Corticosteroid-Antibiotic Interactions in Bacteria that Cause Corneal Infection.

Purpose: Although a comprehensive knowledge of antibiotic/corticosteroid combinations is essential for the appropriate treatment of eye infections, the impact of their co-administration has not been well studied to date. A systematic pharmacodynamic/pharmacokinetic study to determine the effects of cotreatment with various antibiotics and corticosteroids was conducted. Methods: Four bacterial strains, seven antibiotics, and four corticosteroids were used in the analyses. Drug interactions were evaluated by considering antibacterial effects with a checkerboard assay and intracellular concentrations in human corneal epithelial cells. Results: The drug combinations that showed the most stable effects against Pseudomonas aeruginosa was levofloxacin-prednisolone. Stable combinations against the three types of Gram-positive bacteria were neomycin-prednisolone, ofloxacin-dexamethasone, ofloxacin-prednisolone, and polymyxin-dexamethasone. The cellular concentrations were changed for the gatifloxacin-fluorometholone, moxifloxacin-fluorometholone, tobramycin-dexamethasone, and tobramycin-prednisolone combinations. Conclusions: Loteprednol and fluorometholone reduced the antibacterial effects of all of the tested antibiotics in this study. Dexamethasone and prednisolone showed various effects in this regard, depending on the co-administered antibiotic. Prior knowledge of specific antibiotic/corticosteroid interactions provides valuable information to clinical practitioners by combining data on the antibacterial and intracellular uptake effects of their co-administration. Translational Relevance: When using antibiotics and corticosteroids, drug combinations can be selected by referring to the results of this study.

Corneal Involvement in HIV-infected Individuals.

Corneal involvement in HIV-infected individuals may be broadly classified into two categories, namely, infectious and noninfectious with the vast majority of manifestations occurring in the former. In this article, we shall focus on these two categories and strive to highlight those presentations that should alert the clinician to suspect underlying HIV infection. Infectious group mainly consists of Herpitic group of viral infections. Bacterial causes may be due to Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeroginosa, alpha hemolytic Streptococcus, Micrococcus and Bacillus. Fungalf keratitis in HIV-infected individuals depends on the geographic locations from which patient comes. Microsporidia and Acanthamoeba are common Protozoal causes. Non-infective inflammatory causes include peripheral ulcerative keratitis, keratoconjunctivitis sicca, and squamous cell carcinoma of the conjunctiva. Severity which is abnormally severe or very minimally reactive makes the clinician suspect of immunosuppression.

Design, Synthesis, and Biological Evaluation of Membrane-Active Bakuchiol Derivatives as Effective Broad-Spectrum Antibacterial Agents.

Infections caused by drug-resistant bacteria seriously endanger human health and global public health. Therefore, it is urgent to discover and develop novel antimicrobial agents to combat multidrug-resistant bacteria. In this study, we designed and synthesized a series of new membrane-active bakuchiol derivatives by biomimicking the structure and function of cationic antibacterial peptides. The most promising compound 28 displayed potent antibacterial activity against both Gram-positive bacteria (minimum inhibitory concentration, MIC = 1.56-3.125 µg/mL) and Gram-negative bacteria (MIC = 3.125 µg/mL), very weak hemolytic activity, and low cytotoxicity. Compound 28 had rapid bactericidal properties and avoided bacterial resistance. More importantly, compound 28 showed strong in vivo antibacterial efficacy against Staphylococcus aureus and Pseudomonas aeruginosa in murine corneal infection models. This design strategy is expected to provide an effective solution to the antibiotic crisis.

Development of antibiotic resistance in the ocular Pseudomonas aeruginosa clone ST308 over twenty years.

Corneal infection caused by a bacteria Pseudomonas aeruginosa is common cause of ocular morbidity. Increasing antibiotic resistance by ocular P. aeruginosa is an emerging concern. In this study the resistome of ocular isolates of Pseudomonas aeruginosa clone ST308 isolated in India in 1997 (PA31, PA32, PA33, PA35 and PA37) and 2018 (PA198 and PA219) were investigated. All the isolates of ST308 had >95% nucleotide similarity. The isolates from 2018 had larger genomes, coding sequences, accessory and pan genes compared to the older isolates from 1997. The 2018 isolate PA219 was resistant to all antibiotics except polymyxin B, while the 2018 isolate PA198 was resistant to ciprofloxacin, levofloxacin, gentamicin and tobramycin. Among the isolates from 1997, five were resistant to gentamicin, tobramycin and ciprofloxacin, four were resistant to levofloxacin while two were resistant to polymyxin B. Twenty-four acquired resistance genes were present in the 2018 isolates compared to 11 in the historical isolates. All isolates contained genes encoding for aminoglycoside (aph(6)-Id, aph(3')-lIb, aph(3″)-Ib), beta-lactam (blaPAO), tetracycline (tet(G)), fosfomycin (fosA), chloramphenicol (catB7), sulphonamide (sul1), quaternary ammonium (qacEdelta1) and fluoroquinolone (crpP) resistance. Isolate PA198 possessed aph(3')-VI, rmtD2, qnrVC1, blaOXA-488, blaPME-1, while PA219 possessed aadA1, rmtB, qnrVC1, aac(6')-Ib-cr, blaTEM-1B, blaVIM-2, blaPAO-1, mph(E), mph(A), msr(E). In both recent isolates qnrVC1 was present in Tn3 transposon. In 219 blaTEM-1 was carried on a transposon and blaOXA-10 on a class 1 integron. There were no notable differences in the number of single nucleotide polymorphisms, but recent isolates carried more insertions and deletions in their genes. These findings suggest that genomes of P. aeruginosa ocular clonal strains with >95% nucleotide identity isolated twenty years apart had changed over time with the acquisition of resistance genes. The pattern of gene mutations also varied with more insertions and deletions in their chromosomal genes which confer resistance to antibiotics.

First report of a new corneal pathogen: Phaeoacremonium parasiticum.

Keratitis is a public health issue in developing countries and a potentially sight-threatening condition. Collagen fibrils in the corneal stroma are parallels to each other. Fundamental substance maintains the same space between collagen fibrils. That is how corneal transparency can be achieved. Any damage which can modify this structure will lead to corneal opacity and loss of vision. Fungal keratitis might appear in up to one-third of cases. Nevertheless, fungal keratitis remains poorly described and understood. Herein, we present the first ever reported case of corneal infection due to Phaeoacremonium parasiticum in a young patient. We describe the clinical and microbial characteristics, and we also discuss the use of confocal microscopy in early diagnosis of this infection.

In Vitro and in Vivo Evaluation of Membrane-Active Flavone Amphiphiles: Semisynthetic Kaempferol-Derived Antimicrobials against Drug-Resistant Gram-Positive Bacteria.

Because of the rapid increase in bacterial resistance, there is an urgent need for developing new antimicrobial agents to combat multidrug-resistant pathogens. In this study, we designed and synthesized a series of kaempferol derivatives as antimicrobial agents biomimicking the structural properties and biological functions of host defense peptides. After fine-tuning of hydrophobic and cationic hydrophilic moieties linked to the flavone scaffold of kaempferol, we obtained a lead compound (52) that displayed high membrane selectivity (>128), poor hemolytic activity, low cytotoxicity to mammalian cells, and excellent activity against Gram-positive bacteria (minimum inhibitory concentrations = 1.56 µg/mL), including methicillin-resistant Staphylococcus aureus. Compound 52 can kill bacteria quickly by destroying the bacterial membranes and avoid developing bacterial resistance. Moreover, compound 52 exhibited potent in vivo antibacterial activity against S. aureus in a murine corneal infection model. These results indicated that compound 52 had the therapeutic potential as a novel membrane-active antimicrobial to combat Gram-positive bacterial infections.

An Environmental Control Experiment for Contamination of the Production and Storage of 20% Autologous Serum Eye Drops.

Purpose: To investigate the sterility of autologous serum eye drops used for ocular surface diseases. Methods: A total of 100 patients were enrolled. The serum was prepared as follows: 20% serum (20% S), 20% serum with dexamethasone (0.02 mg/ml) (20% S + Dex), and 20% serum with levofloxacin (0.1 mg/ml) (20% S + Lev). Serum samples were collected for normal microbial cultivation at 1, 3, 5, 7, 10, 14, 21, and 28 days. The last samples were also assessed on the 28th day by airtight microbial cultivation. Results: A total of 2400 samples were cultured, and the bacterial contamination rates of 20% S, 20% S+ Dex, and 20% S + Lev group were 4.75%, 3.38%, and 0.88%, respectively, for normal microbial cultivation. There was no significant difference in bacterial contamination among the three groups with times (P = .502). Bacterial contamination of the 20% S + Lev group showed a significant difference in comparison with the 20% S or 20% S + Dex group (P < .05) in two culture methods; however, no significant difference was found between the 20% S and 20% S + Dex group (P = .208). There were two samples positive for fungi in the 20% S and 20% S + Dex group and three samples in the 20% S + Lev group in normal cultivation during 28 days. None of the samples was positive with fungi in airtight cultivation on the 28th day. There was also less bacterial contamination in airtight cultivation than in normal cultivation for the three groups on the 28th day. Conclusions: Our study shows that 20% autologous serum drops can be safely prepared and stored at 4°C in an open system under a strict protocol for at least 28 days, and antimicrobial agents could reduce the risk of contamination.

Improving the Efficiency and the Technique of the Corneal Scrape Procedure via an Evidence Based Instructional Video at a Quaternary Referral Eye Hospital.

Purpose: Corneal culturing requires understanding of aseptic non-touch technique and avoidance of possible contaminants. Currently, there is no formal training in the technique and registrars are typically taught by another registrar in the emergency setting.The aim of the study was to develop an evidence-based instructional video for the corneal scrape procedure in microbial keratitis. The study then aims to assess the effect of the instructional video on clinician performance of the corneal scrape procedure.Method: An instructional video for corneal scraping was developed by identifying key steps for the procedure based on available evidence from a review of the literature and clinical practice. A prospective observational comparative case series that included clinicians at the Sydney Hospital/Sydney Eye Hospital, NSW Australia was conducted. Clinicians performing corneal scrapes had their performance of the procedure assessed prior to and after viewing the instructional video.Results: Sixteen key steps to follow in performing the corneal scrape procedure were found and demonstrated in the instructional video. Fourteen clinicians were observed performing 24 corneal scrapes in 24 patients with a median age of 56 years (IQR 34-65 years) and 45% male. Pre-video 11 scrapes were observed vs 13 scrapes post-video. Descriptive data were summarised and non-parametric categorical data analyzed using IBM SPSS (version 1.0.0.800) to perform chi-square and Wilcoxon signed-rank tests. Statistical significance was defined as p < .05. The steps of the corneal scrape procedure were performed correctly by a greater number of clinicians post-video compared to pre-video (p = .003). There was a significant improvement in inoculation of agar plates with cross-hatched streaks (92% post- vs 55% pre-video) and the maintenance of an intact agar surface (92% post vs 55% pre-video) (p = .033).Conclusion: An instructional video optimized the performance of corneal scraping, by ophthalmology trainees, in patients with microbial keratitis.

The clinical and microbiological features and outcomes of fungal keratitis over 9 years in Sydney, Australia.

To describe the clinical features, management and outcomes in patients with fungal keratitis at the Sydney Eye Hospital, Australia, over a 9-year period to guide appropriate initial therapy. A retrospective case review was conducted. Patients diagnosed with fungal keratitis from 1 January 2009 to 31 December 2017 were identified from hospital coding and pathology databases. Data were extracted from the medical records. A total of 55 episodes from 51 patients were included. Mean age was 60 ± 20 years (range: 19-91 years), and 33 were male. The fungal species was not identified in two patients. Predisposing factors included ocular surface disease in 17 eyes (32%); corneal disease, 15 (28%); corneal trauma, 12 (23%); and contact lens wear, 13 (24.5%). Fusarium spp. (15, 27%) and Candida parapsilosis (10, 18%) were the most common isolates. The median visual acuity at presentation was 1.3 logMAR (range: 0 to 3) and after treatment 0.7 logMAR (range: -0.02 to 3) (P = .008). Despite medical therapy, most commonly with natamycin and topical and oral voriconazole, surgical intervention was required in 21 eyes (40%); including antifungal injections in 9 (16%); corneal transplantation, 16 (30%); evisceration, 2 (4%); and enucleation, 1 (2%). A poor visual outcome was recorded in 27 of 43 (63%) patients. Fungal keratitis remains a cause of significant ocular morbidity; the majority of patients face a poor outcome despite intense medical and at times surgical treatment. In our setting, fungal keratitis was more commonly associated with corneal or ocular surface disease.

Corneal infection due to Moraxella nonliquefaciens / Infección corneal debida a Moraxella nonliquefaciens

No disponible

Accessory genome of the multi-drug resistant ocular isolate of Pseudomonas aeruginosa PA34.

Bacteria can acquire an accessory genome through the horizontal transfer of genetic elements from non-parental lineages. This leads to rapid genetic evolution allowing traits such as antibiotic resistance and virulence to spread through bacterial communities. The study of complete genomes of bacterial strains helps to understand the genomic traits associated with virulence and antibiotic resistance. We aimed to investigate the complete accessory genome of an ocular isolate of Pseudomonas aeruginosa strain PA34. We obtained the complete genome of PA34 utilising genome sequence reads from Illumina and Oxford Nanopore Technology followed by PCR to close any identified gaps. In-depth genomic analysis was performed using various bioinformatics tools. The susceptibility to heavy metals and cytotoxicity was determined to confirm expression of certain traits. The complete genome of PA34 includes a chromosome of 6.8 Mbp and two plasmids of 95.4 Kbp (pMKPA34-1) and 26.8 Kbp (pMKPA34-2). PA34 had a large accessory genome of 1,213 genes and had 543 unique genes not present in other strains. These exclusive genes encoded features related to metal and antibiotic resistance, phage integrase and transposons. At least 24 genomic islands (GIs) were predicated in the complete chromosome, of which two were integrated into novel sites. Eleven GIs carried virulence factors or replaced pathogenic genes. A bacteriophage carried the aminoglycoside resistance gene (AAC(3)-IId). The two plasmids carried other six antibiotic resistance genes. The large accessory genome of this ocular isolate plays a large role in shaping its virulence and antibiotic resistance.

Corneal Biofilm Plaques: A Novel Clinical Presentation.

PURPOSE: To report a novel clinical presentation of corneal biofilms, consisting of formation of superficial and recurrent corneal plaques. METHODS: Interventional case report. A 9-year-old boy presented with subepithelial, whitish, avascular, and recurrent corneal plaques without any clinical manifestations of active corneal inflammation and/or infection. He had a history of minor ocular trauma; otherwise, his medical history was unremarkable. RESULTS: An excisional biopsy was performed under topical anesthesia. Histological analysis identified these plaques as clusters of gram-negative bacilli surrounded by an extracellular matrix. Samples were further evaluated with special stains (calcofluor white, Flamingo fluorescent dye, propidium iodide, and Gomori-Grocott) that demonstrated biofilm structures. CONCLUSIONS: Corneal plaques are a very rare clinical presentation of corneal biofilms that allow prolonged survival of microorganisms even in the absence of prosthetic material and clinical signs or symptoms of corneal active inflammation and/or infection.

Staphylococcus aureus alpha-hemolysin impairs corneal epithelial wound healing and promotes intracellular bacterial invasion.

Colonization by Staphylococcus aureus (S. aureus) has been implicated in many infectious and wound healing disorders. This study was performed to characterize the pathogenic role of S. aureus alpha-hemolysin (alpha-toxin) in corneal epithelial wound healing and infectious keratitis in the setting of a corneal wound. The effect of wild-type and isogenic Hla mutant (α-hemolysin gene deleted) S. aureus bacteria and conditioned media on corneal epithelial wound healing was tested in vitro using a scratch assay and in vivo using a murine epithelial debridement model. The invasiveness of wild-type and Hla mutant S. aureus was evaluated in vitro in human corneal epithelial cells and in vivo in a murine model of infectious keratitis following total epithelial debridement. S. aureus and its conditioned media significantly delayed epithelial wound closure both in vitro (P < 0.05) and in vivo (P < 0.05). The effect of S. aureus on wound healing was significantly diminished with the Hla mutant strain (P < 0.05). Likewise, compared to the wild-type strain, the Hla mutant strain demonstrated significantly reduced ability to invade corneal epithelial cells in vitro (P < 0.05) and infect murine corneas following total epithelial debridement in vivo (P < 0.05). In conclusion, S. aureus alpha-hemolysin plays a major role in the pathologic modulation of corneal epithelial wound healing and the intracellular invasion of the bacteria. Limiting colonization by S. aureus and/or blocking alpha-hemolysin may provide a therapeutic approach for corneal wound healing and infectious disorders.

Water Exposure and the Risk of Contact Lens-Related Disease.

PURPOSE: To describe the association of water exposure with contact lens (CL)-related disease and explore the guidelines regarding water exposure to CL wearers, provided by CL manufacturing industry, global public health, and CL-related professional associations. METHODS: A review of the literature was conducted by searching PubMed, MEDLINE, and Web of Science databases up to September 2017 for articles published or translated in English using keywords: contact lens* AND tap water OR swimming OR showering OR water exposure AND microbial keratitis OR Acanthamoeba keratitis OR corneal infiltrate* OR ocular adverse event*. References in all relevant publications were also reviewed. RESULTS: Water exposure during CL wear is associated with complications ranging from sterile corneal infiltrative events to sight-threatening infections. Despite the documented risks due to water exposure, water-related habits are common among CL wearers. This suggests a lack of awareness and understanding regarding the risks among CL wearers and potentially CL practitioners. Discrepancies exist in guidelines for CL hygiene and compliance provided by the CL manufacturing industry, global public health, and CL-related professional associations. There is also widespread use of water imagery within CL marketing and packaging materials. These factors may give rise to confusion among wearers and may contribute toward risk-taking behaviors. CONCLUSIONS: Consensus among stakeholders about water and CL care is needed. Guidelines should unequivocally advocate for the avoidance of any water exposure including handling CLs with wet hands, rinsing CLs or storage cases in tap water, showering while wearing CLs and swimming with CLs without wearing goggles.

Aspergillus penicillioides Speg. Implicated in Keratomycosis.

The aim of the study was mycological examination of ulcerated corneal tissues from an ophthalmic patient. Tissue fragments were analyzed on potato-glucose agar (PDA) and maltose (MA) (Difco) media using standard laboratory techniques. Cultures were identified using classical and molecular methods. Macro- and microscopic colony morphology was characteristic of fungi from the genus Aspergillus (restricted growth series), most probably Aspergillus penicillioides Speg. Molecular analysis of the following rDNA regions: ITS1, ITS2, 5.8S, 28S rDNA, LSU and ß-tubulin were carried out for the isolates studied. A high level of similarity was found between sequences from certain rDNA regions, i.e. ITS1-5.8S-ITS2 and LSU, what confirmed the classification of the isolates to the species A. penicillioides. The classification of our isolates to A. penicillioides species was confirmed also by the phylogenetic analysis.The aim of the study was mycological examination of ulcerated corneal tissues from an ophthalmic patient. Tissue fragments were analyzed on potato-glucose agar (PDA) and maltose (MA) (Difco) media using standard laboratory techniques. Cultures were identified using classical and molecular methods. Macro- and microscopic colony morphology was characteristic of fungi from the genus Aspergillus (restricted growth series), most probably Aspergillus penicillioides Speg. Molecular analysis of the following rDNA regions: ITS1, ITS2, 5.8S, 28S rDNA, LSU and ß-tubulin were carried out for the isolates studied. A high level of similarity was found between sequences from certain rDNA regions, i.e. ITS1-5.8S-ITS2 and LSU, what confirmed the classification of the isolates to the species A. penicillioides. The classification of our isolates to A. penicillioides species was confirmed also by the phylogenetic analysis.

Effect of storage time and temperature on the detection of Pseudomonas aeruginosa, Acanthamoeba and Herpes Simplex Virus from corneal impression membranes.

The effect of storage time and temperature on the recovery of pathogen DNA from polytetrafluorethylene (PTFE) was investigated. PTFE impression membranes were inoculated with Pseudomonas aeruginosa, Herpes Simplex Virus-1 (HSV-1) or Acanthamoeba and stored at -70 °C, -20 °C, +4 °C or +35 °C. PCR was performed on days 0, 1, 2, 3, 7 and months 1, 3 and 10 post-inoculation. We found no reduction in the DNA recovery of any of the studied microorganisms for the first 3 days of storage up to +35 °C. For HSV-1 and P. aeruginosa, storage for 3 months at +35 °C was associated with a significant reduction in DNA recovery (P<0.001), but not at +4 °C, -20 °C or -70 °C for 1 month for P. aeruginosa and for 10 months for HSV-1. Acanthamoeba DNA recovery was not affected by any storage parameters (P=0.203). These results will inform the investigation of microbial keratitis where access to microbiological testing is not readily available.