Incidence of Endophthalmitis after Intravitreal Bevacizumab using Aliquots Prepared On-site in 2 Operating Rooms in Kuwait.

PURPOSE: To report the incidence of endophthalmitis after intravitreal injection of bevacizumab and the outcomes of treatment of endophthalmitis at two centers in Kuwait. SUBJECTS AND METHODS: The aliquots of bevacizumab were prepared under aseptic precautions and administered in the operating theater on the same day at both centers. All patients received antibiotic drops after injection of bevacizumab. Data were collected on the number of cases that received intravitreal bevacizumab (IVB) and those that developed endophthalmitis were identified at the two centers. All cases of endophthalmitis received an intravitreal antibiotic injection and additional treatments as warranted. Data were collected on the outcomes of endophthalmitis treatment.
RESULTS: There were 5 cases of endophthalmitis among a total of 5429 injections (0.09%: Confidence interval: 0.084-0.1). The incidence was 3 cases among 4690 (0.06%) and 2 cases among 739 injections (0.027%) at each center, respectively (P = 0.08). Four cases of endophthalmitis were culture-positive and organisms isolated were, coagulase negative Staphylococcus in 2 cases, Staphylococcus lugdunensis and Streptococcus pneumoniae in 1 case each. The final visual acuity was better than pre-IVB in 3 cases, same as pre-IVB in 1 case and worse in 1 case with streptococcal infection. No eyes developed phthisis bulbi or required enucleation.
CONCLUSIONS: The incidence of endophthalmitis after intravitreal injection of bevacizumab using aliquots prepared in the operating room is comparable to other studies. There were no clusters of endophthalmitis cases.

INTRODUCTION

Bevacizumab (Avastin; Genentech, San Francisco, California, USA) is a recombinant humanized monoclonal antibody against all isoforms of vascular endothelial growth factor (VEGF) A and is being increasingly used as an off-label treatment for common retinal diseases.1234 Ranibizumab (Lucentis, Genentech, San Francisco, California, USA) and aflibercept (Eylea, Regeneron, Tarrytown, NY, USA) are the Federal Drug Administration (FDA) approved anti-VEGFs for intraocular use and are commercially available in single dose vials for intravitreal injection. Bevacizumab is available in vials of 100 mg in 4 ml from which aliquots of the required dose of 1.25 mg/0.05 ml are prepared thus reducing the cost of one injection to as low as US$43 per injection compared to a cost of US$1543 per injection of ranibizumab.5 However, the risk of contamination while preparing the aliquots of bevacizumab leading to endophthalmitis is a concern. The risk of endophthalmitis can be reduced by preparing the aliquots in a compounding pharmacy strictly adhering to the guidelines for preparation of the <797> US pharmacopeia.67

However, the facilities for compounding are not universally available and various techniques have evolved. These techniques include aspirating the required dose from the bevacizumab vial multiple times89101112 or preparing multiple vials from the original vial and then aspirating from these vials1112 or preparing multiple doses in separate glass ampoules prepared under sterile conditions.13 In North America, generally the aliquots of bevacizumab injections are obtained from compounding pharmacies and the reported incidence of endophthalmitis after intravitreal bevacizumab (IVB) in these centers varies from 0% to 0.54%.12141516171819 In studies that used bevacizumab aliquots that were not dispensed by a pharmacy, the rates of endophthalmitis varied from 0% to 0.41%.89101120

The aim of this study is to report the incidence of endophthalmitis after IVB in two centers in Kuwait. The aliquots were prepared in the operating room under sterile conditions just prior to administering IVB to patients in the operating room. We also present the clinical features, treatment and outcomes of the cases of endophthalmitis after IVB.

SUBJECTS AND METHODS

This retrospective study was performed at Al-Bahar Ophthalmology Center and the Department of Ophthalmology at Al-Adan Hospital. Both institutions are part of the Ministry of Health, Kuwait. The Ethics Committee of Al-Bahar Ophthalmology Center approved this study. All efforts were made to adhere to the guidelines of the Declaration of the Helsinki Principles. The study period at Al-Bahar Center was from June 1, 2006 to July 31, 2012 and June 1, 2009 to July 31, 2012 at Al-Adan Hospital. Cases of IVB were identified from the operating room registers in both institutions. Cases that received IVB in conjunction with phacoemulsification or pars plana vitrectomy were excluded.

At both institutions the aliquots of bevacizumab were prepared and administered intravitreally in the operating rooms. IVB is prepared for administration with the following procedure at both institutions. A scrub nurse wears surgical gowns, masks and sterile gloves and prepares a metal trolley covered with a sterile towel. The required number of empty sterile insulin syringes (Becton, Dickinson and Company, Franklin Lakes, New Jersey, USA) are placed on this trolley. A second staff nurse wearing a surgical mask removes the metal cap from the vial of bevacizumab and the rubber cap is wiped with an alcohol swab. All 4 ml of bevacizumab are withdrawn through a 22 gauge (G) needle by the scrub nurse with a sterile 5 ml syringe. The needle is removed and a new 22-G needle is fixed to the 5 ml syringe and 0.1 ml of bevacizumab are transferred to the insulin syringes with the piston removed by the scrub nurse. The piston of the insulin syringe is replaced and the dose is adjusted to 0.05 ml. This procedure is repeated until the required number of syringes are loaded with bevacizumab. All the insulin syringes are placed on the sterile trolley and are covered by a sterile towel. The remaining bevacizumab in the 5 ml syringe, is discarded once all the cases are treated for the day. The protocol for administration of IVB includes instillation of oxybuprocaine hydrochloride 0.4% (Benoxinate Minims, Chauvin Pharmaceuticals Ltd., Romford, England) drops in the eye followed by a drop of povidone-iodine 5%. This is repeated two more times. A scrub nurse wearing sterile gloves and a surgical mask prepares a separate trolley with a sterile towel with one insulin syringe containing the bevacizumab from the first trolley that contains all the prepared insulin syringes. The eyelids and eyelid margins are cleaned with povidone-iodine 10% in a sterile fashion. The physician and nurses who are involved in the procedure wear surgical masks. The physician washes his/her hands and wears sterile surgical gloves.

At the Al-Bahar Center, sterile lid speculum is used for maximum globe exposure and the injection is delivered to inferotemporal quadrant while the patient is sitting on a reclining chair. At the Al-Adan Hospital, a disposable sterile drape is used to exclude the eye lashes from surgical field and the injection is performed in the superotemporal quadrant while the patient is supine on the operating table. At both institutions the IVB was delivered at a distance of 3.0 mm from the limbus in aphakic or pseudophakic eyes and 3.5 mm from the limbus in phakic eyes respectively. At both institutions, after injection of IVB, chloramphenicol ophthalmic ointment is placed in the eye and the eye is patched for 24 h. The following day, the patient is examined and the patch is removed and a topical antibiotic is prescribed for use 4 times a day for 5 days. The choice of topical antibiotic was based on surgeon preference and was usually ofloxacin or moxifloxacin. The patient was examined at 7 days and then 1-month later.

Cases of endophthalmitis were identified from the operating room register. At both institutions, all the cases of endophthalmitis irrespective of the cause, receive intravitreal antibiotics or undergo pars plana vitrectomy in the operating room.

We evaluated endophthalmitis cases that occurred after IVB. Data were collected on age, sex, preinjection best corrected visual acuity (BCVA), indication for IVB, date of injection, date of onset of symptoms of endophthalmitis, nature of symptoms, date of presentation to the institution and date of diagnosis of endophthalmitis. Data were also collected on the findings of examination at presentation, treatment, response to treatment, any additional procedures and findings at final follow-up and BCVA at last follow-up and the duration of follow-up. Data were collected on the results of microbial laboratory investigations such as Gram's-stain, culture and sensitivity to antimicrobials of the organism if isolated.

The incidence of the endophthalmitis was calculated by dividing the number of eyes that developed endophthalmitis after IVB by the number of total cases receiving IVB and converted into a percentage value. The 95% of confidence intervals (CIs) were calculated by using free online software at http://vassarstats.net/prop1.html.

The incidence in the two centers was compared with the Chi-square test. A P < 0.05 was considered statistically significant.

RESULTS

There were 5429 injections performed during the study period for various retinal conditions. The number of injections performed at Al-Bahar Center and Al-Adan Hospital were 4690 and 739, respectively. There were 5 cases of endophthalmitis in the study period resulting in an incidence of 0.09% (95% CI: 0.084–0.1). There were 3 cases of endophthalmitis at the Al-Bahar Center with incidence of 0.0006 per injection (95% CI: 0.0002–0.0018). In the Al-Adan Hospital, there were 2 cases of endophthalmitis with incidence of 0.0027 per injection (95% CI: 0.0007–0.0098). The difference in the incidence of endophthalmitis between institutions was not statistically significant (P = 0.08). The percentage incidence of endophthalmitis at Al-Bahar Center and Al-Adan Hospital were 0.06 and 0.27, respectively.

All 5 cases of endophthalmitis occurred in males with mean age of 59.6 years (range, 48–73). The indications for IVB in these 5 cases were, diabetic macular edema in 4 cases (80%) and wet age-related macular degeneration (AMD) in 1 case (20%). The mean interval between the time of injection to diagnosis of endophthalmitis was 6.4 days (range, 1–21 days). One case of endophthalmitis presented 21 days after the diagnosis as the patient had mild pain. The presenting complaints included decreased vision in all cases and pain in 4 cases (80%). Hypopyon was present in 4 (80%) out of 5 cases and the view of the fundus was limited in 4 (80%) cases. The pre-IVB visual acuity ranged from 20/25 to 20/400 and the visual acuity at the time of diagnosis of endophthalmitis ranged from perception of light (PL) to 20/40.

All 5 cases underwent anterior chamber and vitreous tap at the time of injection of the intravitreal of ceftazadime 2.25 mg and vancomycin 1 mg followed by topical fortified antibiotics. Four (80%) cases were culture-positive only from the vitreous samples and no mircoorganisms were isolated either from aqueous or vitreous in 1 case. The isolated organisms were, Streptococcus pneumonia in 1 case, coagulase negative Staphylococcus in 2 cases and Staphylococcus lugdunensis in 1 case. Two cases with coagulase negative Staphylococcus and 1 case with culture-negative endophthalmitis responded well to administration of intravitreal antibiotics. However, one patient with coagulase negative Staphyococcus endophthalmitis developed a rhegmatogenous retinal detachment 2 weeks after the intravitreal antibiotic injection and underwent pars plana vitrectomy with successful reattachment of the retina.

One case of endophthalmitis due to Streptococcus pneumoniae did not respond well to intravitreal antibiotic injection twice and underwent pars plana vitrectomy and reinjection of intravitreal antibiotics. The infection in this case resolved but with poor final visual acuity of no light perception. Another case of endophthalmitis due to S. lugdunensis responded after administration of intravitreal antibiotics twice in an interval of 4 days. This patient regained his preinjection visual acuity and he also underwent further IVB for the treatment of choroidal neovascular membrane without sequelae. The final visual acuity of the 5 cases varied from no PL to 20/20. The visual acuity improved in all but 1 case compared to the visual acuity at the time of diagnosis of endophthalmitis. The final visual acuity was better than the preinjection visual acuity in 3 cases, the same in 1 case and worse in 1 case. The salient features of these 5 cases are summarized in Table 1.

Table 1

Clinical features of endophthalmitis cases

DISCUSSION

The method of preparing aliquots of bevacizumab from one vial in the operating room described in the current study differs from other studies.8910111213 The operating rooms in our institutions do not have a hood with laminar airflow to prepare the injections. The incidence of endophthalmitis after IVB in our series was 0.09% which is comparable to other reports in the literature irrespective of the method of preparation of IVB injections.811131921 The incidence of endophthalmitis at Al-Adan Hospital was higher than in Al-Bahar Center although the 95% CI of the incidences overlapped each other and there was no statistical difference between institutions. The higher rate of endophthalmitis at Al-Adan Hospital could be due to a lower number of IVB injections at this center. Studies with lower numbers of IVB injections have reported an incidence of endophthalmitis from 0.2% to 0.9%122022 and has been termed a small study effect by McCannel.23

The method of obtaining the aliquots of bevacuzimab injection varies in places where compounding pharmacies are not available. Some authors withdraw the required dose from the vial of bevacizumab directly to an insulin syringe and then change the needle and inject it intravitreally.89101112 Among these, some authors withdrew a maximum of ten doses from the vial during a session of treatment of 10 patients and discarded the remaining drug in the vial.911 Some authors used the maximum number of doses that are required on that day and discarded the remaining drug.12 However, other authors withdrew bevacizumab from the same vial using separate needle and syringe every time for several patients for a period of 3 weeks after the first injection was withdrawn.8 These methods have not reported any clusters of endophthalmitis and the rate of endophthalmitis in these series was 0–0.41.89101112 However, Khan et al. reported a cluster of endophthalmitis among patients who received bevacizumab injection that was withdrawn from the same vial multiple times.24

This shows that contamination can occur by multiple punctures of the rubber cap of the vial despite aseptic precautions such as wiping the cap with alcohol swab or betadine before each aspiration and changing needles and syringes. If the bevacizumab vial becomes contaminated during multiple withdrawals and is kept for further use for a longer period, the bacterial burden within the vial may gradually increase. This increase is aided by the fact that the vial does not contain any preservatives that may inhibit the growth of bacteria. By avoiding puncturing the vial multiple times and using all the syringes within a period of 6 h, we think we significantly mitigated the risk of contamination that can occur with multiple punctures of a vial.25

Inoue et al.10 used two methods to obtain the required dose of bevacizumab. Either withdraw bevacizumab directly from the commercially available vial of the drug or aliquot the commercially available vial in to ten smaller vials of 0.4 mg/ml in an aseptic manner and then withdraw from these smaller vials.10 All the 5 cases of endophthalmitis in their study received the bevacizumab drawn directly from the commercially available separate vials on different occasions.10

Lee et al.12 also reported two methods for obtaining the required dose of IVB. One method was to aspirate directly from the commercially available vial of bevacizumab and use it for injection after changing the needle and another was to aliquot the drug in to 10 airtight shielded vials under strict aseptic precautions including laminar airflow benches.12 These airtight vials were used within 15 days of compounding. In 2 cases of endophthalmitis in their series, the patients had received IVB from the vials on 15th day after they were compounded. None of the 18 patients who received the IVB from vials that were compounded 7 days earlier developed endophthalmitis although these patients had received IVB on the same day as the two patients who developed endophthalmitis.12 The authors speculate that the delay in the use of the two vials up to 15 days might have increased the bacterial load in the vials as the bevacizumab liquid is preservative free, offering no inhibition of bacterial growth.12

However, other studies that have shown the safety, sterility, and stability of bevacizumab withdrawn multiple times from the same vial after following appropriate aseptic measures.262728 Falavarjani et al. used bevacizumab withdrawn multiple times from the same vial yet reported a very low incidence of endophthalmitis of 0.01% in 8037 eyes.29

The absence of a laminar airflow hood in our operating rooms can still make contamination possible. In both institutions, bevacizumab is transferred from the 5 ml syringe to insulin syringes. However, as the syringes are used within 6 h of preparation it is possible that the bacterial burden may be too low to cause a clinical infection. There were 5 cases of endophthalmitis in our series with no clusters of endophthalmitis. The endophthalmitis vitrectomy study showed that most cases of endophtalmitis were due to bacteria from the patient's conjunctival sac gaining entry in to the eye at the time of surgery.30

In most of the developed countries where bevacizumab is available from compounding pharmacies for intraocular use, the rate of endophthalmitis varies from 0% to 0.54%.1214151617181921 However, an outbreak of endophthalmitis has occurred due to contamination at the compounding pharmacy supplying the bevacizumab aliquots with extremely poor visual results.31 This caused a debate on the use off-label bevacizumab without FDA approval for economic reasons and the methods to prepare multiple doses from a single vial.313233

However, for economic reasons, the use of bevacizumab for intravitreal administration will continue. Hence, measures are required to reduce the incidence of endophthalmitis. Furthermore, a study comparing the efficacy of bevacizumab and ranibizumab in the treatment of AMD reported that both drugs provided equivalent visual acuity outcomes justifying the continued use of bevacizumab as an anti-VEGF drug.34

The instillation of povidone-iodine 5% in the conjunctival sac prior to the IVB procedure is universally accepted for reducing the chances of infection. Use of a sterile speculum and sterile gloves are not uniformly practiced by all the physicians administering IVB. These factors were not considered significant in decreasing the risk of endophthalmitis after IVB in some studies.161935

Sterile drapes were used in our study only at Al-Adan Hospital. Abell et al. reported the use of surgical drapes in their cases.36 Many authors do not use sterile drapes for the procedure81116192135 and, additionally, some do not wear sterile gloves.21

We performed IVB in the operating room. However, it is common to perform this procedure in offices in many countries and the incidence of endophthalmitis remains low.116192134 However, Abell et al. reported a decreased incidence of endophthalmitis after the procedure was shifted to the operating room.36 They reported a no cases of endophthalmitis in 8873 IVB procedures performed in the operating room compared to 4 cases of endophthalmitis in 3376 IVB procedures performed in an office setting.36

McCannel's meta-analysis showed that the occurrence of streptococcal endopthalmitis was more common in post-anti-VEGF injection than in postcataract endophthalmitis.23 This was attributed to the practice of performing intravitreal injections in the office setting where surgical masks are not worn by the physician and staff, thus increasing the chances of aerosol contamination of the room and the chances of infection.23 In the current study, the staff and surgeons wore masks during preparation of IVB aliquots and administration of the IVB. There was 1 case of endophthalmitis due to streptococcal pneumoniae in our study, indicating that surgical masks may not completely stop streptococcal endophthalmitis. Streptococcal endophthalmitis is notable because treatment of this infection can still result in poor visual outcomes.23 Our experience in the current study with streptococcal endophthalmitis was similar [Table 1].

In the current study, patients received topical antibiotics after IVB during the study period. However, reports suggest that the use of topical antibiotics can increase the incidence of endophthalmitis after intravitreal injection of anti VEGFs.821 Since July 2013 the practice of using topical antibiotics after the administration of IVB has been discontinued in our hospitals.

The results of treatment of post-IVB endophthalmitis in our series were encouraging with 80% of cases regaining their preinjection visual acuities. This may be due to the low virulence of organisms isolated from the 3 out of 4 culture-positive cases of endophthalmitis. However, postinjection endophthalmitis can be devastating in a significant number of patients.101220 All the cases that developed endophthalmitis had final visual acuity worse than preinjection visual acuity in a study by Gordon et al.20 Inoue et al. reported worse final visual acuity than the preinjection visual acuity in 60% of the cases developing endophthalmitis.10 Lee et al. reported a total loss of vision in two patients who developed endophthalmitis after IVB caused by Serratia marcescense.12 However, some studies reported good visual results after treatment of endophthalmitis in at least 80% of cases.119

The intravitreal injection of various anti-VEGFs is becoming one of the most common procedures in ophthalmology due to the good visual results in various retinal diseases.37 Two meta-analyses by McCannel and Fileta et al. reported low incidences of endophthalmitis after anti-VEGF varying between 0.049% and 0.056% respectively.2338 Though the incidence of endophthalmitis after intravitreal injection of anti-VEGFs is low, the absolute number of post-anti-VEGF injection endophthalmitis can be high due to the recent increases in the number of patients receiving anti-VEGF treatments. Hence constant monitoring and evaluation of any method, including ours, is needed to determine risk factors for the development of endophthalmitis and for prevention. Table 2 compares the incidence of endophthalmitis after IVB in various studies.

Table 2

Comparison of studies

A drawback of our study is the retrospective and observational nature with no control arm. However, the method of preparing the aliquots of IVB in the operating theater under sterile conditions has yielded acceptable results in the absence of availability of the facility of compounding pharmacy. We believe our method is an alternative to withdrawing bevacizumab multiple times from the same vial although more studies are required to prove safety. In conclusion, the incidence of endophthalmitis in our study was comparable to the incidences reported in the literature and the outcomes of treatment of endophthalmitis was satisfactory in 4 out of 5 cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.