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Antimicrobial resistance is a multifaceted crisis, imposing a serious threat to global health. The traditional antibiotic pipeline has been exhausted, prompting research into alternate antimicrobial strategies. Inspired by nature, antimicrobial peptides are rapidly gaining attention for their clinical potential as they present distinct advantages over traditional antibiotics. Antimicrobial peptides are found in all forms of life and demonstrate a pivotal role in the innate immune system. Many antimicrobial peptides are evolutionarily conserved, with limited propensity for resistance. Additionally, chemical modifications to the peptide backbone can be used to improve biological activity and stability and reduce toxicity. This review details the therapeutic potential of peptide-based antimicrobials, as well as the challenges needed to overcome in order for clinical translation. We explore the proposed mechanisms of activity, design of synthetic biomimics, and how this novel class of antimicrobial compound may address the need for effective antibiotics. Finally, we discuss commercially available peptide-based antimicrobials and antimicrobial peptides in clinical trials.

Flame-retardants and biocides are well-established functional additives that enhance key properties of polymer and porous materials. Conventional additives and their secondary emissions may render materials hazardous in the long-term, incrementing human exposure to a toxic load of persistent bio-cumulative substances in the indoor built environment. The present study developed a novel multifunctional green additive formulated for the optimization of thermoplastic-lignocellulose hybrid sheet materials engineered for indoor building applications. The compound was developed from two marine bio-materials, Kelp Macroalgae (Eklonia spp.) and Bivalve mollusc shells (Veneridae spp.), selected due to their exceptional properties for these functions, as result of the complex mixture of biogenic carbonate/halide/oxide inorganic phases intricately connected through a hierarchical structure. Oxidative flame propagation was investigated under fire conditions and thermal degradation coupled with gas analysis was investigated under inert gas purge for the temperature range 30–1300 °C. The microbial biomass was analysed with culture-dependent and independent methods. The marine panel prototypes exhibited superior flame-retardant characteristics as result of synergistic mechanisms occurring at the solid-gas interface through the disruption of volatiles flame reactions in the gas-phase, endothermic reactions, and self-catalytic activation. This resulted in self-extinguishing, flame-inhibition, slow-flame propagation rate; and the formation of hierarchically porous carbonaceous phase of high-adsorptive capacity. The biodegradation and ecotoxicity analyses indicated very low-moisture absorption and a possible inhibitory effect on microbial development due to the CaCO3/alginate destabilizing effect on the cell membrane. This promising result demonstrates that the synergistic effect of the marine additive has high-potential rendering the novel hybrid materials non-toxic, biodegradation resistant, whilst increasing the recyclability potential at their end-of-life.

Purpose This study analyzed the susceptibilities of 17 contact lens (CL)-related keratitis isolates of Pseudomonas aeruginosa from Australia to antibiotics, multipurpose contact lens disinfecting solutions (MPDS), and disinfectants through minimum inhibitory (MIC) and minimum bactericidal concentrations. Methods Antibiotics included ciprofloxacin, levofloxacin, gentamicin, tobramycin, piperacillin, imipenem, ceftazidime, and polymyxin B. The MPDS OPTI-FREE PureMoist, Complete RevitaLens OcuTec, Biotrue, and Renu Advanced Formula and the constituent disinfectants; alexidine dihydrochloride, polyquaternium-1, polyaminopropyl biguanide, and myristamidopropyl dimethylamine (Aldox) were analyzed. The combined susceptibility of disinfectants based on the MPDS formulation was assessed through fractional inhibitory concentration. Results All isolates were susceptible to levofloxacin and gentamicin, 2/17 were resistant to ciprofloxacin; 1/17 was resistant to tobramycin, piperacillin, and polymyxin; and 3/17 were resistant to ceftazidime whereas 12/17 were resistant to imipenem. Of the four MPDSs, for Renu Advanced Formula 8/17 strains have an MIC ≤ 11.36 for OPTI-FREE PureMoist 14/17 strains have an MIC ≤ 11.36% for Complete RevitaLens 9/17 strains have an MIC ≤ 11.36, and for Biotrue 5/17 strains have MIC = 11.36. All strains were killed by 100% MPDS. At the concentrations used in the MPDSs, individual disinfectants were not active. From three tested isolates, no synergy was found in dual combinations of disinfectants. However, synergy was found for triple combination of disinfectants for three tested strains. Conclusions Australian CL-related isolates of P aeruginosa were susceptible to most antibiotics. There was variability in susceptibility to different MPDS. Individual disinfectant excipients had limited activity. The combination of the disinfectants showed synergy, antagonism, and no interaction. Translational relevance This study will help to choose better preventive and treatment measures for microbial keratitis.

Staphylococcus aureus is a common bacterial isolate from cases of microbial keratitis. The virulence factors that contribute to its pathogenicity during this disease have not been fully resolved. The aim of the current study was to examine the effects of the extracellular protease Staphopain A on corneal virulence. Two strains were used, one Staph 38 that gives a high pathology score during keratitis and a less virulent strain ATCC 8325-4. The effect of inhibition of Staphopain by general or specific protease inhibitors on adhesion of strains to fibronectin-coated glass or PMMA was determined. This was followed by an analysis of the effect of Staphopain A on the ability of the bacteria to adhere to and invade corneal epithelial cells. Finally, the effect of inhibiting Staphopain A on pathogenesis in a mouse model of keratitis was studied. Staphopain A increased the adhesion of strains to fibronectin–coated substrata and inhibition of Staphopain A reduced adhesion. The inhibition of Staphopain A by staphostatin A significantly decreased both association with and invasion into human corneal epithelial cells by 15-fold for strain Saur38. Inhibition of Staphopain A significantly reduced the pathology associated with S. aureus keratitis, reducing the infecting numbers of bacteria from 1.8x105 to

Early diagnosis of clinical markers of contact lens discomfort can help clinicians set realistic expectations and monitor and provide prophylactic management for contact lens wearers.The purpose of this study was to evaluate the potential of eyelid- and tear film-related clinical markers to be used as predictive factors for diagnosing discomfort in contact lens wearers.A cross-sectional study was performed on 30 contact lens wearers (6 male, 24 female) with median age of 23 years (range, 18 to 41 years). Eyelid signs and tear film characteristics were evaluated during a single visit, and subjects completed the Contact Lens Dry Eye Questionnaire to evaluate ocular discomfort. Area under the curve (AUC) statistics and sensitivity and specificity values from receiver operating characteristic curves were analyzed to evaluate the predictive potential of clinical signs in discriminating symptoms of contact lens discomfort.The presence of foam at meibomian gland orifices (AUC, 0.944; P.05; sensitivity0.7), meibomian gland secretion volume (AUC, 0.935; P.05; sensitivity0.7), quality (AUC, 0.969; P.05; sensitivity0.7), and expressibility (AUC, 0.933; P.05; sensitivity0.7) were significant and strong predictors of discomfort in lens wear. Tear evaporation rates with (AUC, 0.779; P.05; sensitivity0.7) or without contact lenses (AUC, 0.788; P.05; sensitivity0.7), palpebral conjunctival roughness (AUC, 0.859; P.05; sensitivity0.7), palpebral conjunctival staining (AUC, 0.817; P.05; sensitivity0.7), palpebral conjunctival hyperemia (AUC, 0.746; P.05; sensitivity0.7), meibomian gland orifice capping (AUC, 0.873; P.05; sensitivity0.7), pouting (AUC, 0.891; P.05; sensitivity0.7), and lid-parallel conjunctival folds (AUC, 0.770; P.05; sensitivity0.7) were other acceptable discriminators of symptoms of discomfort during contact lens wear. An equation was developed to identify symptomatic from asymptomatic lens wearers based on the significant predictors: Symptom discriminant function score = 3.378 (meibomian gland secretion grade) + 0.224 (meibomian gland morphology grade) + 0.61 (tear evaporation rate without contact lenses) + 0.439 (lid-parallel conjunctival folds grade) - 0.346 (palpebral conjunctival health grade) - 4.625.This study demonstrated that clinical signs related to meibomian gland secretions and morphology, tear evaporation, lid-parallel conjunctival folds, and palpebral conjunctival health may successfully predict symptoms of discomfort in contact lens wearers.

The large and complex genome of Pseudomonas aeruginosa, which consists of significant portions (up to 20%) of transferable genetic elements contributes to the rapid development of antibiotic resistance. The whole genome sequences of 22 strains isolated from eye and cystic fibrosis patients in Australia and India between 1992 and 2007 were used to compare genomic divergence and phylogenetic relationships as well as genes for antibiotic resistance and virulence factors. Analysis of the pangenome indicated a large variation in the size of accessory genome amongst 22 stains and the size of the accessory genome correlated with number of genomic islands, insertion sequences and prophages. The strains were diverse in terms of sequence type and dissimilar to that of global epidemic P. aeruginosa clones. Of the eye isolates, 62% clustered together within a single lineage. Indian eye isolates possessed genes associated with resistance to aminoglycoside, beta-lactams, sulphonamide, quaternary ammonium compounds, tetracycline, trimethoprims and chloramphenicols. These genes were, however, absent in Australian isolates regardless of source. Overall, our results provide valuable information for understanding the genomic diversity of P. aeruginosa isolated from two different infection types and countries.

Copyright © 2018 American Chemical Society. Melimine and its derivatives are synthetic chimeric antimicrobial agents based on protamine and melittin. The binding of solubilized melimine and its derivative, with a cysteine on N-terminus, (cys-melimine) on tethered bilayer lipid membranes (tBLMs) was examined using ac electrical impedance spectroscopy. The addition of melimine and cys-melimine initially increased membrane conduction, which subsequently falls over time. The results were obtained for tBLMs comprising zwitterionic phosphatidylcholine, anionic phosphatidylglycerol, or tBLMs made using purified lipids from Escherichia coli. The effect on conduction is more marked with the cysteine variant than the noncysteine variant. The variation in membrane conduction most probably arises from individual melimines inducing increased ionic permeability, which is then reduced as the melimines aggregate and phase-separate within the membrane. The actions of these antimicrobials are modeled in terms of altering the critical packing parameter (CPP) of the membranes. The variations in the peptide length of cys-melimine were compared with a truncated version of the peptide, cys-mel4. The results suggest that the smaller molecule impacts the membrane by a mechanism that increases the average CPP, reducing membrane conduction. Alternatively, an uncharged alanine-replacement version of melimine still produced an increase in membrane conduction, further supporting the CPP model of geometry-induced toroidal pore alterations. All the data were then compared to their antimicrobial effectiveness for the Gram-positive and Gram-negative strains of bacteria, and their fusogenic properties were examined using dynamic light scattering in 1-oleoyl-2-hydroxy-sn-glycero-3-phosphocholine lipid spheroids. We conclude that a degree of correlation exists between the antimicrobial effectiveness of the peptides studied here and their modulation of membrane conductivity.

© 2018 Subedi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Virulent strains of Pseudomonas aeruginosa are often associated with an acquired cytotoxic protein, exoenzyme U (ExoU) that rapidly destroys the cell membranes of host cells by its phospholipase activity. Strains possessing the exoU gene are predominant in eye infections and are more resistant to antibiotics. Thus, it is essential to understand treatment options for these strains. Here, we have investigated the resistance profiles and genes associated with resistance for fluoroquinolone and beta-lactams. A total of 22 strains of P. aeruginosa from anterior eye infections, microbial keratitis (MK), and the lungs of cystic fibrosis (CF) patients were used. Based on whole genome sequencing, the prevalence of the exoU gene was 61.5% in MK isolates whereas none of the CF isolates possessed this gene. Overall, higher antibiotic resistance was observed in the isolates possessing exoU. Of the exoU strains, all except one were resistant to fluoroquinolones, 100% were resistant to beta-lactams. 75% had mutations in quinolone resistance determining regions (T81I gyrA and/or S87L parC) which correlated with fluoroquinolone resistance. In addition, exoU strains had mutations at K76Q, A110T, and V126E in ampC, Q155I and V356I in ampR and E114A, G283E, and M288R in mexR genes that are associated with higher beta-lactamase and efflux pump activities. In contrast, such mutations were not observed in the strains lacking exoU. The expression of the ampC gene increased by up to nine-fold in all eight exoU strains and the ampR was upregulated in seven exoU strains compared to PAO1. The expression of mexR gene was 1.4 to 3.6 fold lower in 75% of exoU strains. This study highlights the association between virulence traits and antibiotic resistance in pathogenic P. aeruginosa.

Purpose Knowledge of whether microorganisms reside in protected niches of the conjunctiva is potentially significant in terms of minimizing risks of contact lens inflammation/infection and endophthalmitis. We define if and how microbial communities from limbal and forniceal conjunctival tissue differ from those on the conjunctival surface. Methods Human limbal and forniceal conjunctival tissue was obtained from 23 patients undergoing pterygium surgery and analyzed with data from a recent study of conjunctival surface swabs (n = 45). Microbial communities were analyzed by extracting total DNA from tissue samples and surface swabs and sequencing the 16S rRNA gene using the Illumina MiSeq platform. Sequences were quality filtered, clustered into operational taxonomic units (OTUs) at 97% similarity. OTUs associated with blank extraction and sampling negative controls were removed before analysis. Fluorescent in situ hybridization (FISH) was performed on cyrosections of limbal and forniceal conjunctival tissue. Results There was a significant difference in bacterial community structure between the conjunctival surface and fornix (P = 0.001) and limbus (P = 0.001) tissue. No difference was found in bacterial communities between the limbus and fornix (P = 0.764). Fornix and limbal samples were dominated by OTUs classified to the genus Pseudomonas (relative abundance 79.9%), which were found only in low relative abundances on conjunctival surfaces (6.3%). Application of FISH showed the presence of Pseudomonas in the forniceal tissue sample. Conclusions There is a discrete tissue-associated microbiome in freshly-collected human limbal and fornix tissue, which is different from the microbial community structure and composition of the ocular surface microbiome.

AIM A series of proof-of-principle extended wear (EW) contact lens studies were conducted to assess what effect different interventions had on adverse events (AEs). Comparative analysis of AEs across studies was conducted to determine whether some interventions were more effective at reducing inflammatory AEs. METHOD Multiple logistic regression analysis of AEs from 30-day EW studies each with a different intervention including (1) nightly replacement (NR) of lenses, (2) morning replacement (MR) of lenses, (3) instillation of prophylactic antibiotic drops (AB) each morning/evening, (4) daily lens cleaning (LC) each morning. All studies conducted at the same site using same lens type (lotrafilcon A) and EW schedule. RESULTS Comparison of the different interventions to the individual control groups showed no difference in significant corneal infiltrative event (CIE) or mechanical events. Replacing lenses nightly, during an EW schedule, had the highest incidence of significant CIEs (4.9% [NR] vs. 2.5% [MR] vs. 1.8% [AB] vs. 0% [LC]); however, adjusted logistic regression analysis of the combined control data compared with the individual interventions showed no difference in significant CIEs (P=0.086) or mechanical AEs (P=0.140). CONCLUSIONS Replacing lenses each night seemed to be inferior compared with the other interventions of replacing lenses each morning, daily lens cleaning, and daily antibiotic drop instillation during EW. The results of the collective studies and additional analysis suggest that overnight wear of contact lenses seems to create an adverse environment that remains, despite the various interventions intended to improve this adverse environment.

We describe a library of amphiphilic anthranilamide compounds as antimicrobial peptide (AMP) mimics. These contain a hydrophobic naphthoyl side chain and different hydrophilic cationic groups such as amino, quaternary ammonium and guanidino groups. These are prepared via the ring-opening of different isatoic anhydrides. The antibacterial activity against S. aureus and E. coli of compounds containing guanidino cationic groups was greater than that for amino and quaternary ammonium cationic groups. The fluoro-substituted guanidinium compound 9b showed a minimum inhibitory concentration (MIC) of 2.0 μM against S. aureus, and reduced established biofilms of S. aureus by 92% at 64 μM concentration. The bromo-substituted guanidinium compound 9d exhibited good MIC against S. aureus (3.9 μM) and E. coli (15.6 μM) and disrupted established biofilms of S. aureus by 83% at 62.4 μM concentration. Cytoplasmic membrane permeability studies suggested that depolarization and disruption of the bacterial cell membrane could be a possible mechanism for antibacterial activity and the in vitro toxicity studies against MRC-5 human lung fibroblast cells showed that the potent compounds are non-toxic against mammalian cells.

The (O-acyl)-ω-hydroxy FAs (OAHFAs) comprise an unusual lipid subclass present in the skin, vernix caseosa, and meibomian gland secretions. Although they are structurally related to the general class of FA esters of hydroxy FAs (FAHFAs), the ultra-long chain (30–34 carbons) and the putative ω-substitution of the backbone hydroxy FA suggest that OAHFAs have unique biochemistry. Complete structural elucidation of OAHFAs has been challenging because of their low abundance within complex lipid matrices. Furthermore, because these compounds occur as a mixture of closely related isomers, insufficient spectroscopic data have been obtained to guide structure confirmation by total synthesis. Here, we describe the full molecular structure of ultra-long chain OAHFAs extracted from human meibum by exploiting the gas-phase purification of lipids through multi-stage MS and novel multidimensional ion activation methods. The analysis elucidated sites of unsaturation, the stereochemical configuration of carbon-carbon double bonds, and ester linkage regiochemistry. Such isomer-resolved MS guided the first total synthesis of an ultra-long chain OAHFA, which, in turn, confirmed the structure of the most abundant OAHFA found in human meibum, OAHFA 50:2. The availability of a synthetic OAHFA opens new territory for future investigations into the unique biophysical and biochemical properties of these lipids.

We report on the development of a novel optical imaging technique for visualizing tear film lipid using scandium doped silicone quantum dots with varying surface chemistries; lipophilic and hydrophilic.

To assess the association between the levels of lens case contamination and lens wearers' hygiene behaviors.Contact lens wearers were surveyed for information on wearer demographics and contact lens hygiene behavior. Microbial analysis of lens cases was performed. Multivariate analysis was used to identify factors associated with contact lens storage case contamination.One hundred nineteen contact lens wearers responded. The mean (±SD) age of the participant was 32 (±1) years (range, 18 to 69 years). Seventy percent of the participants were female. Sixty-six percent of lens cases were contaminated (median, 25; range, 0 to 10⁷ colony-forming units [CFUs]). In the multivariate analysis, washing hands with soap and water (1.8 ± 2.0 log10 CFU/case) rather than just water or no washing was associated with lower levels of lens case contamination (2.4 ± 2.1 log10 CFU/case; p = 0.005). Lens cases received wet had higher levels of contamination than dry cases (1.5 ± 1.5 vs. 2.4 ± 2.5 log10 CFU/case; p = 0.015). Mismatching lens case and disinfecting solution was a risk factor for lens case contamination (p = 0.019). Lens wearers who had more than 2 years of wearing experience had higher levels of contamination than those who had less than 2 years of wearing experience (2.1 ± 2.1 vs. 1.1 ± 1.5 log10 CFU/case; p = 0.04).Major factors that can reduce lens case contamination were washing hands with soap and water, air-drying lens cases, and matching of the disinfecting solution with lens case (i.e., from the same manufacturer). This information is beneficial when advising lens wearers in clinical practice.

Gram-negative bacteria such as Pseudomonas aeruginosa use N-acylated L-homoserine lactones (AHLs) as autoinducers (AIs) for quorum sensing (QS), a major regulatory and cell-to-cell communication system for social adaptation, virulence factor production, biofilm formation and antibiotic resistance. Some bacteria use indole moieties for intercellular signaling and as regulators of various bacterial phenotypes important for evading the innate host immune response and antimicrobial resistance. A range of natural and synthetic indole derivatives have been found to act as inhibitors of QS-dependent bacterial phenotypes, complementing the bactericidal ability of traditional antibiotics. In this work, various indole-based AHL mimics were designed and synthesized via the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and N,N'-dicyclohexylcarbodiimide (DCC) mediated coupling reactions of a variety of substituted or unsubstituted aminoindoles with different alkanoic acids. All synthesized compounds were tested for QS inhibition using a P. aeruginosa QS reporter strain by measuring the amount of green fluorescent protein (GFP) production. Docking studies were performed to examine their potential to bind and therefore inhibit the target QS receptor protein. The most potent compounds 11a, 11d and 16a showed 44 to 65% inhibition of QS activity at 250 μM concentration, and represent promising drug leads for the further development of anti-QS antimicrobial compounds.

Established reusable contact lens (CL) wearers show higher tear inflammatory cytokine concentrations and greater conjunctival metaplasia in the region covered by standard soft CLs. The balance of proinflammatory to anti-inflammatory cytokines, but not individual tear cytokine concentrations, was associated with self-reported CL discomfort.Daily disposable (DD) lenses are often used to improve CL discomfort, but the effect on ocular inflammatory responses has not been fully investigated. This study aimed to compare the concentrations of tear cytokines and conjunctival cell morphology in healthy habitual DD and reusable soft CL wearers.Thirty-six established daily CL wearers, including 14 DD and 24 reusable wearers, were enrolled. Symptoms and ocular surface integrity were evaluated. The concentration of tear cytokines (interleukin 1β [IL-1β], IL-6, IL-10, IL-12(p70), IL-17A, and tumor necrosis factor α) were determined using Multiplex assays. The ratios of proinflammatory and anti-inflammatory cytokines were calculated. Impression cytology was performed on the conjunctiva, and goblet cell density and epithelial squamous metaplasia were quantified. Differences in variables by CL replacement schedules and the associations between variables were analyzed.Reusable CL wearers had higher concentrations (in pg/mL) of IL-1β (26 ± 7 vs. 16 ± 11), IL-6 (42 ± 14 vs. 25 ± 20), IL-10 (83 ± 23 vs. 49 ± 36), IL-12(p70) (145 ± 44 vs. 91 ± 68), IL-17A (93 ± 26 vs. 54 ± 44), and tumor necrosis factor α (312 [171 to 468] vs. 189 [6 to 447]) (all P.01) and greater conjunctival metaplasia in the region covered by CLs (0.7 [0.2 to 1.6] vs. 0.4 [0.04 to 1.2], P = .01) compared with DD wearers. There was a positive association between CL discomfort and ratios of IL-1β to IL-10 and IL-12(p70) to IL-10 (ρ = 0.42 and ρ = 0.33, P.05).Higher ocular inflammatory responses, as indicated by higher tear cytokine concentrations and higher conjunctival epithelial metaplasia, were found in reusable CL wearers than in DD CL wearers. The balance of proinflammatory and anti-inflammatory cytokines may be helpful to assess the inflammatory status of the eye.

To determine if there is a core ocular surface microbiome and whether there are microbial community changes over time, the conjunctiva of 45 healthy subjects were sampled at three time points over three months and processed using culture-dependent and -independent methods. Contaminant taxa were removed using a linear regression model using taxa abundances in negative controls as predictor of taxa abundances in subject samples. Both cultured cell counts and sequencing indicated low microbial biomass on the ocular surface. No cultured species was found in all subjects at all times or in all subjects at any one time. After removal of contaminant taxa identified in negative controls using a statistical model, the most commonly detected taxon was Corynebacterium (11.1%). No taxa were found in all subjects at all times or in all subjects in any one time, but there were 26 taxa present in at least one or more subjects at all times including Corynebacterium and Streptococcus. The ocular surface contains a low diversity of microorganisms. Using culture dependent and independent methods, the ocular surface does not appear to support a substantial core microbiome. However, consistently present taxa could be observed within individuals suggesting the possibility of individual-specific core microbiomes.

© 2017 Elsevier Masson SAS Antimicrobial peptides (AMPs) and their synthetic mimics have received recent interest as new alternatives to traditional antibiotics in attempts to overcome the rise of antibiotic resistance in many microbes. AMPs are part of the natural defenses of most living organisms and they also have a unique mechanism of action against bacteria. Herein, a new series of short amphiphilic cationic peptidomimetics were synthesized by incorporating the 3′-amino-[1,1′-biphenyl]-3-carboxylic acid backbone to mimic the essential properties of natural AMPs. By altering hydrophobicity and charge, we identified the most potent analogue 25g that was active against both Gram-positive Staphylococcus aureus (MIC = 15.6 μM) and Gram-negative Escherichia coli (MIC = 7.8 μM) bacteria. Cytoplasmic permeability assay results revealed that 25g acts primarily by depolarization of lipids in cytoplasmic membranes. The active compounds were also investigated for their cytotoxicity to human cells, lysis of lipid bilayers using tethered bilayer lipid membranes (tBLMs) and their activity against established biofilms of S. aureus and E. coli.

The concentration of selected proteins and inflammatory mediators in tears of symptomatic and asymptomatic contact lens wearers were quantified. The level of leukotriene B4 was higher in the symptomatic group. This may suggest that inflammation can be the cause of discomfort sensation at the end of day.The present study aims to quantify the concentration of selected tear lipids and proteins in symptomatic and asymptomatic contact lens wearers.Unstimulated evening tears were collected using glass capillary tubes from 45 healthy, adapted contact lens wearers. Twenty-two had self-described symptoms of dryness and discomfort with contact lenses and 23 were asymptomatic. Tear proteins were assayed using selected reaction monitoring mass spectrometry. Enzyme immunoassay kits were used to measure prostaglandins, leukotriene B4, and cysteinyl leukotrienes. Ocular comfort was rated on a scale of 1 to 100 at the time of tear collection.The average evening comfort level was above 70 for the asymptomatic (83.96 ± 9.51, mean ± SE) and equal or below 70 for the symptomatic group (57.28 ± 12.38) (P.001). LTB4 was significantly higher in symptomatic than asymptomatic contact lens wearers (0.32 ± 0.06 ng/μL vs. 0.17 ± 0.04 ng/μL, respectively; P = .03). Lysozyme was slightly but not significantly lower in symptomatic subjects (symptomatic 0.58 ± 0.10 mg/mL vs. asymptomatic 1.73 ± 0.46 mg/mL; P = .10). The levels of lactoferrin, lipocalin 1, proline-rich 4, prolactin-induced protein, prostaglandins, and cysteinyl leukotrienes were unchanged (P.1) between symptomatic and asymptomatic subjects.The LTB4 concentration was significantly higher in symptomatic contact lens wearers compared to the asymptomatic group, and this may partly mediate the discomfort response during lens wear in the symptomatic lens wearers. No other differences were found in the level of tear factors of interest between the two groups.

Purpose To determine the interaction of contact lenses of different materials with corneal epithelial cells grown in tissue culture. Methods Two different corneal epithelial cell lines were grown to confluence in culture media. Two hydrogel contact lenses with and without polyvinylpyrrolidone (PVP) {1-DAY ACUVUE MOIST (1-Day ACUVUE [hydrogel lenses]) and a silicone hydrogel contact lens, AIR OPTIX NIGHT & DAY} were removed from their blister packs, washed in phosphate-buffered saline, and applied to the cells. After exposure for 24 hr at 37°C, lenses were removed, and the corneal cells and supernatants processed. Supernatants from the cell assays were used to quantify the amount of 17 different cytokines that were produced using a multiplex bead assay. Cells were stained to assess amount of cell death (apoptosis or necrosis) or stained to determine the level of mitochondrial activity. Stimulants of necrotic death (latex) or apoptotic death (sorbitol) were used as positive controls. Results Cells produced cytokines during normal growth. Exposure of cells to the hydrogel lenses resulted in only minimal changes to normal production of cytokines, but latex or sorbitol produced the most change. Exposure of the cells to all three lenses caused 4% to 23% reduction in mitochondrial activity, whereas exposure to the positive controls caused 71% to 98% reduction in mitochondrial activity. Exposure of the corneal epithelial cells to contact lenses produced minimal morphological changes, whereas exposure to latex or sorbitol produced significant changes to the human corneal epithelial cell line. Conclusions Exposure of corneal epithelial cells to contact lenses had minimal impact on their physiology. There was no difference in epithelial cell responses to hydrogel with or without PVP compared with the silicone hydrogel contact lens.

We describe a simple and solvent-free method to generate nitric oxide (NO)-releasing coatings by incorporating diazeniumdiolate (NONOate) into allylamine or diallylamine plasma polymer coatings. The resulting coatings demonstrate continuous release of NO for over 48 hours and are effective at reducing the adhesion and biofilm formation of medically-relevant Gram-negative and Gram-positive opportunistic pathogens.

The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.

Diabetes mellitus is a chronic disease that results from inadequate insulin production or ineffective insulin utilization. It is one of the most common systemic diseases worldwide with increasing prevalence. Diabetes mellitus is associated with premature mortality, macrovascular complications such as cardiovascular disease, and microvascular complications, including nephropathy leading to kidney failure, potentially blinding diabetic retinopathy, and diabetic neuropathy. While the retinal complications of diabetes are well recognized by eye care professionals, the effects on the ocular surface are poorly understood. Recent studies have reported on the association between peripheral neuropathy and corneal neuropathy, showing the latter to be of predictive value for the systemic disease. Corneal neuropathy can lead to loss of corneal sensation and can ultimately result in neurotrophic ulcers and significant visual morbidity. The epithelial fragility and poor wound healing that result from reduced epithelial adhesion to the underlying basement membrane in diabetes, together with corneal neuropathy, are thought to increase the susceptibility to persistent corneal erosions and infection, as well as to increase the risk of post-surgical complications. The aim of this article is to review the impact of diabetes on corneal nerve morphology and ocular surface integrity. Changes in the tear film and ocular surface microbiome are highlighted in discussion of the mechanisms that underpin ocular surface changes that increase the susceptibility to corneal erosion and infection.

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. “Gender” and “sex” are words that are often used interchangeably, but they have distinct meanings. “Gender” refers to a person's self-representation as a man or woman, whereas “sex” distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

© The Royal Society of Chemistry. Antimicrobial resistance in bacteria is becoming increasingly prevalent, posing a critical challenge to global health. Bacterial biofilm formation is a common resistance mechanism that reduces the effectiveness of antibiotics. Thus, the development of compounds that can disrupt bacterial biofilms is a potential strategy to combat antimicrobial resistance. We report herein the synthesis of amphipathic guanidine-embedded glyoxamide-based peptidomimetics via ring-opening reactions of N-naphthoylisatins with amines and amino acids. These compounds were investigated for their antibacterial activity by the determination of minimum inhibitory concentration (MIC) against S. aureus and E. coli. Compounds 35, 36, and 66 exhibited MIC values of 6, 8 and 10 μg mL−1 against S. aureus, respectively, while compounds 55 and 56 showed MIC values of 17 and 19 μg mL−1 against E. coli, respectively. Biofilm disruption and inhibition activities were also evaluated against various Gram-positive and Gram-negative bacteria. The most active compound 65 exhibited the greatest disruption of established biofilms by 65% in S. aureus, 61% in P. aeruginosa, and 60% in S. marcescens respectively, at 250 μM concentration, while compound 52 inhibited the formation of biofilms by 72% in S. marcescens at 250 μM. We also report here the in vitro toxicity against MRC-5 human lung fibroblast cells. Finally, the pore forming capability of the three most potent compounds were tested using tethered bilayer lipid membrane (tBLM) technology.

Staphylococcus aureus is a leading cause of corneal infection. CXC receptor 2 binding chemokines have been implicated in the pathogenesis of Pseudomonas aeruginosa keratitis. The role of this receptor in immune responses during Staphylococcus keratitis remains to be fully understood. Corneas of CXC receptor 2 knockout and wild-type mice (Cmkar -/- & Cmkar +/+) were scratched and 1 × 10(8) cfu/ml of strain Staph 38 applied. Twenty-four hours post-infection, mice were sacrificed and eyes harvested for enumeration of bacteria and measurement of myeloperoxidase levels. Production of inflammatory mediators, cellular adhesion molecules and chemokines in response to infection were investigated by ELISA, and PCR. 24 h after challenge with S. aureus, Cmkar -/- mice had developed a more severe response with a 50-fold higher bacterial load than WT mice. PMNs failed to penetrate the corneas of Cmkar -/- mice. However, concentrations of KC, MIP-2, IL-1β and IL-6 were significantly elevated (6-13 fold) in Cmkar-/- mice. The concentration of LTB4 was decreased (2 fold). Cmkar-/- mice failed to upregulate mRNA for VCAM-1 or PECAM-1 in response to infection, but had constitutively higher levels of ICAM-1. A lack of CXC receptor 2 lead to an inability to control bacterial numbers as a result of failure of PMNs to penetrate the cornea to the site of infection, even when chemokines were more highly produced. These results imply that CXCR2-mediated signaling through upregulation of adhesion molecules is essential to margination of PMNs in this infection model.

Purpose. Covalent immobilization of antimicrobial peptide melimine onto contact lenses can produce broad-spectrum antimicrobial lenses. The purpose of this study was to investigate the performance of melimine-coated contact lenses in an animal model and human clinical trial. Methods. Melimine was covalently attached onto the surface of contact lenses via EDC (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride) coupling. A rabbit model of daily contralateral wear of lenses for 22 days was conducted to assess the lens safety. A prospective, randomized, double-masked, one-day human clinical trial was used to evaluate subjective responses and ocular physiology during contralateral wear of melimine-coated (test) and uncoated (control) lenses. Delayed reactions were monitored during follow-up visits after 1 and 4 weeks. Ex vivo retention of antimicrobial activity of worn lenses was assessed by reduction in numbers of viable Pseudomonas aeruginosa and Staphylococcus aureus. Results. Melimine-coated lenses produced no ocular signs or symptoms that would indicate cytotoxicity during the lens wear of rabbits. No histological changes were found in rabbit corneas. During the human trial, no differences were observed in wettability, surface deposition, lens-fitting centration, movement, tightness, and corneal coverage between test and control lenses (p 9 0.05). There were no significant differences in bulbar, limbal, or palpebral redness or conjunctival staining (p 9 0.05). Mean corneal (extent, depth, and type) staining was higher for test lenses compared with that for control lenses (p G 0.05). There was no significant difference in subjective responses for lens comfort, dryness, and awareness (p 9 0.05). No delayed reactions were associated with the test lenses. Worn test lenses retained more than 1.5 log inhibition against both bacterial types. Conclusions. Melimine-coated contact lenses were worn safely by humans. However, they were associated with higher corneal staining. The melimine-coated lenses retained high antibacterial activity after wear. (Optom Vis Sci 2014;91:570Y581)

PURPOSE Overnight lens wear is associated with increased lens contamination and risk of developing a corneal infiltrate or infectious event. Antibacterial lenses have been proposed as a potential strategy for reducing lens contamination. A proof-of-principle study was conducted to investigate what effect control of potential pathogens, through the use of antibiotic eye drops, would have on the incidence of corneal infiltrative events (CIEs) and on the ocular microbiota and lens contamination. METHODS This is a prospective, open-label, controlled, parallel-group, 1-month clinical study in which 241 subjects were dispensed with lotrafilcon A silicone hydrogel lenses for 30 days of continuous wear. Subjects were randomized into either test (moxifloxacin 0.5%) or control (rewetting solution) group. One drop was instilled into each eye on waking and before sleeping, while lenses were on-eye. Follow-ups were conducted after one night and 1 month. Lid margin swabs were taken at baseline and at 1 month and worn lenses were aseptically collected at 1 month. RESULTS The incidence of CIEs was not significantly different between the test (2.6%) and control (3.9%) groups (p = 0.72). Microorganism levels from the test group swabs were significantly lower than those from the control group (p = 0.001). Gram-positive bacteria were less frequently recovered from lower lid swabs from the test group (39.6% vs. 66.0% [p < 0.001], test vs. control, respectively) or from contact lens samples (1.9% vs. 10.5% [p = 0.015], test vs. control, respectively), but there was no difference in gram-negative bacteria (GNB). Corneal infiltrative events were associated with higher levels of lens contamination (p = 0.014) and contamination of lenses with GNB (CIE: 7.3% vs. 0.6% [p = 0.029], GNB contamination vs. no GNB contamination, respectively). DISCUSSION Twice-daily antibiotic instillation during continuous wear of lenses did not significantly influence the rate of inflammatory events. Corneal infiltrative events were associated with higher levels of lens contamination in general and with contamination by GNB specifically.

Purpose To investigate the utility of additional microbial analyses to detect the causative microorganism of microbial keratitis and to determine the strength of association between clinical variables. Methods This retrospective study included 125 eyes of 123 people presenting with presumed infectious keratitis associated with contact lens wear, and examined between January 2001 and November 2011. Results Sixty-three male and 60 female patients with a mean age of 24.14 ( ±6.7) and 26.7 (±10.0) years, respectively, were included in the study. Among the samples tested, 38 (40%) corneal cultures, 85 (92%) contact lens cultures, and 49 (80%) contact lens case cultures yielded positive results. In the samples for which all microbial investigations were performed and corneal culture was positive, cultures of contact lenses and corneas yielded the same microbes in 94% of cases, and for contact lens case and corneal cultures 77% of cases yielded the same microbes. Importantly, these were monocultures of the same microbe isolated from the cornea in the contact lens and lens case cultures. The odds of having a positive corneal culture was 37 times higher (p = 0.008) when patients presented to the clinic 2 weeks after the onset of symptoms. Pseudomonas aeruginosa was the predominant organism isolated, and most isolates were susceptible to commonly used antimicrobials. Conclusions Contact lens culture might be an effective test to perform to detect and determine the causative microorganism when corneal cultures are unavailable or yield no microorganisms upon culture. A longer duration of symptoms before presenting to the clinic was significantly associated with obtaining a positive corneal culture.

OBJECTIVE To compare the short-term clinical performance of two dual-disinfectant multipurpose disinfecting solutions (MPDS) when used in conjunction with two silicone hydrogel contact lenses. METHODS Participants wore galyfilcon A and balafilcon A lenses, randomly allocated one type to each eye. Multipurpose disinfecting solutions were double-masked and allocated using a randomized crossover design. Lenses were presoaked overnight in the allocated MPDS, containing either polyquaternium-1/alexidine dihydrochloride (PQ-alexidine) or polyquaternium-1/myristamidopropyl dimethylamine (PQ-MAPDA). Lenses were worn daily for 4 days and disinfected with the same MPDS in which they had been soaked. Clinical assessments occurred immediately after insertion, 2 hours after insertion, and after 2 hours of wear on day 4. Subjective ratings were collected at each assessment and after 6 hours of wear on days 1 to 3. Linear mixed models were used for statistical analysis. RESULTS Solution-induced corneal staining (SICS) incidence was significantly different between MPDS lens combinations (P=0.01) with PQ-MAPDA-balafilcon A showing the highest incidence (27.8%). The incidence of SICS was significantly higher when balafilcon A lenses were worn compared with galyfilcon A (19.4% vs. 2.8%; P=0.04). There was no significant difference in SICS incidence between MPDS (PQ-alexidine=5.6%, PQ-MAPDA=16.7%; P=0.08). Polyquaternium-1/alexidine dihydrochloride was associated with significantly fewer symptoms of burning/stinging (9.7±0.6 vs. 9.1±2.2; P=0.03) and self-assessed redness (9.8±0.5 vs. 9.2±1.9; P=0.03) on initial lens insertion. There were no significant differences between MPDS for comfort ratings (P>0.05). CONCLUSION These short-term clinical results provide an initial indication that PQ-alexidine is associated with fewer symptoms on insertion but no significant difference in ocular comfort compared with PQ-MAPDA. Longer studies are required to provide further evidence.

Background Contact lens wear can result in adverse events including bacterially-driven corneal infection and inflammation. These are the result of various kinds of bacteria adhering to contact lenses and either initiating infection of the cornea or producing inflammation of the cornea and conjunctiva. In order to reduce the incidence of these events antimicrobial contact lenses are being developed. In this study, antimicrobial contact lenses containing nanoparticles of silver or copper, or a combination of the two, were produced and evaluated. Methods Silver and copper nanoparticles were produced in polyvinyl alcohol (PVA) polymers by incorporating salts of these metals and then reducing the salts to nanoparticles with sodium hydroxide. Incorporation of nanoparticles into the PVA was confirmed using transmission electron microscopy, attenuated total reflection (ATR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The nanoparticle-containing polymers were then evaluated for physical characteristics such as tensile strength, water content and coloration. PVA containing polymers were evaluated for cytotoxicity to mammalian cells using a standard assay, and for antimicrobial activity using three different assays that measured their ability to inhibit microbial growth on agar plates, inhibit microbial growth in bacterial suspensions, and to inhibit the viability of adherent bacteria. Results Nanoparticles of between 50 and 75 nm were produced in PVA polymers. The production of nanoparticles was also confirmed by characteristic spectral peaks in ATR and XPS. The addition of silver or copper nanoparticles doubled the strength of PVA polymers but halved their elongation before fracture. Silver-containing PVA was cytotoxic but PVA containing copper alone was not cytotoxic. In the agar diffusion assay and inhibition of microbial growth in suspension only silver-containing lenses produced antibacterial activity, but silver and copper nanoparticle-containing lenses reduced bacterial adhesion to lenses. Conclusion both silver and copper nanoparticle-containing lenses were antibacterial, but this depended on the assay used. PVA containing only copper was not cytotoxic. This indicates the copper nanoparticle-containing lenses might be useful to control bacterial colonisation of lenses, and hence the production of bacterially-drive adverse events during lens wear.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Purpose We evaluate the in vitro antibacterial activity of silver-copolymerized barrel cases compared to nonsilver barrel cases in combination with a multipurpose disinfecting solution (MPDS). Methods The ability of silver and nonsilver cases to reduce the number of adherent Gram-positive and Gram-negative bacteria was assessed. Additionally, the efficacy of silver cases along with MPDS was investigated in the presence of organic soil and contact lenses. Contact lens cases were challenged with 106 colony-forming units (CFU)/mL of five bacterial species. Adherent bacteria were dislodged from lens cases and surviving organisms enumerated. Results Significantly lower numbers of microbes were recovered from silver cases compared to controls, for all bacterial strains (P < 0.005). The combination of silver case along with MPDS showed added efficacy against Gram-positive and -negative bacteria with a maximum reduction of 3.00 ± 0.5 Log10 CFU/mL, compared to the efficacy of silver cases alone (1.97 ± 0.4 Log10 CFU/mL). The addition of organic soil and a contact lens resulted in a significant (P < 0.005) decrease (a maximum of 1.68 ± 0.2 log10 CFU/mL) in disinfection efficacy when MPDS and either silver or control cases were used. Conclusions Silver-copolymerized barrel cases work on conjunction with a hypochlorite producing MPDS in the presence of contact lenses and organic soil to reduce microbial contamination of lens cases. Transitional Relevance Silver-copolymerized barrel contact lens cases show promising in vitro antibacterial activity against bacterial types commonly implicated in contact lens-related corneal infections. This intervention may limit storage case contamination during use and reduce the frequency of contact lens-related microbial disease.

The ocular surface is continually exposed to the environment and as a consequence to different types of microbes, but whether there is a normal microbiota of the ocular surface remains unresolved. Using traditional microbial culture techniques has shown that

Using an in vitro cell culture model, bovine lactoferrin (BLF) stimulates healing of alkali-induced human corneal epithelial wounds. The present study examined the efficacy of BLF in promoting healing of corneal injury in vivo and explored BLF modulation of interleukin-1 (IL-1) during wound healing.Alkali injury was induced to BALB/c mice by exposure of the mouse cornea to a sodium hydroxide (NaOH)-soaked filter disc for 2 min. The corneal surface was irrigated after the injury with saline. Topical BLF in phosphate buffered saline (PBS) (10 µl, 62.5 μM), bovine serum albumin (BSA) (10 µl, 62.5 μM in PBS) or PBS only (10 µl) were applied three times daily to both the alkali-injured and uninjured eyes for 3 d. Wound healing was assessed using 0.1% fluorescein staining under slit lamp microscope. The corneas at 6 h, 24 h or 3 d post-injury and treatment were excised and examined histologically, homogenized corneal tissue was evaluated for expression of IL-1α and IL-1β.After 6 h post-wounding and treatment no significant reduction of wound area was observed between treatments and infiltrating cells or IL-1 expression were not elevated in any group. By 24 h, BLF-treatment resulted in accelerated wound closure (100%) compared to PBS and BSA treatment (70% and 65%, respectively). BLF treatment reduced infiltrating cells compared to controls and no elevation of IL-1, whereas controls displayed elevated infiltrating cells and increased levels of IL-1. After 3 d, mice treated with BLF exhibited complete wound closure while control corneas still exhibited some minor defects. Resolution of inflammation with minimal remaining infiltrating cells was observed in all corneas by day 3, coincident to normal levels of IL-1α and IL-1β.BLF accelerated healing of corneal alkali injury in BALB/c mice which was associated with suppression of IL-1 and reduced infiltrating cells.

Purpose To evaluate subjective responses, rates of solution-induced corneal staining (SICS), and corneal infiltrative events (CIEs) associated with a silicone hydrogel when worn under a daily disposable (DD) or daily wear (DW) modality. Methods Data were obtained from seven prospective clinical trials, involving 283 subjects wearing Senofilcon A contact lenses (Johnson and Johnson Vision Care, Jacksonville, FL). Four groups wore the contact lens on a DW basis using multipurpose solutions (DW-MPS, n = 160), two groups using hydrogen peroxide (DW-H2O2, n = 83), and one group as a DD (n = 40). Participants were followed for 3 months using the same protocol. Subjective ratings were compared between DD and DW groups using a linear mixed model. Rates of SICS and CIE were calculated as the percent frequency of first events within the 3-month study. Association of SICS and CIE with subjective responses was analyzed using a linear mixed model. Results End-of-day comfort and dryness ratings were significantly better for DD (8.5 ± 1.7 and 8.6 ± 1.7, respectively) compared with DW-H2O2 (7.7 ± 1.8, p = 0.01; 7.6 ± 1.9, p = 0.006, respectively) and DW-MPS (7.7 ± 1.7, p = 0.004; 7.6 ± 2.0, p = 0.003, respectively). Compared with DD, a higher incidence of CIE and SICS was found for DW-MPS (0.0 vs. 3.9%, p = 0.021; 0.9 vs. 8.6%, p = 0.002, respectively). Comfort at insertion and end of day and end-of-day dryness scores were significantly lower for participants who experienced SICS (8.2 ± 1.6, 7.0 ± 1.9, and 7.0 ± 2.2) than those who did not (8.8 ± 1.2, p = 0.004; 7.9 ± 1.7, p = 0.002; and 7.9 ± 1.8, p = 0.003, respectively). Comfort at insertion scores were significantly lower for participants who experienced CIEs than those who did not (8.2 ± 1.5 vs. 8.8 ± 1.4, p = 0.032). Conclusions Senofilcon A clinical response is modulated by the lens care products. All lens care products tested reduced subjective responses relative to DD modality, whereas MPS increased the incidence of CIEs and SICS. Senofilcon A performs best when used on a DD basis.

Purpose During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. Methods The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. Results Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. Conclusions Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.

The deposition of biological material (biofouling) onto polymeric contact lenses is thought to be a major contributor to lens discomfort and hence discontinuation of wear. We describe a method to characterize lipid deposits directly from worn contact lenses utilizing liquid extraction surface analysis coupled to tandem mass spectrometry (LESA-MS/MS). This technique effected facile and reproducible extraction of lipids from the contact lens surfaces and identified lipid molecular species representing all major classes present in human tear film. Our data show that LESA-MS/MS is a rapid and comprehensive technique for the characterization of lipid-related biofouling on polymer surfaces.

Background Rabbits have a longer inter-blink time (approximately 10 minutes) compared with humans (five to eight seconds), suggesting that rabbits have a much more stable tear film. Using fluorescein, the tear break-up time of rabbits has been reported to be similar to that of humans. This study set out to measure the tear break-up time in rabbits using non-invasive methods and to establish the pattern of tear break-up compared to humans. Methods The tear break-up time was measured and the pattern of tear break-up was observed in six New Zealand White rabbits on two separate occasions using both the Keeler Tearscope-plusTM and a slitlamp biomicroscope. Results The mean rabbit tear break-up time was 29.8 ± 3.4 (SD) minutes. This contrasts with the reports of human tear break-up time of eight to 30 seconds. The tear breaking spread very slowly and was often restricted to the area of the initial break. Conclusion Rabbit tears have a significantly higher tear break-up time than humans and this aligns with previously demonstrated differences in inter-blink time between rabbits and humans. Understanding the underlying mechanisms of tear stability may lead to novel ways of increasing human tear film stability.

Antimicrobial peptides (AMPs) are promising alternatives to current treatments for bacterial infections. However, our understanding of the structural-functional relationship of tethered AMPs still requires further investigation to establish a general approach for obtaining consistent antimicrobial surfaces. In this study, we have systematically examined the effects of surface orientation of a broad-spectrum synthetic cationic peptide, melimine, on its antibacterial activity against Gram-positive and Gram-negative bacteria. The attachment of melimine to maleimide-functionalized glass was facilitated by addition of a single cysteine amino acid into the peptide sequence at the N-terminus (CysN) or C-terminus (CysC), or at position 13 (Cys13, approximately central). The successful attachment of the modified melimine was monitored using X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with principle component analysis. The ToF-SIMS analysis clearly demonstrated structural difference between the three orientations. The peptide density for the modified surfaces was found to be between 3.5-4.0×10(-9)molcm(-2) using a modified Bradford assay. The ability of the surfaces to resist Pseudomonas aeruginosa and Staphylococcus aureus colonization was compared using fluorescence confocal microscopy. Reductions in total P. aeruginosa and S. aureus adhesion of 70% (p

PURPOSE. To determine the ability of antimicrobial peptide melimine-coated contact lenses to reduce the incidence of microbial keratitis (MK) in a rabbit model of contact lens wear. METHODS. In vitro antimicrobial activity of melimine-coated contact lenses was determined against Pseudomonas aeruginosa by viable count and a radiolabeled assay. The amount of lipopolysaccharide (LPS) associated with bacteria bound to melimine-coated and control lenses was determined. Ocular swabs from rabbit eyes were collected for assessment of ocular microflora. A rabbit model for MK was developed that used overnight wear of contact lenses colonized by P. aeruginosa in the absence of a corneal scratch. During lens wear, detailed ocular examinations were performed, and the incidence of MK was investigated. Bacteria associated with worn lenses and infected corneas were determined by viable plate count. RESULTS. Inhibition in viable and total P. aeruginosa adhesion by melimine-coated contact lenses was 3.1 log10 and 0.4 log10, respectively. After colonization, the amount of LPS on lenses was approximately the same with or without melimine. Gram-positive bacteria were found in all the ocular swabs followed by fungus (42%). Melimine-coated lens wear was protective and significantly (odds ratio 10.12; P = 0.012) reduced the incidence of P. aeruginosa-driven MK in the rabbit model. The antimicrobial lenses were associated with significantly (P < 0.001) lower ocular scores, indicating improved ocular signs compared with controls. CONCLUSIONS. This study showed that contaminated contact lenses can produce MK without corneal epithelial defect in an animal model. Melimine-coated contact lenses reduced the incidence of MK associated with P. aeruginosa in vivo. Development of MK requires viable bacteria adherent to contact lenses, and bacterial debris adherent at the lens surface did not cause keratitis.

Purpose To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia , Stenotrophomonas , Elizabethkingia , Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans. Methods In vitro antimicrobial activity of Mel4 was determined against the four Gram negative bacteria by investigating growth curves for 24h followed by viable counts to determine the minimum inhibitory concentration (MIC). Contact lenses were coated by covalently binding Mel4, characterized by amino acid analysis, and were investigated for changes in lens parameters. Safety of Mel-4 coated lenses were determined in a rabbit model of daily contralateral wear. A prospective, randomised, double-masked, contralateral, 1week daily wear human clinical trial was used to evaluate subjective responses and ocular physiology. Results Mel4 was active against all the bacteria tested (MIC 50 ranged from 31–1000μgml −1 ) and produced an antimicrobial surface on contact lenses. Mel4-coating resulted hydrophilic surface without any significant change in contact lens parameters, and showed no signs of cytotoxicity or ocular irritation during rabbit wear. During human clinical trial, there were no differences between Mel4 coated and uncoated contact lenses in lens performance indicators and ocular signs such as corneal fluorescein staining. Mel4 and control uncoated lenses had no differences in ocular symptoms during lens wear. Conclusion Mel4 has achieved antimicrobial activity against variety of Gram negative bacteria that are often resistant to the action of cationic peptides and have been implicated in contact lens related adverse events. Mel4-coated contact lenses were safe to wear.

PURPOSE To establish the effect of lipid supplements on tear lipid biochemistry and their influence on lens wear comfort in habitual lens wearers. METHODS Forty habitual soft contact lens wearers were recruited to a double-masked, randomized crossover trial. An emulsion drop containing phosphatidylglycerol (Systane Balance; Alcon) and a liposomal spray containing phosphatidylcholine (Tears again; BioRevive) along with saline placebos were used three times a day for 14 days with 48 hours of washout between each intervention. The Contact Lens Dry Eye Questionnaire categorized participants into symptomatic and asymptomatic wearers. Ocular comfort was measured using the Ocular Comfort Index. Basal tears (15 μl from each eye) were collected with lenses in situ and assayed for the concentration and activity of phospholipase (sPLA2) and the concentration of a malondialdehyde (MDA). Electrospray ionization mass spectrometry characterized the tear lipidome. RESULTS Neither of the lipid supplements improved lens wear comfort compared to baseline. The spray treatment did not affect the concentration of the majority of lipid classes either at day 1 or at day 14. Both the lipid and placebo drops resulted in increased concentration of several lipid classes after day 1 of use, but by day 14, the concentration of most of the lipid classes had returned to baseline levels. With the lipid spray, sPLA2 activity (0.38 ± 0.2 vs. 0.73 ± 0.6 mmol/min/ml, p = 0.03) and lysophosphatidylethanolamine (LPE) (1.3 ± 0.5 vs. 2.7 ± 0.07 pmol/μl, p = 0.02) were higher in the symptomatic group compared to asymptomatic group at day 1 but not at day 14. The lipid drop resulted in increased LPE concentration in symptomatic wearers at day 1 (1.7 ± 0.3 vs. 2.4 ± 0.3 pmol/μl, p = 0.01) and at day 14 (1.7 ± 0.4 vs. 2.5 ± 0.5 pmol/μl, p = 0.04). Ocular comfort was inversely proportional to the level (r = -0.21, p = 0.007) and activity of sPLA2 (r = -0.20, p = 0.01). There was an association between sPLA2 and LPC (r = 0.41, p < 0.001) and LPE (r = 0.40, p = 0.001), and a negative association with (O-acyl)-ω-hydroxy fatty acids (OAHFAs) (r = -0.30, p = 0.03) in tears. CONCLUSIONS Contact lens wear comfort was associated with sPLA2 concentration and activity in tears. Lipid biochemistry was transiently influenced by exogenous supplements. Although the specific supplement formulations tested did not differ from placebo in this study, the results do suggest a potential role for lysophospholipids and OAHFAs in modulating symptoms during contact lens wear.

Lactoferrin and lactoferricin were immobilized on glass surfaces via two linkers, 4-azidobenzoic acid (ABA) or 4-fluoro-3-nitrophenyl azide (FNA). The resulting surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The antimicrobial activity of the surfaces was determined using Pseudomonas aeruginosa and Staphylococcus aureus strains by fluorescence microscopy. Lactoferrin and lactoferricin immobilization was confirmed by XPS showing significant increases (p 0.05) in nitrogen on the glass surface. The immobilization of both proteins slightly increased the overall hydrophobicity of the glass. Both lactoferrin and lactoferricin immobilized on glass significantly (p 0.05) reduced the numbers of viable bacterial cells adherent to the glass. For P. aeruginosa, the immobilized proteins consistently increased the percentage of dead cells compared to the total cells adherent to the glass surfaces (p 0.03). Lactoferrin and lactoferricin were successfully immobilized on glass surfaces and showed promising antimicrobial activity against pathogenic bacteria. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2612-2617, 2017.

Staphylococcus is a leading cause of microbial keratitis, characterized by destruction of the cornea by bacterial exoproteins and host-associated factors. The aim of this study was to compare extracellular and cell-associated proteins produced by two different isolates of S. aureus, a virulent clinical isolate (Staph 38) and a laboratory strain (Staphylococcus aureus 8325-4) of weaker virulence in the mouse keratitis model. Proteins were analyzed using 2D polyacrylamide gel electrophoresis and identified by subsequent mass spectrometry. Activity of staphylococcal adhesins was assessed by allowing strains to bind to various proteins adsorbed onto polymethylmethacrylate squares. Thirteen proteins in the extracellular fraction and eight proteins in the cell-associated fractions after bacterial growth were produced in increased amounts in the clinical isolate Staph 38. Four of these proteins were S. aureus virulence factor adhesins, fibronectin binding protein A, staphopain, glyceraldehyde-3-phosphate dehydrogenase 2 and extracellular adherence protein. The clinical isolate Staph 38 adhered to a greater extent to all mammalian proteins tested, indicating the potential of the adhesins to be active on its surface. Other proteins with increased expression in Staph 38 included potential moonlighting proteins and proteins involved in transcription or translation. This is the first demonstration of the proteome of S. aureus isolates from keratitis. These results indicate that the virulent clinical isolate produces more potentially important virulence factors compared to the less virulent laboratory strain and these may be associated with the ability of a S. aureus strain to cause more severe keratitis.