This highly technical microbiology paper concludes that Virkon® S is free from possible Salmonella resistance build-up and the continued use of an oxidising disinfectant such as Virkon® S reduces the potential infectivity of these super strains.

Published in Veterinary Microbiology¹ the study assessed 286 Salmonella isolates against five commonly used poultry disinfectants: formaldehyde, glutaraldehyde/benzalkonium chloride compound, oxidising compound (Virkon® S), tar oil phenol and iodophor. Of the 286 isolates, 256 were sourced in the Danish poultry houses and six of these Salmonella isolates were adapted and re-adapted to mimic the development of resistance. To test the disinfectants even more thoroughly, mutants of the isolates highly resistant to triclosan (a disinfectant linked with multiple antibiotic resistance) were selected. A further potentially highly resistant isolate which was identified as having successfully grown in cyclohexane (associated with resistance) was also added to the study.

Overall, the researchers concluded that there were only small variations in the minimum inhibitory concentrations (MICs) – the lowest concentrations of disinfectant required to inhibit the growth of the Salmonella isolates. However, the researchers noted that the best efficacies were found with Virkon® S and the previous use of an oxidising compound such as Virkon® S reduced the overall MICs.

Commenting, Mark Blackwell MRCVS, DuPont Animal Health Solutions, “This important study presents poultry producers with good news, as it confirms that there is no need to rotate the use of Virkon® S as it is once again proven highly effective against super-resistant strains of Salmonella. We are also particularly pleased that Virkon® S is the best performing of the disinfectants and it would appear it is the disinfectant with the least potential for becoming resistant to these challenging strains of Salmonella.”