In vitro susceptibility of filamentous fungal isolates from a corneal ulcer clinical trial

Antifungal susceptibility profiles for fungal isolates from corneas and contact lenses in the United Kingdom

OBJECTIVE

To report the identification and results of susceptibility testing for fungal isolates from the cornea or contact lens care systems.

MATERIALS AND METHODS

In this retrospective epidemiological study, we searched the results of fungal cultures from cornea or contact lens systems referred for identification and susceptibility testing to the United Kingdom National Mycology Reference Laboratory between October 2016 and March 2022. For each fungal isolate, we recorded the genus and species of the fungus and the minimum inhibitory concentration (MIC) to six antifungal agents available to treat corneal infection (amphotericin, econazole, itraconazole, natamycin, posaconazole, and voriconazole).

RESULTS

There were 600 isolates from 585 patients, comprising 374 (62%) from corneal samples and 226 from contact lenses and care systems, of which 414 (69%) isolates were moulds (filamentous fungi) and 186 (31%) were yeasts. The most frequent moulds isolated were Fusarium spp (234 isolates, 39%) and Aspergillus spp (62, 10%). The most frequent yeasts isolated were Candida spp (112, 19%), predominantly Candida parapsilosis (65, 11%) and Candida albicans (33, 6%), with 35 isolates (6%) of Meyerozyma guilliermondii. In vitro susceptibility was greatest for natamycin (347 moulds tested, mode 4 mg/L, range 0.25-64 mg/L; 98 yeasts tested, mode 4 mg/L, range 0.5-32 mg/L), with susceptibility for 94% for moulds and 99% yeasts. Of the 16 isolates interpreted as highly resistant to natamycin (MIC ≥16 mg/L), 13 were Aspergillus flavus complex.

CONCLUSIONS

In vitro susceptibility supports the use of natamycin for the empiric treatment of fungal keratitis in the UK.

Rapid Point-of-Care Identification of Aspergillus Species in Microbial Keratitis

Importance

Microbial keratitis (MK) is a common cause of unilateral visual impairment, blindness, and eye loss in low-income and middle-income countries. There is an urgent need to develop and implement rapid and simple point-of-care diagnostics for MK to increase the likelihood of good outcomes.

Objective

To evaluate the diagnostic performance of the Aspergillus-specific lateral-flow device (AspLFD) to identify Aspergillus species causing MK in corneal scrape and corneal swab samples of patients presenting with microbial keratitis.

Design, Setting, and Participants

This diagnostic study was conducted between May 2022 and January 2023 at the corneal clinic of Aravind Eye Hospital in Madurai, Tamil Nadu, India. All study participants were recruited during their first presentation to the clinic. Patients aged 15 years or older met the eligibility criteria if they were attending their first appointment, had a corneal ulcer that was suggestive of a bacterial or fungal infection, and were about to undergo diagnostic scrape and culture.

Main Outcomes and Measures

Sensitivity and specificity of the AspLFD with corneal samples collected from patients with MK. During routine diagnostic scraping, a minimally invasive corneal swab and an additional corneal scrape were collected and transferred to aliquots of sample buffer and analyzed by lateral-flow device (LFD) if the patient met the inclusion criteria. Photographs of devices were taken with a smartphone and analyzed using a ratiometric approach, which was developed for this study. The AspLFD results were compared with culture reports.

Results

The 198 participants who met the inclusion criteria had a mean (range) age of 51 (15-85) years and included 126 males (63.6%). Overall, 35 of 198 participants with corneal scrape (17.7%) and 17 of 40 participants with swab samples (42.5%) had positive culture results for Aspergillus species. Ratiometric analysis results for the scrape samples found that the AspLFD achieved high sensitivity (0.89; 95% CI, 0.74-0.95), high negative predictive value (0.97; 95% CI, 0.94-0.99), low negative likelihood ratio (0.12; 95% CI, 0.05-0.30), and an accuracy of 0.94 (95% CI, 0.90-0.97). Ratiometric analysis results for the swab samples showed that the AspLFD had high sensitivity (0.94; 95% CI, 0.73-1.00), high negative predictive value (0.95; 95% CI, 0.76-1.00), low negative likelihood ratio (0.07; 95% CI, 0.01-0.48), and an accuracy of 0.88 (95% CI, 0.73-0.96).

Conclusions and Relevance

Results of this diagnostic study suggest that AspLFD along with the ratiometric analysis of LFDs developed for this study has high diagnostic accuracy in identifying Aspergillus species from corneal scrapes and swabs. This technology is an important step toward the provision of point-of-care diagnostics for MK and could inform the clinical management strategy.

Antimicrobial resistance in topical treatments for microbial keratitis: protocol for a systematic review and meta-analysis

INTRODUCTION

There is evidence for increased resistance against the antimicrobials used to treat keratitis. This review aims to provide global and regional prevalence estimates of antimicrobial resistance in corneal isolates and the range of minimum inhibitory concentrations (MIC) with their associated resistance breakpoints.

METHODS AND ANALYSIS

We report this protocol following Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols guidelines. We will conduct an electronic bibliographic search in MEDLINE, EMBASE, Web of Science and the Cochrane Library. Eligible studies will report in any language data for the resistance or MIC for antimicrobials against bacterial, fungal or amoebic organisms isolated from suspected microbial keratitis. Studies that only report on viral keratitis will not be included. There will be no time restrictions on the date of publication. Screening for eligible studies, assessment of risk of bias and data extraction will be conducted by two reviewers independently, using predefined inclusion criteria and prepiloted data extraction forms. We will resolve disagreements between the reviewers by discussion and, if required, a third (senior) reviewer will arbitrate. We will assess the risk of bias using a tool validated in prevalence studies. The certainty of the evidence will be assessed using the Grades of Recommendation, Assessment, Development and Evaluation approach. Pooled proportion estimates will be calculated using a random-effects model. Heterogeneity will be assessed using the I2 statistic. We will explore differences between Global Burden of Disease regions and temporal trends.

ETHICS APPROVAL AND DISSEMINATION

Ethics approval is not required as this is a protocol for a systematic review of published data. The findings of this review will be published in an open-access, peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023331126.

Dysfunction of FadA-cAMP signalling decreases Aspergillus flavus resistance to antimicrobial natural preservative Perillaldehyde and AFB1 biosynthesis

Aspergillus flavus is an opportunistic fungal pathogen that colonizes agriculture crops with aflatoxin contamination. We found that Perillaldehyde (PAE) effectively inhibited A. flavus viability and aflatoxin production by inducing excess reactive oxygen species (ROS). Transcriptome analysis indicated that the Gα protein FadA was significantly induced by PAE. Functional characterization of FadA showed it is important for asexual development and aflatoxin biosynthesis by regulation of cAMP-PKA signalling. The ΔfadA mutant was more sensitive to PAE, while ΔpdeL and ΔpdeH mutants can tolerate excess PAE compared to wild-type A. flavus. Further RNA-sequence analysis showed that fadA was important for expression of genes involved in oxidation-reduction and cellular metabolism. The flow cytometry and fluorescence microscopy demonstrated that ΔfadA accumulated more concentration of ROS in cells, and the transcriptome data indicated that genes involved in ROS scavenging were downregulated in ΔfadA mutant. We further found that FadA participated in regulating response to extracellular environmental stresses by increasing phosphorylation levels of MAPK Kinase Slt2 and Hog1. Overall, our results indicated that FadA signalling engages in mycotoxin production and A. flavus resistance to antimicrobial PAE, which provide valuable information for controlling this fungus and AF biosynthesis in pre- and postharvest of agricultural crops.

Diagnosing Fungal Keratitis and Simultaneously Identifying Fusarium and Aspergillus Keratitis with a Dot Hybridization Array

Fungal keratitis (FK) is one of the most common microbial keratitis, which often leads to poor prognosis as a result of delayed diagnosis. Several studies implied that early differentiation of the two major FK, Fusarium and Aspergillus keratitis, could be helpful in selecting effective anti-fungal regimens. Therefore, a novel dot hybridization array (DHA) was developed to diagnose FK and differentiate Fusarium and Aspergillus keratitis in this study. One hundred forty-six corneal scrapes obtained from one hundred forty-six subjects impressed with clinically suspected FK were used to evaluate the performance of the DHA. Among these patients, 107 (73.3%) patients had actual FK confirmed by culture and DNA sequencing. We found that the DHA had 93.5% sensitivity and 97.4% specificity in diagnosing FK. In addition, this array had 93.2% sensitivity and 93.8% specificity in diagnosing Fusarium keratitis, as well as 83.3% sensitivity and 100% specificity in diagnosing Aspergillus keratitis. Furthermore, it had 83.9% sensitivity and 100% specificity in identifying Fusarium solani keratitis. Thus, this newly developed DHA will be beneficial to earlier diagnosis, more precise treatment, and improve prognosis of FK, by minimizing medical refractory events and surgical needs.

Drug reservoir function of voriconazole impregnated human amniotic membrane: An in vitro study

Purpose:

Earlier our group has demonstrated the drug reservoir function of the human amniotic membrane (HAM) using stable moxifloxacin and fortified cefazolin ophthalmic formulations and found it as a suitable tool to deliver drugs for an extended duration. The purpose of this study was to evaluate the extended-release kinetics of voriconazole from the impregnated human amniotic membrane (HAM) in vitro.

Methods:

HAM buttons were incubated with freshly prepared 1% topical ophthalmic formulation of voriconazole for 5 different exposure time to investigate the ideal exposure time for the extended-release of voriconazole from HAM. The drug release kinetics was studied in simulated tear fluid for 5 weeks and the amount of voriconazole released at different intervals was estimated using high-performance liquid chromatography (HPLC) with photodiode array (PDA) detector.

Results:

There was a marginal increase in drug entrapment efficiency with increased drug exposure time but neither the drug entrapment nor the drug release was found to be statistically significant (P ≥ 0.5). Voriconazole was detectable even at 5 weeks.

Conclusion:

A sustained release of voriconazole was achieved up to 5 weeks, when voriconazole was incubated with amniotic membrane for all the studied drug soaking times. Thus, voriconazole impregnated amniotic membrane can be considered for the sustained delivery for its in fungal keratitis.

Fungal keratitis at a tertiary eye care in Northern Thailand: Etiology and prognostic factors for treatment outcomes

PURPOSE

To evaluate etiology and prognostic factors for treatment outcomes of fungal keratitis (FK).

METHODS

Culture-positive FK patients between 2012 and 2017 were reviewed. Treatment outcomes were categorized into success (resolved within two weeks), slow response and medication failure (no improvement or required surgery). Etiology and risk factors for poor treatment outcomes were analyzed.

RESULTS

A total of 113 eyes of 113 patients (77% males) were recruited. Ocular trauma (69.0%) was the most common predisposing factor. Of this, 80% were exposed to organic foreign bodies. The most common pathogen was Fusarium spp. (45.2%), while dematiaceous fungi were discovered in 29.6%. Medical treatment was successful in 24.8% of eyes, while 29.2% had a slow response and 42.5% failed medication. Therapeutic keratoplasty was performed in 22.1% of eyes and 11.5% eventually required eye removal. Significant risk factors for medication failure were advanced age (P = 0.005), delayed antifungal treatment (P = 0.038) and large-size lesion (P = 0.003).

CONCLUSIONS

Ocular trauma was the major predisposing factor of FK in the Northern Thailand. Fusarium was the most common identified pathogen. Many cases were refractory to medications and required surgical intervention. Aging, delayed treatment and a large lesion were predictors for poor outcomes.

Human Corneal Epithelial Cells Internalize Aspergillus flavus Spores by Actin-Mediated Endocytosis

Human corneal epithelial (HCE) cells play a significant role in the innate immune response by secreting cytokines and antimicrobial peptides when they encounter fungal pathogens. But the detailed mechanism of attachment and engulfment of the fungal conidia by HCE cells is not well understood. Here, we show the phagocytosis of Aspergillus flavus conidia by RCB2280 cells and primary HCE cultures using confocal microscopy and proteomic analysis of conidium-containing phagosomes. Phalloidin staining showed actin polymerization, leading to an actin ring around engulfed conidia. Cytochalasin D inhibited the actin-mediated endocytosis of the conidia. Immunolabeling of the early endosomal markers CD71 and early endosomal antigen (EEA1) and the late endosomal markers lysosome-associated membrane protein 1 (LAMP1), Rab7, and cathepsin G showed that endosomal proteins were recruited to the site of conidia and showed maturation of the conidium-containing phagosomes. Lysotracker red DND 99 labeling showed the acidification of the phagosomes containing conidia. Phagosome-specific proteome analysis confirmed the recruitment of various phagosomal and endosomal proteins to the conidium-containing phagosomes. These results show that the ocular surface epithelium contributes actively to antifungal defense by the phagocytosis of invading fungal conidia.

Therapeutic response time of topical voriconazole 1% and intrastromal voriconazole 0.05% versus topical natamycin 5% monotherapy in Fusarium keratitis in rabbit

BACKGROUND

Fungal keratitis can be more difficult to treat than bacterial keratitis with worse outcomes.

OBJECTIVE

To evaluate the therapeutic response time of topical voriconazole combined with intrastromal voriconazole, and topical natamycin on Fusarium keratitis.

METHODS

The stroma of corneas of twelve New Zealand White rabbits was inoculated with Fusarium sp spores. Seven days after inoculation, they were divided into 2 groups randomly. Group A was treated with topical natamycin 5% for 21 days. Group B was treated with intrastromal voriconazole 0.05% single injection at the beginning of treatment, continued with topical voriconazole 1% for 21 days. Clinical evaluations for epithelial defect size and clinical scores in each group were performed on 1st, 3rd, 7th, 10th, 14th and 21st days after treatment. Mycological examinations were performed before and after the treatment.

RESULTS

After treatment, there was no statistically significant difference between natamycin and voriconazole in reducing epithelial defect size at first, second or third week after treatment (P = .15; P = .39; and P = .90). The clinical scores on both groups also showed no statistically significant differences at first, second and third weeks after treatment (P = .24; P = .09; and P = .32). Qualitative mycological evaluation before and after the treatment showed no statistically significant difference in KOH examination (P = 1; P = 1) and culture in Sabouraud dextrose agar (P = 1; P = 1).

CONCLUSION

Intrastromal voriconazole injection combined with topical voriconazole seems to give similar response time but not earlier in improving clinical presentation of Fusarium keratitis as topical natamycin.

Sustained-release voriconazole-thermogel for subconjunctival injection in horses: ocular toxicity and in-vivo studies

Background

Keratomycosis is a relatively common, sight threatening condition in horses, where treatment is often prolonged and costly. Subconjunctival (SCo) injections offer less resistance to drug diffusion than the topical route, resulting in better penetration to the ocular anterior segment. Voriconazole, a second generation triazole antifungal, is effective against common fungal organisms causing keratomycosis. If combined with a thermogel biomaterial, voriconazole can be easily injected in the SCo space to provide sustained drug release. The purpose of this study was to evaluate the drug concentrations in the anterior segment and clinical effects after SCo injections of voriconazole-containing thermogel: poly (DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) in healthy equine eyes.

Results

Voriconazole aqueous humor (AH) and tear concentrations were compared between 6 horses, receiving 1% voriconazole applied topically (0.2 mL, q4h) (Vori-Top) or 1.7% voriconazole-thermogel (0.3 mL) injected SCo (Vori-Gel). For the Vori-Gel group, voriconazole concentrations were measured in AH and tears at day 2 and then weekly for 23 days, and at day 2 only for the Vori-Top group. Ocular inflammation was assessed weekly (Vori-Gel) using the modified Hackett-McDonald scoring system. Ocular tissue concentrations of voriconazole following SCo 1.7% voriconazole-thermogel (0.3 mL) injections were evaluated post euthanasia in 6 additional horses at 3 different time points. Three horses received bilateral injections at 2 h (n = 3, right eye (OD)) and 48 h (n = 3, left eye (OS)) prior to euthanasia, and 3 horses were injected unilaterally (OS), 7 days prior to euthanasia. Voriconazole-thermogel was easily injected and well tolerated in all cases, with no major adverse effects. On day 2, drug concentrations in tears were higher in the Vori-Top, but not statistically different from Vori-Gel groups. For the Vori-Gel group, voriconazole was non-quantifiable in the AH at any time point. Total voriconazole concentrations in the cornea were above 0.5 μg/g (the target minimum inhibitory concentration (MIC) for Aspergillus sp.) for up to 48 h; however, concentrations were below this MIC at 7 days post treatment.

Conclusions

Voriconazole-thermogel was easily and safely administered to horses, and provided 48 h of sustained release of voriconazole into the cornea. This drug delivery system warrants further clinical evaluation.

In Vitro Efficacy of Chlorhexidine and a riboflavin/UVA Combination on Fungal Agents of Keratitis

Purpose: Mycotic keratitis is a global ophthalmological problem because it is difficult to diagnose and treat. The aim of the current study was to evaluate the efficiency of using antifungal agents amphotericin B (AMB), voriconazole (VRC), 0.02% chlorhexidine (CHX), and a combination of riboflavin and UVA treatment against two fungal genera (Aspergillus and Fusarium) responsible for keratitis.Methods: We evaluated antifungal efficiencies of riboflavin/UVA and the antifungal drugs VRC, AMB, and CHX (alone and in combination) against fungal inocula at four concentrations. We recorded colony counts of isolates for Aspergillus terreus, A. flavus, A. fumigatus, Fusarium falciforme, F. proliferatum, and F. solani on Mueller-Hinton agar plates.Results: Fungal suspensions exposed to the following treatment combinations did not allow fungal growth: riboflavin/UVA and VRC, riboflavin/UVA and AMB, riboflavin/UVA and CHX, and CHX alone. We observed a statistically significant reduction (P < .05) in the number of colonies on agar plates when fungal suspensions were treated with riboflavin/UVA, VRC, and AMB only.Conclusions: Riboflavin/UVA treatment in combination with AMB, VRC, and CHX are capable of killing keratitis-inducing fungi (P < .05). The antiseptic CHX exerted a considerable antifungal effect on all strains we examined. Therefore, we recommend CHX as additional therapy against mycotic keratitis, particularly when keratitis is caused by multi-resistant members of Fusarium.

Invasive Aspergillosis by Aspergillus flavus: Epidemiology, Diagnosis, Antifungal Resistance, and Management

Aspergillus flavus is the second most common etiological agent of invasive aspergillosis (IA) after A. fumigatus. However, most literature describes IA in relation to A. fumigatus or together with other Aspergillus species. Certain differences exist in IA caused by A. flavus and A. fumigatus and studies on A. flavus infections are increasing. Hence, we performed a comprehensive updated review on IA due to A. flavus. A. flavus is the cause of a broad spectrum of human diseases predominantly in Asia, the Middle East, and Africa possibly due to its ability to survive better in hot and arid climatic conditions compared to other Aspergillus spp. Worldwide, ~10% of cases of bronchopulmonary aspergillosis are caused by A. flavus. Outbreaks have usually been associated with construction activities as invasive pulmonary aspergillosis in immunocompromised patients and cutaneous, subcutaneous, and mucosal forms in immunocompetent individuals. Multilocus microsatellite typing is well standardized to differentiate A. flavus isolates into different clades. A. flavus is intrinsically resistant to polyenes. In contrast to A. fumigatus, triazole resistance infrequently occurs in A. flavus and is associated with mutations in the cyp51C gene. Overexpression of efflux pumps in non-wildtype strains lacking mutations in the cyp51 gene can also lead to high voriconazole minimum inhibitory concentrations. Voriconazole remains the drug of choice for treatment, and amphotericin B should be avoided. Primary therapy with echinocandins is not the first choice but the combination with voriconazole or as monotherapy may be used when the azoles and amphotericin B are contraindicated.

Contribution of ATPase copper transporters in animal but not plant virulence of the crossover pathogen Aspergillus flavus

The ubiquitous fungus Aspergillus flavus is notorious for contaminating many important crops and food-stuffs with the carcinogenic mycotoxin, aflatoxin. This fungus is also the second most frequent Aspergillus pathogen after A. fumigatus infecting immunosuppressed patients. In many human fungal pathogens including A. fumigatus, the ability to defend from toxic levels of copper (Cu) is essential in pathogenesis. In A. fumigatus, the Cu-fist DNA binding protein, AceA, and the Cu ATPase transporter, CrpA, play critical roles in Cu defense. Here, we show that A. flavus tolerates higher concentrations of Cu than A. fumigatus and other Aspergillus spp. associated with the presence of two homologs of A. fumigatus CrpA termed CrpA and CrpB. Both crpA and crpB are transcriptionally induced by increasing Cu concentrations via AceA activity. Deletion of crpA or crpB alone did not alter high Cu tolerance, suggesting they are redundant. Deletion of both genes resulted in extreme Cu sensitivity that was greater than that following deletion of the regulatory transcription factor aceA. The ΔcrpAΔcrpB and ΔaceA strains were also sensitive to ROI stress. Compared to wild type, these mutants were impaired in the ability to colonize maize seed treated with Cu fungicide but showed no difference in virulence on non-treated seed. A mouse model of invasive aspergillosis showed ΔcrpAΔcrpB and to a lesser degree ΔaceA to be significantly reduced in virulence, following the greater sensitivity of ΔcrpAΔcrpB to Cu than ΔaceA.

Efficacy of Luliconazole Against Broad-Range Filamentous Fungi Including Fusarium solani Species Complex Causing Fungal Keratitis

PURPOSE

Fungal keratitis can be difficult to medically treat. Topical antifungals are usually applied empirically as the initial option in treating fungal keratitis. Natamycin (NAT) and/or voriconazole (VRCZ) have been widely used in the treatment of fungal keratitis. However, Fusarium solani species complex (FSSC), which are the dominant species of fungal keratitis, are resistant to VRCZ. This study investigated in vitro efficacy of luliconazole (LLCZ), a new imidazole antifungal, against FSSC and other filamentous fungi.

METHODS

A total of 18 Fusarium isolates and 7 others were grown on potato dextrose agar at 30 and 37°C. For Fusarium, species identification and phylogenetic tree analysis were performed based on elongation factor-1α (EF-1α) DNA sequencing. The broth microdilution method was used for antifungal susceptibility testing of 11 antifungal drugs including LLCZ.

RESULTS

The 18 identified Fusarium isolates belonged to FSSC (n = 13), Fusarium oxysporum species complex (FOSC; n = 2), Fusarium chlamydosporum species complex (FCSC; n = 1), Fusarium incarnatum-equiseti species complex (FIESC; n = 1), and Fusarium fujikuroi species complex (FFSC; n = 1). We further divided 13 FSSC isolates into 3 clades, FSSC5 (n = 8), FSSC3 + 4 (n = 4), and FSSC9-a (n = 1), with 8 FSSC strains growing at 37°C. LLCZ showed lowest minimum inhibitory concentrations (MICs) against all tested filamentous fungi, with a MIC90 against the Fusarium species of 0.06 μg/mL, whereas MIC90 for NAT and VRCZ were 4 and 8 μg/mL, respectively.

CONCLUSIONS

LLCZ has the strongest in vitro antifungal activity among all drugs used against broad-range filamentous fungi including FSSC. LLCZ may potentially be a new medical treatment option for fungal keratitis.

Epidemiology of antifungal susceptibility: Review of literature

Fungal infections are a major cause of morbidity and mortality despite the latest developments of diagnostic tools and therapeutic options. Early initiation of the appropriate antifungal therapy has been demonstrated to have a direct impact on the patient's outcome. Antifungal susceptibility testing methods are available to detect antifungal resistance and to determine the best treatment for a specific fungus. American and European standards have been developed, as well as equivalent commercial systems, which are more appropriate for clinical laboratories. These studies have allowed the development of interpretative breakpoints against the most frequent agents of fungal infections in the world. Surveillance of antifungal susceptibility patterns can provide the local drug resistance data to the clinicians, which can further aid better management of patients. Antifungal susceptibility tests have become essential tools to identify resistance to antifungals, to know the local and global disease epidemiology and to guide the treatment of fungal diseases. The distribution of species and the prevalence of antifungal resistance in fungi isolates varied among different areas. Here we summarize the epidemiology of antifungal susceptibility pattern of different fungal species.

Regression Discontinuity and Randomized Controlled Trial Estimates: An Application to The Mycotic Ulcer Treatment Trials

PURPOSE

We compare results from regression discontinuity (RD) analysis to primary results of a randomized controlled trial (RCT) utilizing data from two contemporaneous RCTs for treatment of fungal corneal ulcers.

METHODS

Patients were enrolled in the Mycotic Ulcer Treatment Trials I and II (MUTT I & MUTT II) based on baseline visual acuity: patients with acuity ≤ 20/400 (logMAR 1.3) enrolled in MUTT I, and >20/400 in MUTT II. MUTT I investigated the effect of topical natamycin versus voriconazole on best spectacle-corrected visual acuity. MUTT II investigated the effect of topical voriconazole plus placebo versus topical voriconazole plus oral voriconazole. We compared the RD estimate (natamycin arm of MUTT I [N = 162] versus placebo arm of MUTT II [N = 54]) to the RCT estimate from MUTT I (topical natamycin [N = 162] versus topical voriconazole [N = 161]).

RESULTS

In the RD, patients receiving natamycin had mean improvement of 4-lines of visual acuity at 3 months (logMAR -0.39, 95% CI: -0.61, -0.17) compared to topical voriconazole plus placebo, and 2-lines in the RCT (logMAR -0.18, 95% CI: -0.30, -0.05) compared to topical voriconazole.

CONCLUSIONS

The RD and RCT estimates were similar, although the RD design overestimated effects compared to the RCT.

Fungal keratitis: An overview of clinical and laboratory aspects

Mycotic keratitis or keratomycosis is a fungal infection with global distribution. The dominant aetiology of this disease varies based on geographical origin, socioeconomic status, and climatic condition. Generally, Aspergillus spp. and Fusarium spp. are common in tropical and subtropical regions and Candida spp. are dominant in temperate areas. Demonstration of fungal elements in microscopic examination besides the isolation of fungi in culture is the gold standard of laboratory diagnosis. As the culture is a time-consuming procedure, other approaches such as in vivo confocal microscopy which produces real-time imaging of corneal tissue and molecular techniques have been developed to facilitate rapid diagnosis of fungal keratitis. The first choice of treatment is topical natamycin, although topical amphotericin B is the best choice for Aspergillus and Candida keratitis. Regarding the diversity of fungal aetiology and the emergence of drug resistance in some genera and species, proper identification using molecular methods and antifungal susceptibility testing could provide useful data. Furthermore, as the better efficacy of combination therapy in comparison to monotherapy is reported, in vitro determination of interactions between various drugs seem informative. This review aims to provide a general and updated view on the aetiology, risk factors, epidemiology, clinical and laboratory diagnosis, and management of fungal keratitis.

In vitro susceptibility and multilocus sequence typing of Fusarium isolates causing keratitis

Fungal keratitis is recognized as a significant cause of ocular morbidity and blindness especially in developing countries. In this study, we aimed to present the molecular identification and susceptibility of Fusarium isolates causing fungal keratitis in a university hospital in southern Brazil. The samples were identified using the second largest subunit of the RNA polymerase gene (RPB2) and the translation elongation factor 1-alpha (TEF1), while the antifungal susceptibility was tested by the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) methodology. The majority of the isolates belonged to the Fusarium solani species complex (F. solani, F. keratoplasticum and F. falciforme) and Fusarium oxysporum species complex. Antifungal susceptibility has shown that amphotericin B and natamycin were the most effective antifungals across all isolates, followed by voriconazole. Variation among Fusarium complexes in their antifungal sensitivities was observed in our study. The identification of Fusarium species from human samples is important not only from an epidemiological viewpoint, but also for choosing the appropriate antifungal agent for difficult-to-treat Fusarium infections such as keratitis.

Natamycin and Azithromycin Are Synergistic In Vitro against Ocular Pathogenic Aspergillus flavus Species Complex and Fusarium solani Species Complex Isolates

The interaction of natamycin-azithromycin combination against 60 ocular fungal isolates was tested in vitro The combination produced 100% synergistic interactions when natamycin was added to azithromycin 20, 40, and 50 μg/ml against Aspergillus flavus species complex (AFSC) isolates and to azithromycin 50 μg/ml against Fusarium solani species complex isolates. Addition of 50 μg/ml azithromycin enhanced natamycin's effect against AFSC isolates by reducing natamycin MIC₉₀ from 64 to 0.031 μg/ml. No antagonism was observed.

Antifungal Susceptibility, Morphological and Molecular Characterization of Lasiodiplodia theobromae Isolated from a Patient with Keratitis

Lasiodiplodia theobromae is a rare ocular pathogen. We report a patient with fungal keratitis caused by L. theobromae. The patient was a 75-year-old male, a farmer with diabetes type II, and no previous history of ocular trauma. Histopathology analysis revealed the presence fungi invading Descemet's membrane of the cornea. The fungus was characterized by septate, highly bulged fungal filaments involving full corneal thickness in the corresponding histopathology specimens. A dematiaceous mold was isolated and initally identified as L. theobromae by microscopic and macroscopic morphology, and further confirmed by PCR-based determination of internal transcribed spacer (ITS) regions of ribosomal DNA. Antifungal susceptibility tests showed sensitivity to amphotericin B (AMB) and voriconazole ( VRC), and resistance to other azoles, including itraconazole (ITC) and fluconazole (FLC). Corneal transplant was performed. Despite in vitro itraconazole resistance, the patient was successfully treated with oral itraconazole, topical voriconazole and natamycin, combined with ocular injections of amphotericin B and voriconazole.

In vitro synergy of natamycin and voriconazole against clinical isolates of Fusarium, Candida, Aspergillus and Curvularia spp

Aim

To determine the minimum inhibitory concentrations (MICs) of voriconazole and natamycin, alone and in combination, against the clinical isolates of Fungus and to evaluate the synergy between the drugs in an experimental in vitro study.

Methods

In an experimental in vitro study, clinical isolates of Fusarium, Aspergillus, Candida and Curvularia spp were maintained on Sabouraud Dextrose Agar and used for the study. The MICs of natamycin and voriconazole, used alone and in combination, were evaluated by checkerboard microdilution technique based on the standard protocol proposed by the Clinical Laboratory Standards Institute. The interactions were assessed using the fractional inhibitory concentration (FIC) Index model.

Results

Tested with all the clinical isolates, the MICs ranged between 0.125 and 8 µg/mL both for natamycin and voriconazole. In descending order, maximum synergism (FIC ≤0.5) was observed in Candida spp (33.3%) followed by Curvularia spp and Fusarium spp (23.1%). Synergism was least for Aspergillus spp (22.2%). However, at 61.5% (8/13), maximum additive effect (>0.5–1) was observed in Aspergillus spp and minimum (33.3%, 2/6) in Candida spp. Indifference (FIC value >1 and≤4) was observed in 22.2% (2/9) of Aspergillus spp, 15.4% (2/13) of Fusarium spp, 33.3% (2/6) of Candida spp and 23.1% (3/13) of Curvularia spp. No cases of antagonism (FIC >4) were observed.

Conclusions

Natamycin and voriconazole in combination demonstrated more effective antifungal activity than single-use in vitro treatment in all species tested, which implies that these combinations may be helpful in treating fungal keratitis. There was no antagonism between these two drugs.

Recent advances in diagnosis and management of Mycotic Keratitis

Mycotic keratitis is a major cause of corneal blindness, especially in tropical and subtropical countries. The prognosis is markedly worse compared to bacterial keratitis. Delayed diagnosis and scarcity of effective antifungal agents are the major factors for poor outcome. Over the last decade, considerable progress has been made to rapidly diagnose cases with mycotic keratitis and increase the efficacy of treatment. This review article discusses the recent advances in diagnosis and management of mycotic keratitis with a brief discussion on rare and emerging organisms. A MEDLINE search was carried out for articles in English language, with the keywords, mycotic keratitis, fungal keratitis, emerging or atypical fungal pathogens in mycotic keratitis, investigations in mycotic keratitis, polymerase chain reaction in mycotic keratitis, confocal microscopy, treatment of mycotic keratitis, newer therapy for mycotic keratitis. All relevant articles were included in this review. Considering the limited studies available on newer diagnostic and therapeutic modalities in mycotic keratitis, case series as well as case reports were also included if felt important.

Current antifungal treatment of fusariosis

Fungi of the genus Fusarium are well known as major plant pathogens and soil inhabitants, but also cause a broad spectrum of human infections. Fusariosis is the second most common mould infection after aspergillosis, and keratitis is the most encountered implantation infection in immunocompetent individuals. Natamycin is active against Fusarium species both in vitro and in vivo, and is used along with voriconazole as the mainstay of treatment for Fusarium keratitis. Onychomycosis is treated with terbinafine, voriconazole and sometimes itraconazole. Cure is possible despite high in vitro minimum inhibitory concentrations (MICs). Recently, disseminated infections have increased dramatically, mainly affecting severely immunocompromised patients. The remarkable intrinsic resistance of Fusarium species to most antifungal agents results in high mortality rates in this patient population. Recovery of neutropenia is essential for patient survival and treatment should include voriconazole or amphotericin B as first-line and posaconazole as salvage therapy.

Effect of Oral Voriconazole on Fungal Keratitis in the Mycotic Ulcer Treatment Trial II (MUTT II): A Randomized Clinical Trial

Objective

To compare oral voriconazole with placebo in addition to topical antifungals in the treatment of filamentous fungal keratitis.

Design, Setting, and Participants

The Mycotic Ulcer Treatment Trial II (MUTT II), a multicenter, double-masked, placebo-controlled, randomized clinical trial, was conducted in India and Nepal, with 2133 individuals screened for inclusion. Patients with smear-positive filamentous fungal ulcers and visual acuity of 20/400 (logMAR 1.3) or worse were randomized to receive oral voriconazole vs oral placebo; all participants received topical antifungal eyedrops. The study was conducted from May 24, 2010, to November 23, 2015. All trial end points were analyzed on an intent-to-treat basis.

Interventions

Study participants were randomized to receive oral voriconazole vs oral placebo; a voriconazole loading dose of 400 mg was administered twice daily for 24 hours, followed by a maintenance dose of 200 mg twice daily for 20 days, with dosing altered to weight based during the trial. All participants received topical voriconazole, 1%, and natamycin, 5%.

Main Outcomes and Measures

The primary outcome of the trial was rate of corneal perforation or the need for therapeutic penetrating keratoplasty (TPK) within 3 months. Secondary outcomes included microbiologic cure at 6 days, rate of re-epithelialization, best-corrected visual acuity and infiltrate and/or scar size at 3 weeks and 3 months, and complication rates associated with voriconazole use.

Results

A total of 2133 patients in India and Nepal with smear-positive ulcers were screened; of the 787 who were eligible, 240 (30.5%) were enrolled. Of the 119 patients (49.6%) in the oral voriconazole treatment group, 65 were male (54.6%), and the median age was 54 years (interquartile range, 42-62 years). Overall, no difference in the rate of corneal perforation or the need for TPK was determined for oral voriconazole vs placebo (hazard ratio, 0.82; 95% CI, 0.57-1.18; P = .29). In prespecified subgroup analyses comparing treatment effects among organism subgroups, there was some suggestion that Fusarium species might have a decreased rate of perforation or TPK in the oral voriconazole-treated arm; however, this was not a statistically significant finding after Holms-Šidák correction for multiple comparisons (effect coefficient, 0.49; 95% CI, 0.26-0.92; P = .03). Patients receiving oral voriconazole experienced a total of 58 adverse events (48.7%) compared with 28 adverse events (23.1%) in the placebo group (P < .001 after Holms-Šidák correction for multiple comparisons).

Conclusions and Relevance

There appears to be no benefit to adding oral voriconazole to topical antifungal agents in the treatment of severe filamentous fungal ulcers. All patients in this study were enrolled in India and Nepal; therefore, it is possible that organisms in this region may exhibit characteristics different from those in other regions of the world.

Trial Registration

clinicaltrials.gov Identifier: NCT00996736.

Antifungal Susceptibility Testing of Fusarium: A Practical Approach

In vitro susceptibility testing of Fusarium is becoming increasingly important because of frequency and diversity of infections and because resistance profiles are species-specific. Reference methods for antifungal susceptibility testing (AFST) are those of Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility (EUCAST), but breakpoints (BPs) have not yet been established. One of the problems is that phylogenetic distances between Fusarium species are much smaller than between species of, e.g., Candida. Epidemiological cutoff values (ECVs) for some Fusarium species have been determined in order to differentiate wild-type from non-wild-type isolates. In clinical routine, commercially available assays such as Etest, Sensititre or others provide essential agreement with reference methods. Our objective is to summarize antifungal susceptibility testing of Fusarium genus in the clinical laboratory: how to do it, when to do it, and how to interpret it.

Rifampin Enhances the Activity of Amphotericin B against Fusarium solani Species Complex and Aspergillus flavus Species Complex Isolates from Keratitis Patients

The in vitro activities of amphotericin B in combination with rifampin were assessed against 95 ocular fungal isolates. The interactions between amphotericin B and rifampin at 4, 8, 16, and 32 μg/ml were synergistic for 11.8%, 51.0%, 90.2%, and 94.1%, respectively, of Fusarium solani species complex isolates and for 13.6%, 45.5%, 93.2%, and 95.5%, respectively, of Aspergillus flavus species complex isolates. Antagonism was never observed for the amphotericin B-rifampin combinations.

In vivo confocal microscopy appearance of Fusarium and Aspergillus species in fungal keratitis

Background

Clinical outcomes in fungal keratitis vary between Fusarium and Aspergillus spp, therefore distinguishing between species using morphological features such as filament branching angles, sporulation along filaments (adventitious sporulation) or dichotomous branching may be useful. In this study, we assessed these three features within Heidelberg Retina Tomograph 3 in vivo confocal microscopy (IVCM) images from culture-positive Fusarium and Aspergillus spp keratitis participants.

Methods

Prospective observational cohort study in Aravind Eye Hospital (February 2011–February 2012). Eligibility criteria: age ≥18 years, stromal infiltrate ≥3 mm diameter, Fusarium or Aspergillus spp culture-positive. Exclusion criteria: previous/current herpetic keratitis, visual acuity <6/60 in fellow eye, >80% corneal thinning. IVCM was performed and images analysed for branch angle, presence/absence of adventitious sporulation or dichotomous branching by a grader masked to the microbiological diagnosis.

Results

98 participants were included (106 eligible, 8 excluded as no measurable branch angles); 68 were positive for Fusarium spp, 30 for Aspergillus spp. Mean branch angle for Fusarium spp was 59.7° (95% CI 57.7° to 61.8°), and for Aspergillus spp was 63.3° (95% CI 60.8° to 65.8°), p=0.07. No adventitious sporulation was detected in Fusarium spp ulcers. Dichotomous branching was detected in 11 ulcers (7 Aspergillus spp, 4 Fusarium spp).

Conclusions

There was very little difference in the branching angle of Fusarium and Aspergillus spp. Adventitious sporulation was not detected and dichotomous branching was infrequently seen. Although IVCM remains a valuable tool to detect fungal filaments in fungal keratitis, it cannot be used to distinguish Fusarium from Aspergillus spp and culture remains essential to determine fungal species.

A rare case of Phialemonium obovatum keratitis

Purpose

We report a rare case of Phialemonium obovatum fungal keratitis in a patient sustaining a corneal laceration from impact with a piece of moldy plaster.

Observations

The patient was treated with topical voriconazole with resolution of active keratitis and formation of a stromal scar. The patient's final visual acuity was 20/20 in the affected eye.

Conclusions and importance

There is only one other case of Phialemonium obovatum keratitis reported in the literature. The patient in the previous case required amniotic membrane transplantation for persistent stromal melting with resultant visual acuity of hand motions only. The present case demonstrates that the early use of topical antifungal medication with close follow-up can prevent corneal perforation and result in excellent visual acuity.

Epidemiological and Genomic Landscape of Azole Resistance Mechanisms in Aspergillus Fungi

Invasive aspergillosis is a life-threatening mycosis caused by the pathogenic fungus Aspergillus. The predominant causal species is Aspergillus fumigatus, and azole drugs are the treatment of choice. Azole drugs approved for clinical use include itraconazole, voriconazole, posaconazole, and the recently added isavuconazole. However, epidemiological research has indicated that the prevalence of azole-resistant A. fumigatus isolates has increased significantly over the last decade. What is worse is that azole-resistant strains are likely to have emerged not only in response to long-term drug treatment but also because of exposure to azole fungicides in the environment. Resistance mechanisms include amino acid substitutions in the target Cyp51A protein, tandem repeat sequence insertions at the cyp51A promoter, and overexpression of the ABC transporter Cdr1B. Environmental azole-resistant strains harboring the association of a tandem repeat sequence and punctual mutation of the Cyp51A gene (TR34/L98H and TR46/Y121F/T289A) have become widely disseminated across the world within a short time period. The epidemiological data also suggests that the number of Aspergillus spp. other than A. fumigatus isolated has risen. Some non-fumigatus species intrinsically show low susceptibility to azole drugs, imposing the need for accurate identification, and drug susceptibility testing in most clinical cases. Currently, our knowledge of azole resistance mechanisms in non-fumigatus Aspergillus species such as A. flavus, A. niger, A. tubingensis, A. terreus, A. fischeri, A. lentulus, A. udagawae, and A. calidoustus is limited. In this review, we present recent advances in our understanding of azole resistance mechanisms particularly in A. fumigatus. We then provide an overview of the genome sequences of non-fumigatus species, focusing on the proteins related to azole resistance mechanisms.

Suppositional area for the search of bacterial products for anticancer therapy

It is well-known that bacteria can produce compounds which show anticancer effects. In present time, it is impossible to check all bacterial species on their possible production of anticancer compounds (AC) under different conditions. Thus, it is necessary to limit the area for search of bacterial products for the anticancer therapy. We propose that production of AC by bacteria is a part of microbial biological strategy under natural conditions. We propose that bacteria in soils, in water and on plants do not meet human tumors and their AC serve for the competition with eukaryotic organisms. Most probably, an epiphytic growth of bacilli is accompanied with production of compounds inhibiting eukaryotes. According to awaited profit for the AC-producing bacteria, the epiphytic groups of bacilli show inhibition of mycelial fungi which are a natural model of eukaryotic cells. An example of strain isolation and a primary test is presented.

Time-Kill Kinetics and In Vitro Antifungal Susceptibility of Non-fumigatus Aspergillus Species Isolated from Patients with Ocular Mycoses

Aspergillus species can cause ocular morbidity and blindness, and thus, appropriate antifungal therapy is needed. We investigated the in vitro activity of itraconazole, voriconazole, posaconazole, caspofungin, anidulafungin, and amphotericin B against 14 Aspergillus isolates obtained from patients with ocular mycoses, using the CLSI reference broth microdilution methodology. In addition, time-kill assays were performed, exposing each isolate separately to 1-, 4-, and 16-fold concentrations above the minimum inhibitory concentration (MIC) of each antifungal agent. A sigmoid maximum-effect (E_max) model was used to fit the time-kill curve data. The drug effect was further evaluated by measuring an increase/decrease in the killing rate of the tested isolates. The MICs of amphotericin B, itraconazole, voriconazole, and posaconazole were 0.5–1.0, 1.0, 0.5–1.0, and 0.25 µg/ml for A. brasiliensis, A. niger, and A. tubingensis isolates, respectively, and 2.0–4.0, 0.5, 1.0 for A. flavus, and 0.12–0.25 µg/ml for A. nomius isolates, respectively. A. calidoustus had the highest MIC range for the azoles (4.0–16.0 µg/ml) among all isolates tested. The minimum effective concentrations of caspofungin and anidulafungin were ≤0.03–0.5 µg/ml and ≤0.03 µg/ml for all isolates, respectively. Posaconazole demonstrated maximal killing rates (E_max = 0.63 h⁻¹, r² = 0.71) against 14 ocular Aspergillus isolates, followed by amphotericin B (E_max = 0.39 h⁻¹, r² = 0.87), voriconazole (E_max = 0.35 h⁻¹, r² = 0.098), and itraconazole (E_max = 0.01 h⁻¹, r² = 0.98). Overall, the antifungal susceptibility of the non-fumigatusAspergillus isolates tested was species and antifungal agent dependent. Analysis of the kinetic growth assays, along with consideration of the killing rates, revealed that posaconazole was the most effective antifungal against all of the isolates.

Unpredictable susceptibility of emerging clinical moulds to tri-azoles: review of the literature and upcoming challenges for mould identification

Tri-azoles represent the front-line drugs for the treatment of mould diseases; nevertheless, some emerging moulds, such as Fusarium spp., Scedosporium spp., Mucorales and others, may be less susceptible or resistant to these antifungals. A review of the literature was conducted on the susceptibility of rare moulds to the tri-azoles itraconazole, posaconazole and voriconazole. Particular attention was paid to isolates identified by molecular analyses. The range of susceptibility values described for the three tri-azoles was frequently large (from 0.06 to >16), and a high variability was found within each species; isolates were rarely reported as entirely susceptible to all tri-azoles. In addition, the susceptibility of 76 emerging moulds from our collection (including Hypocreales, Dothideomycetes, Scedosporium spp., Mucorales and rare Aspergillus spp.) to itraconazole and voriconazole was determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 and European Committee for Antimicrobial Susceptibility Testing (EUCAST) methods. Susceptibility discrepancies (of two dilutions) were found comparing CLSI and EUCAST for Dothideomycetes; the values for the remaining moulds were similar. More practical, faster and inexpensive susceptibility tools are welcome for testing emerging moulds, as these tests still represent a critical tool to support clinicians on the selection of proper antifungal treatment. The susceptibility of emerging moulds to tri-azoles cannot be predicted exclusively following mould identification, as the isolates' susceptibilities showed highly variable values. Some emerging moulds still remain very difficult to identity, even following standard molecular analyses which result in complex fungal collections. This fact limits the definition of epidemiological cut-offs and clinical breakpoints that are still imperative for emerging moulds.

Medical interventions for fungal keratitis

BACKGROUND

Fungal keratitis is a fungal infection of the cornea. It is common in lower income countries, particularly in agricultural areas but relatively uncommon in higher income countries. Although there are medications available, their effectiveness is unclear.

OBJECTIVES

To assess the effects of different antifungal drugs in the management of fungal keratitis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to March 2015), EMBASE (January 1980 to March 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to March 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 16 March 2015.

SELECTION CRITERIA

We included randomised controlled trials of medical therapy for fungal keratitis.

DATA COLLECTION AND ANALYSIS

Two review authors selected studies for inclusion in the review, assessed trials for risk of bias and extracted data. The primary outcome was clinical cure at two to three months. Secondary outcomes included best-corrected visual acuity, time to clinical cure, compliance with treatment, adverse outcomes and quality of life.

MAIN RESULTS

We included 12 trials in this review; 10 trials were conducted in India, one in Bangladesh and one in Egypt. Seven of these trials were at high risk of bias in one or more domains, two of these studies were at low risk of bias in all domains. Participants were randomised to the following comparisons: topical 5% natamycin compared to topical 1% voriconazole; topical 5% natamycin compared to topical 2% econazole; topical 5% natamycin compared to topical chlorhexidine gluconate (0.05%, 0.1% and 0.2%); topical 1% voriconazole compared to intrastromal voriconazole 50 g/0.1 mL (both treatments combined with topical 5% natamycin); topical 1% voriconazole combined with oral voriconazole compared to both oral voriconazole and oral itraconazole (both combined with topical 5% natamycin); topical 1% itraconazole compared to topical 1% itraconazole combined with oral itraconazole; topical amphotericin B compared to topical amphotericin B combined with subconjunctival injection of fluconazole; intracameral injection of amphotericin B with conventional treatment compared to conventional treatment alone (severe fungal ulcers); topical 0.5% and 1% silver sulphadiazine compared to topical 1% miconazole. Overall the results were inconclusive because for most comparisons only one small trial was available. The exception was the comparison of topical natamycin and topical voriconazole for which three trials were available. In one of these trials clinical cure (healed ulcer) was reported in all 15 people allocated to natamycin and in 14/15 people allocated to voriconazole (risk ratio (RR) 1.07; 95% confidence interval (CI) 0.89 to 1.28, low quality evidence). In one trial people randomised to natamycin were more likely to have a microbiological cure at six days (RR 1.64; 95% CI 1.38 to 1.94, 299 participants). On average, people randomised to natamycin had better spectacle-corrected visual acuity at two to three months compared to people randomised to voriconazole but the estimate was uncertain and the 95% confidence intervals included 0 (no difference) (mean difference -0.12 logMAR, 95% CI -0.31 to 0.06, 434 participants; 3 studies, low quality evidence) and a decreased risk of corneal perforation or therapeutic penetrating keratoplasty, or both (RR 0.61; 95% CI 0.40 to 0.94, 434 participants, high quality evidence). There was inconclusive evidence on time to clinical cure. Compliance with treatment and quality of life were not reported. One trial comparing natamycin and voriconazole found the effect of treatment greater in Fusarium species, but this subgroup analysis was not prespecified by this review.

AUTHORS' CONCLUSIONS

The trials included in this review were of variable quality and were generally underpowered. There is evidence that natamycin is more effective than voriconazole in the treatment of fungal ulcers. Future research should evaluate treatment effects according to fungus species.

In vitro susceptibility of filamentous fungi from mycotic keratitis to azole drugs

OBJECTIVE

The in vitro antifungal activities of azole drugs viz., itraconazole, voriconazole, ketoconazole, econazole and clotrimazole were investigated in order to evaluate their efficacy against filamentous fungi isolated from mycotic keratitis.

METHODS

The specimen collection was carried out from fungal keratitis patients attending Aravind eye hospital and Post-graduate institute of ophthalmology, Coimbatore, India and was subsequently processed for the isolation of fungi. The dilutions of antifungal drugs were prepared in RPMI 1640 medium. Minimum inhibitory concentrations (MICs) were determined and MIC50 and MIC90 were calculated for each drug tested.

RESULTS

A total of 60 fungal isolates were identified as Fusarium spp. (n=30), non-sporulating moulds (n=9), Aspergillus flavus (n=6), Bipolaris spp. (n=6), Exserohilum spp. (n=4), Curvularia spp. (n=3), Alternaria spp. (n=1) and Exophiala spp. (n=1). The MICs of ketoconazole, clotrimazole, voriconazole, econazole and itraconazole for all the fungal isolates ranged between 16 μg/mL and 0.03 μg/mL, 4 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL and 32 μg/mL and 0.06 μg/mL respectively. From the MIC50 and MIC90 values, it could be deciphered that in the present study, clotrimazole was more active against the test isolates at lower concentrations (0.12-5 μg/mL) when compared to other drugs tested.

CONCLUSION

The results suggest that amongst the tested azole drugs, clotrimazole followed by voriconazole and econazole had lower MICs against moulds isolated from mycotic keratitis.

Aspergillus flavus endophthalmitis after penetrating keratoplasty combined with cataract phacoemulsification and IOL implantation

To report the clinical findings and management of a case of Aspergillus flavus endophthalmitis following penetrating keratoplasty (PKP) and combined cataract extraction. Clinical cornea appearance was evaluated by slit-lamp examination. Ocular ultrasonography was performed to evaluate the anterior chamber and vitreous cavity. The cornea was scraped. The corneal-scleral donor rim and media were cultured. The diagnosis of A. flavus infection was made. The patient received fortified antifungal drops (voriconazole 1 % solution) plus systemic voriconazole 400 mg/die. A second corneal transplant was performed, and the anterior chamber was cleaned and washed with a solution of voriconazole 1 %. At the end of follow-up, CDVA was 20/20 and slit-lamp examination showed a clear cornea graft. This case illustrates a severe A. flavus endophthalmitis after PKP and demonstrates the possibilities of visual function restoration. Furthermore, this case describes the different sources of fungal infection after PKP and the different clinical appearances.

Safety and efficacy of intrastromal injection of 5% natamycin in experimental fusarium keratitis

PURPOSE

To compare the efficacy of combined intrastromal injection and topical natamycin 5% to standard topical therapy alone in an experimental rabbit model of Fusarium keratitis.

METHODS

Fungal keratitis was induced in the right eyes of 12 New Zealand rabbits by stromal injection of Fusarium solani spore suspension into the cornea. Four days after inoculation, animals were randomly assigned to 2 different treatment groups (n=6 in each group). The study group received intrastromal injections of natamycin 5% on treatment day 1 and 4, combined with topical natamycin 5% eye drops given hourly between 8:00 and 20:00 for the first 2 days, followed by 4 times daily on days 3-11. The control group received only topical natamycin 5% at identical intervals. Eyes were examined clinically on days 1, 4, 7, and 11 for status of corneal healing, corneal vascularization, and hypopyon. Animals were sacrificed on day 11, and corneas were subjected to histopathological examination.

RESULTS

Both groups showed significant improvement in terms of conjunctival hyperemia, size and density of corneal infiltrate, corneal edema, and total clinical score. In the study group, there was a significant improvement in the height of hypopyon in the anterior chamber, while there was also an increased amount of vascularization.

CONCLUSIONS

This study showed that intrastromal injection of natamycin 5% combined with topical treatment has little beneficial effect over topical therapy in a Fusarium keratitis rabbit model. The addition of intrastromal injection should be reserved to the most severe or recalcitrant cases.

Association between in vitro susceptibility to natamycin and voriconazole and clinical outcomes in fungal keratitis

PURPOSE

To assess the association between minimum inhibitory concentration (MIC) and clinical outcomes in a fungal keratitis clinical trial.

DESIGN

Experimental study using data from a randomized comparative trial.

PARTICIPANTS

Of the 323 patients enrolled in the trial, we were able to obtain MIC values from 221 patients with monocular fungal keratitis.

METHODS

The Mycotic Ulcer Treatment Trial I was a randomized, double-masked clinical trial comparing clinical outcomes of monotherapy with topical natamycin versus voriconazole for the treatment of fungal keratitis. Speciation and determination of MIC to natamycin and voriconazole were performed according to Clinical and Laboratory Standards Institute guidelines. The relationship between MIC and clinical outcome was assessed.

MAIN OUTCOME MEASURES

The primary outcome was 3-month best spectacle-corrected visual acuity. Secondary outcomes included 3-month infiltrate or scar size; corneal perforation and/or therapeutic penetrating keratoplasty; and time to re-epithelialization.

RESULTS

A 2-fold increase in MIC was associated with a larger 3-month infiltrate or scar size (0.21 mm; 95% confidence interval [CI], 0.10-0.31; P < 0.001) and increased odds of perforation (odds ratio, 1.32; 95% CI, 1.04-1.69; P = 0.02). No correlation was found between MIC and 3-month visual acuity. For natamycin-treated cases, an association was found between higher natamycin MIC with larger 3-month infiltrate or scar size (0.29 mm; 95% CI, 0.15-0.43; P < 0.001) and increased perforations (odds ratio, 2.41; 95% CI, 1.46-3.97; P < 0.001). Among voriconazole-treated cases, the voriconazole MIC did not correlate with any of the measured outcomes in the study.

CONCLUSIONS

Decreased susceptibility to natamycin was associated with increased infiltrate or scar size and increased odds of perforation. There was no association between susceptibility to voriconazole and outcome.