Detection and genetic characterisation of vanA-containing Enterococcus strains in healthy Lusitano horses.

The research article focuses on the detection and genetic characterization of vanA-containing, antibiotic-resistant Enterococcus strains in Lusitano horses, indicating these horses could be potential reservoirs for such bacteria.

Objective of the Research

The main aim of the study was to investigate the presence of vancomycin-resistant enterococci, specifically those containing the vanA gene, in Lusitano horses. This gene is known to confer high-level resistance to the antibiotics vancomycin and teicoplanin.

• Vancomycin and teicoplanin are antibiotics used in treating infections caused by Gram-positive bacteria. High-level resistance to these drugs makes the treatment of infections caused by these bacteria challenging.
• The research becomes significant as Lusitano horses could potentially serve as reservoirs for these antibiotic-resistant bacterial strands, posing a threat to other horses and humans in close contact.

Findings of the Study

The investigation revealed that the vanA isolates in the horses showed considerable resistance to vancomycin, teicoplanin, as well as to other antibiotics like ciprofloxacin, erythromycin, and tetracycline.

• The minimum inhibitory concentration (MIC), which is the lowest concentration of an antibiotic that prevents visible growth of a bacterium, was found to be ≥128mg/l for vancomycin and 64mg/l for teicoplanin, confirming the high-level antibiotic resistance.
• Apart from resistance to vancomycin and teicoplanin, the vanA isolates also showed resistance to other antibiotics such as ciprofloxacin, erythromycin, and tetracycline.

Genetic Characterization

The genetic characterization of the vanA isolates revealed the presence of tet(L) and erm(B) genes, which are associated with tetracycline and erythromycin resistance, respectively.

• All vanA isolates contained tet(L) and erm(B) genes, further confirming the multi-drug resistance property of these bacteria.
• The presence of these genes provides these bacteria the ability to withstand treatment with a range of antibiotics, making them a significant concern in public health.

The findings of this study suggest the need for further research to understand the implications and management of antibiotic-resistant bacteria in horses, and possibly other animals too, to mitigate potential risks to public health.