Identification of the tetracycline resistance gene, tet(M), in Erysipelothrix rhusiopathiae

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• Molecular Biology

Background:

• Erysipelothrix rhusiopathiae causes swine erysipelas, a significant disease in pigs.
• Tetracycline resistance is a growing concern in animal agriculture.
• The tet(M) gene is a common determinant of tetracycline resistance in various bacteria.

Purpose of the Study:

• To investigate the presence and prevalence of the tet(M) gene in tetracycline-resistant Erysipelothrix rhusiopathiae isolates from swine.
• To characterize the tet(M) gene identified in E. rhusiopathiae.

Main Methods:

• Isolation and sequencing of the tet(M) gene from E. rhusiopathiae strain KY5-42.
• Comparison of nucleotide and amino acid sequences with known tet(M) genes.
• Detection of the tet(M) gene in 114 tetracycline-resistant E. rhusiopathiae isolates using polymerase chain reaction (PCR).
• Functional analysis of the tet(M) gene in Escherichia coli.

Main Results:

• The tet(M) gene was successfully isolated from E. rhusiopathiae strain KY5-42.
• The identified tet(M) gene showed 99% identity to that found in Enterococcus faecalis.
• The tet(M) gene conferred tetracycline resistance when expressed in Escherichia coli.
• PCR analysis confirmed the presence of the specific tet(M) DNA fragment in all 114 tetracycline-resistant E. rhusiopathiae isolates.

Conclusions:

• This study provides the first evidence of the tet(M) gene in naturally occurring, tetracycline-resistant Erysipelothrix rhusiopathiae.
• The tet(M) gene is likely widespread among field isolates of tetracycline-resistant E. rhusiopathiae in swine.
• The findings highlight the potential for horizontal gene transfer and the dissemination of antimicrobial resistance in swine pathogens.