Tristan Bourcier

Bacterial keratitis: predisposing factors, clinical and microbiological review of 300 cases

Aim: To identify predisposing factors and to define clinical and microbiological characteristics of bacterial keratitis in current practice. Methods: A retrospective analysis of the hospital records of patients presenting with bacterial keratitis and treated at the Quinze-Vingts National Center of Ophthalmology, Paris, France, was performed during a 20 month period. A bacterial keratitis was defined as a suppurative corneal infiltrate and overlying epithelial defect associated with presence of bacteria on corneal scraping and/or that was cured with antibiotic therapy. Risk factors, clinical and microbiological data were collected. Results: 300 cases (291 patients) of presumed bacterial keratitis were included. Potential predisposing factors, usually multiple, were identified in 90.6% of cases. Contact lens wear was the main risk factor (50.3%). Trauma or a history of keratopathy was found in 15% and 21% of cases, respectively. An organism was identified in 201 eyes (68%). 83% of the infections involved Gram positive bacteria, 17% involved Gram negative bacteria, and 2% were polymicrobial. Gram negative bacteria were associated with severe anterior chamber inflammation (p=0.004), as well as greater surface of infiltrates (p=0.01). 99% of ulcers resolved with treatment, but only 60% of patients had visual acuity better than the level at admission, and 5% had very poor visual outcome. Conclusions: Contact lens wear is the most important risk factor. Most community acquired bacterial ulcers resolve with appropriate treatment.

In vivo confocal microscopy in fungal keratitis

Background: Fungal keratitis is a major blinding eye disease found throughout the world, particularly in developing countries. Given the recent increase in Fusarium keratitis infections in contact lens wearers owing to contact lens solutions, a warning was recently issued by the Food and Drug Administration, making it a public health concern in developed countries. Objective: To show the advantages of in vivo confocal microscopy imaging using the Heidelberg Retina Tomograph II-Rostock Cornea Module (HRTII-RCM) in the early diagnosis of fungal keratitis. Methods: HRTII-RCM confocal microscopy was performed on five patients presenting with fungal keratitis and on three donor corneas contaminated with Fusarium solani, Aspergillus fumigatus and Candida albicans. Results: Direct microscopic evaluation of corneal smears and culture revealed the presence of F solani in four cases and C albicans in one case. HRTII-RCM examination of the infected patients and contaminated donor corneas revealed numerous high-contrast elements resembling Fusarium, Aspergillus hyphae or Candida pseudofilaments in the anterior stroma. Conclusion: HRTII-RCM in vivo confocal microscopy is a new, non-invasive and rapid technique for the early diagnosis of fungal keratitis, showing high-resolution images resembling fungal structures in the early phase of the disease.

Cytokine Profiles in Toxoplasmic and Viral Uveitis

BACKGROUND Uveitis is a major cause of visual impairment throughout the world. Analysis of cytokine profiles in aqueous humor specimens may provide insight into the physiopathological processes that underly retinal damage in this context. METHODS Using a multiplex assay, we determined the concentrations of 17 cytokines and chemokines in aqueous humor specimens obtained from patients with ocular toxoplasmosis or viral uveitis and compared these concentrations with those in specimens obtained from patients with noninfectious intermediate uveitis or cataract. RESULTS Five mediators (interleukin [IL]-8, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, IL-4, and IL-10) were detected in >50% of patients in all groups. In contrast, IL-5 and IL-12 were specific for ocular toxoplasmosis, and granulocyte monocyte colony-stimulating factor and IL-1 were specific for viral uveitis; these mediators could present specific markers for diagnostic purposes. Interferon-gamma, IL-6, and macrophage inflammatory protein-1beta were common markers of ocular toxoplasmosis and viral uveitis. IL-17 was a common marker of ocular toxoplasmosis and intermediate uveitis. CONCLUSIONS We found specific cytokine profiles for each type of uveitis, with large interindividual variations and no etiological or clinical correlations. Ocular cytokine mapping contributes to a better understanding of the physiopathology of specific forms of uveitis and provides guidance for new targeted treatment.

Late bacterial keratitis after implantation of intrastromal corneal ring segments

We report a case of bacterial keratitis that occurred after implantation of intrastromal corneal ring segments (Intacs). The patient presented with decreased vision, inflammation, and stromal infiltrates localized at the extremity of an Intacs channel 3 months after surgery. Culture were positive for Clostridium perfringens and Staphylococcus epidermidis. The infiltrates progressed despite treatment with topical fortified and systemic antibiotics. The Intacs were removed. The keratitis slowly resolved, and the patient recovered a best corrected visual acuity of 20/20.

In Vitro Efficacy of Antifungal Treatment Using Riboflavin/UV-A (365 nm) Combination and Amphotericin B

PURPOSE To demonstrate the antimicrobial properties of riboflavin/UV-A (365 nm) against fungal pathogens. METHODS The antimicrobial properties of riboflavin/UV-A (365 nm), with or without previous treatment with amphotericin B, were tested on three groups of fungi selected from severe cases of keratomycosis: Candida albicans, Fusarium sp, and Aspergillus fumigatus. They were tested by using Kirby-Bauer discs with empty disc (control), riboflavin 0.1% alone (R), UV-A alone (UV-A), riboflavin 0.1% and additional UV-A exposure (R+UV-A), amphotericin B alone (A), amphotericin B and riboflavin 0.1% (A+R), amphotericin B and UV-A (A+UV-A), amphotericin B and riboflavin 0.1%, and additional UV-A exposure (A+R+UV-A). The mean growth inhibition zone (GIZ) was measured around the discs. RESULTS C. albicans, Fusarium sp, and A. fumigatus did not show any increased GIZ after treatment without previous amphotericin B medication. However, GIZ was significantly greater after pretreatment with amphotericin B and riboflavin/UV-A (A+R+UV-A) for C. albicans (P = 0.0005), Fusarium sp (P = 0.0023) and A. fumigatus (P = 0.0008) compared with A, A+R, and A+UV-A. CONCLUSIONS Amphotericin B is believed to interact with fungi membrane sterols to produce aggregates that form transmembrane channels. Given that collagen is one of the principal components of the cornea, it is also probable that amphotericin B may diffuse easily after cross-linking. Previous treatment with amphotericin B allowed riboflavin/UV-A effectiveness against C. albicans, Fusarium sp, and A. fumigatus. This schema might be used in the future for the treatment of keratomycosis.

Severe South American ocular toxoplasmosis is associated with decreased Ifn-γ/Il-17a and increased Il-6/Il-13 intraocular levels.

In a cross sectional study, 19 French and 23 Colombian cases of confirmed active ocular toxoplasmosis (OT) were evaluated. The objective was to compare clinical, parasitological and immunological responses and relate them to the infecting strains. A complete ocular examination was performed in each patient. The infecting strain was characterized by genotyping when intraocular Toxoplasma DNA was detectable, as well as by peptide-specific serotyping for each patient. To characterize the immune response, we assessed Toxoplasma protein recognition patterns by intraocular antibodies and the intraocular profile of cytokines, chemokines and growth factors. Significant differences were found for size of active lesions, unilateral macular involvement, unilateral visual impairment, vitreous inflammation, synechiae, and vasculitis, with higher values observed throughout for Colombian patients. Multilocus PCR-DNA sequence genotyping was only successful in three Colombian patients revealing one type I and two atypical strains. The Colombian OT patients possessed heterogeneous atypical serotypes whereas the French were uniformly reactive to type II strain peptides. The protein patterns recognized by intraocular antibodies and the cytokine patterns were strikingly different between the two populations. Intraocular IFN-γ and IL-17 expression was lower, while higher levels of IL-13 and IL-6 were detected in aqueous humor of Colombian patients. Our results are consistent with the hypothesis that South American strains may cause more severe OT due to an inhibition of the protective effect of IFN-γ.

Heavy chain-only antibodies and tetravalent bispecific antibody neutralizing Staphylococcus aureus leukotoxins

Panton–Valentine leukocidin (PVL) is a pore-forming toxin associated with current outbreaks of community-associated methicillin-resistant strains and implicated directly in the pathophysiology of Staphylococcus aureus-related diseases. Humanized heavy chain-only antibodies (HCAb) were generated against S. aureus PVL from immunized transgenic mice to neutralize toxin activity. The active form of PVL consists of the two components, LukS-PV and LukF-PV, which induce osmotic lysis following pore formation in host defense cells. One anti–LukS-PV HCAb, three anti–LukF-PV HCAbs with affinities in the nanomolar range, and one engineered tetravalent bispecific HCAb were tested in vitro and in vivo, and all prevented toxin binding and pore formation. Anti–LukS-PV HCAb also binds to γ-hemolysin C (HlgC) and inhibits HlgC/HlgB pore formation. Experiments in vivo in a toxin-induced rabbit endophthalmitis model showed that these HCAbs inhibit inflammatory reactions and tissue destruction, with the tetravalent bispecific HCAb performing best. Our findings show the therapeutic potential of HCAbs, and in particular, bispecific antibodies.

3-day treatment with azithromycin 1.5% eye drops versus 7-day treatment with tobramycin 0.3% for purulent bacterial conjunctivitis: multicentre, randomised and controlled trial in adults and children

Aim: To compare the efficacy and safety of Azyter, azithromycin 1.5% eye drops, for 3 days with tobramycin 0.3% for 7 days to treat purulent bacterial conjunctivitis. Methods: This was a multicentre, randomised, investigator-masked study including 1043 children and adults with purulent bacterial conjunctivitis. Patients received either azithromycin 1.5% twice-daily for 3 days or tobramycin 0.3%, 1 drop every two hours for 2 days, then four times daily for 5 days. Clinical signs were evaluated and cultures obtained at D0, D3 and D9 (where D refers to “day”). Primary variable was the clinical cure at the Test-of-Cure (TOC)-visit (D9±1), for patients with D0-positive cultures. The cure was defined as: bulbar conjunctival injection and discharge scores of 0. Results: Among 471 patients with D0-positivity in the per protocol set, 87.8% of the azithromycin 1.5% group and 89.4% of the tobramycin group were clinically cured at the TOC-visit. Azithromycin was non-inferior to tobramycin for clinical and bacteriological cure. Clinical cure was significantly higher with azithromycin 1.5% at D3. The safety profile of azithromycin was satisfactory with a good patient and investigator’s acceptability. Conclusions: Azithromycin 1.5% for 3 days was as effective and as safe as tobramycin for 7 days. Furthermore, more azithromycin than tobramycin patients presented an early clinical cure at Day 3. Due to its twice daily dosing regimen for 3 days, azithromycin represents a step forward in the management of purulent bacterial conjunctivitis, especially in children.

Effects of topical anaesthetics and fluorescein on the real-time PCR used for the diagnosis of Herpesviruses and Acanthamoeba keratitis

Background: The early microbiological diagnosis of corneal infections may prevent the condition from worsening. Aim: To study the potential interferences of oxybuprocain and fluorescein solutions used by ophthalmologists on the performances of the real-time polymerase chain reaction (PCR) carried out as routine test for diagnosis of keratitis. Methods: Quantified suspensions of Herpes simplex virus (HSV1), Varicella zoster virus (VZV), Cytomegalovirus (CMV) and Acanthamoeba with and without oxybuprocain or fluorescein added before DNA extraction were tested by real-time PCR. Results: The capacities of the real-time PCR to detect HSV, VZV, CMV and Acanthamoeba were reduced by oxybuprocain and fluorescein. Both products diluted to 1/16 reduced the PCR detection capacities for more than 2 logs (DNA copies/sample). Conclusions: The simultaneous introduction of fluorescein or topical anaesthetics into the tubes containing the specimens to be tested by PCR may lead to false negative results. Because corneal specimens for microbiological diagnosis of keratitis are obtained after topical administration of anaesthetics and corneal staining with fluorescein, ophthalmologists should be aware to rinse the eye surface intensively with appropriate eye solutions to minimise the risks of misdiagnosis.

Efficacy and safety of short duration azithromycin eye drops versus azithromycin single oral dose for the treatment of trachoma in children: a randomised, controlled, double-masked clinical trial

Aims: Efficacy and safety of a short-duration treatment of azithromycin 1.5% eye drops versus oral azithromycin to treat active trachoma. Methods: Randomised, controlled, double-masked, double-dummy, non-inferiority explanatory study including 670 children from Guinea Conakry and Pakistan if: 1–10 years old; active trachoma (TF+TI0 or TF+TI+ on simplified World Health Organisation (WHO) scale). Three groups received either: azithromycin 1.5% eye drops twice daily for 2 days, for 3 days or azithromycin single 20 mg/kg oral dose. Patients’ contacts were treated whenever possible. Clinical evaluation was performed using a binocular loupe. Primary efficacy variable was the cure (no active trachoma (TF0)) at day 60. Non-inferiority margin for difference between cure rates was 10%. Results: Cure rate in per protocol set was as follows: 93.0%, 96.3% and 96.6% in 2-day group 3-day group, and oral treatment group, respectively. Azithromycin 1.5% groups were non-inferior to oral azithromycin. The intend to treat (ITT) analysis supported the results. Clinical re-emergence rate was low: 4.2%. Ocular tolerance was similar for all groups. No treatment related adverse events were reported. Logistic regression analyses found prognostic factors such as: country (p<0.001) and trachoma severity (p = 0.003). Conclusions: In active trachoma, azithromycin eye drops twice daily for 2 or 3 days are as efficient as the WHO’s reference treatment and represent an innovative alternative to oral azithromycin.