Proper understanding of recurrent stress urinary incontinence treatment in women (PURSUIT): a randomised controlled trial of endoscopic and surgical treatment

BACKGROUND

Women with stress urinary incontinence (SUI) experience urine leakage with physical activity. Currently, the interventional treatments for SUI are surgical, or endoscopic bulking injection(s). However, these procedures are not always successful, and symptoms can persist or come back after treatment, categorised as recurrent SUI. There are longstanding symptoms and distress associated with a failed primary treatment, and currently, there is no consensus on how best to treat women with recurrent, or persistent, SUI.

METHODS

A two-arm trial, set in at least 20 National Health Service (NHS) urology and urogynaecology referral units in the UK, randomising 250 adult women with recurrent or persistent SUI 1:1 to receive either an endoscopic intervention (endoscopic bulking injections) or a standard NHS surgical intervention, currently colposuspension, autologous fascial sling or artificial urinary sphincter. The aim of the trial is to determine whether surgical treatment is superior to endoscopic bulking injections in terms of symptom severity at 1 year after randomisation. This primary outcome will be measured using the patient-reported International Consultation on Incontinence Questionnaire - Urinary Incontinence - Short Form (ICIQ-UI-SF). Secondary outcomes include assessment of longer-term clinical impact, improvement of symptoms, safety, operative assessments, sexual function, cost-effectiveness and an evaluation of patients' and clinicians' views and experiences of the interventions.

DISCUSSION

There is a lack of high-quality, randomised, scientific evidence for which treatment is best for women presenting with recurrent SUI. The PURSUIT study will benefit healthcare professionals and patients and provide robust evidence to guide further treatment and improve symptoms and quality of life for women with this condition.

TRIAL REGISTRATION

International Standard Randomised Controlled Trials Number (ISRCTN) registry ISRCTN12201059. Registered on 09 January 2020.

Tertiary Lymphoid Organs: A Primer for Otolaryngologists

OBJECTIVES/HYPOTHESIS

Lymphoid neogenesis or the development of organised, de novo lymphoid structures has been described increasingly in chronically inflamed tissues. The presence of tertiary lymphoid organs (TLOs) has already been demonstrated to result in significant consequences for disease pathology, severity, prognosis and patient outcomes. Whilst the wider medical community has embraced TLOs as important markers of disease and potential therapeutic targets, the otolaryngology field has only begun turning to these entities in an academic capacity. This review aims to outline the role of tertiary lymphoid organs in disease and summarise key early findings in the ENT field. We also an overview of TLOs, their developmental process and clinicopathological implications.

STUDY DESIGN

Literature review.

METHODS

A literature search for all relevant peer-reviewed publications pertaining to TLOs and ENT diseases. Search was conducted using PubMed, Embase and CINAHL databases.

RESULTS

A total of 24 studies were identified relevant to the topic. The majority of TLO research in ENT fell into the areas of oral squamous cell carcinoma (SCC) and chronic rhinosinusitis (CRS).

CONCLUSIONS

Early research into both oral SCC and CRS suggests that TLOs have significant roles within ear, nose and throat (ENT) diseases. At this point in time, however, TLOs remain somewhat a mystery amongst otolaryngologists. As information in this field increases, we may develop a better understanding of how lymphoid neogenesis can influence disease outcomes amongst our patients and, ultimately, how they can be utilised in an immunotherapeutic manner. Laryngoscope, 131:1697-1703, 2021.

The international sinonasal microbiome study: A multicentre, multinational characterization of sinonasal bacterial ecology

The sinonasal microbiome remains poorly defined, with our current knowledge based on a few cohort studies whose findings are inconsistent. Furthermore, the variability of the sinus microbiome across geographical divides remains unexplored. We characterize the sinonasal microbiome and its geographical variations in both health and disease using 16S rRNA gene sequencing of 410 individuals from across the world. Although the sinus microbial ecology is highly variable between individuals, we identify a core microbiome comprised of Corynebacterium, Staphylococcus, Streptococcus, Haemophilus and Moraxella species in both healthy and chronic rhinosinusitis (CRS) cohorts. Corynebacterium (mean relative abundance = 44.02%) and Staphylococcus (mean relative abundance = 27.34%) appear particularly dominant in the majority of patients sampled. Amongst patients suffering from CRS with nasal polyps, a statistically significant reduction in relative abundance of Corynebacterium (40.29% vs 50.43%; P = .02) was identified. Despite some measured differences in microbiome composition and diversity between some of the participating centres in our cohort, these differences would not alter the general pattern of core organisms described. Nevertheless, atypical or unusual organisms reported in short-read amplicon sequencing studies and that are not part of the core microbiome should be interpreted with caution. The delineation of the sinonasal microbiome and standardized methodology described within our study will enable further characterization and translational application of the sinus microbiota.

Strategies to Improve Recruitment to a De-escalation Trial: A Mixed-Methods Study of the OPTIMA Prelim Trial in Early Breast Cancer

AIMS

De-escalation trials are challenging and sometimes may fail due to poor recruitment. The OPTIMA Prelim randomised controlled trial (ISRCTN42400492) randomised patients with early stage breast cancer to chemotherapy versus 'test-directed' chemotherapy, with a possible outcome of no chemotherapy, which could confer less treatment relative to routine practice. Despite encountering challenges, OPTIMA Prelim reached its recruitment target ahead of schedule. This study reports the root causes of recruitment challenges and the strategies used to successfully overcome them.

MATERIALS AND METHODS

A mixed-methods recruitment intervention (QuinteT Recruitment Intervention) was used to investigate the recruitment difficulties and feedback findings to inform interventions and optimise ongoing recruitment. Quantitative site-level recruitment data, audio-recorded recruitment appointments (n = 46), qualitative interviews (n = 22) with trialists/recruiting staff (oncologists/nurses) and patient-facing documentation were analysed using descriptive, thematic and conversation analyses. Findings were triangulated to inform a 'plan of action' to optimise recruitment.

RESULTS

Despite best intentions, oncologists' routine practices complicated recruitment. Discomfort about deviating from the usual practice of recommending chemotherapy according to tumour clinicopathological features meant that not all eligible patients were approached. Audio-recorded recruitment appointments revealed how routine practices undermined recruitment. A tendency to justify chemotherapy provision before presenting the randomised controlled trial and subtly indicating that chemotherapy would be more/less beneficial undermined equipoise and made it difficult for patients to engage with OPTIMA Prelim. To tackle these challenges, individual and group recruiter feedback focussed on communication issues and vignettes of eligible patients were discussed to address discomforts around approaching patients. 'Tips' documents concerning structuring discussions and conveying equipoise were disseminated across sites, together with revisions to the Patient Information Sheet.

CONCLUSIONS

This is the first study illuminating the tension between oncologists' routine practices and recruitment to de-escalation trials. Although time and resources are required, these challenges can be addressed through specific feedback and training as the trial is underway.

Microbiotyping the Sinonasal Microbiome

This study offers a novel description of the sinonasal microbiome, through an unsupervised machine learning approach combining dimensionality reduction and clustering. We apply our method to the International Sinonasal Microbiome Study (ISMS) dataset of 410 sinus swab samples. We propose three main sinonasal "microbiotypes" or "states": the first is Corynebacterium-dominated, the second is Staphylococcus-dominated, and the third dominated by the other core genera of the sinonasal microbiome (Streptococcus, Haemophilus, Moraxella, and Pseudomonas). The prevalence of the three microbiotypes studied did not differ between healthy and diseased sinuses, but differences in their distribution were evident based on geography. We also describe a potential reciprocal relationship between Corynebacterium species and Staphylococcus aureus, suggesting that a certain microbial equilibrium between various players is reached in the sinuses. We validate our approach by applying it to a separate 16S rRNA gene sequence dataset of 97 sinus swabs from a different patient cohort. Sinonasal microbiotyping may prove useful in reducing the complexity of describing sinonasal microbiota. It may drive future studies aimed at modeling microbial interactions in the sinuses and in doing so may facilitate the development of a tailored patient-specific approach to the treatment of sinus disease in the future.

Safety and efficacy of a bacteriophage cocktail in an in vivo model of Pseudomonas aeruginosa sinusitis

Pseudomonas aeruginosa (PA) is a bacterial pathogen that frequently displays antibiotic resistance. Its presence within the sinuses of chronic rhinosinusitis sufferers is associated with poorer quality of life. Obligately lytic bacteriophages (phages) are viruses that infect, replicate within, and lyse bacteria, causing bacterial death. The aims of this study were to assess the safety and efficacy of a PA phage cocktail (CT-PA) in a sheep model of rhinosinusitis. The sheep rhinosinusitis model was adapted to simulate PA infection in sheep frontal sinuses. To assess efficacy, after a 7-day biofilm formation period, sheep received twice-daily frontal trephine flushes of CT-PA or saline for 1 week. Biofilm quantitation on frontal sinus mucosa was performed using LIVE/DEAD BacLight staining. To assess safety, sheep received twice-daily frontal trephine flushes of CT-PA or vehicle control for 3 weeks. Blood and fecal samples were collected throughout treatment. Histopathology of frontal sinus, lung, heart, liver, spleen, and kidney tissue was performed. Sinus cilia were visualized using scanning electron microscopy (SEM). The Efficacy arm showed a statistically significant reduction in biofilm biomass with all concentrations of CT-PA tested (P < 0.05). Phage presence in sinuses was maintained for at least 16hours after the final flush. All Safety arm sheep completed 3 weeks of treatment. Phage was detected consistently in feces and sporadically in blood and organ samples. Histology and SEM of tissues revealed no treatment-related damage. In conclusion, CT-PA was able to decrease sinus PA biofilm at concentrations of 10⁸-10¹⁰ PFU/mL. No safety concerns were noted.

Effect of commercial nasal steroid preparation on bacterial growth

BACKGROUND

Topical budesonide (Pulmicort; AstraZeneca AB, Sodertalje, Sweden) is commonly used in the management of chronic rhinosinusitis (CRS). Although its use is due to its perceived anti-inflammatory effect, studies have suggested that it may also have antibacterial properties. To make the hydrophobic steroid molecule suitable for topical administration, pharmaceutical excipients are used in commercial steroid formulations. Herein we investigated the antibacterial action of commercial budesonide and its excipients.

METHODS

Planktonic and biofilm forms of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) were treated with Pulmicort or its excipients at clinically relevant concentrations. Bacterial growth was determined by optical density, resazurin assays, colony-forming unit counts, and Giemsa staining. Minimum inhibitory concentration (MIC) studies assessed excipients' potentiation of antibiotics. Experiments were conducted in triplicate and results analyzed using one-way analysis of variance.

RESULTS

There was significant reduction in planktonic and biofilm growth of S aureus and MRSA on exposure to budesonide (p < 0.0001) and its excipients (p < 0.0001). Excipient ethylene diamine-tetraactic acid (EDTA) demonstrated an antibacterial property even at the low concentrations used in topical preparations (p < 0.0001). With amoxicillin, excipients exhibited a potential additive/synergistic effect on MIC, whereas erythromycin and aminoglycosides showed an antagonistic action.

CONCLUSION

The commercial product Pulmicort has a direct antibacterial effect on the planktonic and biofilm forms of S aureus and MRSA. This effect is at least in part mediated through the excipient EDTA in the product. Excipients also influenced the antimicrobial activity of antibiotics depending on the bacterial strain and antibiotic tested.

The Association Between Disease Severity and Microbiome in Chronic Rhinosinusitis

OBJECTIVE

The role of the microbiome in the etiology of chronic rhinosinusitis (CRS) is still in debate. Reductions in richness and diversity have been implicated in CRS; however, limited knowledge exists regarding the impact of the severity of disease on the microbiome. The associations between constituents of the microbiome and the degree of mucosal inflammation and tissue eosinophilia are described.

METHODS

A cross-sectional study of CRS and non-CRS patients who underwent endoscopic sinus surgery was performed. Sinus mucosal biopsies were assessed for the degree of inflammation and tissue eosinophilia. Middle-meatal swabs were subjected to 16S rRNA gene sequencing, which quantified the prevalence, mean relative abundance, richness, and diversity. Comparisons between the microbiome at the genus level and degree of inflammation (absent, mild, moderate, severe) and tissue eosinophilia (absent, < 10, 10-100, > 100 per high-powered field) were performed.

RESULTS

Eight-nine patients (52.8 ± 14.21 years, 64.0% male) were assessed. Of those, 52 had CRS and 37 were controls. Corynebacterium and Staphylococcus were the most abundant genera in both the CRS (29% and 16%) and non-CRS groups (40% and 20%). Richness decreased in more severely inflamed patients (23.2 ± 13.9 vs. 18.1 ± 16.1 vs. 16.8 ± 12.3 vs. 14.7 ± 10.9; P < 0.01), as did diversity (1.4 ± 0.7 vs. 1.2 ± 1.0 vs. 1.2 ± 0.8 vs. 0.9 ± 0.7; P = 0.05). Richness was associated with higher tissue eosinophilia (23.2 ± 13.9 vs. 19.3 ± 17.2 vs. 15.9 ± 11.6 vs. 13.4 ± 6.6; P < 0.01).

CONCLUSION

The loss of richness and diversity seen in the CRS microbiome appears to be a product of severity of inflammation and tissue eosinophilia. Whether this dysbiosis is causative or a result of the disease with impaired epithelial integrity requires ongoing research.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1265-1273, 2019.

Adaptation of the By-Band randomized clinical trial to By-Band-Sleeve to include a new intervention and maintain relevance of the study to practice

Background

Recruitment into surgical RCTs can be threatened if new interventions available outside the trial compete with those being evaluated. Adapting the trial to include the new intervention may overcome this issue, yet this is not often done in surgery. This paper describes the challenges, rationale and methods for adapting an RCT to include a new intervention.

Methods

The By‐Band study was designed in the UK in 2009–2010 to compare the effectiveness of laparoscopic adjustable gastric band and Roux‐en‐Y gastric bypass for severe obesity. It contained a pilot phase to establish whether recruitment was possible, and the grant proposal specified that an adaptation to include sleeve gastrectomy would be considered if practice changed and recruitment was successful. Information on changing obesity surgery practice, updated evidence and expert opinion about trial design were used to inform the adaptation.

Results

The pilot phase recruited over 13 months in 2013–2014 and randomized 80 patients (79 anticipated). During this time, major changes in obesity practice in the UK were observed, with gastric band reducing from 32·6 to 15·8 per cent and sleeve gastrectomy increasing from 9·0 to 28·1 per cent. The evidence base had not changed markedly. The British Obesity and Metabolic Surgery Society and study oversight committees supported an adaptation to include sleeve gastrectomy, and a proposal to do so was approved by the funder.

Conclusion

Adaptation of a two‐group surgical RCT can allow evaluation of a third procedure and maintain relevance of the RCT to practice. It also optimizes the use of existing trial infrastructure to answer an additional important research question. Registration number: ISRCTN00786323 (http://www.isrctn.com/).

Something to consider

An in vivo safety and efficacy demonstration of a topical liposomal nitric oxide donor treatment for Staphylococcus aureus biofilm-associated rhinosinusitis

The burden of drug resistance emerges in the wake of chronic and repeated antibiotic use. This underpins the importance of discovering alternatives to current antibiotic regimens. In chronic rhinosinusitis (CRS), topical therapy such as nasal douches and steroid sprays is the mainstay of treatment. However, bacterial sinusitis such as those with Staphylococcus aureus biofilm infection point to more recalcitrant CRS subtypes, focusing research efforts into topical antimicrobial therapies. In the sinuses, both local mucosal and systemic effects must be considered in designing any new topical medication. Nitric oxide (NO), an endogenous antimicrobial agent, is found at extremely low levels in CRS sinuses and high levels in healthy sinuses. As a novel treatment modality, we have designed a liposomal formulation of an NO donor (LFNO) using isosorbide mononitrate, as a topical sinus wash in a sheep model of S. aureus biofilm rhinosinusitis. Heart rate (HR), blood pressure, mean arterial pressure (MAP), and histologic and ciliary analyses were assessed in the safety component. Efficacy was assessed by quantifying biofilm biomass post-treatment. LFNO-treated sheep had lesser inflammation (P = 0.02), and comparable ciliary preservation (P = 0.86) than the control group. A transient increase in HR and decrease in MAP were observed in the LFNO group (P < 0.05), but this was not accompanied by observable side effects. LFNO sheep had significantly lower biofilm biomass vs controls (P = 0.044). Our findings demonstrate the localized and systemic safety of LFNO in an animal model despite using high NO concentrations, thus warranting further investigation for its possible therapeutic role in CRS.

The Use of Chitosan–Dextran Gel Shows Anti-Inflammatory, Antibiofilm, and Antiproliferative Properties in Fibroblast Cell Culture

Background

Chitosan-dextran gel has been used as an antihemostatic agent and antiadhesive agent after endoscopic sinus surgery. Because Staphylococcus aureus biofilms have been implicated in recalcitrant chronic rhinosinusitis, this study aimed to further investigate the (i) anti-inflammatory, (ii) bacterial biofilm inhibition, (iii) antiproliferative effects, and (iv) wound-healing properties of chitosan and chitosan-dextran gel.

Methods

Fibroblasts were isolated from human nasal tissue and were used to determine the effects of chitosan and chitosan-dextran gel on (i) cell proliferation, (ii) wound healing, (iii) inflammation in fibroblast cultures challenged with superantigens S. aureus enterotoxin B (SEB) and toxic shock syndrome toxin (TSST), and (iv) on S. aureus biofilms.

Results

Chitosan was highly effective at reducing IL-8 expression after TSST and SEB challenge. Chitosan was also effective at reducing IL-8 expression of nonchallenged fibroblasts showing its anti-inflammatory effects on fibroblasts in a diseased state. Chitosan-dextran gel showed strong antibiofilm properties at 50% (v/v) concentration in vitro. Dextran, on its own, showed antibiofilm properties at 1.25% (w/v) concentration. Chitosan, on its own, reduced proliferation of fibroblasts to 82% of control proliferation and chitosan-dextran gel reduced proliferation of the fibroblasts to 0.04% of control proliferation. Relative to the no treatment controls, chitosan-dextran gel significantly delayed the wound-healing rate over the first 48 hours of the experiment.

Conclusion

Chitosan-dextran gel reduced fibroblast proliferation and wound-healing time, showing a possible mechanism of reducing adhesions in the postsurgical period. Chitosan reduced IL-8 levels, showing its anti-inflammatory properties. Chitosan-dextran gel and dextran treatment showed antibiofilm properties in our model.

Early and late complications of endoscopic hemostatic techniques following different carotid artery injury characteristics

BACKGROUND

The most dreaded hemorrhagic complication in endoscopic endonasal surgery is injury to the internal carotid artery (ICA). Although a number of treatment protocols are currently used, none have been formally investigated. This study aims to compare the efficacy of the muscle patch, bipolar diathermy, and aneurysm clip on hemostasis, pseudoaneurysm formation, and long-term vessel patency for different injury types in a sheep model of carotid bleeding.

METHODS

Twenty-seven sheep underwent ICA dissection/isolation followed by the artery placement within a modified "sinus model otorhino neuro trainer" (SIMONT) model. Standardized linear, punch, and stellate injuries were made. Randomization of sheep to receive 1 of 3 hemostatic techniques was performed (muscle, bipolar, clip). Specific outcome measures included attainment of primary hemostasis, time to hemostasis, blood loss, pseudoaneurysm formation, and carotid patency on follow-up magnetic resonance imaging (MRI).

RESULTS

Bipolar achieved primary hemostasis in 7 of 9 cases and 2 cases of secondary hemorrhage. It had no associated pseudoaneurysm formation. Carotid patency was variable on follow-up MRI. Muscle patch achieved 100% primary hemostasis with 2 cases of secondary hemorrhage. There were 2 cases of pseudoaneurysm and 100% patency rate on follow-up MRI. Aneurysm clip achieved 100% primary hemostasis with 1 case of secondary hemorrhage. No pseudoaneurysm formation and a 50% rate of carotid insufficiency on MRI.

CONCLUSION

This study shows that the crushed muscle patch and aneurysm clip can be viable options in the management of ICA injury with short-term and long-term benefits. Complications associated with these techniques were comparable if not reduced when compared to the published literature.

Methylglyoxal-augmented manuka honey as a topical anti-Staphylococcus aureus biofilm agent: safety and efficacy in an in vivo model

BACKGROUND

Bacterial biofilms are thought to contribute to recalcitrance in chronic rhinosinusitis (CRS) patients. Manuka honey (MH) and its active component methylglyoxal (MGO) have demonstrated antibiofilm activity in vitro. This study evaluated the safety and efficacy of these agents in an in vivo model.

METHODS

To assess safety, ovine frontal sinuses were flushed twice daily for 14 days. In each sheep, 1 sinus was flushed with a panel of MGO concentrations ranging from 0.5 to 7.2 mg/mL alone and flushed with a panel of with 16.5% wt/vol MH enriched with MGO at the same range of concentrations (0.5-7.2 mg/mL; designated MH/MGO). Contralateral sinuses were flushed with saline control. Tissue morphology was assessed histologically and with scanning electron microscopy. Efficacy was tested by developing Staphylococcus aureus biofilms in sheep sinuses. Twice-daily irrigation for 5 days was commenced with either saline, MGO (0.5-3.6 mg/mL) alone, or MH/MGO (with 0.5-3.6 mg/mL MGO). Biofilm biomass was compared between the groups (n = 4) using LIVE/DEAD BacLight staining and confocal scanning laser microscopy.

RESULTS

The results of the safety assessment, for normal sinuses treated with MGO alone or with MH/MGO (≤1.8 mg/mL) showed normal pseudostratified epithelium and cilia structure; however, higher concentrations caused cilia denudation and squamous metaplasia. As for efficacy, when compared to saline flush, treatment with MH/MGO at 0.9 mg/mL (0.608 ± 0.110 vs 0.316 ± 0.197 μm(3) /μm(2) , respectively; p = 0.015) and 1.8 mg/mL (0.676 ± 0.079 vs 0.114 ± 0.033 μm(3) /μm(2) , respectively; p = 0.001) significantly reduced biofilm biomass.

CONCLUSION

Sinus irrigation with MH/MGO at MGO concentrations between 0.9 and 1.8 mg/mL is both safe to mucosa and efficacious against S. aureus biofilm. MH/MGO irrigation could represent a viable treatment option for recalcitrant CRS.

Safety evaluation of a sinus surfactant in an explant-based cytotoxicity assay

OBJECTIVES/HYPOTHESIS

Biofilms are associated with clinical relapse following surgery for chronic rhinosinusitis. Encased bacteria are protected from innate immunity and antimicrobial therapy. Surfactants can disperse the biofilm into its planktonic phenotype so that traditional treatments may be effective. The aim of this study was to assess a surfactant for its cytotoxicity profile.

STUDY DESIGN

In vitro explant-based cytotoxicity study.

METHODS

Sinonasal mucosa harvested from patients undergoing sinus surgery was tested using an air-liquid interface explant system. Surfactant at 1×, 2×, and 3× manufacturer's recommended concentrations were compared to control (saline) and Zinc Sulphate (ZnSO4 ), a known cytotoxic agent. Culture supernatant was analyzed for lactate dehydrogenase (LDH) as a marker of cellular toxicity. After 7 days, specimens were imaged using structured histopathology and scanning electron microscopy.

RESULTS

Application of surfactant at 1× concentration did not elicit an elevation in LDH, whereas ZnSO4 caused a significant rise 1 day after application. Specimens tested with a 2× and 3× surfactant demonstrated LDH rises 4 days and 2 days after application, respectively. Mucosa tested with the 1× surfactant and control demonstrated intact cellular structures on histopathology and preserved cilial ultrastructure on SEM. In ZnSO4 -treated specimens, marked cellular degradation and ciliary denudation occurred.

CONCLUSION

The surfactant does not appear to elicit cellular toxicity using an in vitro explant model at the manufacturer's recommended concentration. At higher concentrations, there may be dose-related toxicity that requires further investigation. In vivo testing is required to prove its efficacy in the treatment of recalcitrant chronic rhinosinusitis.

LEVEL OF EVIDENCE

N/A.

The effects of nitric oxide on Staphylococcus aureus biofilm growth and its implications in chronic rhinosinusitis

BACKGROUND

The relationship between sinonasal nitric oxide (NO) levels and the pathogenic organism Staphylococcus aureus is yet to be established. High NO levels measured in healthy sinuses likely contribute to maintenance of relative sterility. Lower concentrations such as is found in the sinuses of chronic rhinosinusitis (CRS) patients may decrease this effect. S. aureus in biofilm form has recently been implicated in recalcitrant CRS, its isolation predicting a higher risk of posttreatment reinfection. This in vitro study aims to characterize the changes in S. aureus biofilm formation when exposed to different NO levels mimicking the normal and diseased NO sinus concentrations reported in previous literature in an in vitro setting.

METHODS

S. aureus ATCC 25923 and 7 clinical isolates were cultured in biofilm form using the MBEC device and the established biofilms exposed to 1 to 1000 μM NO concentrations. Biofilms were visualized using Live/Dead Baclight stain and confocal scanning laser microscopy, and quantified using Comstat2, a biofilm quantification software.

RESULTS

Biofilm biomass decreases from an average of 0.105 to 0.057 μm(3) /μm(2) at higher NO concentrations (125-1000 μM), but is increased to 0.470 μm(3) /μm(2) at lower NO concentrations (0.9-2.0 μM). The average biomass at high vs low concentrations are statistically significant (p < 0.001).

CONCLUSION

S. aureus biofilm formation varies across exposure to different NO levels, with antibiofilm effects at higher concentrations, and enhanced biofilm formation at lower or subphysiologic concentrations. These results coincide with the often dualistic function of NO, and have implications in its future use in the treatment of CRS.