Multiresistant and blaCTX-M-14-Carrying Salmonella ser. Typhimurium Isolated During a Salmonellosis Outbreak in an Equine Hospital in Argentina.

This research paper investigates the genetic profiles and drug resistance of Salmonella Typhimurium strains that were isolated during an outbreak of salmonellosis at an equine hospital in Argentina. This Salmonella strain, found to be resistant to multiple antibiotics and carrying the resistance gene blaCTX-M-14, previously detected in human and pork isolates, underscores the need for preventative measures and routine drug susceptibility tests for effective treatment of salmonellosis in horses.

Objective of Research

• The aim of this study was to understand the clonal (genetic) relationship and antimicrobial susceptibility profiles of Salmonella ser. Typhimurium that were found during an outbreak of salmonellosis at an Argentinian equine hospital.

Methodology of Research

• Salmonella Typhimurium isolated from three diarrheal horses were studied in the year 2017. The researchers conducted genotypic studies and evaluated the strains’ responses to antimicrobials.
• The pulsed-field gel electrophoresis (a laboratory technique used for the separation and identification of large genetic molecules) was used to identify the strains’ genotypic profile.

Findings of the Research

• All isolates displayed the same pulsotype (genotypic profile) which had previously been detected in isolates from humans and pigs, indicating the cross-species circulation of this Salmonella strain.
• The team identified multiple drug-resistant isolates exhibiting different β-lactam susceptibility profiles. β-lactam antibiotics are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, and others.
• They discovered the blaCTX-M-14 gene, linked to antibiotic resistance, in an equine-origin isolate for the first time in Argentina. This gene creates an enzyme that breaks down antibiotics, rendering them ineffective.

Implications of the Research

• The research emphasized the need for prevention and control strategies against Salmonella infections in both public and veterinary health settings.
• The study argues for routine antibiotic susceptibility tests of diseases causing strains at local levels. This could lead to improvements in the empirical treatment of Equine salmonellosis.