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This paper seeks to outline the history, market situation, clinical management and product performance related to the correction of presbyopia with both contact lenses and spectacles. The history of the development of various optical forms of presbyopic correction are reviewed, and an overview is presented of the current market status of contact lenses and spectacles. Clinical considerations in the fitting and aftercare of presbyopic contact lens and spectacle lens wearers are presented, with general recommendations for best practice. Current options for contact lens correction of presbyopia include soft simultaneous, rigid translating and rigid simultaneous designs, in addition to monovision. Spectacle options include single vision lenses, bifocal lenses and a range of progressive addition lenses. The comparative performance of both contact lens and spectacle lens options is presented. With a significant proportion of the global population now being presbyopic, this overview is particularly timely and is designed to act as a guide for researchers, industry and eyecare practitioners alike.
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Lentes de Contacto , Anteojos , Presbiopía , Presbiopía/terapia , Presbiopía/fisiopatología , Humanos , Diseño de EquipoRESUMEN
PURPOSE: All neophyte contact lens wearers require training on how to handle contact lenses. Currently, almost no published information exists describing the most common approaches used by those involved in such training in soft contact lens wearers. This study aimed to gather information on the approaches taken by those conducting this training worldwide. METHODS: An online survey was created in English and translated to Spanish and distributed internationally via social media, conference attendees, and professional contacts. The anonymous survey included information on workplace setting of respondents, information about the typical approaches used for application and removal of soft contact lenses, length of the appointment, and success rate with their approach. Survey responses were received between May 2021 and April 2022. RESULTS: A total of 511 individuals completed the survey and responses were received from 31 countries with 48.7% from the UK. The most common approach taught for application was to have the patient hold the upper eyelashes (84.7%) and to hold the lower eyelid with the same hand as the lens (89.4%). Lenses were applied directly to the cornea by 57.7% of the respondents. The most common approach taught for lens removal was to drag the lens inferiorly from the cornea prior to removal (49.3%). Most respondents did not use videos to aid the teaching appointment (62.0%); however, they felt that their approach was successful in most cases (90). Application and removal training sessions lasted a median of 30 min and contact lenses were typically dispensed after the instructor witnessing successful application and removal three times. CONCLUSION: Various methods are adopted globally for training of application and removal of soft contact lenses, with many advising a patient-specific approach is required for success. The results of this survey provide novel insights into soft contact lens handling training in clinical practice.
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Lentes de Contacto Hidrofílicos , Humanos , Córnea , Párpados , Encuestas y CuestionariosRESUMEN
OBJECTIVES: Human tears have the potential to be used as biomarkers to aid in the diagnosis and management of dry eye disease (DED). This prospective, controlled pilot study aimed to investigate the hypothesis that a panel of tear protein profiles can be detected and are repeatable when analyzed using a miniaturized quantitative microfluidic system. METHODS: Ten participants were recruited following institutional ethics committee approval. Participants attended two visits 1 week apart when the following measurements were taken in a sequence: tear meniscus height, noninvasive breakup time, ocular redness, tear collection, and corneal and conjunctival staining. Basal tears (>4 µL) were collected using glass microcapillary tubes. Tears were processed to analyze a panel of proteins (14-230 kDa) following the manufacturer's guidelines using a miniaturized quantitative microfluidic system (Protein 230 LabChip with Agilent 2100 Bioanalyzer). Demographics of the clinical measurements and a comparison of the panel of identified proteins and their repeatability were made. RESULTS: Mean age of the participants was 20.8±1.6 years, nine were females, three fulfilled the TFOS DEWS-II diagnostic criteria for DED. The total protein concentration across participants was 6.72±3.56 mg/mL. Several proteins (lysozyme C, lipocalin 1, IgA light chain, zinc-α2-glycoprotein, albumin, and lactoferrin) were identified at both visits for seven or more participants. There were no significant differences ( P >0.05) in individual protein concentrations between the two visits. A high correlation was found between the two visits for all proteins where correlation coefficient ranged between 0.63 and 0.98 ( P <0.05). CONCLUSION: The protein profiles measured by the quantitative microfluidic system are repeatable, thus validating quantitative microfluidic system as a reliable method for investigating a panel of tear proteins. This method is quick, affordable, requires only 4 µL of tear, and is relatively easy method to perform that can be incorporated in a clinical setting. Further studies in larger clinical setting may be beneficial exploring the usability of this method in various patient groups.
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Síndromes de Ojo Seco , Microfluídica , Femenino , Humanos , Masculino , Adulto Joven , Córnea/metabolismo , Síndromes de Ojo Seco/diagnóstico , Síndromes de Ojo Seco/metabolismo , Proyectos Piloto , Estudios Prospectivos , Lágrimas/metabolismoRESUMEN
PURPOSE: In light of the increased roles of optometrists working in primary care in the UK, this research study aimed to gain an insight into perceptions of dry eye disease (DED), knowledge and confidence in diagnosis and management, and satisfaction with currently available treatment options. METHODS: Links to an online survey were distributed to optometrists across the UK via optometry websites newsletters, conferences, and local optical committee data bases, between October 2021 and July 2022. The anonymous questionnaire contained a variety of question types including multiple choice, likert-type scale, and free text questions. RESULTS: The survey was completed by 131 optometrists, with a broad range of experience, who reported examining 33.3 ± 31.0 dry eye patients per month. Forty-eight percent of respondents were involved in the provision of an extended service. Fluorescein tear breakup time, corneal fluorescein staining, and anterior lid assessment were the most used clinical procedures, both for diagnosis and monitoring purposes. Sixty percent of respondents reported that they believed their patients were satisfied/managed with artificial tear alone, with the availability of a preservative free option being the top consideration, particularly with increasing severity. Of the 18.7% of respondents who held Independent prescriber status, 68% felt this had widened their ability to diagnose and treat DED. This was evidenced by an increase in steroid recommendation for moderate and severe disease. CONCLUSIONS: Although dry eye disease was perceived to be an important condition, opinions varied widely regarding knowledge and confidence in diagnosis and management. Involvement in an extended service did not alter patient management. However, an increase in therapeutic management and the employment of a stepwise approach to management has been identified.
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Síndromes de Ojo Seco , Optometristas , Humanos , Pautas de la Práctica en Medicina , Síndromes de Ojo Seco/diagnóstico , Síndromes de Ojo Seco/terapia , Fluoresceína , Reino UnidoRESUMEN
The corneal epithelium is a layer in the anterior part of eye that contributes to light refraction onto the retina and to the ocular immune defense. Although an intact corneal epithelium is an excellent barrier against microbial pathogens and injuries, corneal abrasions can lead to devastating eye infections. Among them, Pseudomonas aeruginosa-associated keratitis often results in severe deterioration of the corneal tissue and even blindness. Hence, the discovery of new drugs able not only to eradicate ocular infections, which are often resistant to antibiotics, but also to elicit corneal wound repair is highly demanded. Recently, we demonstrated the potent antipseudomonal activity of two peptides, Esc(1-21) and its diastereomer Esc(1-21)-1c. In this study, by means of a mouse model of P. aeruginosa keratitis and an in vivo corneal debridement wound, we discovered the efficacy of these peptides, particularly Esc(1-21)-1c, to cure keratitis and to promote corneal wound healing. This latter property was also supported by in vitro cell scratch and ELISA assays. Overall, the current study highlights Esc peptides as novel ophthalmic agents for treating corneal infection and injury, being able to display a dual function, antimicrobial and wound healing, rarely identified in a single peptide at the same micromolar concentration range.
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Lesiones de la Cornea , Queratitis , Infecciones por Pseudomonas , Animales , Ratones , Pseudomonas aeruginosa , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/microbiología , Queratitis/tratamiento farmacológico , Queratitis/microbiología , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Antibacterianos/química , Lesiones de la Cornea/tratamiento farmacológico , Péptidos/uso terapéutico , Cicatrización de HeridasRESUMEN
Artificial tears are the mainstay of dry eye disease management, but also have a role in corneal abrasion and wound healing, pain and inflammation management, conjunctivitis, keratitis, contact lens rewetting and removal, and foreign body removal. A systematic review of randomized controlled trials (PROSPERO registration CRD42022369619) comparing the efficacy of artificial tears in patients with dry eye to inform prescribing choices using Web of Science, PubMed and Medline databases identified 64 relevant articles. There is good evidence that artificial tears improve symptoms of dry eye disease within a month of regular use, applied about four times a day, but signs generally take several months to improve. Not all patients with dry eye disease benefit from artificial tears, so if there is no benefit over a month, alternative management should be considered. Combination formulations are more effective than single active ingredient artificial tears. Artificial tears containing polyethylene glycol are more effective than those containing carboxymethylcellulose/carmellose sodium and hydroxypropyl methylcellulose. Those classified as having evaporative dry eye disease, benefit from artificial tears with liposomes, especially of higher concentration. The data available is limited by the definition of dry eye disease applied in published studies being variable, as well as the disease severity examined and compliance with artificial tears being rarely quantified.
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A clinical study of antimicrobial contact lenses containing the cationic peptide Mel4 was conducted. The few adverse events that occurred with this lens occurred on or after 13 nights of wear. The current study examined whether the Mel4 contact lenses lost activity during wear and the mechanism of this loss. Participants wore contact lenses for up to 13 nights. Lenses were tested for their ability to reduce the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus. The amount of protein and lipid extracted from lenses was measured. The ability of trypsin to affect the antimicrobial activity of Mel4-coated contact lenses was measured. Mel4-coated contact lenses lost their antimicrobial activity at six nights of wear for both bacteria. The amount of lipids (13 ± 11 vs. 21 ± 14 µg/lens at 13 nights wear) and proteins (8 ± 4 vs. 10 ± 3 mg/lens at 13 nights of wear) extracted from lenses was not different between Mel4-coated and uncoated lenses, and was not different after three nights when antimicrobial activity was maintained and thirteen nights when they had lost activity (lipid: 25 ± 17 vs. 13 ± 11, p = 0.2; protein: 8 ± 1 vs. 8 ± 4 mg/lens, p = 0.4). Trypsin digestion eliminated the antimicrobial activity of Mel4-coated lenses. In summary, Mel4-coated contact lenses lost antibacterial activity at six nights of wear, and the most likely reason was proteolytic digestion of the peptide. Future studies will design and test proteolytically stable peptide mimics as coatings for contact lenses.
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PURPOSE: To determine the effects of a thermo-mechanical action-based peri-orbital fractional skin treatment (Tixel®) on dry eye disease. METHODS: This prospective, controlled, open labelled study was conducted at two study centres: Midland Eye, Solihull, UK, and Vallmedic Vision, Andorra. Participants were screened at the baseline visit (visit-1), received three Tixel® treatments at 2-weeks intervals including further assessment (visits 2, 3 and 4). Participants were followed up for three months post-treatment (visit 5). Vision, intraocular pressure (IOP), dry eye symptomatology were assessed, including the Ocular Surface Disease Index (OSDI) questionnaire, non-invasive tear break-up time (NIBUT) and tear osmolarity as well as detailed ophthalmic assessments. RESULTS: Seventy-four participants (41 in Birmingham and 33 in Andorra) with periorbital wrinkles and moderate to severe dry eye disease (DED) were enrolled. The mean age was 59.3 ± 13.3 years and 57 were females. No adverse events, no change in vision (p = 0.310) or IOP (p = 0.419) were observed. Tixel treatment was associated with clinically and statistically significant improvement in the DED symptoms, which was supported by a reduction of 21.40 ± 15.08 (P < 0.001) of the OSDI index. Non-invasive tear break-up time improved by 2.10 ± 0.91 s (p < 0.001) in the Birmingham cohort and 6.60 ± 2.13 s (p < 0.001) in the Andorra cohort. Tear osmolarity reduced from 299.8 ± 13.3 mOsm/L to 298.8 ± 15.6 mOsm/L following the Tixel treatment (p = 0.271). CONCLUSIONS: Thermo-mechanical action-based peri-orbital fractional skin treatment Tixel® could be an attractive, safe and effective treatment for DED. This treatment is associated with high clinical and statistically significant improvement in DED signs and symptoms with no adverse events.
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Síndromes de Ojo Seco , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Síndromes de Ojo Seco/terapia , Síndromes de Ojo Seco/tratamiento farmacológico , Estudios Prospectivos , Lágrimas , Resultado del TratamientoRESUMEN
Infection of the ocular surface can have devastating consequences if not appropriately treated with antimicrobials at an early stage [...].
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The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2) was used. Pseudomonas aeruginosa, Staphylococcus aureus, Fusarium solani, and Candida albicans agar plate lawns were exposed to the device beams for 15 and 30 s at 8 mm distance. Following the exposure, the diameter of the growth inhibition zone was recorded. Contact lenses made of Delfilicon-A, Senofilicon-A, Comfilicon-A, Balafilicon-A, Samfilicon-A and Omafilicon-A and a commercially available contact storage case was used. They were exposed to bacterial and fungal strains for 18 h at 37 °C and 25 °C respectively. After this, the samples were exposed to UVC for 30 s at 8 mm distance to determine the antimicrobial efficacy. Samples were then gently washed and plated on appropriate agar for enumeration of colonies. The UVC exposure reduced microbial growth by 100% in agar lawns, and significantly (p < 0.05) reduced microbial contamination to contact lenses and cases, ranging between 0.90 to 4.6 log. Very short UVC exposure has high antimicrobial efficacy against most of the predominant causative microorganisms implicated in contact lens related keratitis. UVC could be readily used as a broad-spectrum antimicrobial treatment for lens disinfection.
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(1) Purpose: This study aimed to investigate the effects of Mel4 antimicrobial contact lenses (MACL) on the ocular surface and comfort during extended wear. (2) Methods: A prospective, randomised, double-masked, contralateral clinical trial was conducted with 176 subjects to evaluate the biocompatibility of contralateral wear of MACL. The wearing modality was 14-day extended lens wear for three months. The participants were assessed at lens dispensing, after one night, two weeks, one month and three months of extended wear and one month after study completion. (3) Results: There were no significant differences (p > 0.05) in ocular redness or palpebral roughness between Mel4 and control eyes at any of the study visits. There was no significant difference (p > 0.05) in corneal staining between Mel4 and control eyes. There were no significant differences in front surface wettability or deposits or back surface debris (p > 0.05). No statistically significant differences (p > 0.05) were found in comfort, dryness, CLDEQ-8 scores lens or edge awareness. There was no evidence for delayed reactions on the ocular surface after cessation of lens wear. (4) Conclusion: The novel MACLs showed similar comfort to control lenses and were biocompatible during extended wear. Thus, these lenses were compatible with the ocular surface.
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Assessment of bacterial dye release following exposure to antimicrobial peptides (AMPs) provides a detailed understanding regarding their interaction with the inner and outer membrane of bacteria, and the leak of bacterial intracellular materials. This underpins the overall antimicrobial mechanism of these membrane-active peptides. DiSC3(5) is a membrane potential sensitive dye and can characterize the changes in bacterial membrane potential following exposure to AMPs (see Note 1). SYTOX Green is a nucleic acid stain that enters the cell upon loss of membrane integrity after exposure to AMPs and binds to DNA. SYTO9 is another nucleic acid stain, whereas propidium iodide (PI) is a fluorescent intercalating agent that can be used to stain cells and nucleic acids. Both of these stains are widely used to monitor the viability of bacteria following exposure to AMPs. This chapter describes the methods of using these as bacterial dye release experiments for assessment of the antimicrobial mechanism of AMPs.
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Péptidos Antimicrobianos/química , Antibacterianos , Péptidos Catiónicos Antimicrobianos/farmacología , Bacterias , Pruebas de Sensibilidad Microbiana , Ácidos Nucleicos , PropidioRESUMEN
AIM: To determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. METHOD: Across four sites, 74 neophytes (18-28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0-100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4-6 days and 12-14 days after lens fitting. Subjective scores were also repeated after 7 days. RESULTS: There was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4-6 days, but was similar by 12-14 days. Subjective scores were also similar across the visits and lens types with the exception of 'lens awareness' (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12-14 days. CONCLUSION: There seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients.
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Lentes de Contacto Hidrofílicos , Hidrogel de Polietilenoglicol-Dimetacrilato , Humanos , Hidrogeles , Satisfacción del Paciente , SiliconasRESUMEN
PURPOSE: The purpose of this study was to investigate the effect of Mel4 antimicrobial peptide-coated contact lenses (MACL) on the microbiota of the conjunctiva and lenses during three months of extended wear. METHODS: One hundred and seventy-six participants were recruited into a randomised, contralateral, double masked, biweekly extended wear MACL and uncoated control lens trial. At the one month and 3-month visit, the conjunctival microbiota was sampled using sterile cotton swabs and contact lenses were collected aseptically. Standard microbiological procedures were employed for culture of the swabs and contact lenses and identification of the isolated microorganisms. RESULTS: Gram-positive bacteria (predominantly coagulase-negative staphylococci) were the most frequently isolated microbes from both contact lenses and conjunctiva. There was no difference in the frequency of isolation of most bacteria or fungi from the conjunctival swabs of eyes wearing either MACL or control lenses. The only exception was a higher frequency of eyes harbouring Staphylococcus arlettae when wearing control lenses (5%) versus MACL (<1%) (p = 0.002). There was no significant difference in the frequency of microbes isolated from MACL or control contact lenses. There were also no differences between lens types in the frequency of isolation of >1 microbial type per sampling occasion for either conjunctiva swabs or contact lenses. CONCLUSION: MACL wear did not change the conjunctival microbiota during extended wear, and the types of microbes isolated from MACL were similar to those isolated from control lenses.
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Lentes de Contacto de Uso Prolongado , Lentes de Contacto Hidrofílicos , Lentes de Contacto , Microbiota , Antibacterianos , Péptidos Antimicrobianos , Bacterias , HumanosRESUMEN
Staphylococcus aureus can develop resistance by mutation, transfection or biofilm formation. Resistance was induced in S. aureus by growth in sub-inhibitory concentrations of ciprofloxacin for 30 days. The ability of the antimicrobials to disrupt biofilms was determined using crystal violet and live/dead staining. Effects on the cell membranes of biofilm cells were evaluated by measuring release of dyes and ATP, and nucleic acids. None of the strains developed resistance to AMPs while only S. aureus ATCC 25923 developed resistance (128 times) to ciprofloxacin after 30 passages. Only peptides reduced biofilms of ciprofloxacin-resistant cells. The antibiofilm effect of melimine with ciprofloxacin was more (27%) than with melimine alone at 1X MIC (p < 0.001). Similarly, at 1X MIC the combination of Mel4 and ciprofloxacin produced more (48%) biofilm disruption than Mel4 alone (p < 0.001). Combinations of either of the peptides with ciprofloxacin at 2X MIC released ≥ 66 nM ATP, more than either peptide alone (p ≤ 0.005). At 2X MIC, only melimine in combination with ciprofloxacin released DNA/RNA which was three times more than that released by melimine alone (p = 0.043). These results suggest the potential use of melimine and Mel4 with conventional antibiotics for the treatment of S. aureus biofilms.
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Purpose: To determine whether Mel4-coated antimicrobial contact lenses (MACLs) can reduce the incidence of corneal infiltrative events (CIEs) during extended wear. Methods: A prospective, randomized, double-masked, single-center, contralateral, extended contact lens wear clinical trial was conducted with 176 subjects. Each participant was randomly assigned to wear a MACL in one eye and an uncoated control contact lens in the contralateral eye or an extended-wear biweekly disposable modality for 3 months. The main outcome measures were the incidence of CIEs per 100 eye-months, identification of the microbial types colonizing the contact lenses or eyes at the time of the CIEs, and their susceptibility to Mel4. Results: Nine participants (5.1%) experienced unilateral CIEs; six participants had contact lens acute red eye, and three participants had infiltrative keratitis. The incidence rate for CIEs (0.4 events per 100 participant months; 1.7%) in the Mel4-coated lenses (test) was 69% less than that of the control lenses (1.3 events per 100 participant months; 3.4%; P = 0.29). All Gram-negative bacteria isolated from lenses and lids of participants with CIEs (Citrobacter diversus, Acinetobacter haemolyticus, and Acinetobacter lwoffii) were susceptible to Mel4 peptide; minimum inhibitory concentrations ranged from 15.6 to 62.5 µg/mL. Reduction of adhesion of these bacteria by Mel4-coated lenses ranged from 2.1 to 2.2 log10 colony-forming units/lens. Conclusions: MACLs had the capacity to reduce CIEs by at least 50% compared with uncoated control lenses during extended wear over 3 months; however, due to the relatively low rates of CIEs, the reduction was not statistically different compared with control lenses. Translational Relevance: This study provides evidence that antimicrobial contact lenses have the potential to reduce the incidence of corneal infiltrative events during extended wear.
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Lentes de Contacto , Acinetobacter , Antibacterianos , Humanos , Estudios ProspectivosRESUMEN
A key element of contact lens practice involves clinical evaluation of anterior eye health, including the cornea and limbus, conjunctiva and sclera, eyelids and eyelashes, lacrimal system and tear film. This report reviews the fundamental anatomy and physiology of these structures, including the vascular supply, venous drainage, lymphatic drainage, sensory innervation, physiology and function. This is the foundation for considering the potential interactions with, and effects of, contact lens wear on the anterior eye. This information is not consistently published as academic research and this report provides a synthesis from all available sources. With respect to terminology, the report aims to promote the consistent use of nomenclature in the field, and generally adopts anatomical terms recommended by the Federative Committee for Anatomical Terminology. Techniques for the examination of the ocular surface are also discussed.
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Lentes de Contacto , Lágrimas , Conjuntiva , Córnea , Párpados , HumanosRESUMEN
Melimine and Mel4 are cationic antimicrobial peptides which can resist biofilm development once bound to biomaterials. The aim of the current study was to determine the mode of action of bound melimine and Mel4 against S. aureus. The peptides were covalently attached to glass using an azidobenzoic acid linker. The amount of attached peptides was confirmed by XPS and amino acid analysis and their covalent attachment by SDS extraction. The release of autolysins after interaction of S. aureus with immobilized peptides was determined in cell free supernatants. The interaction of immobilized peptides with lipoteichoic acid was confirmed by ELISA. Membrane damage by surface bound peptides was assessed using DiSC(3)-5 (membrane potential sensitive), Syto-9 (membrane permeable) and PI (membrane impermeable) dyes with fluorescence microscopy. Release of ATP and nucleic acids (DNA/RNA) was measured in the surrounding fluid. Attachment of the peptides resulted in increased N% for melimine (5.4 ± 1.8%) and for Mel4 (4.8 ± 1.8%). The concentrations of immobilised amino acids were 0.297 nmole for melimine and 0.358 nmole for Mel4. SDS extraction released < 15% of peptides from the glass. The immobilized peptides bound ≥ 4 times more LTA than control surfaces. More autolysins (8 ± 2%; p = 0.026) were released from Mel4 than melimine or control surfaces. Membrane depolarization occurred at 15 min and was associated with a reduction in bacterial viability ≥ 37% for both peptides (p < 0.001). Disruption of the membrane potential resulted in loss of ATP from melimine (0.9 ± 0.4 nM) or Mel4 (0.6 ± 0.3 nM) coated surfaces compared to control (p < 0.001). Melimine coatings yielded 27 ± 11% (p = 0.026) and Mel4 gave 17 ± 12% (p = 0.150) PI stained cells after 4 h. DNA/RNA was released only by melimine coatings (2.1 ± 0.1 times; p = 0.011) compared to process control at 6 h. Both bound peptides resulted in the release of ATP, but only melimine released DNA/RNA while Mel4-coating resulted in the release of autolysins. Since the mode of action of melimine and Mel4 relate to the cell surface, they have potential for the development of infection-resistant implants.
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Staphylococcus aureus , Péptidos Catiónicos Antimicrobianos , Pseudomonas aeruginosa , Propiedades de SuperficieRESUMEN
Pseudomonas aeruginosa is increasingly resistant to conventional antibiotics, which can be compounded by the formation of biofilms on surfaces conferring additional resistance. P. aeruginosa was grown in sub-inhibitory concentrations of the antimicrobial peptides (AMPs) melimine and Mel4 or ciprofloxacin for 30 consecutive days to induce the development of resistance. Antibiofilm effect of AMPs and ciprofloxacin was evaluated using crystal violet and live/dead staining with confocal microscopy. Effect on the cell membrane of biofilm cells was evaluated using DiSC(3)-5 dye and release of intracellular ATP and DNA/RNA. The minimum inhibitory concentration (MIC) of ciprofloxacin increased 64-fold after 30 passages, but did not increase for melimine or Mel4. Ciprofloxacin could not inhibit biofilm formation of resistant cells at 4× MIC, but both AMPs reduced biofilms by >75% at 1× MIC. At 1× MIC, only the combination of either AMP with ciprofloxacin was able to significantly disrupt pre-formed biofilms (≥61%; p < 0.001). Only AMPs depolarized the cell membranes of biofilm cells at 1× MIC. At 1× MIC either AMP with ciprofloxacin released a significant amount of ATP (p < 0.04), but did not release DNA/RNA. AMPs do not easily induce resistance in P. aeruginosa and can be used in combination with ciprofloxacin to treat biofilm.