The influence of needle gauge and infection source on vitreous aspirate cultures.
OBJECTIVE
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.
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Jesse M
JM
Smith
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Marc T
MT
Mathias
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Scott C
SC
Oliver
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Naresh
N
Mandava
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Jeffrey L
JL
Olson
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Hugo
H
Quiroz-Mercado
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Alan G
AG
Palestine
D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001419:Bacteria / Q000302:isolation & purification*; D001707:Biopsy, Needle; D015169:Colony Count, Microbial; D009877:Endophthalmitis / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D006801:Humans; D008828:Microbiological Techniques; D008875:Middle Aged; D009339:Needles; D012189:Retrospective Studies; D014821:Vitrectomy; D014822:Vitreous Body / Q000382:microbiology* / Q000473:pathology
D000900:Anti-Bacterial Agents
Infection; Inflammation; Microbiology; Treatment Medical; Vitreous