Isolation and identification of Mycobacterium bovis in bovines with positive reaction to the tuberculin test in the state of Paraíba, northeast Brazil

Joelson Marcolino Ramos,Sérgio Santos De Azevedo,Nicolás Céspedes Cárdenas,Antonio Francisco De Souza Filho,Clebert José Alves,Marcos Bryan Heinemann,José Soares Ferreira Neto,Antônio Flávio Medeiros Dantas

doi:10.1590/1808-1657000842016

Abstract

ABSTRACT: In areas where human tuberculosis and bovine tuberculosis coexist, differentiation between M. bovis and M. tuberculosis is important for monitoring the spread of M. bovis among cattle and from cattle to humans. The objective of this study was to isolate and identify M. bovis in bovines with positive diagnosis identified on tuberculin test in the State of Paraíba, Northeastern Brazil. Thirty-two bovines that tested positive in the comparative tuberculin test were used, from which samples of any organ with lesions suggestive of tuberculosis were collected, as well as lymph nodes, when no gross lesions were observed. Samples were submitted to histopathological exam, mycobacterial culture, Ziehl-Neelsen staining and molecular diagnosis. Twenty-one (65.6%) animals presented lesions suggestive of tuberculosis. As to body region 77.7% of lesions were found in the thoracic cavity, 12.4% in the head and 9.9% in the abdominal cavity. Among 55 samples submitted to mycobacterial culture, mycobacteria were isolated in 31 (56.4%), being 13 (41.9%) identified as M. bovis and 18 (58.1%) as Mycobacterium spp. Conclusion is that isolation and identification of M. bovis and Mycobacterium spp. in cattle suggests that humans are exposed to the risk of infection. This reinforces the need for intensification and optimization of prevention and control measures foreseen in the Brazilian National Program for the Control and Eradication of Bovine Brucellosis and Tuberculosis. Mycobacteria isolation and identification surveys are, therefore, encouraged in other Northeastern states.

Highlights

Bovine tuberculosis is a chronic zoonotic disease caused by Mycobacterium bovis, which belongs to the Mycobacterium tuberculosis complex (BRASIL, 2006)
Tuberculosis in humans is mostly caused by M. tuberculosis, 3.1% of the cases of human tuberculosis across the world are caused by M. bovis (EL SAYED et al, 2015)
The differentiation between M. bovis and M. tuberculosis is important for the identification of pos‐ sible source of infection and routes of transmission, which are fundamental for an effective control and eradication of the infirmity (ZANINI et al, 2001; RODRIGUEZ et al, 2004)

Summary

Introduction

Bovine tuberculosis is a chronic zoonotic disease caused by Mycobacterium bovis, which belongs to the Mycobacterium tuberculosis complex (BRASIL, 2006). Direct methods involve detection and identification of the etiologic agent in biological material, and the combination of isolation in culture medium and molecular identification with genotyping has contributed to a better understanding of the epidemiology of M. bovis infections, which provides greater efficiency to control pro‐ grams (CAZOLA et al, 2015). Human diseases caused by M. tuberculosis and M. bovis are indistinguishable by clinical, radiological and pathological methods (ROCHA et al, 2011). The differentiation between M. bovis and M. tuberculosis is important for the identification of pos‐ sible source of infection and routes of transmission, which are fundamental for an effective control and eradication of the infirmity (ZANINI et al, 2001; RODRIGUEZ et al, 2004). Transmission of M. bovis to humans occurs through ingestion of meat, raw milk and dairy products from infected cattle or contact with secretions of fistulized abscesses and aerosols

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