In vitro susceptibility to antimicrobial drugs of 62 Salmonella strains isolated from horses in The Netherlands.

This is a study that examines how various strains of Salmonella found in horses respond to 17 different antimicrobial drugs. The study concludes with a suggested treatment plan for equine salmonellosis based on the results.

Research Scope

• Involved testing the susceptibility of various types of Salmonella to a range of antimicrobial drugs. The Salmonella strains used in the tests were isolated from horses at the Large Animal Clinics of Utrecht University in The Netherlands.
• Studied a total of seven different strains of Salmonella, including Salmonella typhimurium (the most common type where 52 strains were examined), Salmonella thompson, Salmonella heidelberg, Salmonella hadar, Salmonella enteritidis, Salmonella infantis, and Salmonella derby.

Testing Method

• Utilized the agar dilution method to test how 17 different antimicrobial drugs affect 62 different Salmonella strains.

Findings

• Discovered that a majority of the Salmonella strains responded best to gentamicin, amikacin, kanamycin, enrofloxacin, ciprofloxacin, flumequine, colistine, furazolidone, and ceftiofur – they were susceptible to these drugs, meaning they had an effect in inhibiting their growth or killing these bacteria.
• However, all fourteen strains of Salmonella typhimurium, a specific phage type 200, were found to be multiresistant – they were unaffected by several drugs including ampicillin, amoxycillin, amoxycillin in combination with clavulanic acid, chloramphenicol, nitrofurantoin, trimethoprim, aditoprim and baquiloprim. Two of these multiresistant strains also showed resistance to gentamicin.

Recommended Treatment

• Based on the susceptibility data and existing pharmacokinetic literature, researchers proposed a treatment plan for horses with salmonellosis.
• First choice is a combination of gentamicin (at a dosage of 3 mg/kg) and ampicillin (at a dosage of 20 mg/kg), administered intravenously every 8-12 hours.
• The alternative treatment involves the intravenous administration of a trimethoprim/sulfonamide combination twice daily at a combined dose of 30 mg/kg.