Challenges in diagnosing bovine tuberculosis through surveillance and characterization of Mycobacterium species in slaughtered cattle in Kolkata

BMC Vet Res. 2024 Oct 18;20(1):478. doi: 10.1186/s12917-024-04272-9.

Abstract

Background: Tuberculosis in cattle is caused by Mycobacterium tuberculosis complex (MTBC) species. Apart from MTBC, different Nontuberculous Mycobacteria (NTM) species have also been isolated from cattle. The presence of NTM infection in bovines makes the diagnosis of bovine tuberculosis (bTB) a cumbersome task. Therefore, a cross sectional study was conducted to isolate and characterize different Mycobacterium spp. from a slaughterhouse situated in Kolkata, a city in the eastern part of India.

Results: Out of 258 morbid samples, 98 isolates were found to be positive for bacterial growth, and 35% (n = 34) were positive for Mycobacterium. 94% of Mycobacterial cultural isolates were NTM (n = 32), and the rest (n = 2) were found to be MTBC. Species-level identification of the isolates by hsp65 sequencing revealed that out of 32 isolates, 24 were M. fortuitum, three were M. abscessus, two each were M. chelonae and M. parascrofulaceum, and one was M. novocastrense. A phylogenetic tree with partial hsp65 gene sequences was also constructed to determine the relatedness of the unknown isolates to the reference strains.

Conclusion: Both NTM species and MTBCs were identified from TB-like lesions in cattle that were slaughtered at the Kolkata abattoir. This discovery may indicate that NTM contributes to the development of lesions in cattle. Also, we recommend implication of more specific diagnostic tests for bTB.

Keywords: hsp65; Abattoir; Duplex PCR; Nontuberculous Mycobacteria; Zoonotic bovine tuberculosis.

MeSH terms

  • Abattoirs*
  • Animals
  • Bacterial Proteins / genetics
  • Cattle
  • Chaperonin 60 / genetics
  • Cross-Sectional Studies
  • India / epidemiology
  • Mycobacterium* / classification
  • Mycobacterium* / genetics
  • Mycobacterium* / isolation & purification
  • Nontuberculous Mycobacteria / classification
  • Nontuberculous Mycobacteria / genetics
  • Nontuberculous Mycobacteria / isolation & purification
  • Phylogeny*
  • Tuberculosis, Bovine* / diagnosis
  • Tuberculosis, Bovine* / microbiology

Substances

  • Chaperonin 60
  • Bacterial Proteins