Intracameral antibiotics: Questions for the United States based on prospective studies

The Routine Use of Intracameral Antibiotics to Prevent Endophthalmitis After Cataract Surgery: How Good is the Evidence?

Post-operative endophthalmitis (POE) following cataract surgery is an uncommon, vision-threatening complication that has been reported to occur at rates of between approximately 0.03% and 0.2%. Prompt diagnosis and treatment of endophthalmitis is critical for minimizing vision loss, but most recent efforts have focused on the prophylactic administration of antibiotics to prevent the development of endophthalmitis. Surgeons from around the world have different topical and intracameral antibiotic usage patterns to prevent endophthalmitis, and to date no general consensus regarding best practice has emerged. Several studies have reported on the routine use of intracameral cefuroxime, moxifloxacin, and vancomycin, including a single randomized clinical trial by the European Society of Cataract and Refractive Surgery (ESCRS) in 2007. These studies have notable shortcomings, but many authors suggest that intracameral cefuroxime together with topical antibiotics probably decreases the risk of endophthalmitis. However, the deleterious effects of routine prophylactic antibiotics, which include toxicity, cost, and increasing antimicrobial resistance, among others, are noteworthy. In contrast, aseptic technique with pre-operative instillation of povidone-iodine remains the only technique supported by level I evidence to reduce the incidence of endophthalmitis. Although the routine use of intracameral antibiotics continues to increase throughout the world, data from multicenter, randomized, prospective trials is needed to provide better guidance regarding the prophylactic use of antibiotics.

Risks of Cefuroxime Prophylaxis for Postcataract Endophthalmitis

BACKGROUND:

Endophthalmitis after cataract surgery is a rare but vision-threatening complication. Intracameral cefuroxime (ICC) has been reported to be effective at reducing the risk, but concerns regarding the risks associated with this intervention remain.

METHODS:

Systematic review and synthesis of the literature on ICC, with a focus on the risks of therapy.

RESULTS:

Level 2a evidence was found to support the use of cefuroxime in penicillin-allergic patients. Compounding or dilutional errors are associated with ocular toxicity, but the incidence and risk of this occurrence are unknown. Level 4 evidence supports interventions that reduce the risk of dilutional errors. The association of cefuroxime injection with toxic anterior segment syndrome (TASS) is not established; Level 5 evidence supports standard measures to reduce the incidence of TASS related to cefuroxime administration.

CONCLUSION:

Cefuroxime can be administered safely to penicillin-allergic patients, and steps should be taken to reduce the risk of compounding or dilutional errors to avoid negating the benefits of this intervention. Recommended practice patterns for endophthalmitis prophylaxis should consider the risks and benefits of ICC.

Postcataract endophthalmitis prophylaxis using irrigation, incision hydration, and eye pressurization with vancomycin

PURPOSE

This study aimed to determine whether switching from balanced salt solution (BSS) to vancomycin 20 g/mL BSS for incision hydration and eye pressurization reduces the rate of postcataract endophthalmitis.

METHODS

This was a patient safety/quality improvement project, including all patients undergoing cataract surgery at the Kaiser Permanente Colorado Ophthalmology Department from January 2002 to December 2014. Throughout the study, patients received vancomycin 20 μg/mL in the irrigating solution. During the baseline period from 2002 to 2005, surgeons pressurized eyes and hydrated incisions with plain BSS. During the intervention period from 2006 through 2014, surgeons switched from BSS to the vancomycin/BSS irrigating solution for eye pressurization and incision hydration.

RESULTS

A total of 57,263 cataract operations were performed by 24 surgeons at seven surgical centers: 12,400 in the baseline period and 44,863 in the intervention period. The rate of post-cataract endophthalmitis declined significantly from 5/12,400 (rate: 0.4/1,000) in the baseline period to 1/44,863 (rate: 0.022/1,000) during the intervention period (odds ratio [OR]: 18.1, 95% confidence interval [CI]: 2.11-154.9; χ (2)=13.5, P=0.00024). Accounting for an estimated 2.05-fold risk reduction due to confounding variables, the risk reduction attributed to the intervention remained significant: (adjusted OR: 8.78, 95% CI: 1.73-44.5; χ (2)=10.06, P=0.0015). Since 2009, we have not experienced any cases of postcataract endophthalmitis after 32,753 operations.

CONCLUSION

We experienced a significant reduction in postcataract endophthalmitis when we switched from BSS to the vancomycin/BSS irrigating solution for incision hydration and eye pressurization. The pharmacokinetics profile indicates that this switch was important for effective prophylaxis.

Cohort study of intracameral moxifloxacin in postoperative endophthalmitis prophylaxis

We conducted a cohort study to evaluate post-cataract surgery endophthalmitis rates in relation to prophylactic intracameral moxifloxacin administration. A total of 2332 patients (2674 eyes) who underwent phacoemulsification by a single surgeon from January 2007 through December 2012 were included in the study. A total of 1056 eyes did not receive intracameral prophylactic moxifloxacin and the antibiotic was injected in 1618 eyes. The incidence of presumed postoperative endophthalmitis in the 2 groups was calculated. The rate of presumed infectious endophthalmitis after cataract surgery between January 2007 and June 2009 (without intracameral moxifloxacin) was 0.094%. The rate in the second period, from July 2009 to December 2012 (with prophylactic intracameral moxifloxacin), was 0%. In our patients, a decline in the incidence of presumed infectious postoperative endophthalmitis appeared to be associated with the application of intracameral moxifloxacin.

Prevention, diagnosis, and management of acute postoperative bacterial endophthalmitis

This distillation of the peer-reviewed scientific literature on infection after cataract surgery summarizes background material on epidemiology, etiology, and pathogenesis, describes the roles of surgical technique and antibiotic prophylaxis in prevention, and discusses diagnostic and therapeutic interventions in cases of suspected endophthalmitis.

Controlled transscleral drug delivery formulations to the eye: establishing new concepts and paradigms in ocular anti-inflammatory therapeutics and antibacterial prophylaxis

IMPORTANCE OF THE FIELD

The use of topical agents poses unique and challenging hurdles for drug delivery. Topical steroids effectively control ocular inflammation, but are associated with the well-recognized dilemma of patient compliance. Although administration of topical antimicrobials as prophylaxis is acceptable among ophthalmologists, this common practice has no sound evidence base. Developing a new antimicrobial agent or delivery strategy with enhanced penetration by considering the anatomical and physiological constraints exerted by the barriers of the eye is not a commonly perceived strategy. Exploiting the permeability of the sclera, subconjunctival routes may offer a promising alternative for enhanced drug delivery and tissue targeting.

AREA COVERED IN THIS REVIEW

Ocular drug delivery strategies were reviewed for ocular inflammation and infections clinically adopted for newer class of antimicrobials, which use a multipronged approach to limit risks of endophthalmitis.

WHAT THE READER WILL GAIN

The analysis substantiates a new transscleral drug delivery therapeutic approach for cataract surgery.

TAKE HOME MESSAGE

A new anti-inflammatory and anti-infective paradigm that frees the patient from the nuisance of topical therapeutics is introduced, opening a large investigative avenue for future improved therapies.

Pharmacokinetics of azithromycin and moxifloxacin in human conjunctiva and aqueous humor during and after the approved dosing regimens

PURPOSE

To evaluate the ocular pharmacokinetics of azithromycin and moxifloxacin in human conjunctiva and aqueous humor in subjects undergoing cataract surgery.

DESIGN

Multicenter, open-label, randomized study.

METHODS

Subjects scheduled for routine cataract surgery and with normal-appearing conjunctiva were eligible. One conjunctival biopsy sample and 1 aqueous humor sample were obtained from subjects randomly assigned to 1 of 10 prespecified time points (1 to 312 hours) after treatment initiation of azithromycin ophthalmic solution 1% or moxifloxacin ophthalmic solution 0.5%. Samples were assayed using liquid chromatography tandem mass spectrometry.

RESULTS

Azithromycin 1% provided high concentrations (peak level, 559.7 μg/g) in human conjunctiva that were sustained at levels 1 to 2 orders of magnitude higher than those of moxifloxacin 0.5% throughout the 7-day dosing period and for at least 7 days thereafter. Azithromycin also showed an extended half-life (65.7 hours) in conjunctiva relative to that of moxifloxacin (28.6 hours). Accordingly, the concentration of azithromycin was maintained well above the minimum inhibitory concentration required for inhibition of growth of 90% of tested bacterial isolates for at least 7 days, whereas moxifloxacin conjunctival levels fell to levels at or less than the minimum inhibitory concentration required for inhibition of growth of 90% of tested bacterial isolates approximately 24 hours after the last dose. Peak aqueous humor concentration of moxifloxacin was higher (0.77 μg/mL) than that of azithromycin (0.053 μg/mL). No clinically relevant safety findings were observed.

CONCLUSIONS

Azithromycin 1% demonstrated high, therapeutic levels in the conjunctiva that were maintained up to 7 days after completion of a 1-week dosing regimen. Aqueous humor levels, however, were subtherapeutic with this dosing regimen. In comparison, moxifloxacin achieved lower conjunctival tissue levels, but higher aqueous humor levels.

The comparison of clinical outcomes of endophthalmitis from fluoroquinolone-resistant and susceptible bacteria

PURPOSE

To identify patients who developed acute-onset endophthalmitis after clear corneal cataract surgery, and to compare treatment outcomes between cases caused by fluoroquinolone susceptible organisms versus fluoroquinolone resistant organisms.

DESIGN

Retrospective case series.

METHODS

Patients who developed endophthalmitis within six weeks of cataract surgery, and were treated between January 1996 and December 2008 at Bascom Palmer Eye Institute in Miami, Florida, were identified retrospectively. Clinical features, organisms cultured, and visual acuity outcomes were evaluated.

RESULTS

A total of 97 patients met study criteria, and 37 (38%) demonstrated in vitro fluoroquinolone resistance. All fluoroquinolone resistant endophthalmitis in the study was caused by either Staphylococcus epidermidis (n = 32) or Staphylococcus aureus (n = 5). Presenting clinical features were similar between fluoroquinolone resistant and fluoroquinolone susceptible groups. Final visual acuity was >/=20/40 in 49% of fluoroquinolone-resistant cases and 42% of fluoroquinolone-susceptible cases. All fluoroquinolone-resistant isolates were susceptible to vancomycin.

CONCLUSION

In the current study, approximately one-third of isolates were resistant to fluoroquinolones. There was no significant difference in clinical outcomes in this study, regardless of fluoroquinolone susceptibility.

Safety of intracameral injection of gatifloxacin, levofloxacin on corneal endothelial structure and viability

PURPOSE

To investigate the safety of intracameral injection of gatifloxacin, levofloxacin in a rabbit model as prophylaxis against endophthalmitis.

METHODS

Twenty-four eyes of New Zealand white rabbits were randomly divided into 3 treatment groups: levofloxacin, gatifloxacin, and balanced salt solution (BSS) control groups. After 100 microL of each was injected into the anterior chamber, endothelial toxicity was evaluated by measuring the central corneal thicknesses and the clinical toxicity scores using a slit-lamp at post-procedure days 3 and 7. The percent of dead cells was determined by vital staining with alizarin red and trypan blue at 7 days after injection. Finally, in each group, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed for the evaluation of structural integrity.

RESULTS

The toxicity scores were increased at post-procedure days 3 and 7, but the difference among the groups was not statistically significant (P = 0.661, 0.216, respectively). With regard to baseline corneal thickness, only the levofloxacin group exhibited a significant increase from baseline (P = 0.028), whereas the other treatment groups showed no difference from baseline (P = 0.128 in gatifloxacin, 0.161 in BSS group). The mean corneal endothelial damage was 0.81 +/- 0.31% in the levofloxacin group, 0.56 +/- 0.47% in the gatifloxacin group, and 0.53 +/- 0.52% in the BSS group, with no statistically significant difference noted among the groups (P = 0.582). SEM revealed a well-preserved hexagonal endothelial cell mosaic and normal microvilli on the endothelial cell surface in the gatifloxacin and control groups. However, the levofloxacin group showed slightly disintegrated cellular borders. TEM revealed that each group maintained normal intracellular organization, whereas the levofloxacin group exhibited slightly flat cell configuration with irregular folds on the apical cell surface.

CONCLUSIONS

Intracameral injection of gatifloxacin and levofloxacin was nontoxic in terms of clinical toxicity score, corneal thickness, and viability. However, there were changes on electron microscopy in the levofloxacin group, which may indicate microstructural damage to corneal endothelial cells.