Isolation and identification of Mycobacterium avium subspecies silvaticum from a horse.

This research article is about the identification of the bacterium Mycobacterium avium subspecies silvaticum in a horse, using a rapid molecular technique involving the digestion and sequencing of the 85B antigen gene.

Identification Challenge of Mycobacterium avium

• This research focuses on the identification of subspecies of the bacterium Mycobacterium avium. The bacterium is known to have several subspecies that are difficult to distinguish from each other using conventional bacteria cultivation methods.
• While routine cultivation methods can distinguish between Mycobacterium avium and Mycobacterium tuberculosis, it struggles in differentiating between the subspecies in the M. avium complex. This article focuses on two such subspecies; subspecies avium and silvaticum.

Use of Molecular Tools and Techniques

• The research paper indicates the use of molecular tools as an effective method for better identification of these different subspecies.
• The proposed method uses a technique known as HhaI restriction digestion, which targets a segment of a specific gene called the 85B antigen (α-antigen) gene. This gene’s product is a 349 base pair (bp) amplification product, which is created as a response to the digestion process.

Case Study: Identification of M. avium subsp. silvaticum

• Practically applying this method, the researchers identified the M. avium subsp. silvaticum in a three-year-old gelding (a castrated male horse). The animal presented with caseous, necrotizing, granulomatous lesions, symptoms that indicated the presence of the mycobacterium.
• The identified existence of the M. avium subsp. silvaticum was double-checked and confirmed by sequencing the 85B antigen gene.

Conclusion

• This study supports the use of molecular tools, specifically the HhaI restriction digestion of the 85B antigen (α-antigen) gene, as an effective method for distinguishing between the various subspecies of the Mycobacterium avium bacteria.
• The positive identification and confirmation of M. avium subsp. silvaticum in a horse also demonstrate that this more precise method of identification can provide valuable information for the treatment and management of diseases caused by these bacteria.