Survival and Growth of Stenotrophomonas maltophilia in Multipurpose Contact Lens Solutions

Abstract

Purpose: : Stenotrophomonas maltophilia

Methods: : S. maltophilia

Results: : All 13 PHMB formulations resulted in a ≥3.0 log reduction in S. maltophilia after 1-2 hr contact time. No regrowth of the bacterium occurred over 7-14 days for 9 of the solutions in which culturing was undertaken. Solutions based solely on PQ showed <1.0 log kill after 24 hr. The PQ-MAPD-C9ED3A and PQ-MAPD-EDTA formulations showed <1.0 log kill at 6 hr and 3.0-4.0 log kill at 24 hr respectively. After a further 6 days, a 2 log regrowth of the bacterium was observed in the PQ and PQ-MAPD-C9ED3A solutions but not PQ-MAPD-EDTA. Challenge studies in the presence of contact lenses resulted in further loss of biocidal efficacy with the PQ and PQ-MAPD-C9ED3A formulas but not those based on PHMB. S. maltophilia readily supported Acanthamoeba excystment and trophozoite replication.

Conclusions: : S. maltophilia

Keywords: keratitis • contact lens • Acanthamoeba