Microbial keratitis associated with contaminated ocular medications

Evaluating and Managing the Microbial Contamination of Eye Drops: A Two-Phase Hospital-Based Study

The microbial contamination of eye drop tips and caps varies between 7.7% and 100%. In seeking patient protection and continuous improvement, the Pharmacy Department in the Sterile Ophthalmological and Oncological Preparations Unit at Cochin Hospital AP-HP, Paris, France, conducted a two-phase study to compare the antimicrobial efficiency and practical use of standard packaging and a marketed eye drop container incorporating a self-decontaminating antimicrobial green technology by Pylote SAS at the tip and cap sites. The first phase was conducted in situ to identify the microbial contaminants of eye drops used in the hospital and community settings. A total of 110 eye drops were included for testing. Staphylococcus species were the most prevalent bacteria. Candida parapsilosis was detected in only one residual content sample and, at the same time, on the cap and tip. The second phase was performed in vitro, according to JIS Z2801. Reductions above one log in Staphylococcus aureus and Pseudomonas aeruginosa counts were noted in Pylote SAS eye drop packaging after 24 h of contact. The practical tests showed satisfactory results. Pylote SAS antimicrobial mineral oxide technology exhibited promising effects that combined effectiveness, safety, and sustainability to protect the patient by preventing infections due to the contamination of eye drop containers.

Multiple use of preservative-free single dose unit dexamethasone 0.1% eye drops is safe within 24 hours

BACKGROUND

Unpreserved single-dose unit (SDU) eye drops are commonly used to avoid benzalkonium chloride-related toxicity. Although intended for single use, many patients report off-label repeated use of SDUs over a prolonged period. We investigated whether repeated use of dexamethasone 0.1% SDUs in the same patient increases the bacterial contamination rate.

METHODS

We prospectively enrolled patients scheduled for inpatient corneal and glaucoma surgery receiving dexamethasone 0.1% SDU four times per day from the same vial. To assess contamination rates, one drop from the vial was cultured immediately after opening the SDU (t0), 10 hours later after four drop applications (t10) and 24 hours after opening without further drop applications (t24). Conjunctival swabs were taken before and after drop application. Contamination rate was assessed with a standard clinical culturing protocol without introducing a positive control.

RESULTS

110 eyes of 109 patients were evaluated. Drops collected immediately after opening the SDU (t0) were contaminated in 9/110 cultures (8.1%). At t10, 13/110 cultures were contaminated (11.8%; p=0.267) and 11/110 at t24 (10.0%; t24 vs t0; p=1.00). In 5 of 21 cases of contaminated drops at t10 and/or t24, the same isolates were cultured from the initial conjunctival swab and the SDU. In three cases, the same bacterial species was found in consecutive samples.

CONCLUSION

The contamination rate of the SDU did not increase after multiple use within 24 hours. Contamination from fingertip flora was more likely than from ocular surface flora. Reuse of dexamethasone 0.1% SDU in the same patient within 24 hours appears to be safe.

Terahertz Attenuated Total Reflection Spectral Response and Signal Enhancement via Plasmonic Enhanced Sensor for Eye Drop Detection

With chronic ocular diseases such as glaucoma and dry eye syndrome, patients have to apply eye drops over the long term. The therapeutic effects of eye drops depend on the amount of drug contained and the stability of the solution. In addition, contamination during usage and transport can also negatively affect the quality and efficacy of eye drops. The current techniques for the characterization of eye drops are often complicated and time-consuming. Developing a fast and non-invasive way of accurately measuring eye drop quality remains an ongoing challenge. The biggest challenge and primary prerequisite for the application of this new detection technique for eye drops is the obtention of a sufficient spectral response and resolvable signal, considering the large background signal contributed by water. In this work, we use terahertz (THz) attenuated total reflection (ATR) spectroscopy combined with a sensitive hybrid graphene oxide (GO) and carbon nanotube (CNT) thin-film sensors to obtain distinct THz spectral signals in commercial eye drops. Various commercial eye drop products have been tested, and we show that they can be differentiated via their spectral signals. Our results provide a solid foundation for the future fine analysis of eye drops and the detection of their quality. Furthermore, THz spectroscopy combined with GO/CNT films has significant potential and advantages for the non-destructive characterization of aqueous pharmaceutical products.

Highlighting the Microbial Contamination of the Dropper Tip and Cap of In-Use Eye Drops, the Associated Contributory Factors, and the Risk of Infection: A Past-30-Years Literature Review

The sterility of eye drop content is a primary concern from manufacturing until opening, as well as during handling by end users, while microbial contamination of the dropper tip and cap are often disregarded. The contamination of these sites during drug administration represents a risk of microbial transmission and ocular infection. In this review, we aim to assess microbial contamination of the dropper tip and cap of in-use eye drops, the associated contributory factors, and the risk of infection. We conducted a literature search of the MEDLINE, PubMed, and Cochrane Central databases. A total of 31 out of 1503 studies were selected. All the studies conducted in different settings that documented microbiologically contaminated in-use eye drops were included. Our review showed that microbial contamination of the dropper tip and cap of in-use eye drops ranged from 7.7 to 100% of the total contaminated tested samples. Documented contributory factors were conflicting across the literature. Studies investigating the association between eye infection and microbial contamination of the dropper tip and cap were scarce. New technologies offer a promising potential for securing the long-term sterility of eye drop content, tips, and caps, which could benefit from more research and well-defined study protocols under real-life scenarios.

Microbial Contamination of Preservative-Free Artificial Tears Based on Instillation Techniques

Preservative-free artificial tears eliminate the side effects of preservatives but are prone to microbial contamination. This study evaluates the incidence of microbial contaminations in single-use vials of preservative-free 0.1% hyaluronate artificial tears. Based on what touched the vial tip during its first use, 60 unit-dose vials (0.5 mL) were divided into groups A (no touch, n = 20), B (fingertip, n = 20), and C (lid margin, n = 20). The vials were recapped after the first use, and the residual solution was cultured 24 h later. The solution from 20 aseptically opened and unused vials was also cultured (group D). Microbial contamination rates were compared between the groups using the Fisher’s exact test. Groups B and C contained 45% (9/20) and 10% (2/20) contaminations while groups A and D contained undetected microbial growth. The culture positivity rates were significantly different between groups A and B (p = 0.001) and groups B and C (p = 0.013) but not between groups A and C (p = 0.487). We demonstrate a significantly higher risk of contamination when fingertips touch the vial mouth. Therefore, users should avoid the vial tip touching the fingers or eyelid during instillation to prevent contamination of the eye drops.

Contamination of multi dose eyedrops in the intra and perioperative context

In this study, we examined the rate of contamination of multi-dose ophthalmic solutions in the operating theatre and the underlying risk for infection by examining the microbiological load on the tips of the dispenser bottles. A total of 245 samples of eye drop bottles were collected and analysed between June 2018 and January 2019. All were collected in the operating theatre of the University Eye Hospital Hamburg-Eppendorf. Contamination of the dropper tip occurred in 2% of the samples. Although the prevalence of contamination was low, the results of this study reveal the possibility of contamination of multi-dose eyedrops even when used by health care professionals in the controlled environment of an operating theatre. Following these results, we recommend the use of single-dose eyedrops in the pre- and intraoperative context.

Bacteriostatic Effect of Multidose Preservative-free Buffered Saline Used in Scleral Lens Wear

SIGNIFICANCE

Scleral lenses have become an increasingly common treatment for ocular surface disease and irregular corneas. Multidose, preservative-free saline solutions are frequently used off-label to fill scleral lenses. Because the fluid resides over the ocular surface during lens wear, contaminated solutions may increase the risk of infectious complications.

PURPOSE

We sought to assess the viability of skin microorganisms and pathogens associated with keratitis once introduced into a multidose preservative-free saline (MDPFS) solution containing the bacteriostatic agent boric acid (PuriLens Plus; The Lifestyle Co., Inc., Freehold, NJ).

METHODS

Eleven bacterial and one yeast isolate were each inoculated to three lots of MDPFS as well as to sterile normal saline for comparison. Microorganism concentrations were enumerated at baseline and days 1, 3, 7, 14, 21, and 28. Persistence of microorganism viability was compared between MDPFS lots and between MDPFS and normal saline for each organism.

RESULTS

Duration of microorganism viability was ≥24 hours in MDPFS with no significant difference in the distribution of survival duration of microorganisms in MDPFS versus normal saline (P = .15). Candida albicans concentrations declined 14 days earlier in MDPFS, whereas concentrations of viable organisms in MDPFS remained within 1 log of baseline for the longest durations for Pseudomonas aeruginosa (7 days), Escherichia coli (14 days), and Achromobacter xylosoxidans (≥28 days). Gram-positive organism concentrations remained within 1 log of baseline for no more than 3 days. Mild lot-to-lot variation in organism concentrations was noted near the end points of viability. Bacteriostasis was demonstrated in that concentrations of all organisms remained at or below baseline levels throughout the 28-day period.

CONCLUSIONS

After microbial contamination, persistence of organism viability was similar in PuriLens and normal saline. Environmental gram-negative organisms, many of which can contribute to infectious keratitis, can persist for weeks once introduced into saline solutions.

Microbial Cross-contamination in Multidose Eyedrops: The Impact of Instillation Angle and Bottle Geometry

Purpose

To evaluate the impact of instillation angle and nozzle tip geometry on cross-contamination risk of multidose ocular solution bottles.

Methods

Pseudomonas aeruginosa solution was passed exclusively on the outside of the nozzle to simulate contamination on the exterior of topical agents. Three drops were administered from angles of 90° and 45° from bottles with either a round or sharp tip geometry, and the cultures were examined for growth. Two-hundred sixteen cultures from nine lubricant eyedrop brands currently existing in the Brazilian market were assessed for bacterial growth.

Results

After seven days, bacterial contamination was detected in 53.7% of cultures when drops were administered at 90° and in 70.4% of cultures at 45°. Eyedrops collected from a rounded nozzle tip and an instillation angle of 90° transmitted bacteria in 69.4% of cases, whereas those administered from a sharp tip transmitted bacteria in only 22.2% of cases (P = 0.001). At an instillation angle of 45°, contamination was identified in 83.3% of bottles with a rounded tip geometry and in only eight of 18 bottles (44.4%) from those with a sharp nozzle geometry (P = 0.005).

Conclusions

Adjusting the instillation angle of eyedrop solutions to 90°, as well as using a nozzle geometry that prevents flow of the solution to the side of the bottle, significantly reduced contamination rates.

Translational Relevance

Standardizing drop bottles and adjusting delivery angle shows promise in reducing contamination rates and may critically impact the quality of care for patients requiring topical therapeutic agents.

Clinical Evaluation of a Novel Electromechanical Topical Ocular Drug Delivery System: Two Phase 1 Proof of Concept Studies

PURPOSE

Self-administration of topical ophthalmic therapies remains challenging for many patients as errors due to improper technique are common. The aim of the current studies was to evaluate a novel electromechanical topical ocular drug delivery device designed to facilitate precise dosing and accurate delivery with substantially lower drug exposure than conventional eye drops.

PATIENTS AND METHODS

Two randomized Phase 1 studies were performed to evaluate the efficacy and safety of a single dose of a topical ophthalmic solution administered as a ~9 μL microfluid stream via the test device compared with a ~30-40 μL drop delivered via conventional dropper in healthy subjects (Trial 1) and glaucoma patients (Trial 2). In Trial 1, a 1% tropicamide/2.5% phenylephrine solution was administered via the test device in one eye and by conventional dropper in the contralateral eye. Pupil dilation was measured at 30 min intervals post-instillation and subject comfort was assessed using a visual analogue scale (range, 0-100). In Trial 2, patients were randomized to receive latanoprost 0.005% via the test device or conventional dropper. Intraocular pressure was measured at baseline and 4-8 hrs post-instillation.

RESULTS

In Trial 1 (N=20), mean (SD) pupil diameter 30 mins post-instillation increased by 3.4 (0.9) and 3.5 (1.0) mm in the test and control eyes, respectively. The mean comfort score was 81.7 for the test device versus 57.3 for conventional dropper delivery. In Trial 2 (N=18), the mean change in intraocular pressure following administration of latanoprost was -5.0 (1.8) and -4.3 (3.3) mm Hg in the test and control groups, respectively. No serious adverse events were observed in either study.

CONCLUSION

Administration of a single dose of topical ophthalmic therapy via an electromechanical drug delivery device resulted in comparable effects on pupil dilation and intraocular pressure with lower drug exposure and increased patient comfort compared with conventional dropper delivery.

Eye drop technique and patient-reported problems in a real-world population of eye drop users

OBJECTIVE

To assess eye drop technique and patient-reported problems with eye drop instillation in a primary care sample of eye drop users.

METHODS

Cross-sectional observational study in 136 community pharmacies in Belgium. Patient inclusion criteria were being age ≥ 18 years and using eye drops for ≥ 1 month (to ensure that patients were already familiar with eye drop instillation). Participants demonstrated their eye drop technique and completed a self-administered questionnaire.

RESULTS

Participants (n = 678) had a mean age of 68.9 ± 12.4 years. During the demonstration, almost everyone (98.0%) successfully instilled at least one drop in the eye, although 14% required multiple attempts to achieve this. Only 3% of the sample exhibited perfect drop technique, meaning that they performed correctly all the steps. Most common deviations were touching the bottle to the eye or eyelid (40.7% of patients), and failing to close the eye (67.8%) and perform nasolacrimal occlusion for at least 1 min (94.7%) after drop instillation. Importantly, we found that 20% of ophthalmic suspensions were not shaken before use. Forty percent of patients reported ≥ 1 problem with eye drop instillation. Most common problems were difficulties with getting a drop in the eye (18.3% of patients), too many drops coming out of the bottle (14.6%), and difficulty squeezing the bottle (12.2%). About half of the sample recalled having had education in eye drop instillation technique.

CONCLUSION

This study showed suboptimal eye drop technique in real-world clinical practice. A proactive role of community pharmacists in detecting and resolving these problems could be helpful.

Improving eye-drop administration skills of patients - A multicenter parallel-group cluster-randomized controlled trial

Background

Eye-drop administration errors occur in the majority of patients and increase the risk for treatment failure or systemic adverse events. While lacking knowledge is the principal error cause, most patients overestimate their skills and are unaware of often substantial knowledge gaps. Therefore, the impact of including motivational patient education on long-term eye-drop administration skills of patients was investigated.

Methods

This is a cluster-randomized controlled trial in German community pharmacies. Patient education in both groups comprised observation of the patient during eye-drop administration to identify individual errors, pharmaceutical counseling, and teach-back evaluation of the training. In the intervention group, motivational communication techniques were included to increase error awareness and readiness for patient education. In addition, intervention patients were trained on repeated errors until administration was performed correctly. In contrast, patients in the control group only received feedback on erroneous administration steps without another assessment and reinforced training.

Results

In total, 152 adult patients were eligible to the study and 91 patients (intervention group N = 46) agreed to participate in a 1-month, 6-month, and 12-month follow-up. Patient education significantly increased the proportion of patients correctly administering eye-drops from 6% (7 out of 56 intervention patients, 1 out of 82 control patients) at baseline to 35% (12 out of 30 intervention patients, 12 out of 39 control patients, p ≤ 0.001) at the 1-month follow-up, and 64% (11 out of 15 intervention patients, 17 out of 29 control patients, p ≤ 0.001) at the 6-month follow-up irrespective of group allocation. In some patients previously resolved errors recurred during follow-up visits. This emphasizes the need for periodical reevaluation of patient administration skills and the provision of prevention strategies besides education.

Conclusion

Patient education that included demonstration of administration skills and verbal and written counseling on observed errors improved eye-drop administration skills irrespective of the communication technique applied. Whereof, high drop-out rates limited the power to detect a difference between groups. In particular, periodic demonstration of administration skills seemed important for sustainable improvement of administration skills. However, further error prevention strategies such as additional education materials or support by a caregiver may be necessary in some patients.

Microbial contamination of multiple-use bottles of fluorescein ophthalmic solution

BACKGROUND

The contamination of ophthalmic solutions in ophthalmic practices remains an important cause of a myriad of secondary eye infections and a source of aggravation of ocular disorders such as corneal ulcers and keratitis. The aim of this study was to investigate the possible microbial contamination of fluorescein sodium dye solutions used in eye clinics in Ghana.

METHODS

Fluorescein sodium solutions were collected from various eye clinics in Ghana. Twenty-one samples of multiple-use fluorescein ophthalmic solutions were collected from various regions in Ghana. Eighteen unopened bottles yet to be used were also collected to serve as controls from the same facilities. The solutions were inoculated in different culture plates (blood agar, MacConkey agar, Sabouraud dextrose agar and plate count agar). The resulting microbial growth was identified using standard microbial identification techniques. Susceptibility tests were performed to ascertain the clinical importance of the organisms identified.

RESULTS

Positive cultures were recorded for all 21 multiple-use bottles (in-use) collected, but there were no positive cultures for the unopened bottles (yet to be used). Six different genera of bacteria were identified from fluorescein solutions, including resistant strains of Staphylococci spp., Bacillus spp., Klebsiella spp., Pseudomonas spp., Haemophilus spp. and Bordetella spp. Pseudomonas spp. were the most common bacterial contaminants. For fungi contaminations, Aspergillus spp., Penicillium spp. and Cladosporium spp. were isolated. The most common fungal contaminants were Aspergillus spp.

CONCLUSIONS

Multiple-use bottles of fluorescein solution used in eye clinics in Ghana were contaminated with clinically important strains of bacteria and fungi.

Factors affecting eye drop instillation in glaucoma patients with visual field defect

Background

To investigate the success rate of eye drop instillation in glaucoma patients with visual field defect as well as non-glaucoma volunteers. Factors that may affect the success rate of eye drop instillation were also evaluated.

Design

A prospective, observational study.

Participants

Seventy-eight glaucoma patients and 85 non-glaucoma volunteers were recruited in this study.

Methods

Open angle glaucoma patients with visual field defect as well as non-glaucoma volunteers were asked to video record their procedures of eye drop instillation using a 5-mL plastic bottle of artificial tear solution. Success of eye drop instillation was judged on video based on the first one drop of solution successfully applied on the cornea, by two investigators.

Main outcome measures

Success rate of eye drop instillation in glaucoma patients and non-glaucoma volunteers. Factors related to success rate of eye drop instillation, such as visual field defect and clinical characteristics, were also analyzed using multivariable logistic regression.

Results

No significant deference in mean age was observed between two groups (glaucoma: 64.5 ± 14.4 years, non-glaucoma: 60.9 ± 14.1 years, P = 0.1156). Success rate of eye drop instillation was significantly lower (P = 0.0215) in glaucoma patients (30/78; 38.5%) than in non-glaucoma volunteers (48/85; 56.5%). The most frequent reason of instillation failure in glaucoma patients was touching the bulbar conjunctiva, cornea, eyelid or eyelashes with the tip of the bottle (29.5%). Multivariable logistic regression analysis identified lower corrected visual acuity (VA) (≤ 1.0; odds ratio [OR] = 0.20, 95% confidence interval [CI] 0.04–0.93, P = 0.0411), lower mean deviation (MD) (< -12 dB; OR = 0.20, 95% CI 0.05–0.86, P = 0.0307) and visual field defect (VFD) in the inferior hemifield (OR = 0.11, 95% CI 0.02–0.34, P < 0.001) to be significantly related to instillation failure in glaucoma patients.

Conclusions

Success rate of eye drop instillation was significantly lower in glaucoma patients than in non-glaucoma volunteers. Corrected VA ≤ 1.0, MD < -12 dB and/or VFD in the inferior hemifield may be related to failure of eye drop instillation.

Bacterial Contamination of Multi-dose Eye Drops at Ophthalmology Department, University of Gondar, Northwest Ethiopia

PURPOSE:

Ophthalmic solutions used for both diagnostic and therapeutic purposes were found to be contaminated with bacteria pathogens and caused serious ocular infections such as keratitis and endophthalmitis. The objective was to assess the magnitude and pattern of bacterial contamination of multi-dose ophthalmic medications and investigate the drug susceptibility pattern of the isolates in the Department of Ophthalmology at Gondar University Teaching Hospital.

METHODS:

A total of 100 ophthalmic medications in-use by patients and eye-care workers have been taken and cultured for potential bacterial contamination in the Microbiology Department after 1 week and >1 week of use. The dropper tip and the residual eye medications were examined for contamination. The contaminating bacteria were identified using a standard procedure and drug susceptibility testing to selected antimicrobial agents was done.

RESULTS:

Eleven ophthalmic medications were contaminated by different bacterial species with a prevalence of 11%. Multi-use and longer duration of use of eye medications were associated with higher rate of contamination. The contamination level ranges from 0% for antibiotics, 20% for local anesthetics, and 40% for povidone iodine. Among bacteria identified, Staphylococcus aureus and coagulase-negative Staphylococcus species were resistant to methicillin while others were sensitive to the antibiotics tested.

CONCLUSION:

The prevalence of contamination was low, but methicillin-resistant Staphylococcus was a potential risk. It is recommended that the Department of Ophthalmology should design set of rules about duration of use and safe handling of ophthalmic medications by the staff and patients.

An upright eyedrop bottle: accuracy, usage of excess drops, and contamination compared to a conventional bottle

Purpose

This study tested the feasibility of using an upright eyedrop bottle (UEB), a device designed to assist patients with eyedrop placement without reclining their head.

Patients and methods

Experienced eyedrop users were enrolled who answered “yes” to the question, “Do you ever have trouble getting your eyedrops in?” After being shown a multimedia presentation and answering a questionnaire regarding eyedrop usage, participants were observed instilling eyedrops. Participants were instructed to instill a single eyedrop in each eye with both a standard bottle and the UEB. They repeated this process three times. With each trial, the amount of time taken to instill drops was recorded, as well as whether a drop landed in the eye (accuracy), if excess drops were used, and if the bottle tip was contaminated.

Results

Forty participants were enrolled, with an average age of 72.4±8.9 years; the majority were females (24 females). Thirty-four participants had been using eyedrops for at least 1 year. The time required to instill eyedrops was significantly less with the UEB in the second and third trials. There was no difference in accuracy between the conventional bottle and the UEB in the left or right eye in any trials. Significantly more participants used excess number of drops while using the conventional bottle in both the left and right eyes in all three trials. The bottle tip was never contaminated with the UEB. Depending on the trial and the eye, the conventional bottle was contaminated by between 42% and 53% of participants.

Conclusion

The UEB has the potential to assist patients with eyedrop placement. Although there was no difference in accuracy between the UEB and the conventional bottle, the UEB was associated with less use of excess drops and less contamination of the bottle tip, compared to the conventional bottle.

Potency and Sterility of Fortified Tobramycin, Fortified Vancomycin, and Moxifloxacin at 4, 24, and 35°C for 14 Days

PURPOSE

To assess the potency and sterility of ophthalmic antibiotic drops commonly used in the treatment of bacterial keratitis.

METHODS

This was a basic investigation. Three drugs were tested: fortified vancomycin 25 mg/mL, fortified tobramycin 14 mg/mL, and moxifloxacin 5 mg/mL. A bottle of each was stored separately at 4, 24, and 35°C, with the potency determined by microbiological assay at 0, 7, and 14 days. Differences in potency were assessed by 2-way analysis of variance followed by a 1-way repeated-measures analysis of variance with Bonferroni post hoc testing as warranted. Sterility of drugs when handled by patients for varying periods was confirmed by culturing samples on MacConkey and sheep blood agars.

RESULTS

The concentration of fortified tobramycin and moxifloxacin remained constant over 14 days at the 3 tested temperatures. The concentration of fortified vancomycin remained constant at 4°C, but it declined by 38% ± 1% (P = 0.001) at 24°C on day 14 and by 48% ± 1% (P = 0.001) and 78% ± 3% (P = 0.0009) at 35°C on days 7 and 14, respectively. A total of 49 drops (mean, 7.3 days; range, 1-18 days) were tested for sterility, and all were negative for microbial contamination.

CONCLUSIONS

All 3 drugs remained potent at 4°C for up to 14 days. Fortified tobramycin and moxifloxacin also maintained potency for 14 days at 24 and 35°C. In contrast, fortified vancomycin lost its potency by day 14 at 24°C and by day 7 at 35°C. All in-use antibiotic drops tested were sterile. The results indicate that patients should be cautioned to store vancomycin under refrigerator or at least under cool conditions.

Microbial contamination of glaucoma eyedrops used by patients compared with ocular medications used in the hospital

The aim of this study was to compare the percentage of contamination of multiuse eyedrops applied by glaucoma patients at home and by the medical personnel at the outpatient department, the ward, and the operating room of our Department of Ophthalmology. Eyedrops were collected over a period of 11 months. Samples were taken from the dropper tip (smear), drops, and the residual fluid inside the bottle and cultivated on blood agar. Colony forming units were counted and identified by mass spectrometry. The percentage of contamination was significantly higher in eyedrops applied by the patients (29/119; 24.4%, P < 0.01), used in the ward (26/133; 19.5%, P < 0.01), and in the outpatient unit (6/35; 17.1%, P = 0.036) compared with that in the operating room (6/113; 5.3%). The median period of use was 1 week in the operating room compared with 4 weeks in the other groups (P < 0.01). Glaucoma medications were significantly more frequently contaminated than antibiotic and anesthetic eyedrops (P < 0.05). For eyedrops applied by the patients, the tip was more frequently contaminated than the drops and the residual internal fluid. For eyedrops from the ward, the opposite was true. Pathogenic strains (Pseudomonas aeruginosa, Serratia marcescens, Acinetobacter lwoffii, Stenotrophomonas maltophilia, and Staphylococcus aureus) were found only in 6 bottles (1.5%), whereas most of the detected microbes belonged to human or environmental flora. This study underlines the importance of hygienic handling of eyedrops and raises the question of whether single-use glaucoma medication might be preferred to reduce the risk of contamination.

Balancing antimicrobial efficacy and toxicity of currently available topical ophthalmic preservatives

Medical treatment of ophthalmic diseases relies primarily on the use of multidose drugs. Short term use is highly effective usually with little local toxicity. However, chronic use of these preparations not only increases the likelihood of microbial contamination and secondary ocular infection, but also of toxicity from the drug formulation itself. Increasing awareness of the toxicity of ophthalmic preservatives has led to an increasing variety of preservative schemes ranging from "self-preservation" to ionic buffer systems. Beyond outdated testing methods, the anti-microbial efficacy of most of these systems is poorly defined, potentially placing these preparations at an unknown risk of contamination by unmonitored, untested organisms. No uniformity in toxicity testing exists which further complicates the clinician's judgment of the risk-benefit of using a particular drug formulation. In this manuscript we examine in detail each of the current employed ophthalmic preservative regimens with respect to their known antimicrobial activity and potential toxicity, where known. We also survey the most popular ophthalmic preparations, detailing their preservation schemes as well as concentrations to help the clinician in choosing an appropriate formulation for the treatment of various ophthalmic diseases.

Eye drop instillation technique in patients with glaucoma

AIMS

To evaluate the technique of eye drop instillation in patients with glaucoma and assess factors associated with a good technique.

METHODS

A cross-sectional observational study of 85 participants using self-administered topical medication for glaucoma or ocular hypertension. Patients were asked to demonstrate how they normally instil eye drops using a 5-ml bottle of sterile artificial tear solution. The procedure was recorded and assessed by two masked graders. Whether the patient had been previously shown how to instil drops, the number of eye medications used, and self-perceived difficulty of using drops were also recorded. Univariable logistic regression was performed to relate each variable to drop technique and variables with P<0.2 were included in a multivariable logistic regression analysis.

RESULTS

54.1% (46/85) of patients had a poor drop technique, 11.8% (10/85) missed the eye, 15.3% (13/85) touched the tip of the bottle to the bulbar conjunctiva or cornea, and 27.1% (23/85) touched the eyelid or lashes with the bottle tip. 81.2% (69/85) could not recall being shown how to instil eye drops. In the multivariable model, previous instruction regarding drop instillation technique was significantly associated with good technique (adjusted OR=8.17, 95% CI 2.02-33.05, P=0.003) and increasing age was associated with poor technique (adjusted OR=0.95, 95% CI 0.91-0.99, P=0.017).

CONCLUSIONS

Education relating to eye drop instillation technique is significantly associated with a patient's ability to instil drops correctly. The assessment of a patient's ability to instil eye drops correctly should be a routine part of the glaucoma examination.

Pseudomonas aeruginosa growth in Refresh Plus®

PURPOSE

To assess Pseudomonas aeruginosa growth in Refresh Plus(®), a unit-dose preservative-free ophthalmic solution indicated for the treatment of dry eye and after laser-assisted in situ keratomileusis (LASIK) surgery, which contains carboxymethylcellulose 0.5% as its active ingredient.

METHODS

Multiple test tubes of Refresh Plus were inoculated with 3 clinical ocular isolates of P. aeruginosa to achieve a target concentration of ∼100 colony-forming units (CFU)/mL. The tubes were incubated at 25°C and samples were aseptically removed at 6, 12, and 24 h. The samples were cultured to enumerate the population at each time point.

RESULTS

After 6 h incubation, the number of CFU/mL was 3,200 for isolate 1, 2,000 for isolate 2, and 6,480 CFU/mL for isolate 3. For all 3 organisms tested, the number of CFU/mL after 12 and 24 h incubation was >10(6) CFU/mL.

CONCLUSIONS

Under the conditions of this experiment, Refresh Plus appears to support P. aeruginosa growth, suggesting that if the solution in a unit-dose vial of Refresh Plus were contaminated with P. aeruginosa during use, the organism would survive and replicate in the solution over time. Noncompliance with the manufacturer's recommendations (i.e., reuse of an open vial) may result in contamination of the solution with P. aeruginosa, which may cause severe keratitis.

Bacterial contamination of ophthalmic solutions used in an extended care facility

AIM

To assess the frequency of contamination of ophthalmic solutions in a long-term care facility and to describe the characteristics of contaminated solutions.

METHODS

One hundred and twenty-three ophthalmic solutions used for patient treatment in a long-term care facility were cultured for bacteria. The culture results were analysed according to the therapeutic class of the solution, how long the bottle had been in use and the appearance of the bottle on visual inspection.

RESULTS

10 (8%) of the 123 multiple-dose solutions were contaminated with bacteria: 4 (50%) of 8 steroid-containing anti-inflammatory solutions, 2 (33%) of 6 combination antimicrobial and steroid-containing anti-inflammatory solutions, 2 (6%) of 34 solutions for treatment of glaucoma, and 2 (4%) of 57 medications for "dry eye". None of the mydriatic, miotic or non-combination antimicrobial solutions was contaminated. Proteus mirabilis was identified in 8 (80%) of the 10 contaminated solutions. Only 30% of the contaminated solution bottles were classified as "dirty" bottles when the bottles were visually inspected. Neither the length of time the solutions had been in use nor the appearance of the bottle predicted contamination.

CONCLUSIONS

8% of ophthalmic solutions used in a long-term care facility were contaminated with bacteria, most frequently Proteus mirabilis. Compared with solutions not containing steroids, steroid solutions were 5.8 times more likely to be contaminated (RR = 5.84, 95% CI: 2.42 to 14.10, p<0.002). The frequent contamination during reuse of certain steroid-containing ophthalmic solutions raises the question of whether single-use solutions might be preferred for these and other classes of ocular drugs.

Efficacy of Contact Lens Multipurpose Solutions Against Serratia Marcescens

PURPOSE

To compare the susceptibilities of clinical isolates of Serratia marcescens and the standard ISO ATCC 13880 strain to five contact lens multipurpose disinfection solutions (MPDSs).

METHODS

Five commercially available MPDSs, containing either a polymeric biguanide or polyquaternium, were tested using ISO/CD 14729 stand-alone test for contact lens care products against four ocular isolates of S. marcescens and the strain ATCC 13880. An average log reduction in bacterial numbers at the manufacturer's minimum recommended disinfection time was determined and compared with the criteria for stand-alone disinfection products for each MPDS against each bacterial strain.

RESULTS

All the MPDSs tested met the stand-alone criteria of 3-log reduction of viable bacteria against the ATCC strain of S. marcescens. However, there was more variability in their ability to meet disinfection criteria when tested against the clinical isolates. Two of the clinical isolates were significantly more resistant to disinfection than was the recommended ISO strain (p < or = 0.034). Two of the polyquaternium-1-based disinfection solutions (solutions D and E, p < or = 0.005) were less effective overall than the other MPDSs against S. marcescens.

CONCLUSIONS

The importance of strain selection for the testing of MPDSs is indicated, and the use of a single laboratory strain may be insufficient to provide assurance that the disinfection solution will be effective against clinical isolates. Furthermore, clinical isolates of S. marcescens may show increased resistance to disinfection with polyquaternium.

Assessment of bacterial contamination of three multidose ophthalmic solutions

OBJECTIVE

To investigate the frequency of bacterial contamination of multidose proparacaine hydrochloride, tropicamide, and eyewash bottles used in veterinary ophthalmology examination rooms during normal operating procedures.

METHODS

Three representative bottles each of proparacaine hydrochloride, tropicamide, and purified water eye wash were opened at the same time, numbered, and placed into small animal examination rooms. Doctors, students and technicians who were using the solutions were blinded to the study. Aerobic cultures were obtained at the time of opening (time 0), at 1 week (time 1), and at 2 weeks after opening (time 2) the bottles. The sites cultured included a drop of each solution, the inside of the bottle cap, the tip of the bottle, and the bottle threads and medication residue found in these threads.

RESULTS

Aerobic cultures of tropicamide and proparacaine had no growth of bacteria from any of the evaluated sites. Staphylococcus epidermidis was cultured from the tip of one bottle of eye wash after 1 week.

CONCLUSIONS

We conclude that proparacaine, tropicamide, and eyewash solutions used in veterinary examination rooms are adequately preserved for use in ophthalmic examination. They have a low level of bacterial contamination 1 or 2 weeks after opening when used and stored according to the recommendations of the product manufacturers and previous studies.

Comparative study of pH for different saline and multi-purpose contact lens solutions

In this study, we determined the pH of different saline and multipurpose contact lens solutions available on the Spanish market. We examined 10 samples of 14 solutions, seven of which are saline solutions and seven multipurpose ones, from different manufacturers. Both types of solution were found to have significant variations in pH, with values ranging from 6.70 to 7.57 for the saline solutions and 6.84 to 7.63 for the multipurpose solutions. We concluded that the solutions should not affect the ocular physiological performance because their pH values are within the buffering capacity of the eye.

In-use study of potential bacterial contamination of ophthalmic moxifloxacin

PURPOSE

To determine the contamination rate of topical moxifloxacin 0.5% (Vigamox) after clinical use for preoperative and postoperative prophylaxis for cataract surgery.

SETTING

Bascom Palmer Eye Institute, Miami, Florida, USA.

METHODS

A total of 61 bottles of moxifloxacin were collected in a 2-month time period after use preoperatively by patients (n = 21, mean 2.2 days), postoperatively by patients (n = 16, mean 7.2 days), or by nurses in the operating room (n = 24). For each bottle, cultures of the cap, tip, external thread, and solution were inoculated onto chocolate agar plates and incubated at 35 degrees for 7 days. A total of 13 bottles of benzalkonium chloride (BAC)-preserved gatifloxacin ophthalmic solution (Zymar) were also cultured in a similar manner for comparison.

RESULTS

No organisms were found by cultures of the cap, tip, or solution from any bottle in the study. One colony of coagulase-negative Staphylococcus was recovered from the thread of 1 Vigamox bottle. This bottle had negative cultures from its cap, tip, and solution.

CONCLUSIONS

The only contaminant found in this study was cultured from the bottle thread. This is a location with a high rate of skin contact and minimal solution contact. The remaining cultures from this bottle were negative, showing the solution's ability to self-preserve. These data demonstrate that BAC-free Vigamox can be treated no differently than BAC-preserved solutions by patients and medical staff, without concern for solution contamination.

Serratia Corneal Ulcers

PURPOSE

To study the clinical and microbiological profile of Serratia corneal ulcers at the Cornea Service of the Wills Eye Hospital.

METHODS

This was a retrospective, observational case series. The clinical records of patients with Serratia marcescens corneal ulcers seen at the Cornea Service of the Wills Eye Hospital between January 1, 1998 and December 31, 2002 were reviewed.

RESULTS

Twenty-four cases of Serratia keratitis were identified in 21 patients. Two patients (9.5%) had recurrent keratitis, 1 of which recurred twice. Both had corneal graft edema and were on topical steroids and antiglaucoma drops. The Serratia infection in 15 patients (71%) was associated with an abnormal corneal surface. Twelve of these patients (57%) had the ulcer in a corneal graft, 4 (19%) of which were associated with suture infiltrates. Fifteen patients (71%) were on topical medications-15 used corticosteroids and 13 used antiglaucoma drops. Six patients (29%) were contact lens wearers-1 had a concomitant suture infiltrate associated with a corneal graft, and 5 had otherwise healthy corneas. One isolate lacked in vitro susceptibility to ciprofloxacin and ofloxacin but was susceptible to gentamicin and tobramycin. Nineteen patients had a favorable response to medical therapy. Two patients with poor outcome had large corneal ulcers with severe necrosis and thinning associated with delay in treatment.

CONCLUSIONS

Serratia marcescens keratitis is associated with the presence of an abnormal corneal surface, use of topical medications, and contact lens wear. Prompt medical therapy results in a good clinical response in the majority of cases.

Sterility of glaucoma medications among chronic users in the community

PURPOSE

To evaluate the sterility of topical glaucoma medications among chronic glaucoma medication users in the community.

SETTING

Glaucoma service, Sanz Medical Center, Laniado Hospital, Netanya. Research mode: Cross-sectional laboratory and clinical study.

PATIENTS AND METHODS

Chronic glaucoma patients were asked to submit their topical glaucoma preparations to the microbiology laboratory at Laniado hospital. Samples taken from the interior of the bottle and the tip were cultured using MacConkey agar, blood agar, and chocolate agar plates.

RESULTS

Sixty-two bottles of topical glaucoma medications used by 27 patients were tested. Bacterial growth was detected in eight (12.9%) preparations, three of which revealed Pseudomonas aeruginosa, three Staphylococcus epidermidis, one Streptococcus viridans, and one Klebsiella. During the study, acute conjunctivitis was found in one patient, possibly due to the use of infected drops. In another case, two identical medications, which had been used simultaneously for more than 6 weeks by the same patient, were found to be infected.

CONCLUSIONS

Glaucoma topical preparations are generally found safe in terms of sterility, though bacterial growth may be found in a small percentage. In most cases, the cause of the loss of sterility could not be determined. However, in two preparations, contamination was related to the noncompliance of the patient who continued using the same preparation longer than instructed. It is imperative to increase the awareness of glaucoma patients to the fact that improper use can lead to eye-drop contamination.

Ulcerative keratitis caused by Serratia marcescens after laser in situ keratomileusis

We report 2 cases of severe corneal infections caused by Serratia marcescens after laser in situ keratomileusis (LASIK). Twenty-four hours after LASIK, 2 patients developed infectious keratitis, 1 bilaterally. In each eye, the corneal flap was edematous, ulcerated, and detached from the stromal bed. Treatment included removal of the necrotic flap and aggressive antibiotic therapy. Cultures from corneal exudates were positive for S marcescens. After 1 year, both patients had a loss of best corrected visual acuity (BCVA) ranging from 20/40 to 20/22 because of irregular astigmatism. Overrefraction with a hard contact lens resulted in a BCVA of 20/20 in the 3 affected eyes. Slitlamp examination showed trace subepithelial haze without severe corneal scarring. Videokeratography disclosed areas of paracentral inferior steepening resembling keratoconus. Refraction and videokeratography remained stable after 6 months of follow-up. Ulcerative keratitis caused by S marcescens is a potential complication of LASIK. Bilateral involvement may occur if bilateral simultaneous surgery is performed.

Ocular tolerance of preservatives and alternatives

Eye drops are multiple dosage forms protected against microbial contamination by means of preservatives. However, the ocular tolerance of these chemicals can vary and this may result in adverse toxic or allergic reactions. This overview presents the pharmacopoeial requirements for the preservation of eye drops, the factors affecting ocular tolerance as well as the adverse external ocular effects induced by preservatives. The alternatives to the use of preservatives are also discussed, including the recent progress in eye drops packaging.

Severe sclerokeratitis due to Pseudomonas aeruginosa in noncontact-lens wearers

PURPOSE

To review the clinical presentation, treatment and outcome in four cases of severe anterior segment infection by Pseudomonas aeruginosa unrelated to contact lens wear.

METHODS

Four cases presenting over an 18 month period were reviewed.

RESULTS

The cases had variable presenting features and outcomes. Complications such as persistent infection, corneal thinning and phthisis bulbi were noted. Possible factors influencing adherence and tissue disruption are discussed.

CONCLUSIONS

Suspicion of infection by P. aeruginosa and prompt isolation of the organism is needed early in the course of disease. Intensive and prolonged treatment with parenteral and topical antibiotics combined with judicious use of topical steroid gives the best chance of a favourable outcome.

Antimicrobial management of presumed microbial keratitis: guidelines for treatment of central and peripheral ulcers

AIMS

To determine the quantitative relation between the major risk factors for microbial keratitis of previous ocular surface disease and contact lens wear and central and peripheral infiltration, often associated with ulceration, in order to establish a rational chemotherapeutic management algorithm.

METHODS

Data from 55 patients were collected over a 10 month period. All cases of presumed microbial keratitis where corneal scrapes had been subjected to microbiological examination were included. Risk factor data and laboratory outcome were recorded. Antimicrobial regimens used to treat each patient were documented.

RESULTS

57 episodes of presumed microbial keratitis were identified from 55 patients, 24 male and 31 female. There were 30 central infiltrates and 27 peripheral infiltrates of which 28 were culture positive (73% of central infiltrates, 22% of peripheral infiltrates). 26 patients had worn contact lenses of whom 12 had culture positive scrapes (9/14 for central infiltrates, 3/12 for peripheral infiltrates). 31 patients had an ocular surface disease of whom five previous herpes simplex virus keratitis patients developed secondary bacterial infection. Anterior chamber activity and an infiltrate size > or = 4 mm2 were more common with culture positive central infiltrates than peripheral infiltrates (chi 2 test = 11.98, p < 0.001).

CONCLUSIONS

Predisposing factors for "presumed" microbial keratitis, either central or peripheral, were: ocular surface disease (26/57 = 45.6%), contact lens wear (26/57 = 45.6%), and previous trauma (5/57 = 8.8%). Larger ulceration (> or = 4 mm2) with inflammation was more often associated with positive culture results for central infiltration. None of these four variables (contact lens wear, ocular surface disease, ulcer size, anterior chamber activity) were of intrinsic value in predicting if a peripheral infiltrate would yield identifiable micro-organisms. Successful management of presumed microbial keratitis is aided by a logical approach to therapy, with the use of a defined algorithm of first and second line broad spectrum antimicrobials, for application at each stage of the investigative and treatment process considering central and peripheral infiltration separately.

Predictive factors for response to medical therapy in bacterial ulcerative keratitis

BACKGROUND

Fifty-four consecutive cases of culture-positive bacterial ulcerative keratitis presenting at a major university hospital were reviewed to identify factors predictive of response to medical therapy for bacterial ulcerative keratitis (BUK).

METHODS

Eleven patients (20%) failed medical therapy (defined as the need for surgical intervention or cyanoacrylate gluing). Using multivariate logistic regression, the following variables were evaluated: (1) predisposing ocular factors (e.g., contact lens wear), (2) pre-existing ocular diseases, (3) ulcer size, and (4) the number of topical ocular medications used at the time of presentation.

RESULTS

We noted certain factors to be potentially predictive of medical therapy outcome. The average size of the ulcer at the time of presentation was 4.4 +/- 2.4 mm in the failure group but only 2.5 +/- 1.9 mm for the success group (P = 0.027). In addition, patients in the medical failure group used more topical ocular medications at the time of presentation (P = 0.0075). Further analysis of the individual topical ocular medications revealed that the use of corticosteroids was higher in the failure group (56% vs 12%, P = 0.0005 by Fisher's exact test). Other factors such as patient age, the type of organism(s), and the time elapsed between the onset of symptoms and the beginning of definitive therapy were not statistically significant.

CONCLUSION

In this population, ulcer size at the onset of antibacterial treatment and the use of certain ocular medications, specifically corticosteroids, were significant predictive factors for failure of medical therapy for BUK.

Severe microbial keratitis in temperate and tropical Western Australia

To determine the patterns of severe microbial keratitis in Western Australia, all acute admissions over a 2 year period to the Department of Ophthalmology, Royal Perth Hospital were assessed. Fifty-three cases (n = 53) of severe, presumed microbial keratitis were identified. Seventy per cent of these eyes had a visual acuity of 6/60 or less on admission and only 38.8% had 6/12 or better corrected acuity following resolution of the keratitis. The most commonly identified predisposing factors were: prior ocular surgery with or without exposed monofilament sutures (43.4%); contact lens wear (22.6%); lid malposition (17.0%); history of ocular trauma (15.1%); and history of previous herpes simplex keratitis (13.2%). It is notable that 26.4% of the subjects had been applying topical ophthalmic corticosteroids prior to admission. Following corneal scrape or biopsy a positive microbial diagnosis was made in 71% of samples, with Gram-negative and Gram-positive bacterial isolates being equally frequent. Five cases of Acanthamoeba keratitis were identified following corneal biopsy. Where antibiotic sensitivities were available, it was noted that 61.5% of Gram-positive and 46.1% of Gram-negative bacteria were susceptible to chloramphenicol, with 84.6% of Gram-negative bacteria being sensitive to gentamicin. Many of these severe cases of microbial keratitis might have been avoided, or their severity lessened, by earlier identification of predisposing risk factors, more intensive and appropriate antibiotic administration, and improved patient education following ocular surgery.

Microbial contamination of medications used to treat glaucoma

AIMS

A study was conducted to estimate the frequency of contamination of topical antiglaucoma medications used by asymptomatic patients.

METHODS

The drops and the bottle tips of 194 in use topical medications and the conjunctiva from 109 treated glaucoma patients were cultured.

RESULTS

Bacteria were recovered from 55 (28%) medications. The bottle tip was more frequently contaminated than the drops (p = 0.008). Gram positive organisms were cultured from 50 (91%) of 55 contaminated medications. Thirteen patients (12%) had the same microorganism recovered from the conjunctiva and from the contaminated medication. The frequency of contamination of medications increased with increasing duration of use. Bacterial contamination occurred in 19% of eyedrops less than 8 weeks old in contrast with 40% of bottles used for more than 8 weeks.

CONCLUSION

Our data suggest that ocular medications to treat glaucoma frequently become contaminated with bacteria and that contamination is related to duration of use. We therefore recommend that opened topical antiglaucoma eyedrops should be replaced on a regular basis.

Serious Infections Caused by Pseudomonas Aeruginosa

Over the last 3 decades, Pseudomonas aeruginosa has become a leading cause of infectious morbidity and mortality in certain predisposed patient populations. It primarily affects those with impaired host defenses, and its prevalence in the hospital environment makes it an important nosocomial pathogen. Infection with this organism may result in a broad spectrum of clinical manifestations, many of which may be seen in the intensive care setting. This review focuses on epidemiology, clinical presentations, nad treatment of serious Pseudomonas infections.

Survey of the contamination of eyedrops of hospital inpatients and recommendations for the changing of current practice in eyedrop dispensing

Topical ophthalmic medications used on the ward and from the outpatient area have been taken and cultured for potential bacterial contamination in the laboratory. We examined 143 bottles used by patients who had had routine cataract surgery and trabeculectomy. We also examined for bacterial contamination 216 bottles of eyedrops used in the outpatient area of the hospital. No contamination was found in the postoperative eyedrops, but five bottles were contaminated from the outpatient area (2.3%). The bacterial growth from outpatient drops was of the same order of magnitude as in previous studies. The practice in the UK for postoperative eyedrops to be discarded and fresh, separate bottles to take home is discussed. We recommend that this practice be changed so that the postoperative drops used for 72 hours or less are taken home.