A novel resistance mechanism to triclosan that suggests horizontal gene transfer and demonstrates a potential selective pressure for reduced biocide susceptibility in clinical strains of Staphylococcus aureus

作者：Ciusa Maria Laura; Furi Leonardo; Knight Daniel; Decorosi Francesca; Fondi Marco; Raggi Carla; Rosado Coelho Joana; Aragones Luis; Moce Laura; Visa Pilar; Teresa Freitas Ana; Baldassarri Lucilla; Fani Renato; Viti Carlo; Orefici Graziella; Luis Martinez Jose; Morrissey Ian; Oggioni Marco Rinaldo^*

来源：International Journal of Antimicrobial Agents, 2012, 40(3): 210-220.

DOI：10.1016/j.ijantimicag.2012.04.021

• Biocide
• Resistance
• Cross-resistance
• Horizontal gene transfer
• FabI
• Triclosan

The widely used biocide triclosan selectively targets FabI, the NADH-dependent trans-2-enoyl-acyl carrier protein reductase, which is an important target for narrow-spectrum antimicrobial drug development. In relation to the growing concern about biocide resistance, we compared in vitro mutants and clinical isolates of Staphylococcus aureus with reduced triclosan susceptibility. Clinical isolates of S. aureus as well as laboratory-generated mutants were assayed for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) phenotypes and genotypes related to reduced triclosan susceptibility. A potential epidemiological cut-off (ECOFF) MBC of %26gt;4 mg/L was observed for triclosan in clinical isolates of S. aureus. These showed significantly lower MICs and higher MBCs than laboratory mutants. These groups of strains also had few similarities in the triclosan resistance mechanism. Molecular analysis identified novel resistance mechanisms linked to the presence of an additional sh-fabI allele derived from Staphylococcus haemolyticus. The lack of predictive value of in-vitro-selected mutations for clinical isolates indicates that laboratory tests in the present form appear to be of limited value. More importantly, detection of sh-fabI as a novel resistance mechanism with high potential for horizontal gene transfer demonstrates for the first time that a biocide could exert a selective pressure able to drive the spread of a resistance determinant in a human pathogen.

• 出版日期2012-9