Aims: To compare the culture and PCR methods for detection of Brucella
melitensis in blood and lymphoid tissue samples obtained from slaughtered
sheep (n = 162) testing positive ⁄ negative in serological tests (Rose Bengal test
and serum agglutination test).
Methods and Results: Of 162 sheep examined, 45 were positive and 117 nega-
tive in serological tests. A PCR assay based on a pair of Br. melitensis-specific
primers was used to detect DNA in blood and lymphoid tissue. Brucella melit-
ensis was isolated from 1Æ2% (2 ⁄ 162) and 17Æ2% (28 ⁄ 162) of the blood and
lymphoid tissue samples respectively. Positive PCR products with a molecular
size of 731 bp were obtained from 27Æ7% (45 ⁄ 162) of blood and 29Æ0%
(47 ⁄ 162) of lymphoid tissue samples.
Conclusions: The species-specific PCR assay detected a higher number of Br.
melitensis DNA both from serologically positive (P <0Æ01 in blood PCR,
P <0Æ001 in tissue PCR) and serologically negative (P <0Æ001 in both blood
PCR and tissue PCR) sheep compared with classical bacteriological culture
Significance and Impact of the Study: The results emphasize the importance of
using more than one type of diagnostic technique for the detection of animals
positive for brucellosis, especially with epidemiological purposes.