Severe bacterial endophthalmitis: towards improving clinical outcomes

Clinical and Microbiological Manifestations of Endogenous Endophthalmitis in Tertiary Care Hospital, Northern Thailand

PURPOSE

To determine the characteristics, primary sources, pathogens, risk factors, and visual outcomes in patients with endogenous endophthalmitis (EE).

METHODS

We performed a retrospective cohort study of 61 consecutive patients with EE (74 affected eyes) and reported on prevalence, clinical courses, prognostic factors and visual outcomes.

RESULTS

Prevalence of EE was 5% of all patients with endophthalmitis. Among culture-positive cases (89%), Gram-positive species dominating (69%) followed by Gram-negative with 22% and fungal species with 9%. Regarding to visual outcomes, the mean visual acuity (VA, ETDRS letters) at baseline, 3-months, 6-months and 1-year follow-up was 0.85, 9, 8 and 9, respectively. Initial VA of hand movement or better (P 0.007) and bilateral infection (P 0.004) were associated with better visual outcome.

CONCLUSION

The prognosis for EE remained poor despite aggressive and immediate treatment. The high suspicion, early diagnosis and prompt treatment are important factors that might lead to the better outcome.

The Role of CCL Chemokines in Experimental Staphylococcus aureus Endophthalmitis

Purpose

To test the hypothesis that (C-C motif) ligand 2 (CCL2) and CCL3 impact retinal function decline and inflammation during Staphylococcus aureus endophthalmitis.

Methods

Experimental endophthalmitis was initiated by intravitreal injection of 5000 colony-forming units of S. aureus into the eyes of C57BL/6J, CCL2-/-, or CCL3-/- mice. At 12 and 24 hours post-infection, retinal function, bacterial load, and myeloperoxidase levels were quantified.

Results

During S. aureus endophthalmitis, we observed a significant improvement in retinal function in CCL2-/- mice relative to C57BL/6J mice at 12 hours but not at 24 hours. In CCL3-/- mice, retinal function was significantly improved relative to C57BL/6J mice at 12 and 24 hours. The absence of CCL2 did not alter intraocular S. aureus intraocular concentrations. However, CCL3-/- mice had significantly lower intraocular S. aureus at 12 hours but not at 24 hours. No difference in myeloperoxidase levels was observed between C57BL/6J and CCL2-/- mice at 12 hours. CCL3-/- mice had almost no myeloperoxidase at 12 hours. At 24 hours, increased myeloperoxidase was observed in CCL2-/- and CCL3-/- mice relative to C57BL/6J mice.

Conclusions

Although the absence of CCL2 resulted in improved retinal function retention at 12 hours, CCL3 deficiency resulted in improved retinal function at 12 and 24 hours. CCL3 deficiency, but not CCL2 deficiency, resulted in almost no inflammation at 12 hours. However, at 24 hours, the absence of CCL2 or CCL3 resulted in significantly increased inflammation. These results suggest that, although both CCL2 and CCL3 impact intraocular infection outcomes, CCL3 may have a more significant impact in S. aureus endophthalmitis.

A Retrospective Review of Endogenous Endophthalmitis: Three Years of Experience at Sultan Ahmad Shah Medical Centre at International Islamic University Malaysia

Introduction Endogenous endophthalmitis is characterized by severe intraocular inflammation caused by the invasion of microorganisms into the anterior and posterior chambers of the eye. It results from hematogenous spread from distant foci of infection. This, in turn, leads to potential vision loss and blindness due to reduced anatomical and functional outcomes. The latest reported prevalence of endogenous endophthalmitis accounts for at least 2-8% of cases of general endophthalmitis which is fairly significant. Purpose This study aimed to analyze the clinical profile of endogenous endophthalmitis presented in the Ophthalmology Clinic, Sultan Ahmad Shah Medical Centre at International Islamic University Malaysia (SASMEC@IIUM). This study includes the patients' demographics, clinical manifestations, causative organism, treatment, and final visual outcome. Methods This is a retrospective case series of endogenous endophthalmitis patients from January 2020 to June 2023. The data were obtained from the patients' medical records in SASMEC@IIUM. Results A total of six patients (six eyes) were diagnosed with endogenous endophthalmitis from January 2020 to June 2023. Four patients (66.6%) were female, with a mean age of 51.6 ± 17.5 years. Presenting visual acuity ranged between 6/21 to hand movement (HM). Five patients (83.3%) presented with reduced vision, while one presented with eye redness (16.6%). Ocular signs included vitritis and retinitis (five eyes, 83.3%), hypopyon (five eyes, 83.3%), injected conjunctiva (five eyes, 83.3%), and eyelid swelling (one eye, 16.6%). The most common primary infection seen was intraabdominal sepsis (three patients, 50%), septic arthritis, hospital-acquired pneumonia (HAP), and urinary tract infection (UTI). Vitreous biopsy was only positive in two patients (33.3%) However, five out of the six patients (83.3%) had positive blood cultures (two Staphylococcus aureus, two Klebsiella pneumoniae and one Pseudomonas aeruginosa). All patients received intravitreal injections and intravenous antibiotics. Only one patient underwent subsequent trans pars plana vitrectomy (TPPV). Final visual acuity ranged from 6/6 to no light perception (NPL). Conclusion In this case series of six patients, we observed a variety of outcomes with similar presentations despite standardized treatment in all patients. Five out of six patients showed poorer visual outcomes and only one patient showed a final visual acuity of 6/6. Therefore, further study with a larger sample size is needed to evaluate the factors associated with the final visual outcome in endogenous endophthalmitis.

Untargeted and temporal analysis of retinal lipidome in bacterial endophthalmitis

Bacterial endophthalmitis is a blinding infectious disease typically acquired during ocular surgery. We previously reported significant alterations in retinal metabolism during Staphylococcus (S) aureus endophthalmitis. However, the changes in retinal lipid composition during endophthalmitis are unknown. Here, using a mouse model of S. aureus endophthalmitis and an untargeted lipidomic approach, we comprehensively analyzed temporal alterations in total lipids and oxylipin in retina. Our data showed a time-dependent increase in the levels of lipid classes, sphingolipids, glycerolipids, sterols, and non-esterified fatty acids, whereas levels of phospholipids decreased. Among lipid subclasses, phosphatidylcholine decreased over time. The oxylipin analysis revealed increased prostaglandin-E2, hydroxyeicosatetraenoic acids, docosahexaenoic acid, eicosapentaenoic acid, and α-linolenic acid. In-vitro studies using mouse bone marrow-derived macrophages showed increased lipid droplets and lipid-peroxide formation in response to S. aureus infection. Collectively, these findings suggest that S. aureus-infection alters the retinal lipid profile, which may contribute to the pathogenesis of bacterial endophthalmitis.

A survey of Asian Eye Institutions on perioperative antibiotic prophylaxis in cataract surgery

PURPOSE

To determine current institutional practice patterns for the use of perioperative antibiotics and other measures to prevent infection after cataract surgery in Asia.

METHODS

An online survey-based study of leading eye institutions in China, Hong Kong, India, Indonesia, Japan, Malaysia, Pakistan, Philippines, Singapore, South Korea, Taiwan, Thailand and Vietnam was conducted. The survey was administered to 26 representative key opinion leaders from prominent tertiary eye institutions that are also national academic teaching institutions in Asia. Survey responses were collated and anonymized during analysis.

RESULTS

All surveyed institutions used povidone iodine for the preoperative antiseptic preparation of the eye, with notable variations in the concentration of povidone iodine used for conjunctival sac instillation. Preoperative topical antibiotics were prescribed by 61.5% and 69.2% of institutions in low-risk and high-risk cases, respectively. Regarding the use of intra-operative antibiotics, 60.0% and 66.7% of institutions administered intracameral antibiotics in low-risk and high-risk patients, respectively. Postoperative topical antibiotics use patterns were generally very similar in low-risk and high-risk patients. Over half of the institutions (52.2% and 68.0% in low-risk and high-risk patients, respectively) also indicated prolonged postoperative use of topical antibiotics (> 2 weeks). Not all surveyed institutions had established policies/protocols for perioperative antibiotic use in cataract surgery, endophthalmitis surveillance, and/or a monitoring program for emerging antimicrobial resistance.

CONCLUSION

There are variations in antimicrobial prophylaxis approaches to preoperative, intra-operative and postoperative regimens in cataract surgery in Asia. More evidence-based research is needed to support the development of detailed guidelines for perioperative antibiotic prophylaxis to reduce postoperative infections.

National emergency department trends for endogenous endophthalmitis: an increasing public health challenge

BACKGROUND/OBJECTIVE

To characterize incidence rates and identify risk factors for admission and mortality in patients with endogenous endophthalmitis (EE) in the United States (US).

SUBJECTS/METHODS

Patients with EE were identified using the Nationwide Emergency Department (NEDS) Database from 2006 to 2017 in this cross-sectional study. Subjects were required to have diagnoses of both endophthalmitis and septicaemia using contemporary International Classification of Diseases diagnosis codes. Incidence rates, mortality rates and demographics were evaluated. Risk factors for admission and mortality were identified using weighted logistic regression analysis.

RESULTS

A total of 6400 patients with EE were identified. Incidence increased from 0.10 (95% confidence interval [CI]: 0.07-0.12) per 100,000 in the US population in 2006 to 0.25 (95% CI: 0.21-0.30) in 2017 (p < 0.05). Most were female (55.4%), insured with Medicare (53.5%), were in the first income quartile earnings (29.3%) [bottom 25% income bracket], lived in the South (40.5%), and presented to metropolitan teaching hospitals (66.6%). Mortality increased from 8.6% (95% CI: 3.8-18.3%) in 2006 to 13.8% (95% CI: 9.7-19.2%) in 2017 (p = 0.94). Factors predicting admission included older age (odds ratio [OR] 32.59; [95% CI 2.95-359.78]) and intravenous drug use (OR 14.90 [95% CI: 1.67-133.16]). Factors associated with increased mortality included: human immunodeficiency virus infection/immune deficiencies (OR 2.58 [95% CI: 1.26-5.28]), heart failure (OR 2.12 [95% CI: 1.47-3.05]), and hepatic infections/cirrhosis (OR 1.89 [95% CI: 1.28-2.79]). Pneumonia and renal/urinary tract infections (UTI) were associated with both increased hospital admission [(pneumonia OR 9.64 (95% CI: 1.25-74.35, p = 0.030), renal/UTI OR 4.09 (95% CI: 1.77-9.48)] and mortality [(pneumonia OR 1.64 (95% CI: 1.17-2.29, p = 0.030), renal/UTI OR 1.87 (95% CI: 1.18-2.97)]. Patients with diabetes mellitus (DM) had decreased odds ratio for mortality (OR 0.49 [95% CI: 0.33-0.73]).

CONCLUSION

EE has increased in incidence throughout US. The two systemic factors that conferred both an increase in mortality and admission were pneumonia, and renal/UTI. Additional exploration of the potential protective association of DM with decreased mortality in this context is needed.

The Role of C-X-C Chemokines in Staphylococcus aureus Endophthalmitis

Purpose

To test the hypothesis that the C-X-C chemokines CXCL1, CXCL2, and CXCL10 contribute to inflammation during Staphylococcus aureus endophthalmitis.

Methods

S. aureus endophthalmitis was induced by intravitreal injection of 5000 colony forming units of S. aureus into the eyes of C57BL/6J, CXCL1-/-, CXCL2-/-, or CXCL10-/- mice. At 12, 24, and 36 hours postinfection, bacterial counts, intraocular inflammation, and retinal function were assessed. Based on these results, the effectiveness of intravitreal administration of anti-CXCL1 in reducing inflammation and improving retinal function was evaluated in S. aureus-infected C57BL/6J mice.

Results

We observed significant attenuation of inflammation and improvement in retinal function in CXCL1-/- mice relative to C57BL/6J at 12 hours but not at 24 or 36 hours postinfection with S. aureus. Co-administration of anti-CXCL1 antibodies with S. aureus, however, did not improve retinal function or reduce inflammation at 12 hours postinfection. In CXCL2-/- and CXCL10-/- mice, retinal function and intraocular inflammation were not significantly different from those of C57BL/6J mice at 12 and 24 hours postinfection. At 12, 24, or 36 hours, an absence of CXCL1, CXCL2, or CXCL10 did not alter intraocular S. aureus concentrations.

Conclusions

CXCL1 appears to contribute to the early host innate response to S. aureus endophthalmitis, but treatment with anti-CXCL1 did not effectively limit inflammation in this infection. CXCL2 and CXCL10 did not seem to play an integral role in inflammation during the early stages of S. aureus endophthalmitis.

Visual Outcomes and Prognostic Factors of Traumatic Endophthalmitis Treated by Pars Plana Vitrectomy: 11 Years Retrospective Analysis

Aim: To evaluate the visual outcome of traumatic endophthalmitis and describe the risk factors associated with poor visual acuity and retinal detachment (RD) development over an 11-year period. Methods: Medical records of 34 patients with traumatic endophthalmitis who underwent PPV over a period of 11 years (1 January 2010−31 December 2020) were reviewed. We extracted details regarding demographic data, initial and final best corrected visual acuity (BCVA) using a standard Snellen chart, wound and IOFB characteristics, ocular associated lesions, and treatment. The outcome was evaluated according to the final BCVA which was defined as poor < 0.1 or good ≥ 0.1 Results: Endophthalmitis rate was 29.8% in open globe injuries. The mean age was 43.6 ± 16.5 years and the majority of patients were males (32 out of 34, 94.1%). All patients received systemic (moxifloxacin) and intravitreal antibiotherapy. We performed pars plana vitrectomy (PPV) in all cases. Poor visual outcome was associated with wound size ≥ 3 mm (p = 0.02), the association of IOFB (p = 0.016), and the development of RD (p = 0.00). The presence of IOFB (p = 0.01) and wound size ≥ 3 mm (p = 0.01) were statistically associated with RD development. After treatment, 47.05% of patients achieved final BCVA ≥ 0.1. Conclusion: Wound size ≥ 3 mm, IOFB and RD were risk factors for poor visual outcomes in traumatic endophthalmitis.

Comparison of Endogenous Endophthalmitis in Patients with and Without COVID-19 Infection

INTRODUCTION

Endogenous endophthalmitis (EE) is an ophthalmic emergency that can have severe sight-threatening complications. Prompt diagnosis and aggressive treatment are central to the successful management of EE. In recent years, a significant increase has occurred in the number of cases of EE. Some of these individuals had a COVID-19 infection. The current study compared EE in patients with and without COVID-19 infection.

METHODS

All cases of EE admitted to Khalili Hospital between April 2020 and September 2021 were included in this prospective case-control study. Patients were divided into 2 groups: (i) the case group (EE patients with confirmed COVID-19 infection; n = 7) and (ii) the control group (EE patients without a history or evidence of COVID-19 infection; n = 7). Age, sex, presenting and final visual acuity, systemic diseases and risk factors for EE, anterior segment and fundus findings, hospitalization due to COVID-19, intensive care unit (ICU) admission, systemic steroid therapy, results of the sepsis workup, causative microorganism, types of treatment (pars plana vitrectomy vs. intravitreal or antifungal antibiotics), and follow-up period were recorded.

RESULTS

Twenty-four eyes of the 14 patients were included in this study, of which 9 were female. The mean age was 49.57 years. Follow-ups ranged from 1 month to 20 months (mean, 8 months). There were no statistically significant differences in age (P = 0.653), mean follow-up (P = 0.943), gender (P = 0.313), and clinical presentation (P = 0.409) between the case and control groups. Seven patients (50%) had positive intraocular culture results. Two out of 7 patients had a history of COVID-19 infection. The most common causative microorganism was Candida (4 patients [28.57%]; 6 eyes [25%]). No statistically significant differences were observed between the 2 groups in the need for vitrectomy (P = 1.000). The visual outcome between the 2 groups was similar (P = 0.179).

CONCLUSION

The COVID-19 infection does not seem to affect the severity, visual outcomes, improvement rate, or vitrectomy rate of EE. Early diagnosis and management, especially pars plana vitrectomy, can prevent serious complications and save many eyes.

Endophthalmitis: Ursachen, Erreger, Therapie und Visusverlauf mit Fokus auf Glaukompatienten

Hintergrund Endophthalmitiden stellen einen der schwerwiegendsten Notfälle in der Ophthalmologie dar. Um deren Prävalenz zu minimieren, ist eine möglichst genaue Kenntnis auslösender Faktoren von Bedeutung. Eine chirurgische Therapie mit gezielter, Erreger-spezifischer Medikation und ein intaktes Immunsystem sind die Basis für den Visuserhalt. Ferner stellt sich die Frage, ob anhand zugrundeliegender Erkrankungen am Auge ein ungünstiger Verlauf prognostiziert werden kann, sodass ein Vergleich zwischen Glaukom- (G) und Nicht-Glaukompatienten (NG) im Hinblick auf ursächliche Faktoren, Erreger, Therapie und Visusverlauf gezogen wurde. Da bei Glaukompatienten eine potentielle Alteration des lokalen Immunsystems diskutiert wird, ist von Interesse, ob sich die klinischen Verläufe einer Endophthalmitis von Nicht-Glaukompatienten unterscheiden. Patienten und Methoden Es handelt sich um eine retrospektive Analyse von 75 Augen (13 G, 62 NG), die in einem 5-Jahres-Zeitraum aufgrund einer Endophthalmitis an der Augenklinik des Universitätsklinikums Erlangen-Nürnberg behandelt wurden. Auszuwertende Parameter waren u.a. das klinische Bild, operative und medikamentöse Behandlungen, das mikrobielle Spektrum und der Visusverlauf bei Glaukom- sowie Nicht-Glaukompatienten. Ergebnisse Bei Erstvorstellung dominierte bei allen Patienten eine akute Visusverschlechterung (44%) mit Vorderkammerreiz (62,7%), Hypopyon (52%) und reduziertem (40%) oder fehlendem (26,7%) Funduseinblick. Vorangehende intraokulär-chirurgische Eingriffe wurden bei insgesamt 53,3% beobachtet, insbesondere Kataraktoperationen. In beiden Gruppen konnten gram-positive Kokken als häufigster Erreger identifiziert werden (G: 23,1%; NG: 38,7%), wohingegen seltene Keime nur bei Glaukompatienten vorkamen. Bei 76% aller Patienten wurde eine pars-plana-Vitrektomie durchgeführt, eine Enukleation bei 20%, letzteres signifikant häufiger bei Glaukompatienten (p=0,01). Postoperativ konnte eine signifikante Visusverbesserung bei Nicht-Glaukompatienten erzielt werden (p<0,001); im Direktvergleich stellte sich ein schlechteres visuelles Outcome bei glaukomatös vorerkrankten Augen dar. Schlussfolgerung Stellt die Endophthalmitis eine sehr seltene Erkrankung dar, ist eine frühzeitige Diagnosestellung und Behandlung dennoch für die Prognose entscheidend. In der vorliegenden Kohorte zeigt sich ein schlechterer Endvisus bei Glaukompatienten als bei Nicht-Glaukompatienten. Background Endophthalmitis is one of the most serious emergencies in ophthalmology. In order to lower their prevalence, the most accurate knowledge of potential risk factors is important. Surgical therapy with targeted, pathogen-specific medication and an intact immune system are fundamental to preserve visual acuity. Furthermore, the question arises whether an unfavorable course can be predicted on the basis of underlying diseases of the eye, therefore a comparison between glaucoma patients (G) and non-glaucoma patients (NG) with regard to causative factors, pathogens, therapy and visual acuity course was drawn. Since a potential alteration of the local immune system in glaucoma disease has been described, it is of interest whether the clinical courses of endophthalmitis differ from non-glaucoma patients. Patients and methods A retrospective analysis of 75 eyes (13 G, 62 NG) who underwent treatment and surgery due to the diagnosis of endophthalmitis in the Department of Ophthalmology, University of Erlangen-Nuremberg has been evaluated over a period of 5 years. Clinical characteristics, surgical treatment, microbial spectrum and visual acuity in glaucoma and non-glaucoma eyes were investigated. Results A drastic vision impairment (44%) with inflammation of the anterior chamber (62.7%), hypopyon (52%) and reduced (40%) or complete missing sight (26.7%) of the fundus were predominantly present at first diagnosis in all patients. A previous eye surgery was observed in a total of 53%, especially cataract surgery. Gram-positive cocci were seen as the most common causing agent in both groups, (G: 23.1%; NG: 38.7%), whereas other rare pathogens were present only in glaucoma eyes. Pars-plana-vitrectomy was performed in 76% and enucleations in 20% of all patients, the latter significantly increased in glaucomateous eyes (p=0.01). A significant postoperative improvement of visual acuity was yielded in non-glaucoma patients (p<0.001); visual acuity outcome was worsen in glaucoma eyes. Conclusion Despite its rareness, early diagnosis and treatment of endophthalmitis is crucial for prognosis. In the present cohort, a worse visual acuity outcome was yielded in glaucoma patients in comparison to non-glaucoma patients.

A Systematic Review of Multi-decade Antibiotic Resistance Data for Ocular Bacterial Pathogens in the United States

INTRODUCTION

Since 2009, the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) surveillance study has been assessing in vitro antibiotic resistance for bacterial isolates sourced from ocular infections in the US. The main goal of this systematic review was to compare in vitro resistance data for ocular pathogens from published US studies with the most recently published data from the ARMOR study (2009-2018) and, where possible, to evaluate trends in bacterial resistance over time over all studies.

METHODS

A literature search was conducted using MEDLINE®, BIOSIS Previews®, and EMBASE^® databases (1/1/1995-6/30/2021). Data were extracted from relevant studies and antibiotic susceptibility rates for common ocular pathogens (Staphylococcus aureus, coagulase-negative staphylococci [CoNS], Streptococcus pneumoniae, Pseudomonas aeruginosa, and Haemophilus influenzae), longitudinal changes in susceptibility, and multidrug resistance (MDR) were compared descriptively.

RESULTS

Thirty-two relevant studies were identified. High in vitro resistance was found among S. aureus and CoNS to fluoroquinolones, macrolides, and methicillin/oxacillin across studies, with high rates of MDR noted, specifically among methicillin-resistant staphylococci. Data from studies pre-dating or overlapping the early years of ARMOR reflected increasing rates of S. aureus resistance to fluoroquinolones, macrolides, methicillin/oxacillin, and aminoglycosides, while the ARMOR data suggested slight decreases in resistance to these classes between 2009 and 2018. Overall, methicillin-resistant S. aureus (MRSA) prevalence peaked from 2005 to 2015 with a possible decreasing trend in more recent years.

DISCUSSION AND CONCLUSIONS

Data from local and regional US datasets were generally consistent with data from the national ARMOR surveillance study. Continued surveillance of ocular bacterial pathogens is needed to track trends such as methicillin resistance and MDR prevalence and any new emerging antibiotic resistance phenotypes. Susceptibility data from ARMOR can inform initial choice of therapy, especially in practice areas where local antibiograms are unavailable.

Detection of Microorganisms in Body Fluids via MTT-PMS Assay

Early detection of microorganisms is essential for the management of infectious diseases. However, this is challenging, as traditional culture methods are labor-intensive and time-consuming. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-phenazine methosulfate (MTT-PMS) assay has been used to evaluate the metabolic activity in live cells and can thus be used for detecting living microorganisms. With the addition of NaOH and Tris-EDTA, the same approach can be accelerated (within 15 min) and used for the quick detection of common bacterial pathogens. The assay results can be evaluated colorimetrically or semi-quantitatively. Here, the quick detection by MTT-PMS assay was further investigated. The assay had a detection limit of approximately 104 CFU/mL. In clinical evaluations, we used the MTT-PMS assay to detect clinical samples and bacteriuria (>105 CFU/mL). The negative predictive value of the MTT-PMS assay for determining bacteriuria was 79.59% but was 100% when the interference of abnormal blood was excluded. Thus, the MTT-PMS assay might be a potential "rule-out" tool for bacterial detection in clinical samples, at a cost of approximately USD 1 per test. Owing to its low cost, rapid results, and easy-to-use characteristics, the MTT-PMS assay may be a potential tool for microorganism detection.

Retinal Detachment After Endophthalmitis: Risk Factors and Outcomes

Purpose

To analyze the risk factors, clinical course, and visual and anatomic outcomes of retinal detachment (RD) after endophthalmitis.

Patients and Methods

This retrospective study included 108 patients diagnosed with endophthalmitis between August 2014 and May 2019 at a single tertiary referral center. Sixteen patients developed RD after endophthalmitis. Retrospective analysis was performed to compare the cohort of endophthalmitis alone versus the cohort that developed RD after endophthalmitis, with analysis of potential risk factors for RD after endophthalmitis and treatment outcomes.

Results

The incidence of RD after endophthalmitis was 14.8% (N=16/108). The median time to develop RD after endophthalmitis was 27 days (range: 1-581 days, IQR: 25.3). Thirteen (81.3%) cases of RD occurred less than 2 months after the diagnosis of endophthalmitis. The incidence of aphakia (p=0.023) and posterior synechia (PS) (p=0.014) were significantly higher in the RD group. The mean initial and final visual acuity (VA) of the endophthalmitis alone group was 1.9±0.8 logMAR and 1.2±1.0 logMAR (p<0.0001), respectively, and 1.9±0.9 logMAR and 1.3±1.2 logMAR (p=0.07) in the RD group, respectively. Enucleation or evisceration occurred in 31.3% of cases with RD after endophthalmitis. The rate of final retinal re-apposition for the RD cohort was 56.3%.

Conclusion

The anatomic and functional outcomes for RD after endophthalmitis remain poor, with significant risk for permanent vision loss. Aphakia and posterior synechiae were seen more often in cases with RD after endophthalmitis.

Antimicrobial resistance of ocular microbes and the role of antimicrobial peptides

Isolation of antimicrobial-resistant microbes from ocular infections may be becoming more frequent. Infections caused by these microbes can be difficult to treat and lead to poor outcomes. However, new therapies are being developed which may help improve clinical outcomes. This review examines recent reports on the isolation of antibiotic-resistant microbes from ocular infections. In addition, an overview of the development of some new antibiotic therapies is given. The recent literature regarding antibiotic use and resistance, isolation of antibiotic-resistant microbes from ocular infections and the development of potential new antibiotics that can be used to treat these infections was reviewed. Ocular microbial infections are a global public health issue as they can result in vision loss which compromises quality of life. Approximately 70 per cent of ocular infections are caused by bacteria including Chlamydia trachomatis, Staphylococcus aureus, and Pseudomonas aeruginosa and fungi such as Candida albicans, Aspergillus spp. and Fusarium spp. Resistance to first-line antibiotics such as fluoroquinolones and azoles has increased, with resistance of S. aureus isolates from the USA to fluoroquinolones reaching 32 per cent of isolates and 35 per cent being methicillin-resistant (MRSA). Lower levels of MRSA (seven per cent) were isolated by an Australian study. Antimicrobial peptides, which are broad-spectrum alternatives to antibiotics, have been tested as possible new drugs. Several have shown promise in animal models of keratitis, especially treating P. aeruginosa, S. aureus or C. albicans infections. Reports of increasing resistance of ocular isolates to mainstay antibiotics are a concern, and there is evidence that for ocular surface disease this resistance translates into worse clinical outcomes. New antibiotics are being developed, but not by large pharmaceutical companies and mostly in university research laboratories and smaller biotech companies. Antimicrobial peptides show promise in treating keratitis.

BILATERAL ENDOGENOUS ENDOPHTHALMITIS FROM STREPTOCOCCUS PNEUMONIAE

PURPOSE

To report a case of bilateral endogenous endophthalmitis from Streptococcus pneumoniae with devastating sequelae.

METHODS

Interventional case report.

RESULTS

A 56-year-old man presented with acute bilateral blurred vision and floaters with fever and hemodynamic instability. Previously, he was diagnosed with acute otitis externa and reported manually extracting several of his own teeth. He underwent a vitreous tap and intravitreal antibiotic injections. Blood and vitreous cultures were positive for S. pneumoniae. The patient later developed life-threatening medical sequelae. His final visual acuity was no light perception in the right eye and 20/25 in the left eye.

CONCLUSION

Diagnosing endogenous endophthalmitis early is essential to initiating a systemic evaluation for potentially life-threatening medical conditions, including sepsis, endocarditis, and osteomyelitis. A high degree of suspicion, expeditious treatment, and interdisciplinary collaboration are essential to maximizing patient outcomes.

Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis

Intraocular bacterial infections are a danger to the vision. Researchers use animal models to investigate the host and bacterial factors and immune response pathways associated with infection to identify viable therapeutic targets and to test drugs to prevent blindness. The intravitreal injection technique is used to inject organisms, drugs, or other substances directly into the vitreous cavity in the posterior segment of the eye. Here, we demonstrated this injection technique to initiate infection in the mouse eye and the technique of quantifying intraocular bacteria. Bacillus cereus was grown in brain heart infusion liquid media for 18 hours and resuspended to a concentration 100 colony forming units (CFU)/0.5 µL. A C57BL/6J mouse was anesthetized using a combination of ketamine and xylazine. Using a picoliter microinjector and glass capillary needles, 0.5 µL of the Bacillus suspension was injected into the mid vitreous of the mouse eye. The contralateral control eye was either injected with sterile media (surgical control) or was not injected (absolute control). At 10 hours post infection, mice were euthanized, and eyes were harvested using sterile surgical tweezers and placed into a tube containing 400 µL sterile PBS and 1 mm sterile glass beads. For ELISAs or myeloperoxidase assays, proteinase inhibitor was added to the tubes. For RNA extraction, the appropriate lysis buffer was added. Eyes were homogenized in a tissue homogenizer for 1-2 minutes. Homogenates were serially diluted 10-fold in PBS and track diluted onto agar plates. The remainder of the homogenates were stored at -80 °C for additional assays. Plates were incubated for 24 hours and CFU per eye was quantified. These techniques result in reproducible infections in mouse eyes and facilitate quantitation of viable bacteria, the host immune response, and omics of host and bacterial gene expression.

Ophthalmology in Critical Care

Ophthalmic disease encountered in the intensive care unit (ICU) has a wide spectrum of prevalence and severity. Prolonged exposure of the cornea is common and preventable. Trauma, glaucoma, infection, vascular disease, and burns are among the potential causes of vision loss. Patients are predisposed to ocular complications by the ICU environment and critical illness itself. Critically ill patients require prioritization of life-sustaining interventions, and less emphasis is placed on ophthalmic disease, leading to missed opportunities for vision-saving intervention. It is therefore imperative for intensivists, nurses, and other providers to have an increased awareness and understanding of the broad range of ocular conditions potentially seen in the ICU.

Time to Presentation after Symptom Onset in Endophthalmitis: Clinical Features and Visual Outcomes

PURPOSE

To investigate the impact of time from symptom onset to presentation on the clinical course and outcomes of eyes with endophthalmitis.

DESIGN

Retrospective, longitudinal cohort study.

PARTICIPANTS

One hundred thirty-three eyes of 130 patients with endophthalmitis.

METHODS

Adults diagnosed with endophthalmitis at the Duke Eye Center from January 1, 2009, through January 1, 2018, were identified using the Duke Enterprise Data Unified Content Explorer. Patient demographics, time of symptom onset, presenting clinical features, management, and outcomes were recorded by retrospective review. Patients were divided into those seeking medical care either early (within 2 days) or later (delayed, i.e., 3 days or longer) with regard to symptom onset. Clinical features, management, and visual outcomes of eyes with early or delayed presentation were compared.

MAIN OUTCOME MEASURES

Mean corrected visual acuity (VA) at presentation and at 6 months.

RESULTS

In eyes with delayed presentation, VA was significantly worse on initial examination (delayed, 20/2941 vs. early, 20/1124; P = 0.009) and at 6 months (delayed, 20/547 vs. early, 20/173; P = 0.01). When controlling for time to presentation, VA before endophthalmitis was correlated significantly with VA at 6 months (Pearson r = 0.55; R² = 29%; P < 0.0001). Eyes with glaucoma drainage device-related endophthalmitis were more likely to have a delayed presentation (P = 0.03). Eyes with delayed presentation were more likely to have conjunctival injection on initial examination (delayed, 73% vs. early, 52%; P = 0.01). Visual acuity before endophthalmitis, pain, and patient-reported blurred vision were not associated with early or delayed presentation (P > 0.05).

CONCLUSIONS

Delayed presentation was associated with worse VA on initial examination and at 6 months in eyes with endophthalmitis. Presence of pain did not prompt earlier presentation. Visual acuity before endophthalmitis was associated with VA at 6 months, regardless of time to presentation. Further investigation may help to improve anticipatory guidelines for at-risk patients.

Glycolytic inhibitor 2-deoxyglucose suppresses inflammatory response in innate immune cells and experimental staphylococcal endophthalmitis

Previously, we have shown that Staphylococcus (S) aureus induces a glycolytic response in retinal residential (microglia) and infiltrated cells (neutrophils and macrophages) during endophthalmitis. In this study, we sought to investigate the physiological role of glycolysis in bacterial endophthalmitis using a glycolytic inhibitor, 2-deoxyglucose (2DG). Our data showed that 2DG treatment attenuated the inflammatory responses of mouse bone marrow-derived macrophages (BMDM) and neutrophils (BMDN) when challenged with either live or heat-killed S. aureus (HKSA). Among the inflammatory mediators, 2DG caused a significant reduction in levels of cytokines (TNF-α, IL-1β, IL-6) and chemokines (CXCL1 and CXCL2). Western blot analysis of 2DG treated cells showed downregulation of bacterial-induced MEK/ERK pathways. In vivo, intravitreal administration of 2DG both pre- and post-bacterial infection resulted in a significant reduction in intraocular inflammation in C57BL/6 mouse eyes and downregulation of ERK phosphorylation in retinal tissue. Collectively, our study demonstrates that 2DG attenuates inflammatory response in bacterial endophthalmitis and cultured innate immune cells via inhibition of ERK signaling. Thus glycolytic inhibitors in combination with antibiotics could mitigate inflammation-mediated tissue damage in ocular infections.

Clinical profile and outcome of endogenous endophthalmitis at a quaternary referral centre in south India

Purpose:

The purpose of this study is to evaluate the clinical profile, visual, anatomical and survival outcome of patients with endogenous endophthalmitis.

Methods:

Retrospective chart review of consecutive cases with endogenous endophthalmitis presenting from 2009-2016.

Results:

In our study, 41 eyes of 34 patients were included. Most common co-morbidity associated with endogenous endophthalmitis was Diabetes Mellitus (70.7%) and most common infective foci was UTI (73.2%). Among the culture positive cases, fungi and bacteria were evenly distributed, 76.93% were Gram positive bacteria and 23.07% were Gram negative. Fungal endogenous endophthalmitis was more commonly seen in immunosuppressed state (72.7%) and bilateral cases (66.7%). The mean presenting vision (log MAR) of patients who died during the study were poor compared to those who survived (P = 0.014) Poor mean visual acuity at presentation was associated with more death (P = 0.014). Eyes with poor presenting vision, fungal isolates, culture positivity and immune suppression had poor visual and survival outcome. Poor visual outcome was observed more frequently in eyes with Aspergillus infection (85.7%) compared to Candida (75%) and bacteria (58.3%). Evisceration was done for 5 out of 41 eyes (12.2%). Vitrectomy rate was 53.7% in our study, with 40% of them showing overall improvement in vision.

Conclusion:

Endogenous endophthalmitis is a sight threatening condition associated with high mortality particularly when caused by Aspergillus spp. in immunocompromised patients. Contrary to the prior published reports of endogenous endophthalmitis outside India, we found an equal distribution of fungal and bacterial organisms among our cases, with predominance of Aspergillus among fungal isolates and Gram-positive organism among bacteria. Fungal infections, especially with Aspergillus spp., resulted in poor visual and survival outcome.

The cereus matter of Bacillus endophthalmitis

Bacillus cereus (B. cereus) endophthalmitis is a devastating intraocular infection primarily associated with post-traumatic injuries. The majority of these infections result in substantial vision loss, if not loss of the eye itself, within 12-48 h. Multifactorial mechanisms that lead to the innate intraocular inflammatory response during this disease include the combination of robust bacterial replication, migration of the organism throughout the eye, and toxin production by the organism. Therefore, the window of therapeutic intervention in B. cereus endophthalmitis is quite narrow compared to that of other pathogens which cause this disease. Understanding the interaction of bacterial and host factors is critical in understanding the disease and formulating more rational therapeutics for salvaging vision. In this review, we will discuss clinical and research findings related to B. cereus endophthalmitis in terms of the organism's virulence and inflammogenic potential, and strategies for improving of current therapeutic regimens for this blinding disease.

Endogenous endophthalmitis and other ocular manifestations of injection drug use

PURPOSE OF REVIEW

The United States has experienced a dramatic rise in opioid and injection drug use over the past 2 decades. A public health emergency was declared in 2017 and subsequently, there have been several new reports on the rise of endogenous endophthalmitis specifically associated with injection drug use. The purpose of this review is to provide a current perspective of the ocular harms posed by injection drug use.

RECENT FINDINGS

The opioid epidemic has prompted several new studies from New England, one of the US regions most heavily affected, that examine the trends and characteristics of injection drug use-associated endogenous endophthalmitis. Patients may delay seeking care and may be infected with a variety of rare and atypical microbes, and as a result clinical appearance may vary widely. Injection drug use also leads to embolic phenomena such as talc retinopathy and septic emboli from endocarditis. HIV is highly associated with injection drug use and although HAART has drastically reduced the morbidity and mortality of HIV-associated infections, a variety of ocular disease may accompany an immunocompromised patient.

SUMMARY

Healthcare providers must remain vigilant in the recognition of injection drug use patients with vision loss and ocular inflammation to ensure prompt medical and/or surgical treatment.

Disarming Pore-Forming Toxins with Biomimetic Nanosponges in Intraocular Infections

Endophthalmitis is a blinding consequence of bacterial invasion of the interior of the eye. Because of increases in the numbers of ocular surgeries and intraocular injections, the incidence of endophthalmitis is steadily increasing. Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus are leading causes of infection following ocular procedures and trauma and are increasingly more difficult to treat due to multidrug resistance. Each of these pathogens produces pore-forming toxins that contribute to the pathogenesis of endophthalmitis. Treatment of these infections with antibiotics alone is insufficient to prevent damage to the retina and vision loss. Therefore, novel therapeutics are needed that include agents that neutralize bacterial pore-forming toxins. Here, we demonstrate that biomimetic nanosponges neutralize pore-forming toxins from these ocular pathogens and aid in preserving retinal function. Nanosponges may represent a new form of adjunct antitoxin therapy for serious potentially blinding intraocular infections.

Intraocular infections are prevalent after traumatic injuries or after common ocular surgeries. Infections cause inflammation that can damage the retina and architecture of the eye, often resulting in poor visual outcomes. Severe cases may result in blindness or require enucleation of the eye. Treatments for intraocular infections include intravitreal antibiotics and corticosteroids or surgical vitrectomy in serious cases. The increase in multidrug-resistant infections calls for novel treatment options. In the present study, a biomimetic erythrocyte-derived nanosponge was tested for the ability to neutralize pore-forming toxins from the most frequent Gram-positive bacterial causes of intraocular infections (Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus). Nanosponge pretreatment of supernatants reduced hemolytic activity in vitro. In a murine sterile endophthalmitis model, nanosponge pretreatment of injected supernatants resulted in greater retinal function and less ocular pathology compared to that in eyes injected with untreated supernatants from all pathogens except methicillin-resistant S. aureus. In a murine bacterial endophthalmitis model, treatment with gatifloxacin and gatifloxacin-nanosponges reduced intraocular bacterial burdens, except in the case of methicillin-sensitive S. aureus. For all pathogens, eyes in both treatment groups showed decreased ocular pathology and inflammation. Overall, reductions in retinal function loss afforded by gatifloxacin-nanosponge treatment were significant for E. faecalis, S. pneumoniae, and methicillin-resistant S. aureus but not for B. cereus and methicillin-sensitive S. aureus. These results suggest that clinical improvements in intraocular infections following nanosponge treatment were dependent on the complexity and types of toxins produced. Nanosponges might serve as an adjunctive therapy for the treatment of ocular infections.

IMPORTANCE Endophthalmitis is a blinding consequence of bacterial invasion of the interior of the eye. Because of increases in the numbers of ocular surgeries and intraocular injections, the incidence of endophthalmitis is steadily increasing. Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, and Bacillus cereus are leading causes of infection following ocular procedures and trauma and are increasingly more difficult to treat due to multidrug resistance. Each of these pathogens produces pore-forming toxins that contribute to the pathogenesis of endophthalmitis. Treatment of these infections with antibiotics alone is insufficient to prevent damage to the retina and vision loss. Therefore, novel therapeutics are needed that include agents that neutralize bacterial pore-forming toxins. Here, we demonstrate that biomimetic nanosponges neutralize pore-forming toxins from these ocular pathogens and aid in preserving retinal function. Nanosponges may represent a new form of adjunct antitoxin therapy for serious potentially blinding intraocular infections.

INTRAVITREAL THERAPY OF ENDOGENOUS ENDOPHTALMITIS DUE TO UROSEPSIS - A CASE REPORT

A case report of 58-year-old man with endogenous endophtalmitis due to urosepsis and bronchitis. Patient was hospitalized in Department of Internal Medicine another hospital. He was sent to consiliar examination to our Ophtalmology Department with worsening vision and pain in left eye one day after onset. The diagnose endogenous endophtalmitis was set. Visual aquity was a hand movement on the first visit. Intravitreal therapy was realized promptly that day, a combination of two antibiotic drugs (ceftazidim 2mg/ 0.1 ml a vankomycin 1 mg/ 0.1 ml) and antifungal agent (amfotericin B 10 &#956;g/ 0.1 ml). This therapy was applicated 3x totally, in two weeks. Humour from anterior chamber was taken during first intravitreal application and was negative. Blood culture was positive for staphylococcus aureus. Intravenous treatment with antibiotics (gentamycin 240 mg i.v. á 24hours a amoxicilin with clavulan acid 1.2 g i.v. á 8 hod) was set for two weeks then continued antibiotic (ciprofloxacin 500 mg á 12 hours) and antifungal therapy (itrakonazol 100 mg á 12 hod) per os two months. Visual aquity of the left eye was 20/100 after four weeks and 20/40 after two months. We would like to highlight advantage of multidisciplinary co-operation.

Endogenous endophthalmitis: diagnosis, management, and prognosis

Endogenous endophthalmitis is an ophthalmic emergency that can have severe sight-threatening complications. It is often a diagnostic challenge because it can manifest at any age and is associated with a number of underlying predisposing factors. Microorganisms associated with this condition vary along a broad spectrum. Depending upon the severity of the disease, both medical and surgical interventions may be employed. Due to rarity of the disease, there are no guidelines in literature for optimal management of these patients. In this review, treatment guidelines based on clinical data and microorganism profile have been proposed.

In Vivo Role of TLR2 and MyD88 Signaling in Eliciting Innate Immune Responses in Staphylococcal Endophthalmitis

PURPOSE

The purpose of this study was to investigate the protective mechanisms evoked by TLR2 and MyD88 signaling in bacterial endophthalmitis in vivo.

METHODS

Endophthalmitis was induced in wild-type (WT), TLR2(-/-), MyD88(-/-), and Cnlp(-/-) mice by intravitreal injections of a laboratory strain (RN6390) and two endophthalmitis isolates of Staphylococcus aureus. Disease progression was monitored by assessing corneal and vitreous haze, bacterial burden, and retinal tissue damage. Levels of inflammatory cytokines/chemokines were determined using quantitative RT-PCR (qRT-PCR) and ELISA. Flow cytometry was used to assess neutrophil infiltration. Cathelicidin-related antimicrobial peptide (CRAMP) expression was determined by immunostaining and dot blot.

RESULTS

Eyes infected with either laboratory or clinical isolates exhibited higher levels of inflammatory mediators at the early stages of infection (≤24 hours) in WT mice than in TLR2(-/-) or MyD88(-/-) mice. However, their levels surpassed that of WT mice at the later stages of infection (>48 hours), coinciding with increased bacterial burden and retinal damage. Both TLR2(-/-) and MyD88(-/-) retinas produced reduced levels of CRAMP, and its deficiency (Cnlp(-/-)) rendered the mice susceptible to increased bacterial burden and retinal tissue damage as early as 1 day post infection. Analyses of inflammatory mediators and neutrophil levels in WT versus Cnlp(-/-) mice showed a trend similar to that observed in TLR2 and MyD88 KO mice. Furthermore, we observed that even a 10-fold lower infective dose of S. aureus was sufficient to cause endophthalmitis in TLR2(-/-) and MyD88(-/-) mice.

CONCLUSIONS

TLR2 and MyD88 signaling plays an important role in protecting the retina from staphylococcal endophthalmitis by production of the antimicrobial peptide CRAMP.

Pediatric infectious endophthalmitis: a review

Infectious endophthalmitis is a rare but severe complication of septecemia, intraocular surgeries, or penetrating eye trauma. The etiology, prognosis, and management of pediatric endophthalmitis resulting from exogenous and endogenous infections are reviewed. Open-globe trauma and glaucoma surgery are the most frequent causes of endophthalmitis in children, whereas endogenous infection is the least common cause. Streptococcus and Staphylococcus species are common bacterial agents in both posttraumatic and postoperative pediatric endophthalmitis, whereas Candida albicans is a commonly reported organism in endogenous endophthalmitis. Additionally, Streptococcus pneumoniae and Haemophilus influenzae appear more likely as pathogens in children than in adults. The clinical manifestations and outcome usually correlate with the virulence of the infecting organism. The visual prognosis of endophthalmitis is generally poor.

Increased resistance to Staphylococcus aureus endophthalmitis in BALB/c mice: Fas ligand is required for resolution of inflammation but not for bacterial clearance

FasL was recently shown be required for bacterial clearance in C57BL/6 mice that express the FasL.1 allotype. The FasL.2 allotype is expressed in BALB/c mice and exhibits increased binding affinity to and increased cytotoxic activity against Fas(+) target cells. Therefore, we hypothesized that BALB/c mice would be more resistant to Staphylococcus aureus-induced endophthalmitis. To test this hypothesis, C57BL/6, BALB/c, and BALB(gld) mice received intravitreal injections of 2,500 CFU of S. aureus (RN6390). Clinical examinations, electroretinography (ERG), histology, and bacterial quantification were performed at 24, 48, 72, and 96 h postinjection. The myeloperoxidase (MPO) assay was used to quantitate neutrophil infiltration. At 96 h postinfection, 86% of C57BL/6 mice presented with complete destruction of the eye, compared to only 29% of BALB/c mice with complete destruction. To our surprise, in the absence of Fas ligand, BALB(gld) mice showed no difference in bacterial clearance compared to BALB/c mice. However, histology and ERG analysis revealed increased retinal damage and significant loss of retinal function. MPO analysis revealed equal numbers of neutrophils in BALB(gld) and BALB/c mice at 24 h postinfection. However, at 48 h, the neutrophil numbers remained significantly elevated in BALB(gld) mice, correlating with the increased retinal damage observed in BALB(gld) mice. We conclude that the increased resistance to S. aureus induced endophthalmitis in BALB/c mice is not dependent upon the FasL. However, in contrast to C57BL/6 mice, FasL is required for resolution of inflammation and protecting host tissue from nonspecific damage in BALB/c mice.

Neonatal endogenous endophthalmitis: a report of six cases

Endogenous endophthalmitis is a rare but potentially blinding complication of neonatal sepsis. Early diagnosis and aggressive treatment are essential to avoid vision loss. Therapeutic options include systemic and intravitreal antibiotics, as well as vitrectomy in selected cases. We report a series of 6 premature very low birth weight neonates who developed endogenous endophthalmitis in our NICU over the past 3 years. Endophthalmitis was part of early-onset sepsis in 2 newborns, both of whom died, and late-onset sepsis in 4 newborns, of which 1 infant died. None of the neonates had any history of previous trauma or intervention to the eye. Maternal screening for congenital infections, including HIV, was negative in all. Causative organisms included Klebsiella pneumoniae (2 cases), Pseudomonas aeruginosa (2 cases), Methicillin-resistant Staphylococcus aureus (1 case), and Candida albicans (1 case). All bacterial isolates showed resistance to first-line antibiotics. Of the 3 survivors, 2 infants had normal vision in the affected eye, and 1 developed phthisis bulbi after corneal perforation and required enucleation. This report draws attention to the emergence of endophthalmitis as a complication of neonatal sepsis in places where, although survival of very low birth weight newborns has increased significantly due to improved care, the burden of infection continues to be high. We emphasize the importance of daily examination of eyes as a part of routine clinical care in septic newborns for early diagnosis of endophthalmitis and prompt intervention in consultation with an ophthalmologist to optimize the outcome.

Daptomycin versus vancomycin in a methicillin-resistant Staphylococcus aureus endophthalmitis rabbit model: bactericidal effect, safety, and ocular pharmacokinetics

Staphylococcus aureus is a frequent cause of acute endophthalmitis, and infection with this virulent bacterium is often associated with a poor visual outcome. In this study, we investigated the bactericidal efficacy and the safety of intravitreal daptomycin (DAP), a lipopeptide antibiotic with broad-spectrum activity against Gram-positive bacteria, compared with those of intravitreal vancomycin (VAN) in a methicillin-resistant S. aureus endophthalmitis rabbit model. The pharmacokinetics and pharmacodynamics of daptomycin in the infected eyes were also studied. Rabbits were randomly divided into three treatment groups (n = 8) and one untreated group (n = 4), to compare the effect of single intravitreal injections of 0.2 mg and 1 mg of daptomycin (DAP 0.2 and DAP 1 groups, respectively) with that of 1 mg of intravitreal vancomycin (VAN 1 group). Vitreal aspirates were regularly collected and grading of ocular inflammation was regularly performed until euthanasia on day 7. In the DAP 0.2 group, 62.5% of the eyes were sterilized and the mean bacterial count presented a reduction of 1 log unit. In the DAP 1 and VAN 1 groups, the infection was eradicated (100% and 87.5% of eyes sterilized, respectively), with a 4-log-unit reduction of the mean bacterial count. The bactericidal efficacy in the DAP 1 group was not inferior to that in the VAN 1 group and was superior to that of the other regimens in limiting the ocular inflammation and preserving the architecture of the ocular structures (P < 0.05). The elimination half-life (t(1/2β)) of daptomycin was independent of the administered dose (38.8 ± 16.5 h and 40.9 ± 6.7 h, respectively, for the DAP 0.2 and DAP 1 groups) and was significantly longer than the t(1/2β) of vancomycin (20.5 ± 2.0 h for the VAN 1 group) (P < 0.05). This antibiotic could therefore be considered for the treatment of intraocular infections caused by Gram-positive bacteria.