Evaluation of the efficiency of nested q-PCR in the detection of Mycobacterium tuberculosis complex directly from tuberculosis-suspected lesions in post-mortem macroscopic inspections of bovine carcasses slaughtered in the state of Mato Grosso, Brazil

Abstract

Bovine tuberculosis (BTB) is a zoonotic disease caused by Mycobacterium bovis, a member of the Mycobacterium tuberculosis complex (MTC). The quick and specific detection of this species is of extreme importance, since BTB may cause economic impacts, in addition to presenting imminent risks to human health. In the present study a nested real-time PCR test (nested q-PCR) was used in post-mortem evaluations to assess cattle carcasses with BTB-suspected lesions. A total of 41,193 cattle slaughtered in slaughterhouses located in the state of Mato Grosso, were examined. Of the examined animals, 198 (0.48%) showed BTB-suspected lesions. M. bovis was isolated in 1.5% (3/198) of the samples. Multiplex-PCR detected MTC in 7% (14/198) of the samples. The nested q-PCR test detected MTC in 28% (56/198) of the BTB-suspected lesions, demonstrating higher efficiency when compared to the multiplex-PCR and conventional microbiology. Nested q-PCR can therefore be used as a complementary test in the national program for control and eradication of bovine tuberculosis.

Diagnóstico histopatológico e molecular de lesões sugestivas de tuberculose em búfalos abatidos nos municípios de Macapá e Santana, estado do Amapá

“…Araújo et al (2005), analisando lesões sugestivas de tuberculose em bovinos, obtiveram 17 (23,65%) amostras positivas na cultura em meio Stonebrink, confirmando a presença de M. bovis em 13 (76,5%) amostras através de avaliação molecular por PCR. A eficiência da técnica de Nested q-PCR na detecção de CMT diretamente em tecidos bovinos foi descrita por Carvalho et al (2015), em que 28% (56/198) das amostras mostraram positividade, superando os testes de Multiplex--PCR (14/98) e cultura (3/1998). Contudo, em bovinos, Proaño-Pérez et al (2011) obtiveram baixo índice de positividade por meio de Nested-PCR 27,33% (9/33), contra 36,4% de isolamento de M. bovis.…”

Tuberculosis and Cysticercosis in Brazil: A Review

“…People in contact with infected cattle or with products derived from these animals, such as veterinaries, abattoir workers, animal handlers and butchers are prone to be affected by the disease, especially those recovering from other diseases or immunodeficient persons [42] [44] [60]. Moreover, physiological and immunological factors linked to children, elderly people and AIDS patients raise infection risks in these people.…”

“…Several studies[42] [47] [49][50] have assessed the prevalence of tuberculosis-suggesting lesions in bovine carcasses during sanitary inspection. Needless to say, prevalence varied according to region and period of the year.…”

Bovine Tuberculosis: Clinical Presentation and Diagnosis

“…Molecular methods, especially the polymerase chain reaction (PCR) assay, are the most promising. However, the success of the PCR assay depends on the availability of intact and impurity-free DNA [29]. …”