The influence of needle gauge and infection source on vitreous aspirate cultures

Br J Ophthalmol. 2016 Apr;100(4):453-5. doi: 10.1136/bjophthalmol-2015-307081. Epub 2015 Aug 12.


Background/aims: While the Endophthalmitis Vitrectomy Study (EVS) included only post-cataract surgery patients, the methods and data from that study are widely applied in the management of endophthalmitis of all types. We sought to examine how our experience with in-office vitreous aspiration differed from the EVS in two ways: first, by reviewing microbiological culture yields from vitreous aspirates obtained using 30-gauge needles versus 25-27-gauge needles and second, by reviewing culture yields in cases of endogenous versus non-endogenous endophthalmitis.

Methods: Cases of endophthalmitis over a 14-year period were reviewed when vitreous tap was the initial diagnostic procedure. The data included infection source, needle size used to obtain a vitreous aspirate, organism cultured and rates of unsuccessful attempts at vitreous aspiration or dry taps.

Results: 10 cases were endogenous endophthalmitis, while 36 cases were a mix of postoperative, post-traumatic, post-intravitreal injection and miscellaneous patients. A positive microbiological culture was obtained in 11/36 (31%) of vitreous taps using a 25-27-gauge needle and in 8/10 (80%) taps using a 30-gauge needle (p<0.01). A positive vitreous culture was obtained in 18/36 (50%) of all non-endogenous cases, while a positive result was obtained in 0/10 (0%) cases of endogenous endophthalmitis (p<0.01).

Conclusions: The use of a smaller needle in obtaining vitreous samples in endophthalmitis did not lower the microbiological yield. A positive microbiological yield was significantly less likely in cases of endogenous endophthalmitis compared with non-endogenous cases. Vitreous tap as a method for identifying the causative organism in endogenous endophthalmitis was of limited utility.

Keywords: Infection; Inflammation; Microbiology; Treatment Medical; Vitreous.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Anti-Bacterial Agents / therapeutic use
  • Bacteria / isolation & purification*
  • Biopsy, Needle*
  • Colony Count, Microbial
  • Endophthalmitis / drug therapy
  • Endophthalmitis / microbiology*
  • Endophthalmitis / pathology
  • Eye Infections, Bacterial / drug therapy
  • Eye Infections, Bacterial / microbiology*
  • Eye Infections, Bacterial / pathology
  • Humans
  • Microbiological Techniques
  • Middle Aged
  • Needles*
  • Retrospective Studies
  • Vitrectomy
  • Vitreous Body / microbiology*
  • Vitreous Body / pathology


  • Anti-Bacterial Agents