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

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.

Comparative outcomes of the pathogen in cultured Jones tubes used in lacrimal bypass surgery according to follow up periods

AIM

To evaluate the pathogens in cultured Jones tubes used in lacrimal bypass surgery according to the postoperative periods and to obtain data for the prevention of infection of functional lacrimal stent invention.

METHODS

Totally 71 patients (81 eyes) who underwent the removal of Jones tubes were enrolled in study. All the removed Jones tubes were cultured for bacterial and fungal identification and tested for bacterial antibiotic sensitivity. The results were analyzed according to the duration of the inserted Jones tube after lacrimal bypass surgery.

RESULTS

Of the 81 eyes, bacteria were isolated from 69 eyes (85.2%) and fungi from 6 eyes (7.4%). Among 69 eyes, 40.6% showed Staphylococcus aureus (S. aureus), 11.6% were Pseudomonas aeruginosa (P. aeruginosa). Gram-positive bacteria were isolated more than Gram-negative bacteria, but Gram-negative bacteria showed a higher incidence in the Jones tube implanted for over 10y (P=0.035). The antibiotic sensitivity test showed that 46.4% of S. aureus were resistant to oxacillin. In terms of antibiotics commonly used in ocular clinical practice, vancomycin was sensitive to S. aureus and Streptococcus pneumoniae (S. pneumoniae), amikacin responded to P. aeruginosa and Proteus mirabilis (P. mirabilis). Trimethoprim/sulfamethoxazole (TMP/SMX) was all sensitive to S. aureus, S. pneumoniae and P. mirabilis except P. aeruginosa.

CONCLUSION

S. aureus is the most commonly found organism in the Jones tube after lacrimal bypass surgery, and 46.4% of them are methicillin-resistant S. aureus (MRSA), sensitive to vancomycin. Especially, P. mirabilis responded with amikacin is dominantly detected in the Jones tubes implanted for more than 10y.

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.

Antibacterial efficacy of R-type pyocins against Pseudomonas aeruginosa on biofilms and in a murine model of acute lung infection

BACKGROUND

The appearance of MDR strains and the development of biofilms make Pseudomonas aeruginosa infections a therapeutic challenge. To overcome this scenario, bacteriocins have been proposed as a potential adjuvant or alternative to antibiotic treatment.

OBJECTIVES

To study the activity of R-pyocins on biofilms and in a murine model of pneumonia using a high-risk clone of P. aeruginosa.

METHODS

The activity of R-pyocins on P. aeruginosa biofilms was tested on bacteria attached to a silicone surface, before and after biofilm formation. The effectiveness of R1-pyocin was studied in a murine model of pneumonia using ST175, a high-risk clone of P. aeruginosa.

RESULTS

R-pyocins attacked adherent bacteria, preventing biofilm formation, and penetrated into the biofilm, killing P. aeruginosa within it, resulting in a dramatic reduction in bacterial load. R1-pyocin was active in a murine model of P. aeruginosa lung infection, administered before infection as a preventive treatment, and in acute pneumonia, with efficiency higher than standard colistin treatment. In addition, this work is the first to describe histopathological lung changes after administration of R-pyocins, contributing to the resolution of P. aeruginosa pneumonia in a murine model.

CONCLUSIONS

This work highlights the potential use of the R-pyocins as therapeutic agents, alone or as adjuvants, due to its effectiveness on biofilms and in a murine model of pneumonia using ST175, a high-risk clone of P. aeruginosa. It may thus be feasible to consider R-pyocins as a possible therapeutic alternative in XDR infections, where treatment alternatives are limited.

Bacterial Detection Rate and Surgical Outcome in Povidone-Iodine Irrigation After Nasolacrimal Duct Intubation

Purpose

In various ophthalmic surgical procedures, 0.25% povidone-iodine (PI) solution is used to prevent infections. This study examined the bacterial colonisation before and after endoscopic nasolacrimal duct intubation irrigated with PI solution and investigated the relationship between bacterial detection and surgical failure.

Methods

A retrospective study at Saitama Medical University Hospital. We enrolled 113 patients (33 men, 80 women) who underwent lacrimal intubation surgery between April 2016 and December 2018. Preoperatively, the lacrimal pathways were washed with normal saline solution, which was subsequently cultured. The sites of obstruction in the lacrimal pathway were endoscopically determined, perforated, and intubated. The tubes were afterward either irrigated with 0.25% PI or normal saline every 2 weeks. After 8 weeks, a piece of the removed lacrimal tube was cultured. We characterized the pre- and postoperative bacterial cultures.

Results

We enrolled 54 and 52 patients in PI and saline groups (mean age: 69.1±9.2 and 73.2±7.2 years), respectively. In the PI group, Staphylococcus epidermidis was less frequently detected postoperatively than preoperatively. S. oralis and Candida parapsilosis were identified more often postoperatively (P=0.02, P=0.01, respectively). The PI group had significantly lower bacterial detection rate than the saline group (P=0.01). However, the surgical failure rates did not differ between groups. In surgical failure patients, the postoperative rate of Pseudomonas aeruginosa was very high (75%).

Conclusion

PI reduces the bacterial detection rate but does not improve the surgical success rate. P. aeruginosa is associated with an increased risk of surgical failure.

Long-term results of maintenance of lacrimal silicone stent in patients with functional epiphora after external dacryocystorhinostomy

PURPOSE

To evaluate long-term outcomes of maintenance of lacrimal silicone stent for the management of functional epiphora after anatomically patent external dacryocystorhinostomy (DCR).

METHODS

We retrospectively reviewed the medical records of 101 eyes of 75 patients who were diagnosed to have functional epiphora after external DCR from 2005 to 2014. Functional epiphora was defined as epiphora that persisted or recurred even after patent DCR confirmed by a lacrimal irrigation test. Secondary silicone intubation was indicated when the patients wanted a further intervention. The stent was intended to be kept in situ unless there was a stent-related complication or the patient wanted removal.

RESULTS

In total, 34 of 75 patients (45.3%, 52 eyes) who agreed to the intervention underwent secondary silicone intubation. The success rates at 1, 3, and 5 years after surgery were 96.2%, 75.5%, and 70.2%, respectively. At the final follow-up (mean 72.7 ± 26.4 months), 32 (61.5%) eyes chose to retain the silicone tube: silicone stent was well maintained without epiphora and complications once inserted in 18 eyes (34.6%), whereas tube replacement was needed in 14 eyes (26.9%) because of nasal crust or whitish plaque formation on the tube surface. In 13 cases (25.0%), silicone stent was removed because of tube-related complications, and the most common complication was canaliculitis (n = 8, 15.4%).

CONCLUSIONS

Secondary intubation and maintenance of the stent is an effective and simple procedure for functional epiphora. The main obstacle to long-term maintenance is tube-associated canaliculitis.