube
rculin reactors were tested by the same technique, Specific oligonucle
otide primers internal to the IS6110 insertion element were used to am
plify a 580-bp fragment, A 182-bp fragment was obtained by designating
a nested PCR from the first amplification product, This fragment was
cloned and sequenced, and after being labeled it was employed in dot b
lot hybridization, A total of 100 cattle were tested, and PCR analysis
was performed using nasal swab, milk, and lymph node aspirate, Sixty
skin-test-positive cows were also tested to detect mycobacterial DNA i
n tissue samples from lymph nodes, lungs, and udders, and the infectio
n was confirmed in all of the animals, Using PCR analysis of tissue sa
mples from slaughtered animals as a ''gold standard'' we calculated 10
0% values for sensitivity, specificity, and positive and negative pred
ictive values for milk and lymph node aspirate samples, The respective
values for nasal swab samples were 58, 100, 100, and 28%, The respect
ive values for all of the samples were 74, 100, 100, and 35%, while fo
r visual inspection the values were 81, 100, 100, and 58%, respectivel
y, PCR analysis of specimens of lymph node aspirates, milk, and nasal
swabs from skin-test-negative animals showed that 52% of these skin te
st results were false negatives, These animals, not being removed from
the farms, represent a potential source of further infection.