Evaluation of PCR and indirect enzyme-linked immunosorbent assay on milk samples for diagnosis of brucellosis in dairy cattle.
A study was performed to evaluate the previously described PCR (C. Romero, C. Gamazo, M. Pardo, and I. López-Goñi, J. Clin. Microbiol. 33:615-617, 1995) for the diagnosis of brucellosis in dairy cattle. Milk samples from 56 Brucella milk culture-positive cattle and from 37 cattle from Brucella-free herds were examined for Brucella DNA by PCR and for specific antibodies by an indirect enzyme-linked immunosorbent assay (ELISA). The specificities of both tests were 100% when testing the milk samples from Brucella-free cattle. The milk samples from 49 infected cattle were positive by PCR (87.5% sensitivity), and 55 were positive by ELISA (98.2% sensitivity). A PCR-positive sample was negative by ELISA, and 7 ELISA-positive samples were PCR negative, yielding an observed proportion of agreement of 0.91 for the two tests. Although the results suggest that ELISA is a better screening test than PCR, the combined sensitivity of the two assays was 100%, and their simultaneous application could be more useful than one test alone for a rapid screening of brucellosis in dairy cattle.
Romero
C
C
Departamento de Microbiología, Universidad de Navarra, Pamplona, Spain.
Pardo
M
M
Grillo
M J
MJ
Diaz
R
R
Blasco
J M
JM
Lopez-Goñi
I
I
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D001431:Bacteriological Techniques; D002002:Brucella / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D002007:Brucellosis, Bovine / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology; D002417:Cattle; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D005260:Female; D008892:Milk / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial; D004269:DNA, Bacterial