Intravitreal vancomycin and gentamicin concentrations in patients with postoperative endophthalmitis

Posterior vitreous attachment as a risk factor for endophthalmitis following intravitreal antivascular endothelial growth factor injection

PURPOSE

To evaluate the importance of the status of posterior vitreous in eyes with endophthalmitis following intravitreal anti-vascular endothelial growth factor (anti-VEGF).

METHODS

The absence or existence of posterior vitreous detachment (PVD) was elicited in 23 eyes of 23 patients with injection related endophthalmitis, during pars plana vitrectomy (PPV) and compared with 24 control eyes of 24 patients who received intravitreal anti-VEGF without any complication.

RESULTS

Thirtten (54.2%) out of 24 patients in the control group had full PVD, whereas only 2 (9.5%) out of 23 eyes in endophthalmitis group (p < 0.001) had full PVD. In all eyes without PVD, posterior vitreous was inducted to be detached at least from optic nerve and macular area without any iatrogenic tear.

CONCLUSION

The absence of PVD is a factor that increases the risk of endophthalmitis after intravitreal injections. Uncomplicated separation of the posterior vitreous from the retina in PPV contributes to better prognosis.

Tap and inject of intravitreal antibiotics versus pars plana vitrectomy for post-cataract surgery endophthalmitis: a meta-analysis

BACKGROUND

The efficacy and safety of initial tap and inject (T/I) compared with pars plana vitrectomy (PPV) for acute postoperative bacterial endophthalmitis following cataract surgery is unclear. Understanding the comparative safety and efficacy of initial T/I and initial PPV can provide context for treatment decision making in this setting.

METHODS

A systematic literature search was performed on Ovid MEDLINE, EMBASE, and the Cochrane Library from January 1990 to January 2021. Comparative studies reporting on final best-corrected visual acuity (BCVA) following initial T/I or PPV in patients with infectious endophthalmitis secondary to cataract surgery were included. Cochrane's Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) was used to evaluate the risk of bias, and GRADE criteria were used to assess certainty of evidence. A random-effects model was used for meta-analysis.

RESULTS

Seven nonrandomized studies reporting on 188 eyes at baseline were included in this meta-analysis. Initial T/I achieved a significantly better BCVA at last study observation than initial PPV (weighted mean difference [WMD] = -0.61 logMAR; 95% CI, -1.19 to -0.03; p = 0.04; I2 = 89%; n = 7 studies; GRADE = very low). The incidence of enucleation was similar between initial T/I and initial PPV (risk ratio [RR] = 0.73; 95% CI, 0.09-6.25; p = 0.78; I2 = 4%; n = 2 studies; GRADE = very low). The risk of retinal detachment was similar between treatment modalities (RR = 0.29; 95% CI, 0.01-5.94; p = 0.42; I2 = 52%; n = 2 studies; GRADE = very low).

CONCLUSIONS

The quality of evidence in this setting is limited. T/I had a significantly better BCVA at last study observation than initial PPV. Safety profiles were similar between T/I and PPV.

[Bacterial endogenous endophthalmitis : Spectrum of pathogens and drug therapy]

Endogenous endophthalmitis represents an ophthalmological emergency requiring immediate diagnostics and treatment. Pathogens should be detected using appropriate methods, such as the Freiburg endophthalmitis set. In bacterial endophthalmitis both Gram-positive and Gram-negative bacteria can be detected. Frequent underlying sources include endocarditis, gastrointestinal or urogenital surgery, indwelling venous catheters, liver abscesses, skin or soft tissue infections, meningitis or less commonly, intravenous drug abuse. The treatment consists of systemic and intraocular administration of antibiotics and vitrectomy. Systemic or intraocular corticosteroids can additionally be considered.

Preventive factors, diagnosis, and management of injection-related endophthalmitis: a literature review

BACKGROUND

Intravitreal medication injections represent the gold standard treatment for a variety of potentially blinding chorioretinal vascular diseases. Despite their excellent safety profile, they are associated with the feared complication of injection-related endophthalmitis (IRE). Though the overall incidence of IRE is low, due to the ever-increasing number of injections being performed, it is a complication that all retina specialists are likely to encounter. This article reviews various factors that could potentially influence the risk of IRE and discusses evidence-based strategies for management.

METHOD

PubMed was searched for keywords "intravitreal injection" and "endophthalmitis" from the period of 1995-2021. Relevant articles were reviewed and selected articles were analyzed with respect to the incidence, potential preventive factors, clinical presentation, microbial profile, management, and outcomes for IRE.

RESULTS

There is strong consensus supporting the use of povidone iodine topical antiseptic, eyelid retraction away from the injection site, and avoiding treatment of eyes with active surface or eyelid disease, but there is less agreement on the use of face masks versus "no-talking" policies and optimal anesthetic technique. Current evidence comparing tap and inject or early vitrectomy for treatment of IRE is inadequate to determine an optimal treatment strategy.

CONCLUSION

Intravitreal injections are sight saving, but even using established prophylactic measures there remains a small but real risk of infectious injection-related complications. Further investigations comparing tap and inject versus vitrectomy may help to establish optimal treatment, although the rarity of IRE makes designing adequately powered prospective trials a difficult task.

Endophthalmitis After Intravitreal Anti-Vascular Endothelial Factor Injections: Outcomes of Eyes Managed Without Microbiologic Cultures

PURPOSE

To evaluate outcomes of eyes that developed endophthalmitis after intravitreal anti-vascular endothelial growth factor injections that were managed without microbiologic cultures.

DESIGN

Retrospective, single-center, comparative cohort study.

METHODS

We included all eyes with postinjection endophthalmitis from July 1, 2013, to September 1, 2019. Endophthalmitis cases were divided into the culture group if treated with intravitreal antibiotics and a vitreous or aqueous tap sent for microbiologic sampling or into the no culture group if treated with immediate injection of intravitreal antibiotics with an anterior chamber paracentesis that was not sent for microbiologic sampling. The main outcome measures were visual acuity, the incidence of retinal detachment, and the need for additional procedures.

RESULTS

Of 165 endophthalmitis cases identified, 119 (72%) were in the culture group and 46 (28%) were in the no culture group. At endophthalmitis presentation, eyes in the culture group had a mean logMAR VA of 1.98 (∼20/1900) compared with 1.90 (∼20/1600) for eyes in the no culture group (P = .589). At the 6-month follow-up, the mean vision loss was 5.5 lines lost from baseline for the culture group compared with 2.5 lines lost for the no culture group (P = .017). Eyes in the culture group required a subsequent pars plana vitrectomy in 29 of 119 cases (24%) compared with 7 of 46 cases (15%) in the no culture group (P = .29). Six of 119 eyes (5%) in the culture group developed secondary retinal detachments compared with none in the no culture group (P = .143).

CONCLUSIONS

When access to microbiologic facility is not available, the management of postinjection endophthalmitis using intravitreal antibiotics without microbiologic cultures may be an acceptable treatment strategy.

Treatment outcomes of acute poptoperative infectious endophthalmitis

Background

Acute postoperative endophthalmitis is one of the most severe complications of modern ophthalmic procedures including cataract surgeries, vitrectomy and intravitreal injection (IVI). We evaluated the treatment outcomes of acute postoperative infectious endophthalmitis.

Methods

In this retrospective study, we collected data from 82 patients with acute infectious endophthalmitis within 6 weeks after intraocular surgeries, including cataract surgeries, vitreoretinal surgeries, and IVI, from January 2010 to December 2019. We analyzed the pre-treatment, treatment-related and post-treatment factors that affected visual outcomes.

Results

The mean age was 67.65 ± 9.52 years, the proportion of male patients was 56.1%. The mean baseline vision was 1.92 (Snellen Equivalent SE], counting finger [CF]) ± 0.54 logarithm of the minimum angle of resolution (log MAR) and the mean final vision was 0.71 (SE, 39/200) ± 0.80 logMAR. Visual improvement was significant (P < 0.001). The pre-treatment factors affecting final visual outcomes were diabetes, hemodialysis, baseline vision, signs of vitreous opacity, and different surgeries before endophthalmitis; the treatment-related factors affecting visual outcomes were the choice factors between IVI of antibiotics alone and vitrectomy combined with IVI of antibiotics, and the injection numbers of antibiotics; post-treatment factors affecting visual outcomes were complications such as retinal detachment (RD), glaucoma and macular pucker. Furthermore, prior cataract surgery was associated with a better mean final vision of 0.57 (SE, 54/200) ± 0.67 logMAR while prior vitrectomy resulted in the worst mean final vision of 1.38 (SE, 21/500) ± 0.75 logMAR.

Conclusions

The important factors that affected the final visual prognosis, included diabetes, hemodialysis, baseline vision, severity of vitritis, treatment strategies and complications. The treatment outcomes revealed better final vision in prior cataract surgery than vitrectomy.

Endophthalmitis: Changes in Presentation, Management and the Role of Early Vitrectomy

Endophthalmitis is a sight-threatening condition, and its timely and appropriate management is essential in preventing permanent vision loss. Recent changes in clinical practice in endophthalmitis and advances in modern vitreoretinal surgery may limit the applicability of established randomised clinical trial evidence to current management. This review discusses the epidemiology, pathophysiology, changing patient presentation, diagnosis and advances in the management of endophthalmitis, presenting the existing literature on this topic and results from Sydney Eye Hospital.

Factors Associated With Positive Microbial Culture in Patients With Endophthalmitis Based on Clinical Presentation and Multimodal Intraocular Sampling

PURPOSE

The aim of this study was to identify the factors associated with positive culture sample in patients with endophthalmitis based on clinical presentation and multimodal intraocular sampling.

DESIGN

Retrospective review.

METHODS

A total of 259 subjects with a diagnosis of endophthalmitis presented to a tertiary ophthalmic referral center between 2006 and 2018. Patient demographics, presenting clinical findings and the results of aqueous and vitreous sampling were analyzed.

RESULTS

Mean age was 64.2 (± 22.6) years with 52.9% female. Endophthalmitis followed cataract surgery in 84 eyes (32.4%) and was the most common precipitant; intravitreal injections were the next common cause involving 60 eyes (23.2%). Mean visual acuity on presentation was hand movements with a hypopyon present 134 eyes (52%). In total, 135 cases (52.1%) were culture positive. Aqueous sampling was performed in 112 eyes [culture positive 36 (32.1%)]; vitreous sample in 122 eyes [positive in 56 (45.3%)]. Vitrectomy was performed in 169 eyes with 149 sent for culture [70 (47.0%) positive]. A positive vitrectomy culture was observed in 14 eyes (36.9%) of 38, despite initial treatment with intravitreal antibiotics. Factors associated with positive culture were aqueous tap [odds ratio (OR) 2.06, P = 0.02], vitrectomy (OR 2.86, P = 0.001), and absent red reflex (OR 2.73, P = 0.001).

CONCLUSIONS

A multimodal approach to intraocular sampling should be considered in those presenting with endophthalmitis, with both aqueous tap and vitrectomy associated with an increased probability of achieving a positive culture.

A prospective multicentre randomized placebo-controlled superiority trial in patients with suspected bacterial endophthalmitis after cataract surgery on the adjuvant use of intravitreal dexamethasone to intravitreal antibiotics

PURPOSE

We aimed to determine whether intravitreal dexamethasone as an adjuvant to intravitreal antibiotics is beneficial in the treatment of suspected bacterial endophthalmitis after cataract surgery.

METHODS

Randomized, placebo-controlled superiority trial in three tertiary referral centres in the Netherlands. Patients with suspected bacterial endophthalmitis within 6 weeks after cataract surgery were eligible. A diagnostic vitreous biopsy was taken for culture, and patients received intravitreal injections of 400 μg dexamethasone (without preservatives) or placebo, in addition to 0.2 mg vancomycin and 0.05 mg gentamicin. The vancomycin and dexamethasone or placebo injections were repeated once at day 3 or 4. Primary outcome measure was best-corrected visual acuity (BCVA) at 1 year.

RESULTS

Between 1 November 2004 and 1 March 2014 (excluding two interruptions totalling 20 months), 324 eligible patients presented. A total of 167 patients (81 dexamethasone, 86 placebo) were available for the intention-to-treat analysis. Biopsies of 114 patients (68%) were culture-positive. Final BCVA did not differ between the dexamethasone and the placebo group (logMAR 0.31 ± 0.58 versus 0.27 ± 0.50; p = 0.90), nor did the number of patients with final vision of no light perception (LP, 7 versus 13). Pain, corneal oedema, the absence of a red fundus reflex on presentation, LP on presentation and culture of virulent pathogens from biopsy were statistically significantly associated with an unfavourable visual outcome.

CONCLUSION

Intravitreal dexamethasone without preservatives as an adjuvant to intravitreal antibiotics does not improve visual acuity (VA) in patients treated for suspected bacterial endophthalmitis after cataract surgery.

The Effect of Intraoperative Antibiotics in Irrigating Solutions on Aqueous Humor Contamination and Endophthalmitis after Phacoemulsification Surgery

PURPOSE

To determine the efficacy of intraoperative antibiotic use in irrigating solutions on aqueous humor contamination during phacoemulsification surgery and to evaluate the corresponding risk of postoperative endophthalmitis.

METHODS

644 eyes of 640 patients who underwent phacoemulsification surgery with foldable intraocular lens (IOL) implantation were included in this study. Preoperative conjunctival smears were taken and eyes were allocated to receive irrigating infusion fluid containing either balanced salt solution (BSS)-only (group 1; 322 eyes) or BSS with antibiotics (vancomycin and gentamycin) during surgery (group 2; 322 eyes). Bacterial contamination rates of aqueous humor samples taken in the beginning and at the end of operation were compared. Predictive factors for the development of postoperative endophthalmitis were determined by clinical and microbiologic analyses.

RESULTS

The rates of culture-positivity were similar between group 1 and group 2 for both preoperative conjunctival smears and aqueous samples (p > 0.05). Aqueous samples taken at the end of operation were found to be contaminated in 68 (21.1%) eyes in group 1 and 22 (6.8%) eyes in group 2, and the difference was significant (p = 0.0001; OR = 3.65 (2.1-6.0)). Capsular rupture was associated with higher rate of contamination in both groups (p = 0.0001; OR = 7.7 and p = 0.0001; OR = 8.1). Two eyes in the BSS-only group developed postoperative endophthalmitis and these cases had posterior capsular rupture during the surgery and culture-positivity for staphylococcus epidermidis throughout the study.

CONCLUSIONS

Intraoperative antibiotic irrigation decreases aqueous humor contamination during phacoemulsification. Further studies are warranted to determine the interrelationship between aqueous humor contamination and endophthalmitis in eyes with posterior capsular rupture.

A Review of Antimicrobial Therapy for Infectious Uveitis of the Posterior Segment

Treatment of infectious posterior uveitis represents a therapeutic challenge for ophthalmologists. The eye is a privileged site, maintained by blood ocular barriers, which limits penetration of systemic antimicrobials into the posterior segment. In addition, topical and subconjunctival therapies are incapable of producing sufficient drug concentrations, intraocularly. Posterior infectious uveitis can be caused by bacteria, virus, fungi, or protozoa. Mode of treatment varies greatly based on the infectious etiology. Certain drugs have advantages over others in the treatment of infectious uveitis. Topical and systemic therapies are often employed in the treatment of ocular infection, yet the route of treatment can have limitations based on penetration, concentration, and duration. The introduction of intravitreal antimicrobial therapy has advanced the management of intraocular infections. Being able to bypass blood-ocular barriers allows high drug concentrations to be delivered directly to the posterior segment with minimal systemic absorption. However, because the difference between the therapeutic and the toxic doses of some antimicrobial drugs falls within a narrow concentration range, intravitreal therapy could be associated with ocular toxicity risks. In many cases of infectious uveitis, combination of intravitreal and systemic therapies are necessary. In this comprehensive review, the authors aimed at reviewing clinically relevant data regarding intraocular and systemic antimicrobial therapy for posterior segment infectious uveitis. The review also discussed the evolving trends in intraocular treatment, and elaborated on antibiotic pharmacokinetics and pharmacodynamics, efficacy, and adverse effects.

Persistently Vitreous Culture-Positive Exogenous Bacterial Endophthalmitis

PURPOSE

To report the clinical settings, bacterial isolates, antibiotic sensitivities, and visual acuity outcomes of patients with persistently positive vitreous cultures after intravitreal antibiotics.

DESIGN

Consecutive, noncomparative case series.

METHODS

setting: Tertiary care center.

PATIENT POPULATION

Thirty-six eyes of 36 patients with exogenous endophthalmitis with the same bacterial organism identified on at least 2 consecutive vitreous cultures from 1981 to 2015.

OBSERVATION PROCEDURES

Vitreous cultures with intravitreal injections of antibiotics and pars plana vitrectomies with intravitreal antibiotics.

MAIN OUTCOME MEASURES

Bacterial isolates, antibiotic sensitivities, visual outcomes.

RESULTS

Thirty-six eyes of 36 patients met the study criteria. The mean follow-up was 26.5 months. The most common clinical settings were after cataract extraction (18/36, 50%) and glaucoma surgery (11/36, 31%). The mean initial visual acuity was 2.16 ± 0.77 logMAR (Snellen equivalent ≈20/2900), and there was no statistically significant change at the final evaluation (2.08 ± 0.97 logMAR, ≈20/1900, P = .72). The most common bacteria were Staphylococcus (11/36, 31%) and Streptococcus (9/36, 25%). Gram-positive bacteria were sensitive to vancomycin (27/27, 100%); gram-negative bacteria were sensitive to amikacin (5/5, 100%). The antibiotic sensitivities were the same on repeat cultures in 34 of 36 patients (94%). The initial treatment was a vitreous culture and intravitreal injection of antibiotics in 28 of 36 patients (78%). The vision at the last follow-up was 20/200 or better in 12 patients (33%) and no light perception in 11 of 36 patients (31%).

CONCLUSIONS

The most commonly identified organisms were gram-positive bacteria. There was good concordance in the antibiotic sensitivities between initial and subsequent cultures. Patients with persistently vitreous culture-positive endophthalmitis had poor visual outcomes.

Rabbit as an animal model for intravitreal pharmacokinetics: Clinical predictability and quality of the published data

Intravitreal administration is the method of choice in drug delivery to the retina and/or choroid. Rabbit is the most commonly used animal species in intravitreal pharmacokinetics, but it has been criticized as being a poor model of human eye. The critique is based on some anatomical differences, properties of the vitreous humor, and observed differences in drug concentrations in the anterior chamber after intravitreal injections. We have systematically analyzed all published information on intravitreal pharmacokinetics in the rabbit and human eye. The analysis revealed major problems in the design of the pharmacokinetic studies. In this review we provide advice for study design. Overall, the pharmacokinetic parameters (clearance, volume of distribution, half-life) in the human and rabbit eye have good correlation and comparable absolute values. Therefore, reliable rabbit-to-man translation of intravitreal pharmacokinetics should be feasible. The relevant anatomical and physiological parameters in rabbit and man show only small differences. Furthermore, the claimed discrepancy between drug concentrations in the human and rabbit aqueous humor is not supported by the data analysis. Based on the available and properly conducted pharmacokinetic studies, the differences in the vitreous structure in rabbits and human patients do not lead to significant pharmacokinetic differences. This review is the first step towards inter-species translation of intravitreal pharmacokinetics. More information is still needed to dissect the roles of drug delivery systems, disease states, age and ocular manipulation on the intravitreal pharmacokinetics in rabbit and man. Anyway, the published data and the derived pharmacokinetic parameters indicate that the rabbit is a useful animal model in intravitreal pharmacokinetics.

Pharmacokinetics of intravitreal antibiotics in endophthalmitis

Intravitreal antibiotics are the mainstay of treatment in the management of infectious endophthalmitis. Basic knowledge of the commonly used intravitreal antibiotics, which includes their pharmacokinetics, half-life, duration of action and clearance, is essential for elimination of intraocular infection without any iatrogenic adverse effect to the ocular tissue. Various drugs have been studied over the past century to achieve this goal. We performed a comprehensive review of the antibiotics which have been used for intravitreal route and the pharmacokinetic factors influencing the drug delivery and safety profile of these antibiotics. Using online resources like PubMed and Google Scholar, articles were reviewed. The articles were confined to the English language only. We present a broad overview of pharmacokinetic concepts fundamental for use of intravitreal antibiotics in endophthalmitis along with a tabulated compendium of the intravitreal antibiotics using available literature. Recent advances for increasing bioavailability of antibiotics to the posterior segment with the development of controlled drug delivery devices are also described.

A prospective multicenter randomized placebo-controlled trial of dexamethasone as an adjuvant in the treatment of postoperative bacterial endophthalmitis: interim safety analysis of the study drug and analysis of overall treatment results

PURPOSE

In an ongoing prospective multicenter randomised placebo-controlled trial we study the adjuvant use of intravitreal dexamethasone in the treatment of patients with suspected bacterial endophthalmitis after phacoemulsification. In accordance with the study protocol, a mid-inclusion interim analysis of the safety of the study drug was performed.

PATIENTS AND METHODS

Patients with suspected endophthalmitis after phacoemulsification were asked to participate in this study. A diagnostic vitreous biopsy was taken and the patients received intravitreal injections of 400 micrograms dexamethasone or a placebo, plus 0.2 mg vancomycin and 0.05 mg gentamicin. Injections were repeated after 3 or 4 days. The safety analysis included: the number of eyes with an evisceration; no light perception; or a visual acuity of less than 5/200. Treatment outcome was evaluated in terms of: the percentage of patients with a visual acuity of 20/40 or more and 20/100 or more.

RESULTS

The interim analysis included 81 patients with at least 1 year follow-up. Sixty-three patients (65 %) were culture-positive. Safety analysis: 7 eyes were eviscerated (3 dexamethasone, 4 placebo); 4 eyes had no light perception (2 dexamethasone, 2 placebo); and 4 eyes had less than 5/200 vision (3 dexamethasone, 1 placebo). Treatment outcome: 70 % of patients had a visual acuity of at least 20/40.

CONCLUSION

The safety analysis does not warrant premature discontinuation of the study. So far, the overall outcome of our treatment regimen, consisting of merely a diagnostic biopsy instead of a vitrectomy and an optimized antibiotic dosing, compares favourably to published literature.

Antibiotics concentrations in a patient with postoperative endophthalmitis

We report a case of endophthalmitis who underwent a vitreous biopsy to assess sensitivity and to inject broad-spectrum intraocular antibiotics. Minimal inhibitory concentration (MIC) values of antibiotics against a coagulase-negative staphylococcus and Proprionibacterium acnes were also assessed.

Transscleral drug delivery to the posterior eye: prospects of pharmacokinetic modeling

Basic biological research has provided new approaches to treat severe diseases of the retina and choroid, such as age related macular degeneration. Although it is possible to deliver drugs from a subconjunctival drug depot to the retina and choroid, the barriers and kinetics of this route of drug administration are not well known. In this review we investigate the pharmacokinetic aspects of transscleral drug delivery into the posterior eye with emphasis on pharmacokinetic modeling. The existing simulation models related to the transscleral drug delivery are reviewed and future directions for the model development are discussed. In addition, a new simulation model for the transscleral drug delivery based on permeability data is introduced. This compartmental model contains several ocular tissues (sclera, choroid, retinal pigment epithelium and vitreous) and it takes into account the clearance of the drug via choroidal circulation. The model is used to simulate the vitreous delivery of macromolecules based on the available data on FITC-dextran 70 kDa.

An outbreak of endophthalmitis after extracapsular cataract surgery probably caused by endotoxin contaminated distilled water used to dissolve acetylcholine

AIM

To study possible causes of an outbreak of severe endophthalmitis after planned extracapsular cataract surgery in Medan, Indonesia.

METHODS

In a 3 week period in November 2001, 17 of 43 patients developed signs of endophthalmitis after planned extracapsular cataract surgery. A search for possible causes was undertaken 4 months later.

RESULTS

In autoclaved stored distilled water used to dissolve acetylcholine (used in 16 of 17 patients with endophthalmitis) a high amount of endotoxin was detected in a human blood essay, as well as a small number of non-typeable Pseudomonas spp.

CONCLUSIONS

These findings suggest that distilled water used as solvent for acetylcholine was responsible for this outbreak of endophthalmitis. As a consequence, we now rely on solvents that are regularly checked for impurities such as an intravenous infusion fluid, rather than on vials with distilled water that is presumed to be sterile and kept for some time.

The effectiveness of lysostaphin therapy for experimental coagulase-negative Staphylococcus endophthalmitis

PURPOSE

To quantitatively determine the effectiveness of lysostaphin therapy for experimental endophthalmitis mediated by coagulase-negative Staphylococcus species, the leading cause of postsurgical endophthalmitis.

METHODS

Minimal inhibitory concentrations (MIC) of lysostaphin were determined for 54 isolates representing the following species: S. epidermidis, S. warneri, S. haemolyticus, S. cohnii, S. simulans, and S. capitis. The effectiveness of lysostaphin therapy was tested in an experimental model of endophthalmitis by intravitreally injecting log phase bacteria (100 colony-forming units; cfu) into rabbit eyes (n = 3 eyes per group). At 8 hr postinfection (PI), lysostaphin (250 microg) was injected intravitreally, and the number of cfu/ml of vitreous was determined at 24 hr PI.

RESULTS

Average MIC for S. epidermidis was 0.7 microg/ml for 90% of the 33 strains tested. Six methicillin-resistant strains of S. epidermidis (MRSE) had an average MIC of 0.74 micro g/ml. All other species had MIC values of =1.1 microg/ml, except for one strain of S. capitis (MIC = 15.6 microg/ml) and one S. haemolyticus (MIC = 1.41 microg/ml). At 24 hr PI, all untreated eyes had between 5.7 and 8.08 log cfu/ml vitreous humor. Treatment with lysostaphin significantly reduced the cfu/ml as compared with untreated eyes for 13 strains tested in vivo (p = 0.020), but not for two S. haemolyticus strains (p = 0.13), two MRSE strains (p = 0.544), or one S. cohnii strain (p = 0.1366). Treatment with lysostaphin reduced the cfu/ml of methicillin-sensitive S. epidermidis strains by 6 logs; for S. warneri, there was a 2 log reduction; and for the other species a 4 log reduction in cfu/ml relative to untreated eyes.

CONCLUSIONS

Lysostaphin was mostly effective in treating coagulase-negative staphylococcal experimental endophthalmitis.

Intravitreal dexamethasone as adjuvant in the treatment of postoperative endophthalmitis: a prospective randomized trial

PURPOSE

To study whether intravitreal dexamethasone as adjuvant to intravitreal antibiotics improves the outcome in patients with suspected postoperative bacterial endophthalmitis.

DESIGN

Prospective randomized clinical trial.

SETTING

Tertiary referral center.

PATIENT POPULATION

Twenty-nine consecutive patients with suspected postoperative bacterial endophthalmitis within 6 weeks of cataract surgery.

INTERVENTION

Patients underwent a vitreous biopsy followed by intravitreal injection of antibiotics (0.2 mg vancomycin and 0.05 mg gentamicin) and 400 microg dexamethasone or placebo. After 3-4 days the intravitreal injection of antibiotics and dexamethasone or placebo was repeated.

PRIMARY OUTCOME MEASURE

Snellen visual acuity at 3 and 12 months after treatment.

RESULTS

In 20/29 patients (69%) the vitreous cultures were positive. 13/29 patients received dexamethasone. Seven patients had a functionally lost eye (final vision of hand movements or less), in four due to retinal detachment. Visual acuity tended to be better in the dexamethasone treated patients than in those given placebo, at both 3 months (P=0.055) and 12 months (P=0.080).

CONCLUSION

This small prospective, placebo-controlled series showed a trend towards a better visual outcome in patients with suspected bacterial endophthalmitis when treatment with intravitreal antibiotics was combined with intravitreal dexamethasone. Our findings justify a larger multicenter randomized study.

Effect of vancomycin, teicoplanin, and cefuroxime on Staphylococcus epidermidis adherence to intraocular lenses

PURPOSE

To compare the adherence of Staphylococcus epidermidis on AcrySof (Alcon) and poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) treated with vancomycin, teicoplanin, and cefuroxime.

SETTING

Kocaeli University, School of Medicine, Kocaeli, Turkey.

METHODS

The lenses were contaminated with S epidermidis solutions containing 10(8) colony-forming units. Intraocular lenses were placed in sterile triptic soy broth after being held in antibiotic solutions for 15 minutes. After that, sonication and vortex procedures were performed to remove all the attached bacteria that could not be removed by antibiotics. Ten microliters from each broth were taken and inoculated into sheep blood agar. The colonies were counted overnight. The statistical analyses were made using Mann-Whitney U and Kruskal-Wallis tests, and a P value less than 0.05 was considered statistically significant.

RESULTS

Regarding the inhibitory effect of antibiotics on bacterial adhesion, there was no statistically significant difference between AcrySof and PMMA lenses. In the cefuroxime group, the mean numbers of colony-forming units on AcrySof and PMMA lenses were 35.2 +/- 6.94 and 30.8 +/- 18.69, respectively (P>.05). In the teicoplanin group, the mean number of colony-forming units on AcrySof lenses was 100.1 +/- 20.97 and 70.6 +/- 43.75 on the PMMA lenses. The adherence in the vancomycin group was 245 +/- 273.74 colony-forming units for AcrySof lenses and 159.8 +/- 101.94 for PMMA lenses (P>.05). Regarding the inhibitory effect of antibiotics, cefuroxime was the most effective, followed by teicoplanin and vancomycin, respectively. Overall, the mean numbers of colony-forming units on the lenses that were held in cefuroxime, teicoplanin, and vancomycin solutions were 33.0 +/- 13.90, 85.35 +/- 36.66, and 202.4 +/- 205.74, respectively (P = .000).

CONCLUSIONS

The results suggest that cefuroxime, teicoplanin, and vancomycin significantly inhibit bacterial adherence to IOLs. The effect of cefuroxime on adherence inhibition was significantly higher than that of teicoplanin and vancomycin. Bacterial adherence is an important factor in bacterial virulence. Antibiotics, especially cefuroxime, can successfully inhibit bacterial adherence.

Effect of intravitreal dexamethasone on vitreous vancomycin concentrations in patients with suspected postoperative bacterial endophthalmitis

PURPOSE

To study intravitreal dexamethasone and vancomycin concentrations, when used together in patients with suspected postoperative bacterial endophthalmitis. Animal studies had suggested that dexamethasone might decrease the concentration of vancomycin.

DESIGN

Prospective randomized clinical trial in a tertiary referral center.

METHODS

Twenty-nine consecutive patients with suspected postoperative bacterial endophthalmitis underwent a vitreous biopsy followed by intravitreal injection of antibiotics (0.2 mg vancomycin, 0.05 mg gentamicin) and 400 mug dexamethasone or placebo. After 3-4 days, the intravitreal injection of antibiotics and dexamethasone or placebo was repeated. In 18 patients, a second biopsy was taken for repeat culture and measurement of vancomycin and dexamethasone concentrations.

RESULTS

In 20/29 patients (69%) the first vitreous cultures were positive; the second culture was negative in all cases. Thirteen out of 29 patients received dexamethasone. Dexamethasone concentrations showed an average of 25 ng/ml 3 days after injection, with an estimated half-life of 5.5 h. Vancomycin concentrations in patients given dexamethasone tended to be higher compared with those in the placebo group (P=0.061).

CONCLUSION

Intravitreal dexamethasone does not lead to decreased vancomycin concentrations, when given simultaneously in the treatment of patients with suspected bacterial endophthalmitis.

Ciliary neurotrophic factor protects retinal ganglion cells from secondary cell death during acute autoimmune optic neuritis in rats

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS which leads to demyelination, axonal destruction and neuronal loss in the early stages. Available therapies mainly target the inflammatory component of the disease but fail to prevent neurodegeneration. To investigate the effect of ciliary neurotrophic factor (CNTF) on the survival of retinal ganglion cells (RGCs), the neurons that form the axons of the optic nerve, we used a rat model of myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis. Optic neuritis in this model was diagnosed by recording visual evoked potentials, and RGC function was monitored by measuring electroretinograms. This study demonstrates that CNTF has a neuroprotective effect on affected RGCs during acute optic neuritis. Furthermore, we demonstrate that CNTF exerts its neuroprotective effect through activation of the Janus kinase/signal transducer and activator of transcription pathway, mitogen activated protein kinases and a shift in the Bcl-2 family of proteins towards the anti-apoptotic side. In summary, our results demonstrate that CNTF can serve as an effective neuroprotective treatment in a rat model of MS that especially reflects the neurodegenerative aspects of this disease.

Modified High-Performance Liquid Chromatography Technique for Detection of Vancomycin in Human Vitreous

PURPOSE

To standardize the technique and methodology for estimating the level of vancomycin in human vitreous using a modified high-performance liquid chromatographic method.

METHODS

Sample preparation involved spiking the vitreous with known quantities of the drug followed by a brief treatment with 30% trichloroacetic acid. Samples were analyzed on a C18 reverse-phase column using a mobile phase of 50 mM phosphate buffer (pH 4.0) and 10% acetonitrile.

RESULTS

Vancomycin was detected at 198 nm. It showed a retention time of 2.2 min in the vitreous. A linear increase in the area under the peak corresponding to the drug was observed with increase in concentration of vancomycin in the vitreous. The method was applied to detect the vancomycin levels in vitreous of 5 patients with exogenous endophthalmitis, 24-48 h after intravitreal injection of vancomycin 1 mg/0.1 ml. The mean concentration of vancomycin in these samples was 120.022 +/- 59.87 microg/ml (43.859-179.09 microg/ml). The present technique allowed a quantification limit of 1 microg/ml.

CONCLUSION

This technique is suitable to estimate vancomycin levels in human vitreous in a variety of clinical and experimental studies. It has the added advantages of being less expensive, simple and rapid.

Interleukin-1 beta protects neurons via the interleukin-1 (IL-1) receptor-mediated Akt pathway and by IL-1 receptor-independent decrease of transmembrane currents in vivo

Recently, we have demonstrated that tumor necrosis factor-alpha (TNF-alpha) rescues retinal ganglion cells (RGCs) from retrograde cell death in vivo after axotomy of the optic nerve. The mechanism of RGC rescue was dependent on TNF-receptor I-mediated potassium current reduction and consecutive activation of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. Here, we present evidence that interleukin-1 beta (IL-1 beta) also promotes RGC survival, but shows distinct differences with respect to its neuroprotective mechanisms. Using whole-cell and outside-out patch-clamp techniques, we observed that IL-1 beta decreased both inward sodium current amplitudes and outward potassium current amplitudes. Counteracting these effects by sodium or potassium channel opening inhibited the survival-promoting effects of this cytokine. IL-1 beta-induced current reduction could not be abolished by the interleukin-1 receptor antagonist, indicating that the electrophysiological effects of IL-1 beta are independent of interleukin-1 receptor I (IL-1RI) activation. Western blot analysis revealed an IL-1 beta-induced IL-1RI-dependent upregulation of phospho-Akt. Antagonism of the survival-promoting effects of IL-1 beta by PI3-K inhibition revealed the functional relevance of the PI3-K/Akt pathway in IL-1 beta-induced signal transduction in vivo.

Antibiotic therapy in post-operative endophthalmitis

Endophthalmitis following routine cataract surgery is a rare but potentially devastating complication resulting in severe vision loss. Various prophylaxis treatments have been tried. However, none have been demonstrated to completely eliminate the risk. The Endophthalmitis Vitrectomy Study (EVS) helped establish clinical guidelines in the treatment of post-operative endophthalmitis in a prospective, randomized, multicenter trial. The strength and limitation of the study will be discussed as well as the current knowledge of the pharmacokinetics of intravitreous injection of antibiotics. Additionally, the common pathologic organisms, the use of antibiotic therapy, steroids, and vitrectomy will be discussed.