Aqueous level abatement profiles of intracameral antibiotics: A comparative mathematical model of moxifloxacin, cefuroxime, and vancomycin with determination of relative efficacies

New Approaches to Overcoming Antimicrobial Resistance in Endophthalmitis

Endophthalmitis is a rare but vision-threatening infection characterized by marked inflammation of intraocular fluids and tissues, uncommonly seen following surgery and intravitreal injection. Antimicrobials are used worldwide in the prophylaxis and treatment of bacterial and fungal infections of the eye and are standard treatment in the preoperative and postoperative care of surgical patients. However, antimicrobials are reported to be overprescribed in many parts of the world, which contributes to antimicrobial resistance (AMR). AMR complicates the prophylaxis and treatment of endophthalmitis. This article examines the prevalence and mechanisms of AMR in ocular microorganisms, emphasizing the importance of understanding AMR patterns for tailored treatments. It also explores prophylaxis and management strategies for endophthalmitis, with a discussion on the use of intracameral antibiotic administration. The use of prophylactic intracameral antibiotics during cataract surgery is common in many parts of the world but is still controversial in some locations, especially in the US. Finally, it highlights the role of stewardship in ophthalmology and its benefits in the treatment of endophthalmitis.

Susceptibility of Ocular Surface Bacteria to Various Antibiotic Agents in a Romanian Ophthalmology Clinic

Periodic assessment of bacterial contamination is necessary as it allows proper guidance in cases of eye infections through the use of appropriate antibiotics. Due to the extensive use of antibiotic treatment, many strains of the microbiota that cause infections are resistant to the usual ophthalmic antibiotics. The present study provides an updated assessment of the susceptibility of Gram-positive and Gram-negative bacteria found on the ocular surface to the most commonly used antibiotic agents in patients undergoing cataract surgery. A total of 993 patients were included in the study with ages between 44 and 98 years old. Conjunctival cultures were collected 7 days before cataract surgery. The response of Gram-positive and Gram-negative bacteria to various antibiotic classes, such as glycopeptides, cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, phenicols, tetracyclines, rifamycins, macrolides and penicillins, was assessed. From the tested antibiotics, vancomycin had 97.8% efficacy on Gram-positive bacteria. In the cephalosporin category, we observed a high level of resistance of the cefuroxime for both Gram-positive and negative bacteria. Antibiotics that have more than 90% efficacy on Gram-positive bacteria are meropenem, imipenem, netilmicin, amikacin and rifampicin. On Gram-negative bacteria, we found 100% efficacy of all tested fluoroquinolones, i.e., aminoglycosides (except for tobramycin), doxycycline, azithromycin, clarithromycin and chloramphenicol. The current study illustrates patterns of increased resistance in certain bacteria present on the ocular surface to some of the commonly used antibiotics in ophthalmological clinical practice. One such revealing example is cefuroxime, which has been highly used as an intracameral antibiotic for the prevention of bacterial endophthalmitis after cataract surgery.

The impact of antibiotic prophylaxis with intracameral cefuroxime on postoperative infectious endophthalmitis rates in a high-volume cataract surgery center

Our purpose was to compare postoperative infectious endophthalmitis rates before and after the introduction of antibiotic prophylaxis via intracameral with cefuroxime (ATB-P IC) in a high-volume cataract surgery service. Retrospective cohort study considering patients who underwent cataract surgery at Ophthal Hospital Especializado, São Paulo, Brazil, from January/2011 to December/2019. Patients operated from 2013 to 2019 comprised the ATB-P IC group while those operated from 2011 to 2013 formed the control group without the ATB-P IC protocol. A total of 23,184 cataract surgeries were included, with 6,207 in the Control Group and 16,977 in the ATB-P Group. A significantly higher rate of endophthalmitis was observed in the control group (0.0967%) when compared to the ATB-P group (0.0177%) (p = 0.014). Surgeries performed with ATB-P showed 80% less chance of reported endophthalmitis (OR = 0.20; 95% CI 0.05-0.72; p = 0.014) than those without ATB-P. Of the six cases confirmed by culture in the control group, all tested positive for Pseudomonas aeroginosa and the only case confirmed by culture in the ATB-P group was positive for Staphylococcus epidermidis. Our findings strongly support the use of intracameral antibiotic prophylaxis with cefuroxime to reduce postoperative infectious endophthalmitis rates, and we recommend its incorporation into cataract surgery protocols.

ASCRS clinical advisory on intracameral moxifloxacin injection for infection prophylaxis

Moxifloxacin solution is frequently injected at the conclusion of cataract surgery for endophthalmitis prophylaxis. 2 different concentrations are most commonly available in the United States for intracameral (IC) use: 0.5% (5 mg/mL) and 0.1% (1 mg/mL). The recommended volume to be injected is different for the 2 concentrations, and incorrect dosing can increase the risk of toxic anterior segment syndrome or endophthalmitis. In addition, the U.S. Food and Drug Administration recently published an alert regarding potential adverse events associated with intraocular compounded moxifloxacin. This clinical advisory reviews the optimal dosing of IC moxifloxacin based on current evidence.

Relative efficacy of intracameral moxifloxacin injection methods

PURPOSE

To determine the amount of moxifloxacin remaining in the anterior chamber (AC), immediately after its injection using 3 current injection methods, assuming mixing and fluid exchange with the AC contents during injection of the drug, and to determine the most desirable injection method.

SETTING

Department of Ophthalmology and Vision Sciences and Institute of Biomedical Engineering, University of Toronto, Toronto, Canada.

DESIGN

Mathematical modeling.

METHODS

Mathematical modeling using first-order mixing methods were used to assess mixing.

RESULTS

The Kaiser method of injecting 0.5 mL × 100 μg/0.1 mL does not achieve the desired 500 μg level of moxifloxacin in the AC. The "straight from the bottle" method of injecting 0.1 mL × 500 μg/0.1 mL is fraught with potential error, yielding a relatively unreliable final amount in the AC. Injecting 0.5 to 0.6 mL × 150 μg/0.1 mL yields a result closest to the desired goal.

CONCLUSIONS

Based on the calculation, the most accurate of current methods to deliver 500 μg moxifloxacin intracamerally is the method of 150 μg/0.1 mL × 0.5 to 0.6 mL.

Evaluation of the effect of gentamicin in surgical perfusion solution on cataract postoperative endophthalmitis

Objective

To evaluate the effect of gentamicin in surgical perfusion solution on endophthalmitis incidence after cataract surgery.

Methods

A retrospective analysis of endophthalmitis incidence was conducted in two groups of patients who underwent cataract surgery, with (Group B) or without gentamicin (Group A) in the surgical perfusion solution. Endophthalmitis incidence, the isolated pathogenic bacteria strains and their antibiotic sensitivity, and the drug-resistant genotype of the pathogens were examined.

Results

The incidence of endophthalmitis in patients of group A was 0.8‰. Thirteen pathogenic bacterial strains were isolated from the patient samples in group A, including 8 strains of Staphylococcus epidermidis, 1 Staphylococcus aureus, 1 Streptococcus pneumoniae, 1 Streptococcus bovis, 1 Enterococcus faecium and 1 Morganella sp. The incidence of endophthalmitis in group B patients was 0.2‰, which was significantly lower than that in group A (P<0.05). Five strains of pathogenic bacteria were successfully isolated, including 2 strains of Enterococcus faecium, 1 Enterococcus faecalis, 1 Staphylococcus epidermidis and 1 Staphylococcus aureus. There was no significant difference in the proportion of Staphylococcus strains in all isolated bacteria between the two groups (P > 0.05). However, the proportion of Enterococci isolated in group B samples was higher than that in group A (P < 0.05). There were more gentamicin-sensitive strains than levofloxacin-sensitive strains identified (P < 0.05). Interestingly, aminoglycoside-inactivating enzyme resistance gene was detected in Enterococcus strains.

Conclusion

Our data suggest that gentamicin-containing perfusion solution can reduce the incidence of postoperative endophthalmitis in cataract patients. However, the selective pressure imposed by gentamicin may facilitate the development of aminoglycoside-resistant Enterococcos strains.

Acute postoperative endophthalmitis: Microbiology from the laboratory to the bedside

Postoperative endophthalmitis is a dreaded complication of intraocular surgery. Acute presentations need prompt management and good knowledge of differential diagnoses. In the last 10 years, progress in direct microbial detection and identification from intraocular samples included the use of blood culture systems and, more recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, improving the rate of bacterial identification. Whatever the method used, diagnostic sensitivity is better for vitreous samples than for aqueous humor samples. Besides, molecular biology techniques have further improved the identification rate of infectious agents in intraocular samples. They also provide faster results compared to culture-based techniques. Quantitative real-time PCR (qPCR) can also determine the bacterial load in intraocular samples. Several studies have shown that intraocular bacterial loads in endophthalmitis patients are usually high, which helps differentiating infection from contamination. The prognostic value of qPCR remains to be validated. Whole genome DNA sequencing technologies facilitate direct and sequencing of single DNA molecules. They have the potential to increase the rate of microbiological identification. Some antibiotic resistance markers (e.g., methicillin resistance in staphylococci and vancomycin resistance in enterococci) may be detected earlier using molecular techniques (usually real-time PCR tests). Early determination of the involved microorganism and their antibiotic resistances can help establishing an earlier therapeutic strategy.

Immediately sequential bilateral cataract surgery: an academic teaching center's experience

PURPOSE

To evaluate the safety and outcomes of immediately sequential bilateral cataract surgery (ISBCS) at a Canadian academic teaching center.

SETTING

Tertiary university teaching hospital of Laval University, Quebec City, Canada.

DESIGN

Retrospective cohort study.

METHODS

2003 consecutive patients (4006 eyes) who underwent ISBCS under topical anesthesia from January 2019 to December 2019 were included. All charts were retrospectively reviewed. Outcome measures included intraoperative and postoperative complications, postoperative uncorrected distance (UCVA) and pinhole (PHVA) visual acuities, and autorefraction measurements.

RESULTS

4006 eyes from 1218 (60.8%) female and 785 (39.2%) male patients with a mean age of 74 ± 8 years had a mean preoperative visual acuity of 0.503 logMAR (Snellen 20/63). The mean axial length was 23.53 ± 1.37 mm. Most eyes had monofocal intraocular lenses (IOLs) implanted (n = 3738, 93.3%) followed by toric (n = 226, 5.6%), multifocal (n = 25, 0.6%), and multifocal toric (n = 17, 0.4%) IOLs. Intraoperative complications included 14 (0.3%) posterior capsule ruptures with 5 (0.1%) requiring sulcus IOL placement, and 7 (0.2%) partial zonulysis, with 3 requiring capsular tension rings (0.07%). There were no cases of endophthalmitis or toxic anterior segment syndrome. Mean 5-week postoperative UCVA was 0.223 (Snellen 20/33), PHVA was 0.153 (Snellen 20/28) with a mean spherical equivalent of -0.21 diopters.

CONCLUSIONS

ISBCS performed following International Society of Bilateral Cataract Surgeons recommended guidelines is a safe procedure. This cohort of 4006 eyes had very few complications, with none attributable to the surgery being done bilaterally. The UCVA, PHVA, and refractive outcomes were good.

Impact of prophylactic intracameral moxifloxacin on post-cataract surgery endophthalmitis: data from a tertiary eye care facility in rural India

PURPOSE

To study the impact of prophylactic intracameral (IC) moxifloxacin on the incidence, clinical profile and outcomes in eyes developing post-cataract surgery endophthalmitis (PCE).

METHODS

This was a single-centre, retrospective, comparative, observational study in which all eyes with PCE between June 2013 and May 2014 without IC moxifloxacin prophylaxis (group A) and June 2015-May 2016 with IC moxifloxacin prophylaxis (group B) were analysed.

RESULTS

A total of 101,815 cataract surgeries were performed in group A and 112,967 in group B. PCE was diagnosed in 179 eyes (0.18%) in group A and 92 eyes (0.08%) in group B (p < 0.001). Greater reduction in risk of PCE was seen in subsidised patients compared to private. The presenting and final visual acuity was significantly better in group B (p < 0.05).

CONCLUSIONS

Prophylactic IC moxifloxacin reduced the incidence of PCE with maximum benefit being observed for the subsidised patients and also helped achieve a significantly better visual acuity following the resolution of endophthalmitis.

Toxic Anterior Segment Syndrome with Intracameral Moxifloxacin: Case Report and Review of the Literature

A case of severe anterior segment toxicity secondary to high-volume, undiluted intracameral moxifloxacin for endophthalmitis prophylaxis is reported. We examine the other reported cases of toxicity after intracameral moxifloxacin, as well as iris depigmentation and transillumination syndromes after oral and topical fluoroquinolone exposure. Additionally, we review the literature on safety, efficacy, and appropriate dosing of intracameral antibiotics with a focus on moxifloxacin.

Incremental effect of topical and oral moxifloxacin administration with surgical intracameral prophylaxis

OBJECTIVE

To determine how supplemental perioperative topical or oral moxifloxacin administration impacts anterior chamber (AC) antibiotic concentrations beyond those achieved by intracameral (IC) administration alone for postoperative endophthalmitis (POE) prophylaxis.

DESIGN

Mathematical modeling.

METHODS

The mathematical model developed by Arshinoff, Modabber, and Felfeli was adapted to calculate all reported data. A literature review of pharmacokinetic data for topical and oral moxifloxacin was used to inform the expansion of the model.

RESULTS

Our previously constructed IC model yields a dose of moxifloxacin in the AC sufficient to confer bactericidal coverage against the most common POE pathogen, methicillin-sensitive Staphylococcus aureus (MSSA), for ∼40 hours postoperatively. Topical 0.5% moxifloxacin eye drops alone, administered every 4 or 6 hours, achieve an AC concentration just above or at the mutant prevention concentration (MPC) for MSSA, respectively, whereas 8-hour dosing produces levels generally below the MPC. Combining topical moxifloxacin with IC increases the AC concentration above IC alone only after 20 or more hours and maintains the AC concentration at, or just below, the MPC for MSSA for as long as the drops are continued. Combined perioperative oral moxifloxacin with IC increases AC levels over IC alone only after 16 hours and maintains the AC concentration above the MPC for MSSA for an additional 5 hours, owing to the systemic reservoir.

CONCLUSIONS

The addition of topical or oral moxifloxacin supplemental to IC can extend the duration of bactericidal coverage for the most common, but not the most resistant POE-causing pathogens.

Commonly used intracameral antibiotics for endophthalmitis prophylaxis: A literature review

Endophthalmitis is a serious complication of cataract surgery that occurs in thousands of patients each year. To decrease the incidence of postoperative endophthalmitis, many surgeons inject intracameral antibiotics (cefuroxime, moxifloxacin, and vancomycin) routinely at the end of surgery. A large number of recently published retrospective studies and large database analyses have reported decreased endophthalmitis rates with routine antibiotic use, and the only prospective, multicenter, randomized trial performed by the European Society of Cataract and Refractive Surgery demonstrated that intracameral cefuroxime decreases the incidence of postoperative endophthalmitis. Routine cefuroxime use has become common in many European countries, whereas moxifloxacin is the most commonly used drug in India, and vancomycin use predominates in Australia. The decision regarding whether or not to use intracameral prophylaxis and the drug that is selected varies considerably throughout the world because of antibiotic availability and cost, and the spectrum of causative organisms. Adverse events due to intracameral antibiotics are infrequent, but complications such as hemorrhagic occlusive retinal vasculitis have been reported. Because additional prospective, comparative trials have not been performed, a consensus regarding best practices to prevent postoperative endophthalmitis has not been reached. Additionally, many surgeons do not routinely use intracameral antibiotics because they believe them unnecessary with modern aseptic techniques, small incision surgery, and shorter operating times. We discuss the most commonly used intracameral antibiotics, present the risks and potential benefits of this approach, and highlight challenges with drug compounding and safety.