Persistance of Serratia marcescens, Serratia liquefaciens and E. coli in solutions for contact lenses

Twenty-four different brands of contact lens solutions were experimentally inoculated with strains of S. marcescens, S. liquefaciens and E. coli. Only flexol and hexidin could sufficiently suppress the growth of Serratia strains. If a soaking agent is to be effective in suppressing S. marcescens it must have a chlorhexidine concentration of at least 50 micrograms/ml and a thiomersal concentration of 10 micrograms/ml.