2009 OMIG, Abstract 11

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Bacterial Transference by  Needles Passed through Cadaveric Conjunctiva.
M. Mifflin, J. Pettey, W. McEntire, D. Pettey, K. Kamae, Y.F. Khalifa, R.J. Olson
University of Utah Department of Ophthalmology, Moran Eye Center, Salt Lake City, UT

Purpose:  To determine whether needle transference of bacteria occurs after passage through conjunctiva, speciate any bacteria so transferred, and determine the effectiveness of 4th generation fluoroquinolones in blocking this.
Methods:  Prior to procurement of donor eye tissue, conjunctiva of 200 eyes from 100 human cadavers less than 18 hours post mortem were punctured ten times with a 27 gauge needle on a syringe filled with 0.1cc of BSS.  Syringe contents were expressed onto blood agar plates.  The puncturing was repeated ten separate times in each eye for a total of 2,000 culture plates.  Each eye then received either moxifloxacin 0.5% or gatifloxacin 0.3% topically.  15 minutes following instillation, the puncturing and plating procedure was repeated.  Cultures were allowed to grow for 10 days and positive samples were sent for speciation.  
Results:  4000 samples representing 40,000 penetrations of conjunctiva (2000 without antibiotic, 1000 after moxifloxacin, and 1000 after gatifloxacin) were plated.  1039 (25.9%) plates showed positive growth.  Of the 2000 control samples 568 (28.4%) were positive compared with 249 (24.9%) after gatifloxacin and 216 (21.6%) after moxifloxacin treatment.  Statistically significant decreases in positive culture rates in comparison to the pretreatment results were observed for  both gatifloxacin  (p < 0.05) and moxifloxacin (p < 0.0005).  There was no statistical difference between the culture rates for gatifloxacin and moxifloxacin. 
Conclusions:  Transecting the conjunctiva with a needle can transfer bacteria from the ocular surface into the needle bore where it would be injected into the eye for any intraocular injection. The amount of bacteria in the needle bore is sufficient for growth on blood agar cultures, and very little bacteria are needed for intravitreal growth. While both moxifloxacin and gatifloxacin decreased the bacterial rate of recovery, the effect was small and statistically similar.