title: Adaptation and growth of Serratia marcescens in contact lens disinfectant solutions containing chlorhexidine gluconate.
abstract: Serratia marcescens (11 of 12 strains) demonstrated an ability to grow in certain chlorhexidine-based disinfecting solutions recommended for rigid gas-permeable contact lenses. For a representative strain, cells that were grown in nutrient-rich medium, washed, and inoculated into disinfecting solution went into a nonrecoverable phase within 24 h. However, after 4 days, cells that had the ability to grow in the disinfectant (doubling time, g = 5.7 h) emerged. Solutions supporting growth of S. marcescens were filter sterilized. These solutions, even after removal of the cells, showed bactericidal activity against Pseudomonas aeruginosa and a biphasic survival curve when rechallenged with S. marcescens. Adaptation to chlorhexidine by S. marcescens was not observed in solutions formulated with borate ions. For chlorhexidine-adapted cells, the MIC of chlorhexidine in saline was eightfold higher than that for unadapted cells. Cells adapted to chlorhexidine showed alterations in the proteins of the outer membrane and increased adherence to polyethylene. Cells adapted to chlorhexidine persisted or grew in several other contact lens solutions with different antimicrobial agents, including benzalkonium chloride.
authors.affiliation: Biology Department, Georgia State University, Atlanta 30302-4010.
authors.forename: P A
authors.initials: PA
authors.lastname: Gandhi
authors.forename: A D
authors.initials: AD
authors.lastname: Sawant
authors.forename: L A
authors.initials: LA
authors.lastname: Wilson
authors.forename: D G
authors.initials: DG
authors.lastname: Ahearn
mesh_terms: D000220:Adaptation, Biological / Q000187:drug effects*; D001422:Bacterial Adhesion / Q000187:drug effects; D001425:Bacterial Outer Membrane Proteins / Q000187:drug effects; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003261:Contact Lenses; D004202:Disinfectants / Q000494:pharmacology*; D004340:Drug Contamination; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions; D012706:Serratia marcescens / Q000187:drug effects* / Q000254:growth & development* / Q000502:physiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004202:Disinfectants; D009883:Ophthalmic Solutions; C010882:chlorhexidine gluconate; D002710:Chlorhexidine