Bacterial adhesion to rigid and foldable posterior chamber intraocular lenses: in vitro study

Analysis of Intraocular Lens Biofilms and Fluids After Long-Term Uncomplicated Cataract Surgery

PURPOSE

Postoperative endophthalmitis is a potentially sight-threatening complication of cataract surgery. However, the pathophysiological mechanisms are not completely understood. We sought to study and evaluate the intraocular environment (aqueous and vitreous humors), the capsular tissue, and the intraocular lens (IOL) surfaces of normal eyes after long-term uncomplicated cataract surgery.

DESIGN

Experimental laboratory investigation.

METHODS

We studied 69 eyes donated for transplantation that had previously undergone cataract surgery with posterior chamber IOL implantation and that had no recorded clinical history of postoperative inflammation. We assessed the intraocular environment (DNA traces and biofilm formation) by microbiological evaluation of intraocular fluids using conventional microbiology and molecular techniques, including assessment for the presence of microbes (biofilm formation) on the IOL surface by scanning electron microscopy and ultrastructural capsular remnants by transmission electron microscopy.

RESULTS

Isolated or aggregated cocci were probable in 18.8% of IOL optic surfaces (n = 13) studied by scanning electron microscopy, suggesting the presence of bacterial biofilm. In 3 intraocular fluid samples for IOLs with biofilm, we identified 16S rDNA by polymerase chain reaction and sequencing. No microbial contamination was found in intraocular fluids by conventional microbiological methods.

CONCLUSIONS

Our data suggest the possibility of bacterial biofilm formation on the optic surface of IOLs in normal eyes after long-term uncomplicated cataract surgery even in the absence of clinical or subclinical symptoms.

Risk factors for endophthalmitis following cataract surgery-our experience at a tertiary eye care centre in India

AIM

To determine the risk factors for acute endophthalmitis after cataract extraction in a tertiary care centre in India.

METHODS

We performed a nested case control study within a retrospective cohort. The surgical records of all patients with clinically diagnosed endophthalmitis within one month after cataract surgery, performed between January 2006 and December 2009, were reviewed. These were compared with randomly selected age and gender-matched controls, from patients having routine cataract surgery within ±1wk of the endophthalmitis case. Univariable and multivariable analysis were performed to identify risk factors for endophthalmitis.

RESULTS

Of the total 33 856 cataract surgeries performed during this period, there were 57 cases of postoperative acute endophthalmitis that met our study criteria. Thus, the overall incidence of endophthalmitis in our cohort was 1.6 per 1000 cataract extractions performed. Mean age of cases was 55.9y (SD: 10.9y) and for controls was 55.6y (SD: 9.8y). Thirty-five cases (61.4%) and 133 controls (59.6%) were males. Median time of onset of endophthalmitis was 4d (IQR 2-9d; range: 1-30d). Thirty-nine cases (68.4%) presented within 7d and 27 cases (47.4%) were culture positive. Two hundred and twenty-three age and gender matched controls were selected. In multivariate analysis, endophthalmitis was associated with posterior capsular rupture (PCR) during surgery (OR 6.98, 95%CI: 2.22-21.98), phacoemulsification via scleral incision with a foldable intraocular lens (IOL) implantation (OR 3.02, 95%CI: 1.13-8.04) and ocular co-morbidity (OR 2.32, 95%CI: 1.11-4.87).

CONCLUSION

PCR, presence of ocular co-morbidity, and phacoemulsification via scleral incision with foldable-IOL were found to be independent risk factors for acute endophthalmitis.

In vitro biofilm distribution on the intraocular lens surface of different biomaterials

PURPOSE

To study the disposition of bacterial adhesion to intraocular lens (IOL) biomaterials depending on the material and region of the optic IOL surface: center or peripheral edge.

SETTING

School of Medicine, University of Barcelona, Barcelona, Spain.

DESIGN

Experimental study.

METHODS

For the in vivo study, IOLs were explanted from donor ocular globes without clinical symptoms of endophthalmitis. Biofilm formation was qualitatively studied by scanning electron microscopy (SEM). For the in vitro study, 5 IOL biomaterials (hydrophilic acrylic, hydrophobic acrylic, poly[methyl methacrylate] [PMMA], heparinized PMMA, and silicone) were contaminated with a biofilm-producing strain of Staphylococcus epidermidis. Bacterial densities were quantitatively (colony-forming units per area) compared by SEM and direct counting of viable adherent bacteria, according to the biomaterial, region of the IOL optic surface, and time of incubation. For SEM, bacterial adhesion was also qualitatively classified according to the characteristics of biofilm observed: structure, cocci per cluster, homogeneity of cluster distribution, and extracellular matrix production.

RESULTS

At 3 hours of incubation, bacterial counts for hydrophilic acrylic and PMMA IOLs were significantly lower, but at 72 hours there were no statistically significant differences among biomaterials. A higher density of bacteria was observed at the periphery of the IOL's optic of assayed biomaterials for in vitro and in vivo studies. Biofilm formation and the presence of extracellular matrix were predominantly restricted to the edges of IOL optic surface.

CONCLUSION

Bacterial adhesion and biofilm development on the IOL optic surface depended on the region and biomaterial of the IOL.

FINANCIAL DISCLOSURE

Neither author has a financial or proprietary interest in any material or method mentioned.

Biofilms in infections of the eye

The ability to form biofilms in a variety of environments is a common trait of bacteria, and may represent one of the earliest defenses against predation. Biofilms are multicellular communities usually held together by a polymeric matrix, ranging from capsular material to cell lysate. In a structure that imposes diffusion limits, environmental microgradients arise to which individual bacteria adapt their physiologies, resulting in the gamut of physiological diversity. Additionally, the proximity of cells within the biofilm creates the opportunity for coordinated behaviors through cell–cell communication using diffusible signals, the most well documented being quorum sensing. Biofilms form on abiotic or biotic surfaces, and because of that are associated with a large proportion of human infections. Biofilm formation imposes a limitation on the uses and design of ocular devices, such as intraocular lenses, posterior contact lenses, scleral buckles, conjunctival plugs, lacrimal intubation devices and orbital implants. In the absence of abiotic materials, biofilms have been observed on the capsule, and in the corneal stroma. As the evidence for the involvement of microbial biofilms in many ocular infections has become compelling, developing new strategies to prevent their formation or to eradicate them at the site of infection, has become a priority.

Role of Sonication in the Microbiological Diagnosis of Implant-Associated Infections: Beyond the Orthopedic Prosthesis

Implant-associated infections are difficult-to-treat conditions associated with high morbidity, mortality and length of hospitalization. They are characterized by biofilm formation on implant surface, which makes the microbiological diagnosis difficult and requires a complete device removal for the correct management. The sonication method, which is based on the application of long-wave ultrasounds radiating in a liquid medium, has been recently validated for the diagnosis of prosthetic joint infections. Additionally, this technique has been considered a potential tool in order to improve the microbiological diagnosis of infections associated with other foreign bodies, such as breast, urinary, endovascular and cerebral implants. In the present study, the application of sonication in the setting of implant-associated infections other than orthopedics will be reviewed.

Biofilm Formation by Staphylococcus epidermidis on Foldable and Rigid Intraocular Lenses

Background:

Biofilm formation of Staphylococcus epidermidis is a major etiological factor of inducing device-related infections.

Objectives:

The ability of biofilm formation by the S. epidermidis was assessed in vitro on two brands of foldable (hydrophilic) and two brands of rigid (hydrophobic) intraocular lens materials in order to investigate the role of lens material in postoperative endophthalmitis.

Materials and Methods:

To ensure reproducibility of biofilm formation on intraocular lenses, two strains of S. epidermidis and three quantification methods were performed. The S. epidermidis strains, DSMZ3270 (biofilm-producer) and ATCC12228 (non-biofilm-producer) were applied. Organisms were cultivated on disks of different brands of foldable hydrophilic Intra Ocular Lens (IOL) made of acrylic (Didar, Iran; (A) and Omni, India; (B)), and rigid hydrophobic IOL made of polymethyl methacrylate (PMMA; Didar, Iran; (C) and Hexavision, France; (D)). Biofilms were stained with crystal violet (CV) dye, which is an index of biofilm formation. The bacterial population was counted after biofilm homogenization. Scanning electron microscopy (SEM) was performed to examine the extent of biofilm formation.

Results:

Adherence of DSMZ3270 strain on both types of foldable and rigid IOLs, was significantly more than ATCC12228 (P < 0.001-0.05 and, P < 0.01-0.05, respectively). The bacterial populations between the lenses were significantly different (P < 0.05). Subsequent studies demonstrated significant differences between brands of foldable and PMMA IOLs. According to statistical analyses the incubation time influenced the biofilm formation on both types of IOLs which meant that by increasing incubation time, the biofilm formation increased. According to the SEM pictures, biofilm seems to be lysed at 72 hours.

Conclusions:

These data demonstrated that the attachment of bacteria to hydrophilic acrylic IOLs was more than hydrophobic PMMA ones independent of the brand. According to these results the bacterial strain might have more hydrophilic properties. Augmenting the biomass of biofilm by passing of time demonstrated the key role of time in biofilm formation on the IOL surfaces. The differences between IOL brands in the biofilm formation indicated the influence of design parameters for IOLs.

The intraocular lens: challenges in the prevention and therapy of infectious endophthalmitis and posterior capsular opacification

Cataract is the leading cause of visual impairment worldwide. In the UK, some 30% of the population over 65 years of age have visually impairing cataract. Importantly, 88% of those with treatable visual impairment from cataract are not in contact with any ocular healthcare service, representing a major potential healthcare need [1]. In the USA, it has been estimated that 17.2% of the population (approximately 20.5 million) over 40 years of age have cataract in either eye and by 2020, this number is expected to rise to 30.1 million. Currently, cataract is responsible for 60% of Medicare costs associated with vision [2]. Furthermore, as the populations of industrialized countries such as the UK and the USA continue to age, the costs associated with treatment of cataract can only be expected to increase. Consequently, the development of the intraocular lens to replace the cataractous lens and the advances in intraocular lens design and implantation represent a major development in cataract treatment. However, despite such advances, cataract surgery is not without complications, such as postoperative infectious endophthalmitis, a rare but potentially devastating condition, and posterior capsular opacification, a less serious but much more common problem. This review will examine the epidemiology of cataracts, the polymeric construction of intraocular lenses implanted during cataract surgery and the complications of postoperative infectious endophthalmitis and posterior capsular opacification with regard to therapeutic interventions and prophylactic strategies. Advances in biomaterial design and function will be discussed as novel approaches to prevent such postoperative complications.

Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD^™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.

[Endophthalmitis after cataract surgery: epidemiology, clinical features and antibiotic prophylaxis]

PURPOSE

To estimate the incidence of endophthalmitis after cataract surgery and to describe the main epidemiological and clinical data, as well as the role of intracameral antibiotics.

METHODS

A cross-sectional descriptive study was conducted on patients who underwent cataract surgery in a public hospital over an 11-year period. An ocular infection database was used to report endophthalmitis occurrences and to collect the clinical features. Qualitative variables are described with their frequency distribution and qualitative variables, with the mean and the standard deviation.

RESULTS

From January 1999 to December 2009, 15.173 patients underwent cataract surgery. A total of 43 patients suffered from postoperative endophthalmitis, giving an overall infection rate of 0.28% (95% CI: 0.20-0.36%). Among the 43 cases, there were 19 men and 24 women with a mean age of 78.5. Other clinical parameters evaluated were as follows: 25.58% were diabetic, 44.18% had some degree of immunosuppression and there were complications with posterior capsular tears in 18.6%. As regards antibiotic prophylaxis, 2 groups were considered: the first one did not receive intracameral antibiotic (8,099 patients) and the second group received intracameral cefuroxime (7,074 patients). There were 39 endophthalmitis in the first group with an infection incidence of 0.48% and 4 endophthalmitis in the second group with an infection incidence of 0.056%. The relative risk (RR) after-before cefuroxime was 0.12 (0.04-0.33) with P<0.05.

CONCLUSIONS

The incidence of endophthalmitis after cataract surgery in an 11-year period was lower than 0.3%. Almost half of the patients had a higher systemic risk. Intracameral cefuroxime resulted in nearly a 9-fold reduction in the rate of infection.

[Subluxation of hydrophilic acrylate intraocular lenses due to massive capsular fibrosis]

BACKGROUND

Compared with other biomaterials, hydrophilic acrylate provides better uveal biocompatibility, lower adhesion rates of bacteria and silicone oil, and less glare. Because of reduced capsular biocompatibility, increased fibrosis may initiate dislocation of the intraocular lens (IOL).

PATIENTS

In six eyes of four patients, enhanced fibroses led to IOL dislocation, leading to an IOL exchange an average of 40 weeks after implantation of the same hydrophilic acrylate lens type.

DISCUSSION

Predisposing factors were found in 90% of all reported cases of IOL dislocation in the literature, but not in the cases described here. The lens type that was implanted was unable to adapt to the massive fibrosis induced by its hydrophilic biomaterial.

CONCLUSIONS

The pattern of lens opacification should receive attention when one is choosing an IOL type. Eyes showing pseudoexfoliation syndrome as well as post-uveitis eyes might require a hydrophilic IOL for less cellular reaction, whereas a posterior subcapsular cataract might need a hydrophobic IOL to prevent a massive capsular fibrosis. In the case of increased capsular contraction, unreflected YAG laser capsulotomy may result in IOL subluxation when the lens design cannot handle capsule shrinkage, as demonstrated here.

Biofilm Formation on Hydrophilic Intraocular Lens Material

PURPOSE

To estimate bacterial biofilm formation on the hydrophilic acrylic (hydrogel) intraocular lens (IOL) Meridian (HP60M, Baush & Lomb) and to investigate a preventive effect against biofilm formation of hydrogel IOLs presoaked in antibiotics.

METHODS

Two Staphylococcus epidermidis strains, ATCC 12228 and ATCC 35984 (biofilm-producer), and an Enterococcus faecalis strain (KOS1, clinical isolate from an endophthalmitis patient) were used. Biofilms were cultivated on disks of different IOL materials: hydrogel, PMMA (polymethylmethacrylate), and acrylic. Biofilms were stained with crystal violet (CV), which served as an index of biofilm formation. The bacterial population was enumerated after biofilm homogenization. Biofilms were also examined by scanning electron microscopy (SEM). IOLs were presoaked in two antibiotics, levofloxacin (LVFX) and gatifloxacin (GFLX), and then the bacterial population was enumerated. As in vivo experiment, antibiotics-treated and nontreated Meridian IOLs were implanted in rabbit eyes, which served as an endophthalmitis model, and the bacterial population was enumerated.

RESULTS

The amount of biofilm formed was the least on hydrogel from among the three materials tested after 48- and 72-hr incubation (p < 0.05 to 0.01). The bacterial population was the least on hydrogel from among the three materials with ATCC 12228 (p < 0.05 to 0.01), and the bacterial population was significantly different between hydrogel and acrylic after 72-hr incubation with ATCC 35984 (p < 0.05). Biofilm by the two S. epidermidis strains were recognized after 24-hr incubation. Rates of biofilm-positive SEM fields, which were defined as being occupied by biofilm over at least half of the area, were increased through 72 hr with ATCC 35984. While the E. faecalis strain showed no bacterial adherence on the antibiotics-treated hydrogel IOLs, adherence of the S. epidermidis strain, ATCC 35984 was recognized on the LVFX-treated IOLs after 48-hr incubation (103 to 104 CFU/ml). In the rabbit in vivo model, the bacterial populations in eyes with an antibiotics-treated Meridian IOL were significantly smaller than in eyes with a nontreated IOL for 72 hr after surgery (p < 0.05 to 0.01).

CONCLUSIONS

The biofilm formation was less on hydrogel than on other two materials tested. Hydrogel presoaked in antibiotics exhibited a preventive effect against biofilm formation at least for 24 hr in vitro and against bacterial proliferation in the rabbit in vivo endophthalmitis model.

[Intraocular lens and cataract surgery: comparison between bacterial adhesion and risk of postoperative endophthalmitis according to intraocular lens biomaterial]

Cataract surgery is a usually successful procedure that restores vision by replacing the natural lens with an intraocular lens (IOL). Acute postoperative endophthalmitis is still one of the most serious complications of cataract surgery. Its incidence has been reported to be between 0.04% and 0.32%. Precisely why bacteria induce endophthalmitis is not entirely understood. Indeed the risk of its development may be influenced by several factors. Among them, bacterial adhesion to the IOL has been recently emphasized in the ophthalmology literature. Indeed, the ability of an organism to adhere to the IOL surface is believed to be associated with a risk of infection at the implantation site. Several studies have demonstrated that bacterial adhesion is influenced by IOL materials. Ever since, numerous studies have investigated the interactions between bacteria and different types of IOLs to determine which biomaterial would be most permissive to bacterial adherence. This article reviews all the epidemiological and experimental data relating to the study of the relationship between bacterial adhesion, IOL material, and risk of developing postoperative endophthalmitis. Even if discrepancies between these studies exist, mainly stemming from the use of different experimental conditions and protocols, it seems that bacterial adhesion is strongly influenced by IOL material. Epidemiological studies suggest that the implantation of silicone IOLs might be associated with increased rates of endophthalmitis. Experimental studies reach similar conclusions showing that hydrophobic IOLs such as silicone or acrylic hydrophobic IOLs are more permissive to bacterial adhesion and growth than hydrophilic IOLs such as acrylic hydrophilic IOLs. Among the interactions that govern bacterial attachment to the IOLs, it seems that hydrophilic-hydrophobic interactions have the greatest influence. Nevertheless, since bacterial adhesion is a complicated process affected by many factors, the conclusions drawn by these results have to be interpreted with care. Further investigations are still needed to understand the connections between IOL material and endophthalmitis.

[Eye infections associated with ocular implants]

Postoperative endophthalmitis associated with intraocular lens implantation is one of the most severe complications of cataract surgery. The prevalence of endophthalmitis following these procedures reported in several multicenter studies over the last decades is 0.05% to 0.32%. Currently, general consensus measures are available to prevent this serious complication. Abiotic biofilm formation with adhesion of pathogens on the surface of intraocular devices is a novel theory that is little understood, but widely accepted to explain the pathophysiologic aspects of intraocular infection. Bacterial adhesion on intraocular lenses has been observed in clinical practice and investigated with several in vitro approaches in various experimental conditions. Improvements in the surgical techniques used in cataract surgery and the advent of new antimicrobial agents with a wider spectrum of action and better penetration in the eye, have resulted in significant advances in the prevention and treatment of intraocular implant-related infection.

Influence of fibronectin on the adherence of Staphylococcus epidermidis to coated and uncoated intraocular lenses

PURPOSE

To determine the effect of the modification of intraocular lens (IOL) surface properties on the adhesion of Staphylococcus epidermidis caused by fibronectin (FN) as the predominant proadhesive glycoprotein of the eye's initial foreign body reaction.

SETTING

University of Saarland, Homburg/Saar, Germany.

METHODS

Eleven IOL types were tested. The IOLs were of poly(methyl methacrylate), acrylate, or silicone. Some were surface modified with heparin or polysaccharide coating. The IOLs, unadsorbed or preadsorbed with fibronectin (FN), were incubated with [(3)H]-thymidine-labeled S epidermidis Rp62a, and the amount of adherent microorganisms was determined.

RESULTS

Attachment of S epidermidis adhesion to various types of IOLs, both unadsorbed and FN precoated, varied significantly. The attachment to highly adhesive IOLs was almost 4-fold greater than that to low-adhesive IOLs. Attachment to FN precoated IOLs was generally enhanced compared with attachment to unadsorbed IOLs. Heparin surface modification resulted in no or a modest reduction in bacterial adhesion compared with unmodified IOLs. Bacterial adhesion was highly statistically significantly less on IOLs with polysaccharide surface modification.

CONCLUSIONS

There was significant variability in S epidermidis adhesion to IOLs as a function of design, material, surface modification, and FN preadsorption. Application of the findings may foster new developments to further reduce the major complication in cataract surgery, infective endophthalmitis.

Adherence and kinetics of biofilm formation of Staphylococcus epidermidis to different types of intraocular lenses under dynamic flow conditions

PURPOSE

To compare the adherence and biofilm formation of Staphylococcus epidermidis under in vitro flow conditions on intraocular lenses (IOLs) made of 4 biomaterials: poly(methyl methacrylate) (PMMA), silicone, hydrophilic acrylic, and hydrophobic acrylic.

SETTING

Department of Ophthalmology, Croix-Rousse University Hospital and University Research Laboratory, Lyon, France.

METHODS

Intraocular lenses were placed in a bioreactor designed to replicate intraocular conditions. The model consisted of Tygon tubing connected to a vial. Three septa allowed the entry and elimination of the artificial aqueous humor and inoculation of the bacterial suspension. The first of 2 pumps moved the aqueous humor along the circuit; the second pump regulated the flow at which the nutritive environment was regenerated. At various times (12, 16, 24, 40, 48, 60, and 72 hours), IOLs were taken from this environment and the bound bacteria were removed and counted. The distribution of bacterial adhesion on the IOLs was modeled using polynomial Poisson regression. To test the effect of the IOL biomaterial on bacterial adhesion, likelihood ratio tests were performed.

RESULTS

The model provided the kinetics of S epidermidis biofilm growth on IOLs. The biofilm growth on each of the 4 biomaterials occurred in 3 phases: latent, dynamic or accelerated growth, and linear growth. The extent of bacterial binding to IOLs increased from hydrophilic acrylic polymer to PMMA, hydrophobic acrylic, and silicone. The differences were statistically significant.

CONCLUSION

Bacterial adhesion to and biofilm development on the IOL surface depended on the characteristics of the biomaterial.

Surface modification of silicone intraocular lens by 2-methacryloyloxyethyl phosphoryl-choline binding to reduce Staphylococcus epidermidis adherence

PURPOSE

To analyse the in vitro adherence of Staphylococcus epidermidis to the 2-methacryloyl oxyethyl phosphorylcholine (MPC)-modified silicone intraocular lens (IOL).

METHODS

The test IOLs were modified by using an air plasma treatment to bind MPC to the surface. The control IOLs were not modified. Chemical changes on the IOL surface were analysed by X-ray photoelectron spectroscopy (XPS) to confirm the covalent binding of MPC. IOL hydrophilicity was determined by measuring the water contact angle. Two different techniques, direct counting of viable adherent bacteria released by sonication, and scanning electron microscopy (SEM), were used to observe and compare the adherence of S. epidermidis to the IOLs after 1- and 18-h incubation.

RESULTS

XPS analysis confirmed that the test IOLs were surface-modified with MPC. The hydrophilicity of the IOLs was improved by surface modification, and the MPC-modified IOLs exhibited significantly reduced adhesion of S. epidermidis (P = 0.002) after an incubation period of 1 h. The SEM results showed that the MPC modification also suppressed the accumulation of bacteria and biofilm production after 18 h incubation.

CONCLUSIONS

MPC-modified hydrophilic silicone IOLs reduce bacterial adherence and colonization, and thus may help reduce the incidence of postoperative endophthalmitis.

Biofilm formation by Enterococcus faecalis on intraocular lens material

PURPOSE

To compare biofilm formation by Enterococcus faecalis on different intraocular lens (IOL) materials.

METHODS

E. faecalis biofilms were cultivated on disks of IOL material (silicone, PMMA [polymethylmethacrylate], or acrylic). Biofilms were stained with crystal violet (CV), which served as an index of biofilm formation. The bacterial population was enumerated after biofilm homogenization. Biofilms were also examined by confocal microscopy.

RESULTS

At 24 hr, there was no significant difference in biofilm formation, or the population within biofilms, among the three materials tested. However, after 48 and 72 hr, it was observed that silicone supported the least amount of biofilm formation (p < 0.05); biomass on PMMA and acrylic IOLs continued to increase, with acrylic demonstrating the greatest amount of stainable biofilm (p < 0.0005). The population on PMMA was significantly greater than the other IOL materials (p < 0.005). Confocal microscopy confirmed the lack of biomass on silicone.

CONCLUSIONS

Among three IOL materials, E. faecalis biofilms formed more readily on PMMA and acrylic compared to silicone.

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

PURPOSE

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

SETTING

Kocaeli University, School of Medicine, Kocaeli, Turkey.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Recurrent Enterococcus faecalis endophthalmitis after phacoemulsification

We present the first reported case of late recurrence of postoperative Enterococcus faecalis endophthalmitis after cataract surgery in a 45-year-old diabetic man. Culture-positive E faecalis endophthalmitis was diagnosed 2 days after uneventful phacoemulsification. Early vitrectomy with intravitreal and subconjunctival vancomycin and amikacin and topical vancomycin resulted in apparently complete clinical resolution after 4 months and a best corrected visual acuity of 20/25. Recurrent endophthalmitis with hypopyon occurred 7 months postoperatively and resolved with intravitreal vancomycin and topical prednisolone acetate 1%. However, the patient had a similar relapse at 9 months that resulted in deterioration of visual acuity to no light perception despite a repeat vitrectomy, intraocular lens explantation, capsular bag removal, and intravitreal antibiotics. The late recurrences could have been the result of persistent sequestration of the organism in the capsular bag.

Risk factors of acute endophthalmitis after cataract extraction: a case-control study in Asian eyes

AIM

To describe risk factors of acute endophthalmitis after cataract extraction in an Asian population.

METHODS

A retrospective, case-control study. Cases (n = 34) were patients with acute endophthalmitis presenting within 6 weeks after cataract surgery. Three controls per case (n = 102) were randomly selected from the cataract surgery list matched on the date of operation of cases.

RESULTS

Few risk factors were identified. In multivariable analysis, endophthalmitis was associated with silicone intraocular lens (odds ratio 5.1, 95% confidence intervals, 1.2 to 21.6, compared to poly(methylmethacrylate) lens) and posterior capsular rupture during surgery (odds ratio 20.9, 95% confidence intervals 2.3 to 187.9).

CONCLUSION

Silicone intraocular lens and rupture of the posterior capsule are risk factors of acute endophthalmitis after cataract surgery.