Decreased susceptibility to a major component of disinfectant associated to human and equine Pseudomonas aeruginosa (PSAE) isolates

Marine Pottier (1, 2, 3) , Sophie Castagnet (2, 3) , François Gravey (1) , Michel Auzou (4) , Guillaume Leduc (4) , Simon Le Hello (1, 4, 5, 6) , Albertine Léon (2, 3, 6)

1 GRAM 2.0 - Groupe de Recherche sur l'Adaptation Microbienne
2 LABÉO - LABÉO, Pôle d’analyses et de recherche de Normandie
3 U2RM - Unité de Recherche Risques Microbiens
4 Service Microbiologie, Centre Hospitalier Universitaire de Caen
5 Département d'Hygiène Hospitalière [CHU Caen]
6 Equivalent coordination

Background: Didecyldimethylammonium chloride (DDAC) is a quaternary ammonium compound used in several disinfection products in veterinary and hospital environments. In Human medicine, strains of Pseudomonas aeruginosa (PSAE) have been showed to present a decreased susceptibility to DDAC according to the NFEN-13727+A2 referential by incompletely understood mechanisms. Decreased susceptibility to antibiotics and disinfectant agents is a major concern to public health as it allows pathogens to persist in their environment. Objectives: The purpose of this study was to evaluate the existence of PSAE strains with DDAC decreased susceptibility among animals in Normandy, France. Study design: Based on a “One health” approach, our global project aims at a better understanding of the resistance mechanisms to disinfectants and antibiotics for PSAE. Methods: Between 1996 and 2020, 183 strains isolated from animal samples (including 146 equines) were provided by our reference laboratory and routine diagnostic service. Minimum inhibitory concentrations (MICs) of DDAC were determined using broth microdilution method. Decreased susceptibility was defined as MIC≥64mg/L, corresponding to the concentration of DDAC in a disinfectant solution according to the manufacturer’s instructions. Results: During the 1996–2015 period all strain tested were sensitive to DDAC, whereas for years 2017, 2018, 2019 and 2020 respectively 20%; 26.3%; 6.5% and 12% of strains presented decrease susceptibility. Over all 10.4% of the strains presented this phenotype and 84.21% of them were equine. Finally, equine respiratory and genital samples are those which have shown the most decrease in sensitivity, representing respectively 42.11% and 36.84% of all strains. Main limitation: From 1996 to 2015, only 23 strains have been isolated; for years 2017 and 2018, only strains showing antibimicrobial resistances phenotype were selected. Conclusion: Decreased susceptibility to DDAC is also present in the veterinary industry. Genomic analyses are underway to determine the relatedness of theses strains and to understand the mechanisms involved.Short title: Adaptation to a major disinfectant-componentSources of funding: Conseil Régional de Normandie and Ministère de l’Agriculture (EcoAntibio) support this study

Mots clés: Pseudomonas aeruginosa; resistance; disinfectant; adaptation; quaternary ammonium; veterinary medicine; equine; canine; feline; respiratory

Domaines: Microbiologie et Parasitologie

Marine Pottier, Sophie Castagnet, François Gravey, Michel Auzou, Guillaume Leduc, et al.. Decreased susceptibility to a major component of disinfectant associated to human and equine Pseudomonas aeruginosa (PSAE) isolates. 11th International Equine Infectious Diseases Conference, Sep 2021, Online, France. pp.12, ⟨10.1111/evj.02_13495⟩. ⟨hal-03418589⟩