title: Selected Antimicrobial Activity of Topical Ophthalmic Anesthetics.
abstract: OBJECTIVE
  Endophthalmitis is a rare complication of intravitreal injection (IVI). It is recommended that povidone-iodine be the last agent applied before IVI. Patients have reported povidone-iodine application to be the most bothersome part of IVIs. Topical anesthetics have been demonstrated to have antibacterial effects. This study compared the minimum inhibitory concentration (MIC) of topical anesthetic eye drops (proparacaine 0.5%, tetracaine 0.5%, lidocaine 2.0%) and the antiseptic, 5.0% povidone-iodine, against two organisms causing endophthalmitis after IVI.
  
  
  METHODS
  Minimum inhibitory concentration values of topical anesthetics, povidone-iodine, preservative benzalkonium chloride (0.01%), and saline control were determined using five isolates of each Staphylococcus epidermidis and viridans groupStreptococcusspecies (VGS). A broth microdilution technique was used with serial dilutions.
  
  
  RESULTS
  Lidocaine (8.53 × 10-5mol/mL) had MICs of 4.27 to 8.53 × 10-5mol/mL, and tetracaine (1.89 × 10-5mol/mL) had MICs of 9.45 × 10-6mol/mL for all isolates. Proparacaine (1.7 × 10-5mol/mL) had MICs of 1.32 to 5.3 × 10-7and 4.25 × 10-6mol/mL for S. epidermidis and VGS, respectively). Benzalkonium chloride (3.52 × 10-7mol/mL) had MICs of 1.86 × 10-9to 1.1 × 10-8and 4.40 × 10-8mol/mL for S. epidermidis and VGS, respectively. Povidone-iodine (1.37 × 10-4mol/mL) had MICs of 2.14 to 4.28 × 10-6and 8.56 × 10-6mol/mL for S. epidermidis and VGS, respectively.
  
  
  CONCLUSIONS
  Proparacaine was the anesthetic with the lowest MICs, lower than that of povidone-iodine. Benzalkonium chloride had lower MICs than proparacaine. All tested anesthetics and povidone-iodine inhibited growth of S. epidermidis and VGS at commercially available concentrations.
  
  
  CONCLUSIONS
  For certain patients, it could be possible to use topical anesthetic after povidone-iodine for comfort without inhibiting and perhaps contributing additional antimicrobial benefit.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Reynolds
authors.affiliation: Department of Laboratory Medicine, Mayo Clinic, Rochester, MN, USA ; Department of Infectious Disease, Mayo Clinic, Rochester, MN, USA.
authors.forename: Kerryl E
authors.initials: KE
authors.lastname: Greenwood-Quaintance
authors.affiliation: Department of Laboratory Medicine, Mayo Clinic, Rochester, MN, USA ; Department of Infectious Disease, Mayo Clinic, Rochester, MN, USA.
authors.forename: Robin
authors.initials: R
authors.lastname: Patel
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, MN, USA ; Department of Molecular Medicine, Mayo Clinic, Rochester, MN, USA ; VRS Foundation Board Member, Mayo Clinic, Rochester, MN, USA.
authors.forename: Jose S
authors.initials: JS
authors.lastname: Pulido
keywords: Staphylococcus epidermidis; antimicrobials; benzalkonium chloride; endophthalmitis; intravitreal injection; lidocaine; proparacaine; tetracaine; topical ophthalmic anesthetics; viridans group Streptococcus species