title: Vancomycin concentration in the vitreous after intravenous and intravitreal administration for postoperative endophthalmitis.
abstract: OBJECTIVE
  To measure the concentrations of vancomycin in the vitreous of patients with postoperative endophthalmitis after administration of 1 g of vancomycin hydrochloride intravenously and injection of 1 mg of vancomycin hydrochloride into the vitreous, and to determine whether these concentrations are adequate for treatment of gram-positive infections.
  
  
  METHODS
  Patients with acute postoperative endophthalmitis were treated with intravenous administration of 1 g of vancomycin hydrochloride followed by vitrectomy and collection of vitreous samples 1 to 5 hours later. Intravitreal vancomycin and ceftazidime were given. Vitreous samples were cultured and their vancomycin concentrations assayed. Minimal inhibitory concentrations of vancomycin for the isolated vitreal pathogens, and serum and vitreous cidal activity were determined.
  
  
  RESULTS
  Eighteen patients with acute postoperative endophthalmitis were studied. Fourteen vitreous samples were available after intravenous vancomycin administration, and 4 vitreous samples were available after intravitreal vancomycin administration. After intravenous injection, vitreous vancomycin concentrations ranged from 0.4 to 4.5 microg/mL. Minimal inhibitory concentrations in these samples, obtained from 10 bacterial isolates, were below the therapeutic levels for most causative organisms, including staphylococci. Vitreous cidal activity values were negative at a dilution of 1:2 in 9 of 10 patients examined. After a 1-mg intravitreal injection, vancomycin concentrations in vitreous samples obtained by a second tap from 4 patients 44 to 72 hours later were 182, 138, 58, and 25 microg/mL. In 2 patients in whom measurements were obtained, vitreous cidal activity values were 1:512 and 1:32.
  
  
  CONCLUSIONS
  Vitreous vancomycin concentrations for the treatment of gram-positive endophthalmitis were nontherapeutic after intravenous administration but therapeutic after intravitreal administration.
authors.affiliation: Department of Ophthalmology, Meir Hospital, Sapir Medical Center, Kfar-Saba, Israel. ferencz@internet-zahav.net.il
authors.forename: J R
authors.initials: JR
authors.lastname: Ferencz
authors.forename: E I
authors.initials: EI
authors.lastname: Assia
authors.forename: L
authors.initials: L
authors.lastname: Diamantstein
authors.forename: E
authors.initials: E
authors.lastname: Rubinstein
mesh_terms: D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001682:Biological Availability; D002387:Cataract Extraction / Q000009:adverse effects*; D009877:Endophthalmitis / Q000188:drug therapy* / Q000378:metabolism / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D006801:Humans; D007275:Injections, Intravenous; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000493:pharmacokinetics* / Q000627:therapeutic use; D014821:Vitrectomy; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin