NEEDLE CONTAMINATION IN THE SETTING OF INTRAVITREAL INJECTIONS DUNCAN A. FRIEDMAN, MD, MPH, T. PETER LINDQUIST, MD, JOHN O. MASON III, MD, GERALD MCGWIN, PHD Background/Purpose: To evaluate the risk of intravitreal needle contamination through speaking versus breathing in an office setting. Methods: This was a prospective sampling assay. Participants held a sterile 30-gauge half-inch needle 25 cm from their mouth for 30 seconds under 2 conditions: 1) while speaking and 2) while breathing silently. Needles were then cultured and assayed after 6 days of incubation. Absolute colony-forming units were compared between conditions and against control sterile needles and oral swab cultures. Results: Ten physicians were sampled with 15 samples per physician. Participants grew an average of 0.21 colonies (median = 1 CFU) from their talking samples and 0.07 colonies (median = 1 CFU) from their silent breathing samples. Oral swab plates grew an average of 373.4 colonies. None of the control needle plates grew colony-forming units. A nominal regression analysis showed no significant difference between talking and silent samples (P = 0.457). Conclusion: No significant difference in needle contamination was found between talking and breathing. Compared with oral swab plates, a significant difference exists between the amount of flora colonizing the oropharynx and that which was found on the needle cultures (P , 0.0001). These findings suggest that speaking versus remaining silent makes no difference in regard to needle contamination with oral flora during intravitreal injection. RETINA 34:929–934, 2014
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Four recent studies have suggested that oral flora from the physician, patient, or office staff involved in the procedure may be a source of infection during officebased intravitreal injection.23,24,27,28 Doshi et al28 most recently reported on an increase in contamination using agar plates as a source rather than using needles, which better simulate the actual rates of office-based intravitreal procedure. These publications suggest that all those involved in the injection procedure should consider either wearing a face mask or remain silent for the entire procedure to minimize microdroplet transmission. The purpose of this study was to determine if a difference in needle contamination from oral flora exists between needles held in front of a speaking versus silent subject. Secondarily, this study seeks to quantify bacterial contamination of the injection needle from oral flora in the setting of intravitreal injection.
ntravitreal injection has become a common treatment option for ophthalmologists and is one of the most common treatment procedures performed in Europe and the US.1 With the introduction of new pharmacological therapies for the treatment of neovascular age-related macular degeneration, diabetic macular edema, edema secondary to vascular occlusion, and small macular holes, the treatment of vitreoretinal disease is trending toward an office-based primary practice.2–19 Neovascular age-related macular degeneration alone accounts for 1.22 million people in the United States, and this number is only expected to increase.20 The number of annual intravitreal injections, reported to the Medicare database, has increased significantly from 3,305 in 1997 to 812,413 in 2007.21 This does not account for injections reported to other insurances or done without insurance reporting. Although intravitreal injections are generally well tolerated, one of the most serious risks of intravitreal injection is endophthalmitis, which can occur at a rate between 0.009% and 0.87%.22–26
Methods This was a prospective, sampling assay. Institutional review board approval was obtained from the University of Alabama at Birmingham IRB. Participants were physicians who currently perform intravitreal injection
None of the authors have conflicts of interest to disclose. Reprint requests: John O. Mason III, MD, 700 South 18th Street, Suite 601, Birmingham, AL 35294; e-mail: tracy_emond@mac. com
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and were voluntarily recruited. All physicians gave informed consent before sample collection. Participants held a sterile 30-gauge half-inch needle 25 cm from their mouth for 30 seconds under 2 conditions: 1) while speaking and 2) while breathing silently with their mouths closed. The “speaking” group held a conversation typical of examination room settings with an investigator. The investigator (T.P.L.) maintained proximity to the participants and handed them needles, simulating an assistant during a typical intravitreal injection. This was performed to simulate office conditions for intravitreal injection and actual time of needle exposure, although the amount of time the needle was held in front of the mouth was potentially over-estimated to simulate true office conditions. The “breathing” group was instructed not to speak, and no conversation was held between the investigator nor the participants. The needle was then streaked on an Chocolate/5% Sheep Blood Agar Biplate (ThermoFisher Scientific, Auburn, AL) and incubated for 6 days at 37°C. Colony-forming units (CFUs) were counted (by a separate investigator that was masked to the group assignment for each plate) but not identified. This was repeated 15 times for each participant for each condition (N = 300 samples). Participants’ oral mucosa was swabbed with a cotton-tip applicator and streaked on an agar biplate for control comparison. A set of 10 sterile needles was also directly streaked onto agar biplates as a set of negative controls. Statistical analysis was performed using a nominal regression analysis to account for clustering effects imparted by sampling the same participant multiple times. P , 0.05 was used to indicate statistical significance. As demonstrated by previous studies, 100 plates per group would be required to achieve a statistical power of 90%.28
Fig. 1. Needle contamination comparison of CFUs while talking versus breathing.
Results Ten physicians were sampled. A total of 300 needles were streaked on agar biplates. Figure 1 demonstrates the frequency of plates in proportion to the number of CFUs grown. Participants grew an average of 0.21 CFUs (median = 1 CFU) from their talking samples and 0.07 CFUs (median = 1 CFU) from their silent breathing samples. Oral swab plates grew an average of 373.4 CFUs. In total, 5.3% (16/300) of culture plates were positive for any organism, and of those, 68.7% (11/16) grew only a single colony. Ten plates in the talking group and 6 plates in the breathing group showed any sign of growth. A nominal regression analysis showed no significant difference between talking and silent samples (P = 0.457). Both silent and talking plates grew significantly fewer CFUs compared with control oral swabs (P , 0.0001). None of the control plates (i.e., direct needle without exposure) grew CFUs.
Discussion This study showed no significant difference in needle contamination in an intravitreal injection setting between subjects who were talking versus silent. Only a small subset of plates showed any growth (5.3%). Of these plates, 2 were questionable contaminants as most of the CFUs on these plates grew peripherally and not along the areas that were directly streaked with the sample needle. By sampling the amount of bacteria that routinely colonize the oropharynx, this study also provides an idea of how much of a source a practitioner’s oropharynx could provide. Multiple samples from each practitioner were used in both talking and breathing conditions with
NEEDLE CONTAMINATION WITH IV INJECTION FRIEDMAN ET AL
exposure times potentially much longer than the usual needle exposure time before intravitreal injection. Active attempts at needle contamination through breathing or talking failed to produce a large percent of colonized plates. The findings of this study lead to a few questions about the source of recent outbreaks of oropharyngeal related endophthalmitis. As mentioned earlier, 4 key studies point out that practitioners could be a source of ocular surface contamination during intravitreal injection.23,24,27,28 More recently, an outbreak of Streptococcus mitis/oralis was found to originate from oropharyngeal contamination of aliquots of medicine at a compounding pharmacy.29 This has increased the focus on proper sterile technique when handling medicine from a larger source bottle that is being subdivided into individual doses for intravitreal injection. Other suggested sources of possible contamination include the oropharyngeal flora of the patient, the physician, the technicians helping during the procedure, and the fact that viscous lidocaine blocks the sterilizing effects of povidone–iodine.24,27 The inherent problem with these hypotheses is that they lack good studies to validate any of these sources. In our study, practitioners actively tried to contaminate needles multiple times with only 3 plates showing any substantial growth. These findings are similar to the study conducted by Wen et al,27 where plates were contaminated by talking directly over culture plates for 5 minutes, a much longer exposure time than most intravitreal injections. Furthermore, their study only grew between 1 and 6 CFUs which again proves the extreme difficulty in active contamination of the ocular surface. In a similar study, Doshi et al28 showed a significant difference between masked individuals versus speaking individuals and concluded that good antisepsis of the conjunctival surface and practitioner silence is the best means of avoiding droplet dispersion. Significantly fewer CFUs grew when comparing talking conditions to silent conditions. Although the ratio of CFU formation was similar in our study (i.e., mean 0.21 CFUs in speaking versus 0.07 CFUs in breathing), differences in statistical analysis might account for the discrepancy with respect to statistical significance. Specifically, it is not clear whether the authors accounted for the paired nature of the data, nor the nonparametric distribution of the data, which would require nonparametric statistical tests. As the authors of this study used t-tests and analysis of variables in their analysis, it is hard to validate their findings. Furthermore, limitations of the Doshi et al study include the fact that blood agar plates do not simulate the intravitreal injection technique nor the conjunctival surface accurately. In addition, our analysis using
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nominal regression more accurately reflects the distribution of CFUs, which is not likely to be normal. We believe that our analysis of intravitreal needles helps negate their potential as a source of contamination. Other potential sources of bacterial endophthalmitis related to streptococcal species include the patient’s own colonizing bacteria or microdroplets from other individuals who have landed on the conjunctival surface. As the conjunctival mucosa is directly connected to the nasopharynx and oropharynx, it is possible that the same bacteria colonizing the patient’s respiratory secretions would be present on the conjunctival mucosa. Streptococcal species have been readily cultured from the conjunctival surface in a subset of patients undergoing routine conjunctival cultures.30–34 Streptococcal endophthalmitis has also contributed largely to infections in sterile OR situations where practitioners and patients are masked indicating that the conjunctival surface could be a major source for Streptococcal species.24,35 In fact, the landmark study that noted a 3 times greater risk of oral pathogens in the clinical setting compared with the operating room setting actually had more total oral pathogens cultured from the operating room setting infections. Furthermore, there was no statistically significant difference between the number of oral flora– related endophthalmitis cases derived from a sterile operating room setting when compared with a clinic based setting (P = 0.13).24 The findings of this study do not negate the possibility of microdroplets from other practitioners landing on the surface of the conjunctiva, which could later have access through exposed needle tracks. This study only demonstrates the difficulty of needle contamination from talking versus silent breathing. Extrapolation of these findings to their effects on overall rates of endophthalmitis cannot be derived because there are other factors that could be contributing to these rates (i.e., patient conjunctival colonization or subsequent migration of bacteria into the vitreous cavity through open needle tracks). The hypotheses that oropharyngeal sources are the direct cause of bacterial contamination are reinforced by studies related to spinal tap procedures that posit that face masks could help prevent the transmission of oropharyngeal flora that cause iatrogenic meningitis.36 Whether face masks actually decrease oropharyngeal contamination during lumbar puncture has been debated as well with evidence both for and against the protective effect of face masks.37–40 Black and Weinstein concluded that in higher risk situations, such as when the practitioner has an upper respiratory tract infection, the consideration of face mask use would be appropriate.41 It is not recommended to extrapolate these studies to intravitreal injections because the conditions are different: 1) the surface area
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for contamination is much larger in a lumbar puncture procedure; 2) the needle used is a large-bore spinal needle with more potential for intralumenal contamination; 3) the “needle exposure time” of a lumbar puncture is much longer than that of an intravitreal injection; and 4) the lumbar region is not a mucosal surface that could already be contaminated with streptococcal species. Also, international rates of endophthalmitis after intravitreal injection are equivalent between countries that require face mask use and those that do not use face masks routinely.22,42–44 The purpose of this discourse is to discuss the implications of labeling oropharyngeal contaminants as a source for conjunctival contamination. Known sources of bacteria include the conjunctival surface and lid margin, which are precolonized at the time of injection.26,33,35,45–47 As has been shown in previous studies from cataract surgery and intravitreal injection, the most common causes of bacterial endophthalmitis are skin contaminants such as coagulase-negative staphylococcal species or Staphylococcus aureus.26,31,48–50 These studies have further implications in that their conclusions advocate that practitioners wear masks or at least avoid talking during an intravitreal injection procedure. We cannot directly refute the idea that masks could decrease conjunctival contamination because we did not have a masked group. As discussed above, it is also possible that the bacteria could migrate into the vitreous cavity after the procedure because of an open needle track. We believe that this emphasizes the importance of povidone–iodine in sterilizing the patient’s conjunctiva, which has been proven to greatly reduce the number of bacteria on the conjunctival surface and reduce the rate of postoperative endophthalmitis.44,50–61 We realize that there are several limitations to this study, the most important one being its small sample size. Endophthalmitis after intravitreal injection occurs at an extremely low rate. This makes clinical trials difficult in that large sample sizes are necessary for meaningful results. However, our study includes a large sample size with 300 needles sampled and demonstrates that bacteria rarely contaminate the injection needle when “actively” trying to contaminate the surface. Second, using needles to streak agar plates might not have as high a yield as culturing needles in broth. Quantitative analysis of broth media was beyond the ability of our research facility and could potentially be used as a future means of analysis for a higher yield. Third, we did not identify the bacteria that contaminated the injection needle, and therefore cannot comment on the type of organisms found on the needle. Last, we did not include a face-masked group, which could have provided insight into its role in preventing needle contamination.
In conclusion, our study is the first to show no statistical difference in needle contamination whether talking or silent in simulating the intravitreal injection procedure. Because breathing silently can result in a small chance of needle contamination, not only the physician but also the patient would have to wear a mask to decrease the rate of contamination if one were to accept the mask hypothesis. Future studies should try to subspeciate conjunctival contaminants to see whether they coincide with the oral flora of administering practitioners or patients. Key words: intravitreal, injection, endophthalmitis. References 1. Shah CP, Garg SJ, Vander JF, et al. Outcomes and risk factors associated with endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor agents. Ophthalmology 2011;118:2028–2034. 2. Brown DM, Michels M, Kaiser PK, et al. Ranibizumab versus verteporfin photodynamic therapy for neovascular age-related macular degeneration: two-year results of the ANCHOR study. Ophthalmology 2009;116:57–65.e5. 3. Bressler NM, Chang TS, Fine JT, et al. Improved visionrelated function after ranibizumab vs photodynamic therapy: a randomized clinical trial. Arch Ophthalmol 2009;127:13–21. 4. Campochiaro PA, Heier JS, Feiner L, et al. Ranibizumab for macular edema following branch retinal vein occlusion: sixmonth primary end point results of a phase III study. Ophthalmology 2010;117:1102–1112.e1. 5. Varma R, Bressler NM, Suñer I, et al. Improved vision-related function after ranibizumab for macular edema after retinal vein occlusion: results from the BRAVO and CRUISE trials. Ophthalmology 2012;119:2108–2118. 6. Elman MJ, Aiello LP, Beck RW, et al. Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema. Ophthalmology 2010;117:1064–1077.e35. 7. Elman MJ, Qin H, Aiello LP, et al. Intravitreal ranibizumab for diabetic macular edema with prompt versus deferred laser treatment: three-year randomized trial results. Ophthalmology 2012;119:2312–2318. 8. Cunningham ET, Adamis AP, Altaweel M, et al. A phase II randomized double-masked trial of pegaptanib, an anti-vascular endothelial growth factor aptamer, for diabetic macular edema. Ophthalmology 2005;112:1747–1757. 9. Heier JS, Brown DM, Chong V, et al. Intravitreal aflibercept (VEGF trap-eye) in wet age-related macular degeneration. Ophthalmology 2012;119:2537–2548. 10. de Smet MD, Gandorfer A, Stalmans P, et al. Microplasmin intravitreal administration in patients with vitreomacular traction scheduled for vitrectomy: the MIVI I trial. Ophthalmology 2009;116:1349–1355. 11. Stalmans P, Delaey C, de Smet MD, et al. Intravitreal injection of microplasmin for treatment of vitreomacular adhesion: results of a prospective, randomized, sham-controlled phase II trial (the MIVI-IIT trial). Retina 2010;30:1122–1127. 12. Stalmans P, Benz MS, Gandorfer A, et al. Enzymatic vitreolysis with ocriplasmin for vitreomacular traction and macular holes. N Engl J Med 2012;367:606–615.
NEEDLE CONTAMINATION WITH IV INJECTION FRIEDMAN ET AL 13. Boyer DS, Heier JS, Brown DM, et al. A Phase IIIb study to evaluate the safety of ranibizumab in subjects with neovascular age-related macular degeneration. Ophthalmology 2009;116: 1731–1739. 14. Boyer D, Heier J, Brown DM, et al. Vascular endothelial growth factor Trap-Eye for macular edema secondary to central retinal vein occlusion: six-month results of the phase 3 COPERNICUS study. Ophthalmology 2012;119:1024–1032. 15. Brown DM, Heier JS, Clark WL, et al. Intravitreal aflibercept injection for macular edema secondary to central retinal vein occlusion: 1-year results from the phase 3 COPERNICUS study. Am J Ophthalmol 2013;155:429–437.e7. 16. Do DV, Nguyen QD, Boyer D, et al. One-year outcomes of the Da VINCI study of VEGF trap-eye in eyes with diabetic macular edema. Ophthalmology 2012;119:1658–1665. 17. Heier JS, Boyer D, Nguyen QD, et al. The 1-year results of CLEAR-IT 2, a phase 2 study of vascular endothelial growth factor trap-eye dosed as-needed after 12-week fixed dosing. Ophthalmology 2011;118:1098–1106. 18. Nguyen QD, Shah SM, Heier JS, et al. Primary end point (six months) results of the ranibizumab for edema of the mAcula in diabetes (READ-2) study. Ophthalmology 2009;116:2175– 2181.e1. 19. Rosenfeld PJ, Brown DM, Heier JS, et al. Ranibizumab for neovascular age-related macular degeneration. N Engl J Med 2006;355:1419–1431. 20. Friedman DS, O’Colmain BJ, Muñoz B, et al. Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol 2004;122:564–572. 21. Ramulu PY, Do DV, Corcoran KJ, et al. Use of retinal procedures in medicare beneficiaries from 1997 to 2007. Arch Ophthalmol 2010;128:1335–1340. 22. Mason JO, White MF, Feist RM, et al. Incidence of acute onset endophthalmitis following intravitreal bevacizumab (Avastin) injection. Retina 2008;28:564–567. 23. McCannel C. Meta-analysis of endophthalmitis after intravireal injection of anti-VEGF agents: causative organisms and prevention strategies. ASRS 28th Annual Meeting Vancouver, BC, Canada 2010. 24. Chen E, Lin MY, Cox J, Brown DM. Endophthalmitis after intravitreal injection: the importance of viridans streptococci. Retina 2011;31:1525–1533. 25. Scott IU, Flynn HW. The role of topical antibiotic prophylaxis for intravitreal injections. Arch Ophthalmol 2007;125:974–976. 26. de Caro JJ, Ta CN, Ho HK, et al. Bacterial contamination of ocular surface and needles in patients undergoing intravitreal injections. Retina 2008;28:877–883. 27. Wen JC, McCannel CA, Mochon AB, Garner OB. Bacterial dispersal associated with speech in the setting of intravitreous injections. Arch Ophthalmol 2011;129:1551–1554. 28. Doshi RR, Leng T, Fung AE. Reducing oral flora contamination of intravitreal injections with face mask or silence. Retina 2012;32:473–476. 29. Goldberg RA, Flynn HW, Isom RF, et al. An outbreak of streptococcus endophthalmitis after intravitreal injection of bevacizumab. Am J Ophthalmol 2012;153:204–208.e1. 30. Dong Q, Brulc JM, Iovieno A, et al. Diversity of bacteria at healthy human conjunctiva. Invest Ophthalmol Vis Sci 2011; 52:5408–5413. 31. Chung JL, Seo KY, Yong DE, et al. Antibiotic susceptibility of conjunctival bacterial isolates from refractive surgery patients. Ophthalmology 2009;116:1067–1074. 32. Hautala N, Koskela M, Hautala T. Major age group-specific differences in conjunctival bacteria and evolution of antimicrobial
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resistance revealed by laboratory data surveillance. Curr Eye Res 2008;33:907–911. Ta CN, He L, Mino de Kaspar H. In vitro antibiotic susceptibility of preoperative normal conjunctival bacteria. Eye (Lond) 2009;23:559–560. Liu DT, Hui M, Lam DS, Chan WM. Effect of prophylactic antibiotics on antimicrobial resistance of viridans streptococci in the normal flora of cataract surgery patients. J Cataract Refract Surg 2005;31:649–650. Cornut PL, Thuret G, Creuzot-Garcher C, et al. Relationship between baseline clinical data and microbiologic spectrum in 100 patients with acute postcataract endophthalmitis. Retina 2012;32:549–557. Baer ET. Iatrogenic meningitis: the case for face masks. Clin Infect Dis 2000;31:519–521. de Jong J, Barrs AC. Lumbar myelography followed by meningitis. Infect Control Hosp Epidemiol 1992;13:74–75. Sherertz RJ, Reagan DR, Hampton KD, et al. A cloud adult: the Staphylococcus aureus-virus interaction revisited. Ann Intern Med 1996;124:539–547. Philips BJ, Fergusson S, Armstrong P, et al. Surgical face masks are effective in reducing bacterial contamination caused by dispersal from the upper airway. Br J Anaesth 1992;69:407–408. Ransjö U. Masks: a ward investigation and review of the literature. J Hosp Infect 1986;7:289–294. Black SR, Weinstein RA. The case for face masks-zorro or zero? Clin Infect Dis 2000;31:522–523. Inoue M, Kobayakawa S, Sotozono C, et al. Evaluation of the incidence of endophthalmitis after intravitreal injection of antivascular endothelial growth factor. Ophthalmologica 2011; 226:145–150. Lyall DA, Tey A, Foot B, et al. Post-intravitreal anti-VEGF endophthalmitis in the United Kingdom: incidence, features, risk factors, and outcomes. Eye (Lond) 2012;26: 1517–1526. Diago T, McCannel CA, Bakri SJ, et al. Infectious endophthalmitis after intravitreal injection of antiangiogenic agents. Retina 2009;29:601–605. Bhala S, Narang S, Sood S, et al. Microbial contamination in open globe injury. Nepal J Ophthalmol 2012;4:84–89. de Kaspar HM, Kreidl KO, Singh K, Ta CN. Comparison of preoperative conjunctival bacterial flora in patients undergoing glaucoma or cataract surgery. J Glaucoma 2004;13:507–509. Groden LR, Murphy B, Rodnite J, Genvert GI. Lid flora in blepharitis. Cornea 1991;10:50–53. Alexandrou TJ, Hariprasad SM, Benevento J, et al. Reduction of preoperative conjunctival bacterial flora with the use of mupirocin nasal ointment. Trans Am Ophthalmol Soc 2006;104:196–201. Ariyasu RG, Nakamura T, Trousdale MD, Smith RE. Intraoperative bacterial contamination of the aqueous humor. Ophthalmic Surg 1993;24:367–373; discussion 73–4. Ciulla TA, Starr MB, Masket S. Bacterial endophthalmitis prophylaxis for cataract surgery: an evidence-based update. Ophthalmology 2002;109:13–24. Aiello LP, Brucker AJ, Chang S, et al. Evolving guidelines for intravitreous injections. Retina 2004;24:S3–S19. Speaker MG, Menikoff JA. Prophylaxis of endophthalmitis with topical povidone-iodine. Ophthalmology 1991;98:1769–1775. Pilli S, Kotsolis A, Spaide RF, et al. Endophthalmitis associated with intravitreal anti-vascular endothelial growth factor therapy injections in an office setting. Am J Ophthalmol 2008;145:879–882. Apt L, Isenberg SJ, Yoshimori R, Spierer A. Outpatient topical use of povidone-iodine in preparing the eye for surgery. Ophthalmology 1989;96:289–292.
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55. Bhavsar AR, Googe JM, Stockdale CR, et al. Risk of endophthalmitis after intravitreal drug injection when topical antibiotics are not required: the diabetic retinopathy clinical research network laser-ranibizumab-triamcinolone clinical trials. Arch Ophthalmol 2009;127:1581–1583. 56. Binder CA, Miño de Kaspar H, Klauss V, Kampik A. [Preoperative infection prophylaxis with 1% polyvidon-iodine solution based on the example of conjunctival staphylococci]. Ophthalmologe 1999;96:663–667. 57. Caldwell DR, Kastl PR, Cook J, Simon J. Povidone-iodine: its efficacy as a preoperative conjunctival and periocular preparation. Ann Ophthalmol 1984;16:577.
58. Dereklis DL, Bufidis TA, Tsiakiri EP, Palassopoulos SI. Preoperative ocular disinfection by the use of povidone-iodine 5%. Acta Ophthalmol (Copenh) 1994;72:627–630. 59. Ferguson AW, Scott JA, McGavigan J, et al. Comparison of 5% povidone-iodine solution against 1% povidone-iodine solution in preoperative cataract surgery antisepsis: a prospective randomised double blind study. Br J Ophthalmol 2003;87:163–167. 60. Ta CN. Minimizing the risk of endophthalmitis following intravitreous injections. Retina 2004;24:699–705. 61. Wu PC, Li M, Chang SJ, et al. Risk of endophthalmitis after cataract surgery using different protocols for povidone- iodine preoperative disinfection. J Ocul Pharmacol Ther 2006;22:54–61.
I
Four recent studies have suggested that oral flora from the physician, patient, or office staff involved in the procedure may be a source of infection during officebased intravitreal injection.23,24,27,28 Doshi et al28 most recently reported on an increase in contamination using agar plates as a source rather than using needles, which better simulate the actual rates of office-based intravitreal procedure. These publications suggest that all those involved in the injection procedure should consider either wearing a face mask or remain silent for the entire procedure to minimize microdroplet transmission. The purpose of this study was to determine if a difference in needle contamination from oral flora exists between needles held in front of a speaking versus silent subject. Secondarily, this study seeks to quantify bacterial contamination of the injection needle from oral flora in the setting of intravitreal injection.
ntravitreal injection has become a common treatment option for ophthalmologists and is one of the most common treatment procedures performed in Europe and the US.1 With the introduction of new pharmacological therapies for the treatment of neovascular age-related macular degeneration, diabetic macular edema, edema secondary to vascular occlusion, and small macular holes, the treatment of vitreoretinal disease is trending toward an office-based primary practice.2–19 Neovascular age-related macular degeneration alone accounts for 1.22 million people in the United States, and this number is only expected to increase.20 The number of annual intravitreal injections, reported to the Medicare database, has increased significantly from 3,305 in 1997 to 812,413 in 2007.21 This does not account for injections reported to other insurances or done without insurance reporting. Although intravitreal injections are generally well tolerated, one of the most serious risks of intravitreal injection is endophthalmitis, which can occur at a rate between 0.009% and 0.87%.22–26
Methods This was a prospective, sampling assay. Institutional review board approval was obtained from the University of Alabama at Birmingham IRB. Participants were physicians who currently perform intravitreal injection
None of the authors have conflicts of interest to disclose. Reprint requests: John O. Mason III, MD, 700 South 18th Street, Suite 601, Birmingham, AL 35294; e-mail: tracy_emond@mac. com
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and were voluntarily recruited. All physicians gave informed consent before sample collection. Participants held a sterile 30-gauge half-inch needle 25 cm from their mouth for 30 seconds under 2 conditions: 1) while speaking and 2) while breathing silently with their mouths closed. The “speaking” group held a conversation typical of examination room settings with an investigator. The investigator (T.P.L.) maintained proximity to the participants and handed them needles, simulating an assistant during a typical intravitreal injection. This was performed to simulate office conditions for intravitreal injection and actual time of needle exposure, although the amount of time the needle was held in front of the mouth was potentially over-estimated to simulate true office conditions. The “breathing” group was instructed not to speak, and no conversation was held between the investigator nor the participants. The needle was then streaked on an Chocolate/5% Sheep Blood Agar Biplate (ThermoFisher Scientific, Auburn, AL) and incubated for 6 days at 37°C. Colony-forming units (CFUs) were counted (by a separate investigator that was masked to the group assignment for each plate) but not identified. This was repeated 15 times for each participant for each condition (N = 300 samples). Participants’ oral mucosa was swabbed with a cotton-tip applicator and streaked on an agar biplate for control comparison. A set of 10 sterile needles was also directly streaked onto agar biplates as a set of negative controls. Statistical analysis was performed using a nominal regression analysis to account for clustering effects imparted by sampling the same participant multiple times. P , 0.05 was used to indicate statistical significance. As demonstrated by previous studies, 100 plates per group would be required to achieve a statistical power of 90%.28
Fig. 1. Needle contamination comparison of CFUs while talking versus breathing.
Results Ten physicians were sampled. A total of 300 needles were streaked on agar biplates. Figure 1 demonstrates the frequency of plates in proportion to the number of CFUs grown. Participants grew an average of 0.21 CFUs (median = 1 CFU) from their talking samples and 0.07 CFUs (median = 1 CFU) from their silent breathing samples. Oral swab plates grew an average of 373.4 CFUs. In total, 5.3% (16/300) of culture plates were positive for any organism, and of those, 68.7% (11/16) grew only a single colony. Ten plates in the talking group and 6 plates in the breathing group showed any sign of growth. A nominal regression analysis showed no significant difference between talking and silent samples (P = 0.457). Both silent and talking plates grew significantly fewer CFUs compared with control oral swabs (P , 0.0001). None of the control plates (i.e., direct needle without exposure) grew CFUs.
Discussion This study showed no significant difference in needle contamination in an intravitreal injection setting between subjects who were talking versus silent. Only a small subset of plates showed any growth (5.3%). Of these plates, 2 were questionable contaminants as most of the CFUs on these plates grew peripherally and not along the areas that were directly streaked with the sample needle. By sampling the amount of bacteria that routinely colonize the oropharynx, this study also provides an idea of how much of a source a practitioner’s oropharynx could provide. Multiple samples from each practitioner were used in both talking and breathing conditions with
NEEDLE CONTAMINATION WITH IV INJECTION FRIEDMAN ET AL
exposure times potentially much longer than the usual needle exposure time before intravitreal injection. Active attempts at needle contamination through breathing or talking failed to produce a large percent of colonized plates. The findings of this study lead to a few questions about the source of recent outbreaks of oropharyngeal related endophthalmitis. As mentioned earlier, 4 key studies point out that practitioners could be a source of ocular surface contamination during intravitreal injection.23,24,27,28 More recently, an outbreak of Streptococcus mitis/oralis was found to originate from oropharyngeal contamination of aliquots of medicine at a compounding pharmacy.29 This has increased the focus on proper sterile technique when handling medicine from a larger source bottle that is being subdivided into individual doses for intravitreal injection. Other suggested sources of possible contamination include the oropharyngeal flora of the patient, the physician, the technicians helping during the procedure, and the fact that viscous lidocaine blocks the sterilizing effects of povidone–iodine.24,27 The inherent problem with these hypotheses is that they lack good studies to validate any of these sources. In our study, practitioners actively tried to contaminate needles multiple times with only 3 plates showing any substantial growth. These findings are similar to the study conducted by Wen et al,27 where plates were contaminated by talking directly over culture plates for 5 minutes, a much longer exposure time than most intravitreal injections. Furthermore, their study only grew between 1 and 6 CFUs which again proves the extreme difficulty in active contamination of the ocular surface. In a similar study, Doshi et al28 showed a significant difference between masked individuals versus speaking individuals and concluded that good antisepsis of the conjunctival surface and practitioner silence is the best means of avoiding droplet dispersion. Significantly fewer CFUs grew when comparing talking conditions to silent conditions. Although the ratio of CFU formation was similar in our study (i.e., mean 0.21 CFUs in speaking versus 0.07 CFUs in breathing), differences in statistical analysis might account for the discrepancy with respect to statistical significance. Specifically, it is not clear whether the authors accounted for the paired nature of the data, nor the nonparametric distribution of the data, which would require nonparametric statistical tests. As the authors of this study used t-tests and analysis of variables in their analysis, it is hard to validate their findings. Furthermore, limitations of the Doshi et al study include the fact that blood agar plates do not simulate the intravitreal injection technique nor the conjunctival surface accurately. In addition, our analysis using
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nominal regression more accurately reflects the distribution of CFUs, which is not likely to be normal. We believe that our analysis of intravitreal needles helps negate their potential as a source of contamination. Other potential sources of bacterial endophthalmitis related to streptococcal species include the patient’s own colonizing bacteria or microdroplets from other individuals who have landed on the conjunctival surface. As the conjunctival mucosa is directly connected to the nasopharynx and oropharynx, it is possible that the same bacteria colonizing the patient’s respiratory secretions would be present on the conjunctival mucosa. Streptococcal species have been readily cultured from the conjunctival surface in a subset of patients undergoing routine conjunctival cultures.30–34 Streptococcal endophthalmitis has also contributed largely to infections in sterile OR situations where practitioners and patients are masked indicating that the conjunctival surface could be a major source for Streptococcal species.24,35 In fact, the landmark study that noted a 3 times greater risk of oral pathogens in the clinical setting compared with the operating room setting actually had more total oral pathogens cultured from the operating room setting infections. Furthermore, there was no statistically significant difference between the number of oral flora– related endophthalmitis cases derived from a sterile operating room setting when compared with a clinic based setting (P = 0.13).24 The findings of this study do not negate the possibility of microdroplets from other practitioners landing on the surface of the conjunctiva, which could later have access through exposed needle tracks. This study only demonstrates the difficulty of needle contamination from talking versus silent breathing. Extrapolation of these findings to their effects on overall rates of endophthalmitis cannot be derived because there are other factors that could be contributing to these rates (i.e., patient conjunctival colonization or subsequent migration of bacteria into the vitreous cavity through open needle tracks). The hypotheses that oropharyngeal sources are the direct cause of bacterial contamination are reinforced by studies related to spinal tap procedures that posit that face masks could help prevent the transmission of oropharyngeal flora that cause iatrogenic meningitis.36 Whether face masks actually decrease oropharyngeal contamination during lumbar puncture has been debated as well with evidence both for and against the protective effect of face masks.37–40 Black and Weinstein concluded that in higher risk situations, such as when the practitioner has an upper respiratory tract infection, the consideration of face mask use would be appropriate.41 It is not recommended to extrapolate these studies to intravitreal injections because the conditions are different: 1) the surface area
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for contamination is much larger in a lumbar puncture procedure; 2) the needle used is a large-bore spinal needle with more potential for intralumenal contamination; 3) the “needle exposure time” of a lumbar puncture is much longer than that of an intravitreal injection; and 4) the lumbar region is not a mucosal surface that could already be contaminated with streptococcal species. Also, international rates of endophthalmitis after intravitreal injection are equivalent between countries that require face mask use and those that do not use face masks routinely.22,42–44 The purpose of this discourse is to discuss the implications of labeling oropharyngeal contaminants as a source for conjunctival contamination. Known sources of bacteria include the conjunctival surface and lid margin, which are precolonized at the time of injection.26,33,35,45–47 As has been shown in previous studies from cataract surgery and intravitreal injection, the most common causes of bacterial endophthalmitis are skin contaminants such as coagulase-negative staphylococcal species or Staphylococcus aureus.26,31,48–50 These studies have further implications in that their conclusions advocate that practitioners wear masks or at least avoid talking during an intravitreal injection procedure. We cannot directly refute the idea that masks could decrease conjunctival contamination because we did not have a masked group. As discussed above, it is also possible that the bacteria could migrate into the vitreous cavity after the procedure because of an open needle track. We believe that this emphasizes the importance of povidone–iodine in sterilizing the patient’s conjunctiva, which has been proven to greatly reduce the number of bacteria on the conjunctival surface and reduce the rate of postoperative endophthalmitis.44,50–61 We realize that there are several limitations to this study, the most important one being its small sample size. Endophthalmitis after intravitreal injection occurs at an extremely low rate. This makes clinical trials difficult in that large sample sizes are necessary for meaningful results. However, our study includes a large sample size with 300 needles sampled and demonstrates that bacteria rarely contaminate the injection needle when “actively” trying to contaminate the surface. Second, using needles to streak agar plates might not have as high a yield as culturing needles in broth. Quantitative analysis of broth media was beyond the ability of our research facility and could potentially be used as a future means of analysis for a higher yield. Third, we did not identify the bacteria that contaminated the injection needle, and therefore cannot comment on the type of organisms found on the needle. Last, we did not include a face-masked group, which could have provided insight into its role in preventing needle contamination.
In conclusion, our study is the first to show no statistical difference in needle contamination whether talking or silent in simulating the intravitreal injection procedure. Because breathing silently can result in a small chance of needle contamination, not only the physician but also the patient would have to wear a mask to decrease the rate of contamination if one were to accept the mask hypothesis. Future studies should try to subspeciate conjunctival contaminants to see whether they coincide with the oral flora of administering practitioners or patients. Key words: intravitreal, injection, endophthalmitis. References 1. Shah CP, Garg SJ, Vander JF, et al. Outcomes and risk factors associated with endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor agents. Ophthalmology 2011;118:2028–2034. 2. Brown DM, Michels M, Kaiser PK, et al. Ranibizumab versus verteporfin photodynamic therapy for neovascular age-related macular degeneration: two-year results of the ANCHOR study. Ophthalmology 2009;116:57–65.e5. 3. Bressler NM, Chang TS, Fine JT, et al. Improved visionrelated function after ranibizumab vs photodynamic therapy: a randomized clinical trial. Arch Ophthalmol 2009;127:13–21. 4. Campochiaro PA, Heier JS, Feiner L, et al. Ranibizumab for macular edema following branch retinal vein occlusion: sixmonth primary end point results of a phase III study. Ophthalmology 2010;117:1102–1112.e1. 5. Varma R, Bressler NM, Suñer I, et al. Improved vision-related function after ranibizumab for macular edema after retinal vein occlusion: results from the BRAVO and CRUISE trials. Ophthalmology 2012;119:2108–2118. 6. Elman MJ, Aiello LP, Beck RW, et al. Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema. Ophthalmology 2010;117:1064–1077.e35. 7. Elman MJ, Qin H, Aiello LP, et al. Intravitreal ranibizumab for diabetic macular edema with prompt versus deferred laser treatment: three-year randomized trial results. Ophthalmology 2012;119:2312–2318. 8. Cunningham ET, Adamis AP, Altaweel M, et al. A phase II randomized double-masked trial of pegaptanib, an anti-vascular endothelial growth factor aptamer, for diabetic macular edema. Ophthalmology 2005;112:1747–1757. 9. Heier JS, Brown DM, Chong V, et al. Intravitreal aflibercept (VEGF trap-eye) in wet age-related macular degeneration. Ophthalmology 2012;119:2537–2548. 10. de Smet MD, Gandorfer A, Stalmans P, et al. Microplasmin intravitreal administration in patients with vitreomacular traction scheduled for vitrectomy: the MIVI I trial. Ophthalmology 2009;116:1349–1355. 11. Stalmans P, Delaey C, de Smet MD, et al. Intravitreal injection of microplasmin for treatment of vitreomacular adhesion: results of a prospective, randomized, sham-controlled phase II trial (the MIVI-IIT trial). Retina 2010;30:1122–1127. 12. Stalmans P, Benz MS, Gandorfer A, et al. Enzymatic vitreolysis with ocriplasmin for vitreomacular traction and macular holes. N Engl J Med 2012;367:606–615.
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