The microbiological spectrum and antibiotic sensitivity profile of extubated silicone stents following dacryocystorhinostomy

Alterations of Lacrimal Sac Microbiota in Failed Dacryocystorhinostomy: The Lacriome Paper 6

PURPOSE

To study the metagenomics of the microbes isolated from the lacrimal sac in patients with failed dacryocystorhinostomy (DCR).

METHODS

A prospective study was performed on 10 consecutive patients with failed DCR. Lacrimal sac samples were obtained for metagenomic analysis during the revision endoscopic DCR. The samples were collected intraoperatively after a full-length lacrimal sac marsupialization and immediately transported on ice to the laboratory. A whole shotgun metagenome sequencing was performed on the IlluminaTM platform following DNA extraction and library preparation. The downstream analysis of the samples was performed using various software packaged in the Squeeze Metapipeline v1.3.0 and marker gene-based metagenomic phylogenetic analysis using MetaPhlAn4.

RESULTS

The five major phyla identified across the samples of failed DCR include Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Fusobacteria (Figure 1). The prevalent species include Stenotrophomonas maltophilia, Pseudomonas juntendi, Streptococcus pneumoniae, Acinetobacter ursingii, Citrobacter koseri, and Cutibacterium acnes (Figure 2). Among the other organisms identified, few were from genera candida and mezorhizobium. Among the viruses, the most abundant was the BeAn 58058 virus. It was interesting to note the occasional presence of plasmodium and toxoplasma species. The functional category distribution of KEGG (Kyoto encyclopedia of genes and genomes) data showed microbial metabolism to be the most involved function, followed by cellular processes.

CONCLUSION

This is the first whole metagenome sequencing of the lacrimal sac contents from failed DCR patients. The organisms identified varied significantly from those isolated from patients with primary acquired nasolacrimal duct obstruction (PANDO) using similar techniques and reflect altered lacrimal microbiota in surgically unsuccessful DCRs.

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.

Periocular Infection With Nocardia nova Following Dacryocystorhinostomy With Silicone Stent Intubation

Nocardia species are aerobic, rod-shaped, Gram-positive bacteria that are ubiquitous throughout the environment. Nocardia nova has been reported as the second most prevalent Nocardia species. However, reports of ocular and periocular infection caused by this organism are rare. The authors present a case of a 58-year-old woman with a medical history of acquired nasolacrimal duct obstruction of the left eye who underwent a revision dacryocystorhinostomy with silicone stent intubation and developed a surgical site infection that was culture-positive for N. nova . Treatment consisted of removal of the silicone stent and a prolonged course of oral antibiotics, resulting in the patient's full recovery. This is the second reported case of postoperative periocular N. nova infection after dacryocystorhinostomy and silicone stent intubation.

The influence of microorganisms on early relapses after external dacryocystorhinostomy

PURPOSE

Understanding the influence of microorganisms in patients with acquired nasolacrimal duct obstruction (NLDO) and investigating their effect on recurrence after external dacryocystorhinostomy (DCR).

METHODS

This prospective study included 50 patients. Evaluations were made before, on the first postoperative day and monthly after DCR. Nasolacrimal silicon tubes (NST) were removed after three months. Before the DCR, swab samples were taken from both hands and lower conjunctival fornices and from the lacrimal sac during the first DCR and from the relapsed cases during the second DCR.

RESULTS

Growth was observed in 90 (45%) cultures out of 200 and a total of 23 different strains were identified altogether. Staphylococcus aureus (40%) and Streptococcus pneumoniae (28%) were dominantly isolated which were all resistant to penicillin, tetracycline and erythromycin. Lacrimal syringing (LS) was successful in patients (100%) on the first postoperative day. After three months, before NST removal, purulent discharge from the punctum was observed in five patients, and blockage was detected by LS. S. pneumoniae was isolated from all five patients' obstructed side conjunctival cultures. Additionally, from their lacrimal sac, S. pneumoniae (4 patients), Capnocytophaga gingivalis, and Candida spp. (1 patient) strains were isolated. S pneumoniae was isolated in four out of five patients from the ipsilateral conjunctival and lacrimal sac cultures which obtained from the subsequent DCR.

CONCLUSION

Our results showed that S. pneumoniae was an isolated and persistent strain in cases with early recurrence even after a successful DCR.

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.

The Microbiological Profile of Bicanalicular Silicone Tubes Placed During External Dacryocystorhinostomy

Objectives:

To identify microbiological growth on bicanalicular silicone tubes (BST) placed during dacryocystorhinostomy (DCR) surgery and to analyze the association between culture results and surgical outcomes and BST removal time.

Materials and Methods:

A total of 80 lacrimal drainage systems of 68 patients who had external DCR with bicanalicular silicone intubation were included the study. Twenty-five tubes (31.3%) were removed up to 8 weeks, 28 tubes (35.0%) were removed between 9 and 11 weeks, and the remaining 27 tubes (33.7%) were removed 12 weeks or more after surgery. The tubes were transferred to Stuart medium and sent for microbiologic examination. The disc diffusion method was used to determine antibiotic resistance.

Results:

Culture positivity was observed for 96.2% of the tubes. Among a total of 109 isolates, 63 were gram-positive bacteria (57.8%), 37 were gram-negative bacteria (34%), and 9 were fungi (8.2%). The most commonly isolated gram-positive and gram-negative bacteria were Staphylococcus aureus (66.6%) and Enterobacter spp. (29.7%), respectively. Penicillin, clindamycin, erythromycin, and tetracycline resistances were higher among gram-positive pathogens. Cephalothin, amoxicillin-clavulanic acid, and ampicillin resistances were higher among gram-negative pathogens. There was no significant difference in terms of the microbiological profile between the three groups of removed tubes. Haemophilus influenzae was isolated at a significantly higher rate in patients with surgical failure (p=0.04).

Conclusion:

Although a variety of agents were isolated from removed BST, gram-positive organisms were more frequent than gramnegatives and fungi. S. aureus and Enterobacter were the most common gram-positive and gram-negative isolates. Later BST removal was associated with the isolation of significantly more bacterial strains per tube. There was no correlation between multiple infections and surgical failure. H. influenzae was more common in failed DCR cases.

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.

Nasolacrimal stent with shape memory as an advanced alternative to silicone products

Epiphora is the overflow of tears typically caused by obstruction or occlusion of the nasolacrimal duct. More attention is required to address this global health issue owing to the increase in air pollution. Implantation of a silicone stent is the preferred treatment for epiphora; however, introducing a silicone stent into a narrow duct with complex geometry is challenging as it requires guidance by a sharp metal needle. Additionally, silicone can cause adverse reactions such as biofilm formation and tear flow resistance due to its extreme hydrophobicity. To overcome these problems, in this study we developed a new type of biocompatible shape memory polymer (SMP) stent with elasticity capacity for self-expansion. First, SMPs in the form of x%poly(ε-caprolactone)-co-y%poly(glycidyl methacrylate) (x%PCL-y%PGMA) were synthesized via ring opening polymerization by varying the molar ratio of PCL (x%) and PGMA (y%). Second, the shape memory and mechanical properties were tuned by controlling the crosslinking degree and concentration of x%PCL-y%PGMA solution to produce a test type of SMP stent. Lastly, this 94%PCL-06%PGMA stent exhibited more standout critical functions in a series of in vitro and in vivo experiments such as a cell growth-supporting level of biocompatibility with nasal epithelial cells without significant inflammatory responses, better resistance to biofilm formation, and more efficient capacity to drain tear than the silicone control. Overall, 94%PCL-06%PGMA can be suggested as a superior alternative to the currently used materials for nasolacrimal stents. STATEMENT OF SIGNIFICANCE: Silicone intubation (stenting) has been widely used to treat nasolacrimal duct obstruction, however, it can cause adverse clinical effects such as bacterial infection; presents procedural challenges because of the curved nasolacrimal duct structure; and shows poor drainage efficiency stemming from the highly hydrophobic nature of silicone. In this work, we describe an innovative shape memory polymer (SMP) as a superior alternative to conventional silicone-based materials for nasolacrimal duct intubation. We demonstrate the clear advantages of the SMP over conventional silicone, including a much higher drainage capacity and superior resistance to bacterial infection.

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.

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.

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.