Evaluation of activity of selected ophthalmic antimicrobial agents in combination against common ocular microorganisms

Objective-To determine in vitro efficacy of gentamicin, tobramycin, and mic onazole when used in combination, with or without atropine, against Pseudom onas or Aspergillus sp, Procedure-Selected ophthalmic agents were combined for predetermined times. Sterile disks impregnated with the combined solutions were prepared and pl aced on Mueller-Hinton plates that were seeded with Pseudomonas or Aspergil lus sp. Zones of growth inhibition were measured at postincubation hours 24 and 48. Results-Tobramycin alone inhibited growth of Pseudomonas so, whereas micona zole inhibited growth of Aspergillus sp. Significant differences in zones o f growth inhibition when atropine was combined with tobramycin, when gentam icin was combined with miconazole, or when atropine was combined with micon azole and gentamicin, were not detected. Clinical Relevance-Combining selected ophthalmic therapeutic agents for as long as 6 hours does not appear to alter the in vitro efficacy of the agent s against microorganisms used in this study.