Molecular genetic features and prevalence of tetracycline resistance genes in Salmonella enterica

Thu, 20 Aug 2026 15:30:07 +0000

Objective.

To assess prevalence of genetic determinants of tetracycline resistance (tetA, tetB, tetC) in Salmonella in the Krasnoyarsk Territory and to identify the most epidemiologically significant tet genes.

Materials and Methods.

The study included Salmonella cultures isolated in the Krasnoyarsk Territory during the diagnosis of acute intestinal infections, occupational health examinations, and sanitary-epidemiological investigations. Identification was based on morphological and staining characteristics, as well as cultural, biochemical, antigenic properties and phage lysis. Antimicrobial susceptibility was determined using the disk diffusion method. The presence of tetA, tetB, and tetC genes was determined by polymerase chain reaction (PCR), followed by electrophoretic detection of amplification products in agarose gel.

Results.

A total of 67 strains classified as resistant or moderately sensitive to tetracycline based on phenotypic testing were examined. Resistance determinants were detected in 76,1 ± 6,9% of isolates. The prevalence of the tetA gene was 70,1 ± 5,2%, tetB – 7,8 ± 3,4%, and tetC – 8,3 ± 4,0%. Simultaneous presence of tetA and tetB was found in 3,1 ± 5,0% of isolates; tetA and tetC – in 6,3 ± 7,4%. All strains carrying two loci exhibited phenotypic resistance.

Conclusions.

The tetA gene was the main determinant of tetracycline resistance in Salmonella, detected in 70,2 ± 5,6% of isolates. The tetB and tetC genes were significantly less common — 7,8 ± 3,4% and 8,3 ± 4,0%, respectively. Given that tetA, tetB, and tetC are associated with mobile genetic elements, their horizontal transfer to other microorganisms is highly likely and of epidemiological concern.

Irina T. Reshetneva on КМАХ

Molecular genetic features and prevalence of tetracycline resistance genes in Salmonella enterica

Objective.

Materials and Methods.

Results.

Conclusions.