High frequency of Mycobacterium bovis DNA in colostra from tuberculous cattle detected by nested PCR.
We evaluated by nested PCR reaction, different cow secretions from a herd with 48% of prevalence of bovine tuberculosis (BTB), seeking to determine niches where Mycobacterium bovis could be found. Postmortem examination of 18 (75%) tuberculin reacting cows allowed demonstrates BTB-compatible lesions in six, all of them PCR positives in milk and four in colostra samples. Our results showed that up to 62% of the colostra analysed contained M. bovis DNA, whereas only 18% of milk gave a positive reaction. Moreover, in bronchoalveolar lavages from cattle with compatible lesions in lungs or lymph nodes, where macrophages account up to 90% of cells, we did not find evidences of M. bovis. Altogether, these results suggest that differences in the anti-bacterial capacity of bovine macrophages, dependent upon microenvironment and organ-specific factors, exist. Alternatively, we hypothesize that hypoxic conditions that are encountered in mammary glands macrophages could induce M. bovis entrance into a 'dormancy-like' state, and that the high number of colostra samples were M. bovis was detected, could be an indicator of reactivation during 'peripartum'.
Serrano-Moreno
B A
BA
Facultad de Estudios Superiores-Cuautitlán, Universidad Nacional Autonoma de Mexico (UNAM), Estado de México, Mexico.
Romero
T A
TA
Arriaga
C
C
Torres
R A
RA
Pereira-Suárez
A L
AL
García-Salazar
J A
JA
Estrada-Chávez
C
C
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D002417:Cattle; D003126:Colostrum / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D008892:Milk / Q000382:microbiology; D009163:Mycobacterium bovis / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D014380:Tuberculosis, Bovine / Q000175:diagnosis* / Q000382:microbiology / Q000635:transmission*
D004269:DNA, Bacterial