Biofilm on scleral explants with and without clinical infection

Characteristics of Bacterial Biofilm Formation in Nasolacrimal Silicone Tubes Post-dacryocystorhinostomy

PURPOSE

To examine the biofilm formation characteristics of bacteria identified at the genus level in samples obtained from silicone tubes after dacryocystorhinostomy surgery.

METHODS

In the study involving consecutive patients who underwent dacryocystorhinostomy surgery at Ankara Bilkent City Hospital and whose silicone tubes were removed six months after surgery, between January 2023 and May 2023; the tubes were placed in glycerol-PBS (phosphate buffered saline) solution and cultured on descriptive selective media at the genus level. The biofilm-forming properties of the obtained isolates were examined in solid-air and liquid-air interphases. Salmonella Typhimurium ATCC SL1344 strain was used as the control bacterium.

RESULTS

As a result of the analysis of the samples taken from the patients, Pseudomonas spp. was identified in three of the samples, Staphylococcus spp. in five of the samples, and Streptococcus spp. in one of the samples. Among these samples, except for the bacteria identified in samples one and five, the rest were found to be strong biofilm producers. In all strong biofilm producers, the maximum biofilm production time was determined as 72 h and the incubation temperature was 37°C. The presence of cellulose and amyloid proteins in biofilm matrix structures is identified. Swimming and swarming motilities were observed in all bacterial samples.

CONCLUSION

Since biofilms are considered potential factors in the pathogenesis of infectious and inflammatory diseases, they are a subject that needs to be thoroughly investigated. In our study, although there were no clinical infections in any of the patients, biofilm formation was detected in the patient samples. The fact that the bacteria exhibited moderate to strong biofilm formation characteristics suggests that these microorganisms could be persistent infectious agents.

Use of a subpalpebral lavage system as salvage therapy for Pseudomonas aeruginosa panophthalmitis due to an infected scleral buckle

PURPOSE

To present a case and surgical technique for management of Pseudomonas aeruginosa panophthalmitis secondary to an infected scleral buckle.

METHODS

Surgical technique video for management of an infected scleral buckle resulting in panophthalmitis with scleral buckle and suture explant and insertion of a subpalpebral lavage system.

RESULTS

After two months, the visual acuity was restored to hand motion, likely secondary to a fibrotic secondary membrane, and the retina remain attached. This reports the first description of globe salvage for panophthalmitis from a P. aeruginosa-infected scleral buckle.

CONCLUSION

This case encourages surgeons to remove all aspects of an exposed scleral buckle, including sutures, and emphasizes the importance of routine culture of all explanted material, even in the absence of clinical infection. In addition, this case encourages the use of a subpalpebral lavage in cases of severe P. aeruginosa ocular infections.

Microbial Warfare on Three Fronts: Mixed Biofilm of Aspergillus fumigatus and Staphylococcus aureus on Primary Cultures of Human Limbo-Corneal Fibroblasts

Background

Coinfections with fungi and bacteria in ocular pathologies are increasing at an alarming rate. Two of the main etiologic agents of infections on the corneal surface, such as Aspergillus fumigatus and Staphylococcus aureus, can form a biofilm. However, mixed fungal–bacterial biofilms are rarely reported in ocular infections. The implementation of cell cultures as a study model related to biofilm microbial keratitis will allow understanding the pathogenesis in the cornea. The cornea maintains a pathogen-free ocular surface in which human limbo-corneal fibroblast cells are part of its cell regeneration process. There are no reports of biofilm formation assays on limbo-corneal fibroblasts, as well as their behavior with a polymicrobial infection.

Objective

To determine the capacity of biofilm formation during this fungal–bacterial interaction on primary limbo-corneal fibroblast monolayers.

Results

The biofilm on the limbo-corneal fibroblast culture was analyzed by assessing biomass production and determining metabolic activity. Furthermore, the mixed biofilm effect on this cell culture was observed with several microscopy techniques. The single and mixed biofilm was higher on the limbo-corneal fibroblast monolayer than on abiotic surfaces. The A. fumigatus biofilm on the human limbo-corneal fibroblast culture showed a considerable decrease compared to the S. aureus biofilm on the limbo-corneal fibroblast monolayer. Moreover, the mixed biofilm had a lower density than that of the single biofilm. Antibiosis between A. fumigatus and S. aureus persisted during the challenge to limbo-corneal fibroblasts, but it seems that the fungus was more effectively inhibited.

Conclusion

This is the first report of mixed fungal–bacterial biofilm production and morphological characterization on the limbo-corneal fibroblast monolayer. Three antibiosis behaviors were observed between fungi, bacteria, and limbo-corneal fibroblasts. The mycophagy effect over A. fumigatus by S. aureus was exacerbated on the limbo-corneal fibroblast monolayer. During fungal–bacterial interactions, it appears that limbo-corneal fibroblasts showed some phagocytic activity, demonstrating tripartite relationships during coinfection.

Multi-drug resistant Mycobacterium chelonae scleral buckle infection

Purpose

To describe a case of Multi-drug resistant Mycobacterium chelonae scleral buckle infection.

Observations

A 56 year-old male with history of retinal detachment repair with scleral buckle 20 years prior presented with 8 months of intermittent pain and redness in the left eye. The patient was diagnosed with scleral buckle infection, the buckle was removed, and cultures revealed multi-drug resistant Mycobacterium chelonae. The postoperative course included orbital cellulitis treated with systemic linezolid, clarithromycin, and imipenem. All systemic antibiotics were discontinued on post-operative day 25, visual acuity improved to 20/25, the retina remained attached, and no recurrence occurred over 3 years of follow-up.

Conclusions and importance

NTM infections are typically chronic and often require lengthy treatment. SB infection is rare, but often associated with biofilm and antibiotic resistance. In spite of removing the SB, anchoring sutures, sheath surrounding the buckle and associated biofilm, a prolonged course of systemic antibiotics may be necessary in some patients.

Organo-Selenium Coatings Inhibit Gram-Negative and Gram-Positive Bacterial Attachment to Ophthalmic Scleral Buckle Material

Purpose

Biofilm formation is a problem for solid and sponge-type scleral buckles. This can lead to complications that require removal of the buckle, and result in vision loss due to related ocular morbidity, primarily infection, or recurrent retinal detachment. We investigate the ability of a covalent organo-selenium coating to inhibit biofilm formation on a scleral buckle.

Methods

Sponge and solid Labtican brand scleral buckles were coated with organo-selenium coupled to a silyation reagent. Staphylococcus aureus biofilm formation was monitored by a standard colony-forming unit assay and the confocal laser scanning microscopy, while Pseudomonas aeruginosa biofilm formation was examined by scanning electron microscopy. Stability studies were done, by soaking in phosphate buffer saline (PBS) at room temperature for 2 months. Toxicity against human corneal epithelial cell was examined by growing the cells in the presence of organo-selenium–coated scleral buckles.

Results

The organo-selenium coating inhibited biofilm formation by gram-negative and gram-positive bacteria. The buckle coatings also were shown to be fully active after soaking in PBS for 2 months. The organo-selenium coatings had no effect on the viability of human corneal epithelial cells.

Conclusions

Organo-selenium can be used to covalently coat a scleral buckle, which is stable and inhibits biofilm formation for gram-negative and gram-positive bacteria. The organo-selenium buckle coating was stable and nontoxic to cell culture.

Translational Relevance

This technology provides a means to inhibit bacterial attachment to devices attached to the eye, without damage to ocular cells.

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.

Comparison of scanning electron microscopy findings regarding biofilm colonization with microbiological results in nasolacrimal stents for external, endoscopic and transcanalicular dacryocystorhinostomy

AIM

To compare bacterial biofilm colonization in lacrimal stents following external dacryocystorhinostomy (EX-DCR), endoscopic dacryocystorhinostomy (EN-DCR), and transcanalicular dacryocystorhinostomy (TC-DCR) with multidiode laser.

METHODS

This prospective study included 30 consecutive patients with nasolacrimal duct obstruction who underwent EXT-, EN-, or TC-DCR. Thirty removed lacrimal stent fragments and conjunctival samples were cultured. The lacrimal stent biofilms were examined by scanning electron microscopy (SEM).

RESULTS

Eleven (36.7%) of the 30 lacrimal stent cultures were positive for aerobic bacteria (most commonly Staphylococcus epidermidis and Pseudomonas aeruginosa). However anaerobic bacteria and fungi were not identified in the lacrimal stent cultures. Twenty-seven (90%) patients had biofilm-positive lacrimal stents. The conjunctival culture positivity after the DCR, biofilm positivity on stents, the grade of biofilm colonization, and the presence of mucus and coccoid and rod-shaped organisms did not significantly differ between any of the groups (P>0.05). However, a significant difference was found when the SEM results were compared to the results of the lacrimal stent and conjunctival cultures (P<0.001).

CONCLUSION

Type of dacryocystorhinostomy (DCR) surgery did not affect the biofilm colonization of the lacrimal stents. SEM also appears to be more precise than microbiological culture for evaluating the presence of biofilms on lacrimal stents.

Orbital cellulitis following silicone-sponge scleral buckles

Background

Acute or chronic infection of the scleral explant is rare. We report seven cases of scleral explant infections that caused orbital cellulitis.

Materials and methods

This was a retrospective chart review of oculoplastics at oculoplastics and vitreo-retinal units in a secondary referral hospital. All subjects had orbital cellulitis secondary to scleral buckle in the range of January 1990 to March 2010. Demographics, imaging studies, and pathology specimens were reviewed.

Results

A total of 841 silicone-sponge scleral buckle implants for rhegmatogenous retinal detachment were performed. Forty were extracted (4.75%; annual rate of 1.9 cases). Seven (0.83%) had orbital cellulitis. The mean time from implantation to presentation was 5.7 years. There was bacterial growth in all specimens, with Staphylococcus aureus in four.

Conclusions

Patients who are operated on with silicone-sponge scleral buckling for rhegmatogenous retinal detachment sometimes require removal of the implant because of infection. However, the infection rate is low. Patients should be followed in the long term for possible complications.

Scleral buckle removal: indications and outcomes

Primary scleral buckling has been an effective means to reattach the retina for over 50 years. After surgery, complications may arise that require scleral buckle (SB) removal. The most common indications for SB removal are extrusion, infection, and pain. I review the pertinent literature in an effort to develop guidelines for when to remove a SB.

An intractable case of Pseudomonas aeruginosa infection after scleral buckling for rhegmatogenous retinal detachment

BACKGROUND

Scleral buckling is still a common procedure to repair rhematogenous retinal detachment, and acute or chronic infection of the scleral explant is rare. We report an intractable case of acute scleral explant infection by Pseudomonas aeruginosa.

CASE

A 36-year-old man suffered from acute scleral explant infection by P. aeruginosa forty-eight hours after scleral buckling for rhegmatogenous retinal detachment. The infection was treated by intravenous administration of various appropriate antibiotics for eighteen days and washing the scleral explant with appropriate antibiotics, and appeared to be resolved. However, three months after the initial surgery, we had to remove the scleral explant because of recurrent infection.

OBSERVATIONS

We encountered an intractable case of acute scleral explant infection by P. aeruginosa, that recurred and forced the removal of the scleral explant.

CONCLUSIONS

We found that recurrence of infection necessitated removal of the scleral explant, even though the organism was sensitive to the antibiotics used to treat the infection, and there was an appropriate duration of treatment. Early diagnosis and countermeasures, first considering conservative management, which may have a role in delaying buckle removal, and thus reduce the risk of retinal redetachment, and help prolong the time until surgical treatment such as removing the scleral explant is required.

Radiologic findings in infected and noninfected scleral buckles

PURPOSE

To present the radiologic findings in scleral buckle infections and in the early postoperative period after scleral buckling.

METHODS

Retrospective multicenter orbital computed tomography (CT) study of 14 patients and brain magnetic resonance (MR) in one patient with scleral buckle infections, some with the referring diagnosis of endophthalmitis, proliferative vitreoretinopathy, orbital cellulitis, or unilateral headache. The control population consisted of early postoperative prospective CT study of 38 consecutive patients with scleral buckle without clinical infection.

RESULTS

Diffuse scleral thickening and preseptal soft tissue swelling were noted in acute scleral buckle infections. Scleral thickening decreased radiologically following prompt antibiotic therapy in five patients with acute infections. Silicone sponge had low attenuation without infection and high attenuation with infection. In chronically infected scleral buckle, the sclera was thickened around the buckle, with scleral melt under the buckle. MR showed increased signal intensity in the preseptal region in one patient with chronic fungal infection. In the controls, two had thickening of the sclera without soft tissue swelling.

CONCLUSIONS

CT or MR can assist in the early diagnosis and management of scleral buckle infections.

Bacterial Biofilms and Ocular Infections

Serious bacterial infections of the eye are often associated with abiotic prosthetic materials, such as contact lenses, intraocular lenses, and scleral buckles. In recent years, microbiologists have recognized substantial differences between bacteria growing in a sessile community attached to a surface and free-living or planktonic bacteria. These sessile surface-attached communities are known as biofilms, whose properties have important consequences for clinical medicine. As a population, bacteria in biofilms are more resistant to antimicrobial agents and the immune system, and they are more persistent than planktonic bacteria in hostile environments. These characteristics are likely the result of both biofilm-specific phenotypes and increased phenotypic diversity within biofilms as compared with planktonic communities of bacteria. Bacterial biofilm formation has been observed on human tissues, as well as on abiotic prosthetic devices. A better understanding of biofilm formation may lead to the development of novel antimicrobial agents as well as prosthetic devices that are resistant to bacterial colonization.