Microbial Profile and Antibiotic Susceptibility of Culture-Positive Bacterial Endophthalmitis

Eye (Lond). 2011 Mar;25(3):382-7; quiz 388. doi: 10.1038/eye.2010.236. Epub 2011 Feb 18.


Purpose: To assess the distribution of microorganisms isolated from patients with bacterial endophthalmitis and their antimicrobial susceptibility.

Methods: Retrospective analysis of medical and microbiological records of patients with suspected diagnosis of endophthalmitis. The following information was assessed: number of presumed and culture-positive endophthalmitis cases, source of infection, microbiological result (aqueous and/or vitreous culture and Gram staining), microbial characterization and distribution, and antimicrobial susceptibility.

Results: A total of 107 (46%) of 231 patients with bacterial endophthalmitis showed positive results by gram stain or culture. Of these, 97 (42%) patients were positive for culture only. Most of them (62%) were secondary to a surgical procedure (postoperative), 12% were posttraumatic and 26% were secondary to an unknown source or the data were unavailable. A total of 100 microorganisms were isolated (38 aqueous and 67 vitreous samples) from the 97 culture-positive cases (91% were gram-positive and 9% were gram-negative). Coagulase-negative Staphylococcus(CoNS) (48%) were the most frequently isolated, followed by Stretococcus viridans(18%), and Staphylococcus aureus(13%). The antimicrobial susceptibility for CoNS was as follows: amikacin-91.6%, cephalothin-97.9%, ceftriaxone-50%, ciprofloxacin-62.5%, chloramphenicol-91.8%, gatifloxacin-79.5%, gentamicin-72.9%, moxifloxacin-89.5%, ofloxacin-70.8%, oxacillin-58.3%, penicillin-33.3%, tobramycin-85.4%, and vancomycin-100%.

Conclusion: Gram-positive bacteria were the major causes of infectious endophthalmitis in this large series, usually following surgery. CoNS was the most common isolate. Of interest, susceptibility to oxacillin and fourth-generation quinolones was lower than previously published.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / therapeutic use
  • Endophthalmitis / drug therapy
  • Endophthalmitis / microbiology*
  • Gram-Negative Bacteria* / drug effects
  • Gram-Negative Bacteria* / isolation & purification
  • Gram-Positive Bacteria* / drug effects
  • Gram-Positive Bacteria* / isolation & purification
  • Humans
  • Microbial Sensitivity Tests
  • Retrospective Studies


  • Anti-Bacterial Agents