Microbiologic Trends and Biofilm Growth on Explanted Periorbital Biomaterials: A 30-Year Review

Microbiology and management of Staphylococcus aureus lacrimal system infections: A 10-year retrospective study

PURPOSE

To assess the in vitro efficacy of common antimicrobial agents used empirically for methicillin- resistant and sensitive Staphylococcus aureus (MRSA and MSSA) infections of the lacrimal system.

METHODS

A retrospective review of culture-proven S. aureus isolates retrieved from lacrimal system samples collected between January 2013-December 2022 was performed. Microbiologic characteristics such as in vitro susceptibility as well as clinical characteristics including history of recent ocular surgery, presence of lacrimal biomaterial implant, anti-microbial regimen, and treatments outcome were collected.

RESULTS

One hundred and sixteen S. aureus isolates (patients = 116) were identified. Thirty-one (27.4%) and 22 (19.5%) patients had recent ocular procedure and lacrimal intubation, respectively. Fifty (44.2%) patients received a combination of oral and topical antibiotics as first line of treatment. The most common empirically utilized antibiotics were β-lactams (38.9%) and polymyxin B/ trimethoprim (31.0%). The antibiotic regimen was changed at least once in 20.5% of patients due to ineffectiveness. Of the patients with positive cultures from the lacrimal excretory apparatus, 37.3% underwent surgery as part of the treatment approach. Of all isolates identified 44.8% were MRSA. Among the fluoroquinolones, the resistance rate was 38.8% for ciprofloxacin and 30.4% for moxifloxacin, with significantly higher resistance rates in MRSA (P-value <0.0001). The resistance rates for trimethoprim/sulfamethoxazole (TMP/SXT) and gentamicin were 8.6% and 3.4%, retrospectively.

CONCLUSIONS

There is low in vitro efficacy of commonly used antimicrobials such as β-lactams and fluoroquinolones in our study population; thus, we recommend opting for trimethoprim/sulfamethoxazole and gentamicin for systemic and topical single-agent treatments.

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.

Abietic Acid as a Novel Agent against Ocular Biofilms: An In Vitro and Preliminary In Vivo Investigation

Biofilm-related ocular infections can lead to vision loss and are difficult to treat with antibiotics due to challenges with application and increasing microbial resistance. In turn, the design and testing of new synthetic drugs is a time- and cost-consuming process. Therefore, in this work, for the first time, we assessed the in vitro efficacy of the plant-based abietic acid molecule, both alone and when introduced to a polymeric cellulose carrier, against biofilms formed by Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans in standard laboratory settings as well as in a self-designed setting using the topologically challenging surface of the artificial eye. These analyses were performed using the standard microdilution method, the biofilm-oriented antiseptic test (BOAT), a modified disk-diffusion method, and eyeball models. Additionally, we assessed the cytotoxicity of abietic acid against eukaryotic cell lines and its anti-staphylococcal efficacy in an in vivo model using Galleria mellonella larvae. We found that abietic acid was more effective against Staphylococcus than Pseudomonas (from two to four times, depending on the test applied) and that it was generally more effective against the tested bacteria (up to four times) than against the fungus C. albicans at concentrations non-cytotoxic to the eukaryotic cell lines and to G. mellonella (256 and 512 µg/mL, respectively). In the in vivo infection model, abietic acid effectively prevented the spread of staphylococcus throughout the larvae organisms, decreasing their lethality by up to 50%. These initial results obtained indicate promising features of abietic acid, which may potentially be applied to treat ocular infections caused by pathogenic biofilms, with higher efficiency manifested against bacterial than fungal biofilms.

Scanning electron microscopic features of lacrimal drainage silastic stents: Comparison of various Crawford and large-diameter stents

PURPOSE

This study aimed to examine the differences in the biofilms and physical deposits on Crawford stents compared to large-diameter stents.

METHODS

A prospective interventional study was performed on a series of patients undergoing external or endoscopic dacryocystorhinostomy (DCR) and endoluminal lacrimal duct recanalization (ELDR) with either Crawford or large-diameter stents. All the Crawford stents were retrieved at six weeks and the large-diameter ones at eight weeks following the surgical intervention. There was no evidence of post-operative infection in any of the patients. Following extubation, standard protocols of scanning electron microscopy were used to assess the biofilms and physical deposits on the stents.

RESULTS

A total of 15 stents were studied. Of these, twelve were Crawford, and three were large-diameter stents. The Crawford stents were from two different manufacturers. All the stents demonstrated evidence of biofilm formation and physical deposits. The Crawford stents showed thin biofilms and sparse physical deposits, but there were no demonstrable differences amongst stents from different manufacturers. However, the deposits and biofilms were thicker and more extensive in the large-diameter stents than the Crawford ones. The biofilms from all stents showed the presence of polymicrobial communities within the exopolysaccharide matrix.

CONCLUSIONS

The present study found differences in biofilms and physical deposits between Crawford and large-diameter stents. These differences can be partly explained by stent duration, size, and their tissue interactions.

Microbial Metagenomics of the Extubated Lacrimal Stents Following Dacryocystorhinostomy: The Lacriome Paper 4

PURPOSE

To study the metagenome of the microbes present on the extubated lacrimal stents following a dacryocystorhinostomy.

METHODS

A prospective study was performed on 10 consecutive extubated lacrimal stents obtained for the metagenomic analysis from the patients following an endoscopic dacryocystorhinostomy. The stents were extubated at 4 weeks postoperatively under endoscopic guidance and immediately transported on ice to the laboratory. Following DNA extraction and library preparation, a whole shotgun metagenome sequencing was performed on the Illumina platform. The downstream processing and bioinformatics of the samples were performed using multiple software packaged in SqueezeMeta pipeline or MG-RAST pipeline.

RESULTS

The taxonomic hit distribution across the stent samples showed that bacteria were the most common isolates (mean, 69.70%), followed by viruses (mean, 0.02%) and archaea (0.003%). The 3 major phyla identified were Firmicutes, Actinobacteria, and Proteobacteria. The prevalent organisms include Pseudomonas aeruginosa, Staphylococcus aureus, Corynebacterium accolens, Dolosigranulum pigrum, Citrobacter koserii, Staphylococcus epidermidis, E. coli, and Hemophilus influenza . The functional subsystem profiling demonstrated microbial genes associated with metabolism, cellular, and information processing. The functional subsystem categories were metabolism involving carbohydrates, amino acids, DNA and RNA, cell wall or cell capsule biogenesis, membrane transport, virulence, and defense mechanisms.

CONCLUSIONS

The present study is the first whole metagenome sequencing of the microbes isolated from the extubated lacrimal stents. The stents harbor diverse microbial communities with distinct ecosystem dynamics. Further studies on microbes-host interactions in the early postoperative period would provide valuable insights.

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.

A Complication of Mycobacterium chelonae Infection Following Orbital Floor Fracture Repair

ABSTRACT

Mycobacterium chelonae is a rare, atypical nontuberculous bacterium that has been reported to be an underlying cause of persistent wound infections. Although there are several studies highlighting the role of M chelonae as the putative cause of other postoperative wound infections, to our knowledge there are no reports of infection following implant placement for repair of an orbital floor fracture. The authors present a unique case describing the management of a persistent postoperative infection in a young, immunocompetent patient with an orbital floor fracture repaired with a Stryker Medpor Titan implant. The patient was initially treated with broad-spectrum antibiotics with minimal clinical improvement. Following culture-proven M chelonae, a second surgical intervention was undertaken to remove the implant and later, a third intervention for scar revision. The patient has remained free of infection utilizing a long-term tailored 2-drug antibiotic regimen. This case emphasizes the need for recognition of M chelonae as a potential pathogen in certain clinical situations and the difficulty in eradicating M chelonae in the context of infected implantable devices. The comprehensive treatment protocol required to ensure adequate therapy is reviewed.

Ultra-thin, high strength, antibiotic-eluting sutures for prevention of ophthalmic infection

Sutures are applied almost universally at the site of trauma or surgery, making them an ideal platform to modulate the local, postoperative biological response, and improve surgical outcomes. To date, the only globally marketed drug-eluting sutures are coated with triclosan for antibacterial application in general surgery. Loading drug directly into the suture rather than coating the surface offers the potential to provide drug delivery functionality to microsurgical sutures and achieve sustained drug delivery without increasing suture thickness. However, conventional methods for drug incorporation directly into the suture adversely affect breaking strength. Thus, there are no market offerings for drug-eluting sutures, drug-coated, or otherwise, in ophthalmology, where very thin sutures are required. Sutures themselves help facilitate bacterial infection, and antibiotic eye drops are commonly prescribed to prevent infection after ocular surgeries. An antibiotic-eluting suture may prevent bacterial colonization of sutures and preclude patient compliance issues with eye drops. We report twisting of hundreds of individual drug-loaded, electrospun nanofibers into a single, ultra-thin, multifilament suture capable of meeting both size and strength requirements for microsurgical ocular procedures. Nanofiber-based polycaprolactone sutures demonstrated no loss in strength with loading of 8% levofloxacin, unlike monofilament sutures which lost more than 50% strength. Moreover, nanofiber-based sutures retained strength with loading of a broad range of drugs, provided antibiotic delivery for 30 days in rat eyes, and prevented ocular infection in a rat model of bacterial keratitis.

Developing the rabbit canalicular injury model: Biophysical changes of masterkaR stents and implications for future research

BACKGROUND

To describe the preparation of a rabbit lacrimal canalicular injury model, assess the canalicular healing, and determine the suitability of this model to study the biophysical changes of mono-canalicular stents.

METHODS

Twelve canaliculi of twelve eyes of six healthy New Zealand white rabbits were included in the study. A canalicular injury model was prepared under general anesthesia. The injury was then repaired using modified Masterka^R stents and peri-canalicular wound closure. The stents were extubated at eight weeks, and specific surgical techniques used to obtain the healed canaliculi. Histopathological analysis was carried out on the canaliculi samples, and the stents were examined ultra-structurally using the scanning electron microscopy (SEM).

RESULTS

At eight weeks, the canaliculus maintained its integrity and demonstrated good healing with epithelium continuity. However, the area of incision and suture showed hyperplastic epithelium with significant sub-epithelial fibrosis. Lacrimal irrigation following stent extubation confirmed patency of all the canalicular systems studied. SEM study revealed the biofilm formation and physical deposits over the external, luminal, and adluminal surfaces of all Masterka^R stents with intervening skip areas. Although these changes were seen all over the stent, the most preferential site for physical deposits and biofilm aggregates was the ampullary portion of the stent's head. None of the rabbits showed any evidence of a post-operative ocular infection or local inflammation.

CONCLUSION

Rabbits are good candidates for the preparation of a lacrimal canalicular injury model. The canalicular tissues demonstrate changes following repair. The biophysical changes on the extubated stents resembled those obtained from the humans.

Do Mixed-Species Biofilms Dominate in Chronic Infections?-Need for in situ Visualization of Bacterial Organization

Chronic infections present a serious economic burden to health-care systems. The severity and prevalence of chronic infections are continuously increasing due to an aging population and an elevated number of lifestyle related diseases such as diabetes. Treatment of chronic infections has proven difficult, mainly due to the presence of biofilms that render bacteria more tolerant toward antimicrobials and the host immune response. Chronic infections have been described to harbor several different bacterial species and it has been hypothesized that microscale interactions and mixed-species consortia are present as described for most natural occurring biofilms i.e., aquatic systems and industrial settings, but also for some commensal human biofilms i.e., the mouth microbiota. However, the presence of mixed-species biofilms in chronic infections is most often an assumption based on culture-based methods and/or by means of molecular approaches, such as PCR and sequencing performed from homogenized bulk tissue samples. These methods disregard the spatial organization of the bacterial community and thus valuable information on biofilm aggregate composition, spatial organization, and possible interactions between different species is lost. Hitherto, only few studies have made visual in situ presentations of mixed-species biofilms in chronic infections, which is pivotal for the description of bacterial composition, spatial distribution, and interspecies interaction on the microscale. In order for bacteria to interact (synergism, commensalism, mutualism, competition, etc.) they need to be in close proximity to each other on the scale where they can affect e.g., solute concentrations. We argue that visual proof of mixed species biofilms in chronic infections is scarce compared to what is seen in e.g., environmental biofilms and call for a debate on the importance of mixed-species biofilm in chronic infections.

A Case of Pseudomonas Orbital Cellulitis Following Glaucoma Device Implantation

PURPOSE

Orbital cellulitis is a rare complication of aqueous tube shunt surgery. Nine cases have been described in the literature, though the microbiologic etiology is rarely reported. Management with intravenous antibiotics and/or explantation has been described.

METHODS

This is a case report and literature review.

CASE

A 64-year-old woman developed pain, periorbital swelling, limited extraocular motility, proptosis, and conjunctival injection 3 days following implantation of an Ahmed Glaucoma Valve. Computed tomography of the orbits with contrast showed soft tissue fat stranding consistent with orbital inflammation. Initial medical management with topical and intravenous ceftriaxone and vancomycin was unsuccessful. Surgical removal of the implant was performed and intraoperative cultures demonstrated florid Pseudomonas aeruginosa growth. Antibiotic coverage was changed to Piperacillin-Tazobactam for 3 days, with eventual resolution of her orbital symptoms.

CONCLUSIONS

We report the first case of orbital cellulitis after implantation of a glaucoma device associated with P. aeruginosa. Failure of intravenous and topical antibiotics led to explantation of the valve and targeted intravenous antibiotic therapy with subsequent clinical improvement.

Evaluation of bacterial adhesion in exposed orbital implants using electron microscopy and microbiological culture

Three cases are presented of anophthalmic patients with exposed orbital implants. Although only one patient showed evident clinical signs of infection, all three implants were studied to determine the presence of microorganisms adhered to their surface using a scanning electron microscopy (SEM) and microbiological culture. The SEM allowed the visualisation of microorganisms adhered to the three implants, although only one of them showed growth in the microbiological cultures. In addition, the SEM technique used in case No.3 achieved a better orientation and appreciation of the microorganisms with respect to the images of cases No.1 and2. These findings support the idea that the surface of exposed orbital implants is colonised by microorganisms, even when they still do not show obvious signs of infection. Therefore, mechanical removal of the exposed surface of the implant is necessary before covering it with grafts or flaps.

Ultrastructure of the lacrimal drainage system in health and disease: A major review

PURPOSE

To provide a systematic review of the literature on the ultrastructural findings of the lacrimal drainage system in healthy state and in few of the disorders studied so far.

METHODS

The authors performed a PubMed search of all articles published with reference to electron microscopic features of the lacrimal drainage pathways. Data captured include demographics, study techniques, scanning or transmission electron microscopic features, presumed or confirmed interpretations and their implications. Specific emphasis was laid on addressing the lacunae and potential directions for future research.

RESULTS

Ultrastructural studies have led to better understanding of the lacrimal drainage anatomy-physiology correlations. Cellular interactions between fibroblasts and lymphocytes could form a basis for pathogenesis of punctal stenosis. Ultrastructural characterization of peri-lacrimal cavernous bodies and changes in primary acquired nasolacrimal duct obstruction (PANDO) led to them being partly implicated in its etiopathogenesis. Electron microscopic characterization of the dacryolith core promises insights into their evolution. Ultrastructural tissue effects of mitomycin-C during a DCR surgery has provided potential evidence of its role in cases with high-risk of failure. Lacrimal stent biofilms are common but their clinical implications are currently uncertain.

CONCLUSION

Ultrastructural exploration of lacrimal drainage system so far has been limited and sparsely explored. The list of unexplored areas is exhaustive. There is a need for the lacrimal Clinician-Scientist to make themselves familiar with techniques and interpretation of electron microscopy to advance the ultrastructural frontier of this science.

Historical evolution of the diseases caused by non-pigmented rapidly growing mycobacteria in a University Hospital

OBJECTIVE

Non-pigmented rapidly growing mycobacteria (NPRGM) are a group of organisms of increasing interest due to the growing number of potential patients and the difficulties for a proper treatment in many of them. However, the evolution of these diseases in a long period of time and its evolutionary changes has been described only in a scanty number of reports.

METHODS

We performed a retrospective study between January 1st 2004 and December 31st 2017 in order to evaluate the clinical significance and types of diseases caused by NPRGM. Patients with isolates of NPRGM during this period were selected for the study, and clinical charts were reviewed using a predefined protocol.

RESULTS

During this period we identified 59 patients (76 clinical samples) with isolates of NPRGM, with 12 cases of clinical disease and one patient with doubtful significance (including 6 respiratory tract infections, 2 catheter infections, 1 skin and soft tissue infection, 1 disseminated infection, 1 conjunctivitis, 1 prosthetic joint infection and 1 mastitis). Fifty percent of M. chelonae isolates, 37.5% of M. abscessus isolates and 23.33% of M. fortuitum isolates were clinically significant. None of the isolates of other species were significant.

CONCLUSIONS

Most isolates in respiratory samples were contaminants/colonizations. M. abscessus was the main etiological agent in respiratory syndromes, whereas M. chelonae and M. fortuitum were more frequently associated with other infections, especially clinical devices and skin and soft tissue infections.

In vitro adherence of conjunctival bacteria to different oculoplastic materials

AIM

To investigate the resistance to bacterial adhesion of materials used in oculoplastic surgery, particularly materials used in the manufacture of orbital implants.

METHODS

Seven organisms of conjunctival flora (two strains of Staphylococcus epidermidis and one strain each of Staphylococcus aureus, Staphylococcus hominis, Corynebacterium amycolatum, Acinetobacter calcoaceticus, and Serratia marcescens) were selected. A lactic acid bacterium (Lactobacillus rhamnosus) was also included as positive control because of its well-known adhesion ability. Eight materials used to make oculoplastic prostheses were selected (glass, steel, polytetrafluoroethylene, polymethylmethacrylate, silicone from orbital implants, commercial silicone, porous polyethylene, and semi-smooth polyethylene). Materials surfaces and biofilms developed by strains were observed by scanning electron microscopy. Kinetics of growth and adhesion of bacterial strains were determined by spectrophotometry. Each strain was incubated in contact with plates of the different materials. After growth, attached bacteria were re-suspended and colony-forming units (CFUs) were counted. The number of CFUs per square millimetre of material was statistically analyzed.

RESULTS

A mature biofilm was observed in studied strains except Staphylococcus hominis, which simply produced a microcolony. Materials showed a smooth surface on the microbial scale, although steel exhibited 1.0-µm-diameter grooves. Most organisms showed significant differences in adhesion according to the material. There were also significant differences in the total number of CFUs per square millimetre from each material (P=0.044). CFU counts were significantly higher in porous polyethylene than in silicone from orbital implants (P=0.038).

CONCLUSION

Silicone orbital implants can resist microbial colonization better than porous polyethylene implants.

Cultures of Proximal and Distal Segments of Silicone Tubes After Dacryocystorhinostomy

PURPOSE

To compare the results of cultures of the proximal and distal segments of silicone tubes after dacryocystorhinostomy.

METHODS

The medical records of patients undergoing a dacryocystorhinostomy and silicone intubation were reviewed. The inclusion criteria were cultures of both distal and proximal stent segments after removal, dye testing, evaluation of the tear meniscus, and notation of the presence or absence of discharge before and after removal. The exclusion criteria included the use of systemic or topical antibiotics within 1 month before tube removal.

RESULTS

Forty-six lacrimal systems in 40 patients were included, with 6 patients having bilateral dacryocystorhinostomies. There were no cases of dacryocystitis at the time of or after tube removal. Four (9%) of the dacryocystorhinostomies failed. Forty-one (89%) of the distal tube segments had positive cultures. The distal tube cultures grew 17 (36%) gram-positive bacteria, 21 (45%) gram-negative bacteria, 7 (15%) skin flora, and 2 (4%) fungi (6 distal segments had mixed cultures). Thirteen (28%) of the proximal tube segments had positive cultures. The proximal tube cultures were 5 (38%) gram-negative bacteria, 4 (31%) gram-positive bacteria, 3 (23%) skin flora, and 1 (8%) acid-fast bacteria. Four (31%) of the proximal tubes with positive cultures grew the same organism as the distal tube segment. Nine (69%) of the proximal tubes with positive cultures grew different organisms than the distal segment. Forty-two (91%) of all the proximal tube cultures were either negative or grew different organisms than the distal segment cultures.

CONCLUSIONS

The proximal segment of a silicone tube after a dacryocystorhinostomy may be a "privileged" area. There is usually a lack of growth or the growth of different organisms than those present on the distal tube segments. This may be explained by the protective nature of the tear film. The findings may also help to explain the low incidence of dacryocystitis in spite of the growth of virulent organisms on the distal tube segment after a dacryocystorhinostomy.

Species-specific characteristics of the biofilm generated in silicone tube: an in vitro study

Background

To investigate characteristics of biofilm which is usually found in silicone tube for nasolacrimal duct surgery and can be the root of chronic bacterial infections eventually resulted in surgical failure.

Methods

To form a biofilm, sterile silicone tube was placed in culture media of Staphylococcus aureus, Corynebacterium matruchotii, Pseudomonas aeruginosa, or Streptococcus pneumonia. Biofilms formed on these silicone tubes were fixed with 95% ethanol and stained with 0.1% crystal violet. After staining, the optical densities of biofilms were measured using spectrophotometer on a weekly basis for 12 weeks.

Results

Staphylococcus aureus group and Pseudomonas aeruginosa group formed significantly more amounts of biofilms compared to the control group. The maximum optical densities of the two groups were found on week 3–4 followed by a tendency of decrease afterwards. However, the amounts of biofilms formed in other groups of silicone tubes were not statistically significant from that of the control group.

Conclusions

Bacterial species that could form biofilm on silicone tube included Staphylococcus aureus (week 3) and Pseudomonas aeruginosa (Week 4). It is important to first consider that the cause of infection around 1 month after silicone tube intubation can be Staphylococcus aureus and Pseudomonas aeruginosa.

Bacterial Biofilms in Jones Tubes

PURPOSE

To investigate the presence and microbiology of bacterial biofilms on Jones tubes (JTs) by direct visualization with scanning electron microscopy and polymerase chain reaction (PCR) of representative JTs, and to correlate these findings with inflammation and/or infection related to the JT.

METHODS

In this study, prospective case series were performed. JTs were recovered from consecutive patients presenting to clinic for routine cleaning or recurrent irritation/infection. Four tubes were processed for scanning electron microscopy alone to visualize evidence of biofilms. Two tubes underwent PCR alone for bacterial quantification. One tube was divided in half and sent for scanning electron microscopy and PCR. Symptoms related to the JTs were recorded at the time of recovery.

RESULTS

Seven tubes were obtained. Five underwent SEM, and 3 out of 5 showed evidence of biofilms (60%). Two of the 3 biofilms demonstrated cocci and the third revealed rods. Three tubes underwent PCR. The predominant bacteria identified were Pseudomonadales (39%), Pseudomonas (16%), and Staphylococcus (14%). Three of the 7 patients (43%) reported irritation and discharge at presentation. Two symptomatic patients, whose tubes were imaged only, revealed biofilms. The third symptomatic patient's tube underwent PCR only, showing predominantly Staphylococcus (56%) and Haemophilus (36%) species. Two of the 4 asymptomatic patients also showed biofilms. All symptomatic patients improved rapidly after tube exchange and steroid antibiotic drops.

CONCLUSIONS

Bacterial biofilms were variably present on JTs, and did not always correlate with patients' symptoms. Nevertheless, routine JT cleaning is recommended to treat and possibly prevent inflammation caused by biofilms.

Intervention using a novel biodegradable hollow stent containing polylactic acid-polyprolactone-polyethylene glycol complexes against lacrimal duct obstruction disease

Lacrimal duct obstruction disease (LDOD) is a common ophthalmologic disease. Stent implantation surgery is one of the most effective therapies. In this study, we intended to find out the satisfactory biodegradable stents containing poly-L-lactic acid-polycaprolactone-polyethylene glycol (PLLA- PCL- PEG) complexes for therapeutic application in LDOD. Stents made of PLLA- PCL- PEG complexes in various ratios, were prepared and used in vitro to determine stents with appropriate mechanical properties and shorter range of bio-degradation for study in vivo. Thirty-two rabbits were randomized into eight groups of four eyes each in advance for test in vivo. The selected stents were implanted into the left lacrimal ducts of 16 rabbits and silica gel stents as the control for the other 16 rabbits. At four points in time (1, 4, 10 and 16 weeks after the implantation), weight loss rate (WLR) of the stents was measured and analysed. To access the change of lacrimal duct, fluorescein excretion test, lacrimal duct endoscopy and histopathological testing were conducted. The stent containing PLLA: PCL6: 4+ 15%PEG was selected for study in vivo. Analysis of weight loss rate (WLR), fluorescein excretion test, lacrimal duct endoscopy and histopathological testing indicated that the selected stent was biodegradable and caused minimal stimulation and earlier tissue restoration in the lacrimal epithelium compared with the silica gel stent used as the control. The study results suggest that the PLLA: PCL6: 4+ 15% PEG stent is a satisfactory biodegradable stent as a promising alternative for therapeutic application in LDOD, which showed tissue compatibility, biodegradation and adequate mechanical intensity.

Microbiology and Biofilm Trends of Silicone Lacrimal Implants: Comparing Infected Versus Routinely Removed Stents

PURPOSE

To investigate the pathogens and biofilms responsible for clinically significant infection of silicone stents implanted within the lacrimal system.

METHODS

Retrospective review of culture results and patient demographics for all silicone lacrimal stents removed early for clinically significant infection and sent to the Bascom Palmer Microbiology Laboratory through the end of year 2010. As a control, routinely removed, clinically noninfected stents from the same institution were prospectively sent for culture over a 6-month period. Four clinically infected and 6 clinically noninfected stents showing mucus within the lumen at removal were sent for scanning electron microscopy. Images were randomized and graded by a microbiologist for the presence of organisms, matrix deposits, organisms within matrix, and overall impression of significant biofilm formation.

RESULTS

Nineteen stents were included in the study; 100% of clinically infected (n = 10) and noninfected (n = 9) stents were culture positive. Culture positivity for nontuberculous mycobacterium was found in 90% of infected stents and none of the noninfected stents (p < 0.001). Of infected stents, 50% grew Gram-positive organisms compared with 89% of noninfected stents (p = 0.07). Fifty percent of infected versus 67% of noninfected stents were culture positive for Gram-negative organisms (p = 0.46). Electron microscopy of stents revealed organisms consistent with culture results (size, shape) in planktonic and biofilm form. Masked observer image grading revealed a statistically significant higher amount of organism and biofilm on infected versus noninfected specimen.

CONCLUSION

Nontuberculous mycobacteria comprise the primary pathogens responsible for clinically significant infection of silicone stents in the lacrimal system in South Florida. Robust biofilm production by this organism likely plays a role in pathogenesis. Further research into biofilm-related lacrimal implant infection may aid in the development of useful prevention and treatment strategies.

Conjunctival bacterial flora in fellow eyes of patients with unilateral nasolacrimal duct obstruction and its changes after successful dacryocystorhinostomy surgery

PURPOSE

To evaluate the results of conjunctival culture in fellow eyes of patients with unilateral nasolacrimal duct obstruction (NLDO) and its changes after successful dacryocystorhinostomy (DCR) surgery.

METHODS

In this prospective study, 71 adult patients with unilateral NLDO and 41 age and sex-matched controls without NLDO were evaluated. The patients were divided into 2 groups based on clinical examination; group A with purulent regurgitation and group B without purulent regurgitation. They all underwent DCR. Before DCR surgery, microbiologic specimens were taken bilaterally from the conjunctiva of both eyes. Postoperative conjunctival sampling was continued weekly until the culture became negative or the colony count reached to the range of the control group.

RESULTS

There were 38 and 33 patients in groups A and B, respectively. Silicone tube was inserted for 17 patients (23.9%). The culture was positive for bacterial growth in 56 fellow eyes (79%). The conjunctival culture in the control group was positive in 17 eyes (41.4%). The mean count of colonies in a sample unit was 624.73 ± 2412.31, 195.75 ± 407.56, and 9.5 ± 1.5 for group A, group B, and controls, respectively. The mean time of normalization of specimens was 1.43 ± 0.69 weeks (range 1-4). Higher colony count at baseline and presence of silicone tube in infected eye were significantly associated with longer normalization time for fellow eye (P < 0.001 and P = 0.003 respectively).

CONCLUSIONS

This study suggests that after successful DCR surgery, a waiting period of 4 weeks is needed for conjunctival bacterial cultures to become negative or reach the level of the normal eyes, in the fellow eyes of patients with unilateral NLDO.

Delayed onset porous polyethylene implant-related inflammation after orbital blowout fracture repair: four case reports

Background

Porous polyethylene implants are commonly used in orbital blowout fracture repair because of purported biocompatibility, durability, and low frequency of complications. Delayed inflammation related to porous polyethylene sheet implants is very rare and no case series of this condition have been reported.

Case Presentation

This is a retrospective review of clinical presentations, radiographic findings, histopathological findings, treatments, and outcomes of patients who developed delayed complications in orbital blowout fracture repair using porous polyethylene sheets. Four male patients were included with a mean age of 49 years (range 35–69 years). Blowout fracture repair was complicated with implant-related inflammation 10 months, 2 years, 3 years, and 8 years after surgery. Chronic and subacute orbital inflammatory signs were noted in two patients and acute fulminant orbital inflammation was found in two patients. Three patients developed peri-implant abscesses and one patient had a soft tissue mass around the implant. All patients underwent implant removal and two of these patients with paranasal sinusitis had sinus surgery. Histopathological findings revealed chronic inflammatory changes with fibrosis, and one patient had foreign body granuloma with culture positive Staphylococcus aureus.

Conclusions

Delayed complications with porous polyethylene sheets used in orbital blowout fracture repair may occur many years following the initial surgery in immunocompetent patients. Low-grade or fulminant inflammation could complicate blowout fracture repair related with the implant.

Visual recovery following open globe injury with initial no light perception

Background

The purpose of this study was to analyze eyes presenting with no light perception (NLP) after open globe injury (OGI) to determine visual outcomes and prognostic indicators for visual recovery.

Methods

The records of consecutive patients with at least 6 months of follow-up presenting with OGI and NLP to a single institution between January 1, 2003 and December 31, 2013 were reviewed for demographics, ophthalmic history, context and characteristics of injury, ocular examination findings, surgical interventions, and follow-up visual acuity. Unpaired t-tests and Fisher’s Exact tests were used for statistical analysis.

Results

Twenty-five patients met our inclusion criteria. The mean age was 50.4±25.5 (range 8–91) years. Four patients (16%) regained vision (hand motion in three patients and light perception in one patient) while 21 patients (84%) remained with NLP or had a prosthesis at final follow-up. Fourteen eyes (56%) were enucleated; nine (36%) were secondary enucleations. Although the sample sizes were small, neither ocular trauma score nor wound size was found to predict visual recovery.

Conclusion

Four patients regained some vision after presenting with NLP due to OGI. These findings suggest that, in select cases, physicians should discuss the possibility of regaining some vision.

Multisite Infection with Mycobacterium abscessus after Replacement of Breast Implants and Gluteal Lipofilling

Introduction. Medical tourism for aesthetic surgery is popular. Nontuberculous mycobacteria (NTM) occasionally cause surgical-site infections. As NTM grow in biofilms, implantations of foreign bodies are at risk. Due to late manifestation, infections occur when patients are back home, where they must be managed properly. Case Report. A 39-year-old healthy female was referred for acute infection of the right gluteal area. Five months before, she had breast implants replacement, abdominal liposuction, and gluteal lipofilling in Mexico. Three months postoperatively, implants were removed for NTM-infection in Switzerland. Adequate antibiotic treatment was stopped after seven days for drug-related hepatitis. At entrance, gluteal puncture for bacterial analysis was performed. MRI showed large subcutaneous collection. Debridement under general anaesthesia was followed by open wound management. Total antibiotic treatment was 20 weeks. Methods. Bacterial analysis of periprosthetic and gluteal liquids included Gram-stain plus acid-fast stain, and aerobic, anaerobic and mycobacterial cultures.  Results. In periprosthetic fluid, Mycobacterium abscessus, Propionibacterium, and Staphylococcus epidermidis were identified. The same M. abscessus strain was found gluteally. The gluteal wound healed within six weeks. At ten months' follow-up, gluteal asymmetry persists for deep scarring. Conclusion. This case presents major complications of multisite aesthetic surgery. Surgical-site infections in context of medical tourism need appropriate bacteriological investigations, considering potential NTM-infections.

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.

Biofilm formation by clinical isolates and its relevance to clinical infections

Reports of biofilms have increased exponentially in the scientific literature over the past two decades, yet the vast majority of these are basic science investigations with limited clinical relevance. Biofilm studies involving clinical isolates are most often surveys of isolate collections, but suffer from lack of standardization in methodologies for producing and assessing biofilms. In contrast, more informative clinical studies correlating biofilm formation to patient data have infrequently been reported. In this chapter, biofilm surveys of clinical isolates of aerobic and anaerobic bacteria, mycobacteria, and Candida are reviewed, as well as those pertaining to the unique situation of cystic fibrosis. In addition, the influence of host components on in vitro biofilm formation, as well as published studies documenting the clinical impact of biofilms in human infections, are presented.

Clinical and microbiological aspects of biofilm-associated surgical site infections

While microbial biofilms have been recognized as being ubiquitous in nature for the past 40 years, it has only been within the past 20 years that clinical practitioners have realized that biofilm play a significant role in both device-related and tissue-based infections. The global impact of surgical site infections (SSIs) is monumental and as many as 80 % of these infections may involve a microbial biofilm. Recent studies suggest that biofilm- producing organisms play a significant role in persistent skin and soft tissue wound infections in the postoperative surgical patient population. Biofilm, on an organizational level, allows bacteria to survive intrinsic and extrinsic defenses that would inactivate the dispersed (planktonic) bacteria. SSIs associated with biomedical implants are notoriously difficult to eradicate using antibiotic regimens that would typically be effective against the same bacteria growing under planktonic conditions. This biofilm-mediated phenomenon is characterized as antimicrobial recalcitrance, which is associated with the survival of a subset of cells including "persister" cells. The ideal method to manage a biofilm-mediated surgical site wound infection is to prevent it from occurring through rational use of antibiotic prophylaxis, adequate skin antisepsis prior to surgery and use of innovative in-situ irrigation procedures; together with antimicrobial suture technology in an effort to promote wound hygiene at the time of closure; once established, biofilm removal remains a significant clinical problem.