Comparison of Clinical Features and Treatment Outcomes of Pseudomonas aeruginosa Keratitis in Contact Lens and Non-Contact Lens Wearers.

PURPOSE: To compare the outcomes of Pseudomonas aeruginosa keratitis (PAK) in contact lens wearers (CLWs) and non-contact lens wearers (non-CLWs) and identify risk factors for poor visual acuity (VA) outcomes in each group. DESIGN: Retrospective cohort study METHODS: Two hundred fourteen consecutive cases of PAK were included between January 2006 and December 2019. Clinical features, microbiologic results, and treatment course were compared between CLW and non-CLW groups. Analyses of clinical features predicting poor final VA were performed. RESULTS: This study identified 214 infected eyes in 207 patients with PAK, including 163 eyes (76.2%) in CLWs and 51 eyes (23.8%) in non-CLWs. The average age was 39.2 years in CLWs and 71.9 years in non-CLWs (P < .0001). The average logMAR visual acuity (VA) at presentation was 1.39 in CLWs and 2.17 in non-CLWs (P < .0001); average final VA was 0.76 in CLWs and 1.82 in non-CLWs (P < .0001). Stromal necrosis required a procedural or surgical intervention in 13.5% of CLWs and 49.0% of non-CLWs (P < .0001). A machine learning-based analysis yielded a list of clinical features that most strongly predict a poor VA outcome (worse than 20/40), including worse initial VA, older age, larger size of infiltrate or epithelial defect at presentation, and greater maximal depth of stromal necrosis. CONCLUSIONS: Non-CLWs have significantly worse VA outcomes and required a higher rate of surgical intervention, compared with CLWs. Our study elucidates risk factors for poor visual outcomes in non-CLWs with PAK.

Colonization of therapeutic contact lens by dematiaceous fungi.

PURPOSE: To report 2 patients with colonization of therapeutic contact lens with dematiaceous fungi. METHODS: Case report. RESULTS: The first patient had a retained soft contact lens on an opaque cornea for 4 years with brownish black multiple colonies on the soft contact lens and culture grew Bipolaris spp. The second patient was on therapeutic contact lens for pseudophakic bullous keratopathy for 4 months and developed a brownish colonization of contact lens with unidentified dematiaceous fungi. Both the patients had conjunctivitis but did not develop fungal keratitis. CONCLUSION: Judicious use of therapeutic contact lens is required in agrarian countries with adequate emphasis on strict adherence to the standard protocols and frequent replacement of the lens.

Boston Type I Keratoprosthesis: Antibacterial Resistance and Microbiota Evaluation of Soft Contact Lenses.

PURPOSE: To evaluate microbiota colonizing soft contact lenses (CL) in eyes with Boston type I keratoprosthesis (BKPro), and determine the prevalence of resistance to fourth-generation fluoroquinolone (FQ). DESIGN: Prospective, observational study. SUBJECTS: Patients with BKPro using CL as routine who were in postoperative follow-up in the Department of Ophthalmology of the Federal University of Sao Paulo, and volunteered to participate in the study. All patients were under a prophylactic scheme of topical 0.5% moxifloxacin 3 times a day and topical 5% povidone-iodine (PI) at the time of CL exchange. METHODS: Patients on scheduled replacement scheme of CL had their lenses removed and sent for microbiological analysis. Standard culture methods were used for microorganism identification and susceptibility to different antibiotics was tested. Main outcome measure was prevalence of resistance to fourth-generation FQ. RESULTS: Among the 19 eyes, 12 eyes (63%) had at least 1 positive bacterial culture. The most prevalent isolates were Staphylococcus epidermidis and other coagulase-negative staphylococci. Actinomyces viscosus was isolated in 1 CL. Fungal cultures were all negative. Of the 12 eyes with culture bacterial growth, resistance to fourth-generation FQ (0.5% moxifloxacin) was identified in 6 different eyes (50%). None presented infectious complications. CONCLUSIONS: FQ-resistant bacteria were isolated in some patients. Although our prophylactic antibiotic regimen has been efficient in preventing bacterial infection, this analysis demonstrated that prophylaxis with PI and low FQ dose might increase resistance to antibiotics. Investigations in this field may help to outline future changes of prophylactic guidelines and therapeutic strategies.

Dexamethasone diffusion across contact lenses is inhibited by Staphylococcus epidermidis biofilms in vitro.

PURPOSE: This study was designed to measure the impact of bacterial biofilms on diffusion of an ocular therapeutic through silicone hydrogel bandage lenses in vitro. METHODS: An assay was designed to study the passage of a commonly used steroid, dexamethasone, through silicone hydrogel soft contact lenses. Diffused dexamethasone was measured using a spectrophotometer over a period of 18 hours and quantified using a standard curve. This assay was performed with control and Staphylococcus epidermidis biofilm-coated contact lenses comprised of lotrafilcon A and methafilcon. Biofilms were formed in brain heart infusion broth supplemented with D-glucose. RESULTS: The presented data validate a simple in vitro model that can be used to measure the penetration of a topical therapeutic through silicone hydrogel soft contact lenses. Using this model, we measured a reduction in dexamethasone diffusion up to 88% through S. epidermidis biofilm-coated silicone hydrogel lenses compared with control lenses. CONCLUSIONS: The results of this in vitro study demonstrate that bacterial biofilms impede dexamethasone diffusion through silicone hydrogel contact lenses and warrant future studies regarding the clinical benefit of using ocular therapeutics in the setting of bandage contact lens use for corneal epithelial defects.

Benefit of polyhexamethylene biguanide in Fusarium keratitis.

PURPOSE: To report a series of 3 patients with soft contact lens-related Fusarium keratitis. Two of them were treated with the antiamoebic polyhexamethylene biguanide 0.02% (PHMB) in combination with antifungal drugs, and 1 patient was treated with PHMB as sole antifungal regimen. METHODS: Chart review of 3 patients treated with PHMB in Fusarium keratitis. Two of them were refractory to the commonly used therapy. The antifungal power of PHMB and propamidine isethionate was tested against the patients' isolates as well as against the clinical isolates from another 9 patients with ocular mould infections. RESULTS: An excellent outcome could be achieved in 2 patients with Fusarium solani keratitis refractory to common antifungal treatment by the additional use of PHMB 0.02%. In another patient PHMB alone was sufficient to resolve Fusarium proliferatum infection. The drug was well tolerated. In all patients repeated abrasion was done for better penetration of the drugs. PHMB revealed a marked in vitro antifungal activity for the three Fusarium isolates as well as for another 9 isolates of ocular infections from other patients including also the genera Scedosporium, Aspergillus and Rhizopus giving minimal inhibitory concentrations ranging from 1.56 to 3.12 µg/ml. CONCLUSIONS: Fusarium keratitis is a severe ocular infection. We report on the use of PHMB in 3 patients given additionally or as sole antifungal drug. We emphasize the benefit of PHMB 0.02% in Fusarium keratitis which might be considered as a therapeutic option especially in cases refractory to common antifungal therapy and possibly in keratitis due to other fungi.

The effect of nondialyzable material (NDM) cranberry extract on formation of contact lens biofilm by Staphylococcus epidermidis.

PURPOSE: To assess the effects of NDM from cranberries on Staphylococcus epidermidis biofilm formed on soft contact lenses. METHODS: Soft contact lenses were incubated in Tryptic Soy Broth (TSB) together with S. epidermidis (ATCC35984/RP62A) and various concentrations of NDM, and inspected by scanning electron and confocal microscopy. The TSB was collected after sonification and monitored turbidometrically. RESULTS: NDM at ≥500 µg/mL concentration caused a significant (P < 0.01) reduction of biofilm. Scanning electron microscopy of biofilm in the presence of 500 to 1000 µg/mL NDM confirmed these results. In control lenses, multilayered mushroom-shaped biofilm and complete coverage of the lens surface were seen, whereas after incubation with 500 µg NDM per mL TSB, the biofilm was thinner with smaller protuberances, and exposed lens surface was partially seen. In samples incubated with 1000 µg NDM per mL TSB, the lens surface was clearly seen between sporadic microcolonies. CONCLUSIONS: NDM reduces formation of biofilm on soft contact lenses. This has important implications for the prevention of contact lens-related corneal infections caused by S. epidermidis.

The inhibitory activity of pomelo essential oil on the bacterial biofilms development on soft contact lenses.

The aim of present study was to investigate the microbial colonization of worn contact lenses (CLs) and to evaluate the inhibitory effect of pomelo (Citrus maxima) peels essential oil on the biofilm development on unworn CLs. The essential oil was isolated by steam distillation and analyzed by gas chromatography coupled with mass spectrometry, twenty compounds being isolated. The antimicrobial activity of pomelo oil was tested against S. epidermidis and P. aeruginosa strains, known for their ability to develop biofilms on prosthetic devices, by qualitative screening methods and quantitative assay of the minimal inhibitory concentrations (MIC) in order to evaluate the antibiofilm activity. Our study revealed that all worn CLs where 100% colonized by staphylococci and Enterobacteriaceae strains. The pomelo essential oil inhibited the development of bacterial biofilms formed by Gram-positive and Gram-negative microorganisms on soft CLs, its antibiofilm activity being specific and dependent on different physical parameters (contact time and temperature). The architecture of bacterial biofilms developed on soft contact lenses was analyzed using confocal scanning laser microscopy (CSLM).