Idenfication of genes involved in the susceptibility of Serratia marcescens to polyquaternium-1

Abstract

Objectives: Polyquaternium-1 (PQ-1) is a biocide used commercially in a contact lens disinfecting solution, 'Opti-Free Express (Alcon) Multi-Purpose Disinfecting Solution'. The genetic basis for resistance of Serratia marcescens to PQ-1 was investigated using a random transposon-based mutagenesis approach. Methods: S. marcescens was subjected to random transposon mutagenesis using a mini-Tn5Km2 transposon. Mutants with increased susceptibility to PQ-1 were selected and the disrupted genes were identified. Antibiotic susceptibility profiles were also determined for all of the mutants. Results: A wide range of genes were found to be disrupted in the mutants. The most common were genes associated with the cell membranes, or involved in biosynthesis and metabolism. Conclusions: This study shows that random transposon mutagenesis is an effective tool for the elucidation of mechanisms of action and resistance to biocides. The results support our previous findings that PQ-1 is active against the cytoplasmic membrane of S. marcescens. © The British Society for Antimicrobial Chemotherapy 2004; all rights reserved.