Spectrum of fungal keratitis:clinicopathologic study of 44 cases

AIM:To determine the causative agents of fungal keratitis and study the predisposing factors over a period of ten years in a single tertiary care hospital.METHODS:A retrospective analysis of fungal corneal ulcers was done from 2003-2012. Patients’ clinical data were noted from the file records. Correlation of histopathological diagnosis was done with the report on fungal culture.RESULTS: Mycotic keratitis was established in 44 cases by a positive fungal culture. Direct microscopic examination of potassium hydroxide (KOH) mounts revealed fungal elements in 39 cases while 40 cases showed fungus on Gram stained smears. Males (54.55%) were more commonly affected than the females (45.45%). The age ranged from 18 to 82 years. Most common age group to be involved was 41-60 years. Predisposing risk factors were seen in 34 (77.27%) cases. Most common findings on clinical examination were anterior chamber reaction and conjunctival injection seen in all the cases. Other common findings were stromal infiltration and hypopyon seen in 20 (45.45%) and 18 (40.91%) cases respectively. On histopathological examination the fungus was typed, as aspergillus in 34 cases while no definite typing was possible in 10 cases. The predominant isolate was aspergillus flavus (59.09%) followed by fusarium (15.91%). Mixed fungal and bacterial infection was seen in 3 (6.82%) cases.CONCLUSION:Although culture is the gold standard for definitive diagnosis of fungal keratitis, direct microscopic examination of corneal scrapings or histomorphological evaluation of biopsies allow a rapid preliminary diagnosis. Early administration of antifungal treatment helps in preventing dreadful complications.     

Clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis

AIM: To study the clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis. METHODS：A retrospective study was done to 10 patients (10 eyes) who had accepted removal of the necrotic corneal tissue combined with conjunctival flap covering surgery for fungal keratitis,the diagnosis by corneal scraping and smear examination or confocal microscopy check hyphae.Local and systemic antifungal therapy more than one week for all patients, corneal ulcer enlarge or no shrink.Slit lamp microscope examination the diameter of corneal ulcer about 2mm-4mm.Anterior segment optical coherence tomography（AS-OCT）examine the depth of corneal ulcer between 1/3-1/2,infiltrate corneal stroma about 20um-80um,the diameter of corneal ulcer about 3mm-6mm.Type-B ultrasonic exclusion endophthalmitis. Complete removal lesions until transparent of stroma, make conjunctival flap equal or greater than ulcer 1mm nearby conjunctiva. Continued antifungal therapy. The vision, fungal recurrence, conjunctival flap rollback or desquamate were analysed. RESULTS：Ten patients had success done this surgery, the corneal ulcer was not enlarge and healing afteroperation.7 cases were bridging conjunctival flap and 3cases were single conjunctival flap. Preoperation vision above 0.1 had 8 cases,7 cases had vision above 0.1 one week after surgery, while 1 cases vision droped from 0.3 to 0.05.There was not recurrent for fungal,2 cases conjunctival flap rollback:1 case was bridging and 1case was single flap, no conjunctival flap desquamate. CONCLUSION：It is safe and effective to perform removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis which werenot sensitive or aggravate for antifungal drugs.     

Necrotizing Keratitis Caused by Acyclovir-Resistant Herpes Simplex Virus

Background

We report a case of necrotizing keratitis caused by acyclovir (ACV)-resistant herpes simplex virus (HSV) with a clinical appearance similar to a previous fungal keratitis infection.

Methods

Observational case report.

Results

Penetrating keratoplasty was performed in the left eye with a history of herpetic keratitis that resolved with periodic treatment with ACV ointment and a topical steroid. The left eye was painful and red with an abscess and corneal erosion in the peripheral donor cornea. Examination of the scraped corneal epithelium by light microscopy and culturing identified Candida albicans; polymerase chain reaction (PCR) was negative for human herpes viruses. After antifungal treatment, the ocular pain gradually decreased and the lesions slowly improved but recurred with a similar clinical appearance. A second light microscopy examination and cultures were negative for pathogens including C. albicans. PCR was positive for HSV-1 DNA; treatment with 3% topical ACV ointment was unsuccessful. A third examination showed only HSV-1 DNA. Despite antiviral ACV ointment, no clinical improvement occurred based on the HSV DNA copy numbers, which were the same before and after treatment, indicating a possible ACV-resistant strain. When topical trifluorothymidine was substituted for ACV, clinical improvement occurred and the HSV DNA copy numbers decreased.

Conclusion

Necrotizing keratitis induced by ACV-resistant HSV occurred independently after fungal keratitis, with a similar clinical appearance in this case, making diagnosis and treatment difficult. Monitoring the HSV DNA load by real-time PCR could be useful for refractory cases even with atypical clinical appearances.Key words: Herpes simplex virus, Acyclovir-resistant herpes simplex virus, Necrotizing keratitis, Fungal infection, Real-time polymerase chain reaction     

Methicillin-Resistant Staphylococcus aureus Keratitis after Descemet's Stripping Automated Endothelial Keratoplasty

Purpose

We report a case of methicillin-resistant Staphylococcus aureus (MRSA) keratitis after Descemet''s stripping automated endothelial keratoplasty (DSAEK).

Case Report

An 87-year-old woman who had undergone a DSAEK 4 months previously was referred to Tokushima University Hospital with a diagnosis of infectious keratitis after DSAEK. A white abscess and infiltration in the inferior cornea of the right eye were observed. We started an empiric therapy using topical levofloxacin and chloramphenicol on the basis of the microscopic findings of the corneal scraping concurrently with cultivation of the cornea.

Results

A strain of MRSA was isolated from the corneal sample. Although the strain was susceptible to chloramphenicol, it was resistant to quinolone. The keratitis improved rapidly due to empiric therapy, and topical steroids could be resumed 6 days after initiation of the empiric therapy.

Conclusions

To our knowledge, this is the first case of MRSA keratitis, and the second case of bacterial keratitis, after DSAEK. MRSA keratitis can occur following uneventful DSAEK. The empiric therapy on the basis of results from a light microscopic examination of a Gram-stained corneal scraping and restarting topical steroids in the early stages of medication contributed to the good clinical course of this case.Key words: Descemet''s stripping automated endothelial keratoplasty, Methicillin-resistant Staphylococcus aureus, Keratitis     

Incidence and microbiological profile of mycotic keratitis in a tertiary care eye hospital: A retrospective analysis

Purpose

To determine the incidence and microbiological profile of mycotic keratitis seen at a tertiary care eye hospital.

Materials and methods

A retrospective review of microbiology records of patients presenting with suspected microbial keratitis seen between January 2006 and December 2009 was performed. Patients with positive fungal cultures were further analyzed for the type of fungus isolated and associated bacterial pathogens.

Results

Microbiology records of 2300 patients with suspected microbial keratitis were reviewed. A microbiological diagnosis of mycotic keratitis was established in 87 (3.8%) patients over a four year period based on positive fungal cultures. The yearly incidence of mycotic keratitis was 3.2% (2006), 4.9% (2007), 3.3% (2008) and 3.6% (2009). Filamentous fungi were isolated more often than yeasts. Aspergillus species followed by Fusarium species and Trichophyton species were the commonest filamentous fungi isolated while Candida albicans was the most frequently encountered yeast. Mixed infections due to fungal and bacterial pathogens were seen in 25/87 (28.7%) patients.

Conclusion

Cumulative incidence of mycotic keratitis was 3.8% over a four year period. Aspergillus species and Candida albicans were the most frequent pathogenic organisms causing mycotic keratitis in this part of the world. Mixed infections were seen in 28.7% of the patients. Knowledge of the “local” etiology within a region may be valuable in the management of mycotic keratitis in instituting an empirical therapy, especially when facilities for microscopy, cultures and antifungal susceptibility are not readily available. The baseline information presented will also be helpful in the planning of a corneal ulcer management strategy and for future studies on mycotic keratitis.     

Experimental model of Fusarium solani keratitis in rats

AIM: To establish a repeatable rat model of Fusarium solani keratitis (F. solani keratitis) that mimicked fungal keratitis in humans. METHODS: Wistar rats’ corneas were scratched on the superficial stroma after scraping the unilateral corneal epithelia. Then, the corneal surface was inoculated with different inoculum dose of F. solani spore suspension. Doses ranged from 106 to 109 colony-forming unit per milliliter (CFU/mL). The treated corneas were covered by contact lenses that were made of Parafilm M membrane. Negative controls were inoculated with sterile phosphate-buffered saline (PBS). For statistical analysis, corneas were evaluated daily on a 12-point scale to check the state of corneal inflammation. Furthermore, the pathological characteristics of this model were investigated. RESULTS: The rat model of F. solani keratitis was established by the combination methods of corneal trauma and parafilm-made contact lens and inoculation of fungus spore suspension. 106 and 107CFU/mL of F. solani induced mild corneal infection, while 108CFU/mL of F. solani was sufficient to induce moderate infection that was consistent with human keratomycosis. Dose of 109CFU/mL of F. solani was excessive and led to perforated corneas. CONCLUSION: The rat model of F. solani keratitis, established by the combinational methods of corneal trauma, parafilm-made contact lens and the appropriate dose of inoculum, that imitates the developing processes of F. solani keratitis in human beings and provides a repeatable method of creating a rat model.     

Double-biguanide therapy for resistant acanthamoeba keratitis

Aims

To report the clinical and diagnostic findings of a patient with Acanthamoeba keratitis resistant to both polyhexamethylene biguanide (PHMB)-hexamidine and chlorhexidine-hexamidine treatment.

Methods

Slit-lamp biomicroscopy, corneal cell scraping and histopathology were performed on a 39-year-old woman presenting with corneal ulcer in her left eye.

Results

The patient was successfully treated with PHMB-chlorhexidine association therapy. Subsequent perforating keratoplasty remained clear at the last follow-up visit after 7 months and increased visual acuity to 20/20 with correction.

Conclusions

This case emphasizes the proteiform aspects of Acanthamoeba drug resistance, and suggests that PHMB-chlorhexidine association might represent an additional option for cases resistant to standard therapy.Key Words: Acanthamoeba keratitis, Biguanide, Diamidine     

Over-Treated Corneal Abscess May Be Toxic Keratopathy

Background/Aims

Keratitis, especially when long-standing and unresponsive to common antimicrobial treatment, leads to a suspicion of fungal aetiology.

Methods

Photographically documented case report.

Results

A 65-year-old man with diabetes was referred for corneal abscess unresponsive to antibiotic and antifungal treatment lasting 6 weeks. Corneal biopsy was performed following a 72-hour washout for identification of bacteria and fungi. Previously administered drops were withdrawn and only preservative-free artificial tears were maintained. Neither bacteria nor fungi were cultured. After 2 weeks, the clinical situation had conspicuously improved.

Conclusion

Over-treatment of corneal affections fearing mycosis may lead to toxic keratopathy.Key Words: Toxic keratopathy, Corneal abscess, Corneal mycosisToxic keratopathy due to varying aetiologies has been well known for decades [1,2,3,4]. Ophthalmologists, desperate when faced by long-standing ocular inflammation unresponsive to treatment, tend to over-treat corneal affections with every conceivable therapy. Particularly worrying is fungal keratitis. We describe here a typical example of this situation.     

Keratitis with Kocuria palustris and Rothia mucilaginosa in Vitamin A Deficiency

Purpose

To present a case of unusual corneal infection early in the course of peripheral ulcerative keratitis in a patient with severe vitamin A deficiency.

Method

Single observational case report in urban USA.

Case Presentation

An alcoholic patient with pancreatitis, chronic diarrhea, and vitamin A deficiency presented with a marginal corneal ulcer from which two bacteria of the family Micrococcaceae were cultured and identified by genome sequence analysis, namely Kocuria palustris and Rothia mucilaginosa. Soon after, severe bilateral peripheral ulcerative keratitis developed, later accompanied by eyelid cellulitis of one lid. These conditions improved with antibiotics, treatment of the underlying gastrointestinal conditions, and treatment of the vitamin deficiency.

Conclusion

Susceptibility to keratitis with unusual bacteria of the Micrococcaceae family can occur in the setting of alcoholism-related gastrointestinal disease with severe vitamin A deficiency. To our knowledge, K. palustris is a species not previously identified in any human disease, and the Kocuria genus has not previously been reported as a participant in eye infection. Documented cases of R. mucilaginosa in ocular disease are rare. These unusual infections heralded the onset of severe marginal corneal melts.Key words: Kocuria palustris, Rothia mucilaginosa, Peripheral ulcerative keratitis, Vitamin A deficiency     

Argon laser photocoagulation versus intrastromal voriconazole injection in treatment of mycotic keratitis

AIM: To compare argon laser photocoagulation and intrastromal injection of voriconazole as adjunctive treatment modalities in cases of resistant mycotic corneal ulcers. METHODS: Two groups each of them included 20 cases of resistant mycotic corneal ulcers. Both groups treated with local and systemic specific antimicrobial drugs guided with culture and sensitivity results. In one group argon laser photocoagulation was used as an adjunctive therapy to the specific antifungal drugs and in the other group, intrastromal injection of voriconazole was done besides the specific antifungal drugs. The 40 cases included in the study were proven according to culture and sensitivity to be 28 cases with pure fungal results and 12 cases with mixed (fungal and bacterial). In argon laser group, argon laser irradiation of the corneal ulcer was performed using argon laser 532 nm wavelength (Carl Zeiss LSL 532s AG; Meditec, Inc.) after fluorescein staining. In the other group, voriconazole solution (500 μg/mL) was prepared and injected in the corneal stroma. All cases were followed up for 3mo after healing was achieved. RESULTS: Complete healing of the epithelial defect and resolution of stromal infiltration with no adverse effects were achieved in argon laser group in duration ranged from 2-4wk in 90% of cases. In voriconazole group 4 cases needed amniotic membrane graft due to thinning and 16 cases healed in duration ranged from 2-6wk (80% of cases). CONCLUSION: Argon laser photocoagulation is superior to intrastromal voriconazole injection in treatment of resistant fungal corneal ulcers.     

Chronic Ocular Hypertension after Treated Multifocal Bacterial Keratitis

Purpose

To report an unusual case of multifocal bacterial keratitis that despite success-ful treatment caused chronic ocular hypertension.

Methods

A 67-year-old woman with unilateral multifocal keratitis and no previous ocular pathology was admitted to our hospital. Corneal scrapings and conjunctival samples were obtained for culture and the patient received intensive therapy with fortified vancomycin and tobramycin eye drops.

Results

The cultures demonstrated two strains of Staphylococcus epidermidis, one resistant to ciprofloxacin and both sensitive to vancomycin. Treatment was effective and gradually discontinued after total cessation of the inflammatory activity. During the follow-up period, the patient developed late and persistent ocular hypertension of unknown etiology, in absence of any detectable inflammation or complication, and received permanent antiglaucoma therapy.

Conclusion

Differential diagnosis between fungal and bacterial infection is critical in cases of multifocal keratitis. Patients with multifocal bacterial keratitis may need intraocular pressure monitoring, even after complete infection healing.Key words: Keratitis, Ocular hypertension, Staphylococcus epidermidis     

Epidemiological and microbiological profile of infective keratitis in Ahmedabad

Context:

Study of patients attending tertiary care ophthalmology institute at Ahmedabad.

Aims:

To study the microbiological etiology and epidemiological factors associated with suppurative keratitis.

Settings and Design:

A total of 150 corneal scrapings were evaluated from patients presenting with corneal ulcers at a tertiary ophthalmology center, Ahmedabad from July 2007 to June 2008.

Materials and Methods:

Scrapings were subjected to Gram stain, potassium hydroxide preparation and culture for bacterial and fungal pathogens. Socio-demographic data and risk factors were recorded.

Results:

Ninety percent (135/150) people with corneal ulcers had trauma as predisposing factor for keratitis. Trauma due to wooden objects was the leading cause (46/135) followed by vegetable matter and stone injury (23/135). Microbial etiology was established in 59.3% (89/150) of scrapings. Out of 89 positive isolates, 65.1% (58/89) were bacterial while 34.9% (31/89) were fungal. Among the bacterial isolates, 60.3% (35/58) were Gram-positive cocci while 39.7% (23/58) were Gram-negative bacilli. The most common bacterial isolate was Staphylococus aureus (32.7%, 19/58) followed by coagulase-negative Staphylococci (25.8%, 15/58) and Pseudomonas (18.9%, 11/58). Among the 31 fungal pathogens, Aspergillus species was the most common (35.4%11/31), followed by Fusarium species (22.5%, 7/31).

Conclusion:

Trauma with wooden material is the most common predisposing factor for suppurative keratitis. Males were more affected than females. Bacterial ulcers were more common than fungal in areas in and around Ahmedabad. Staphylococcus aureus and Aspergillus were the commonest bacterial and fungal isolates respectively. Geographical variation persists in microbial etiology of suppurative keratitis.     

Review of epidemiological features, microbiological diagnosis and treatment outcome of microbial keratitis: Experience of over a decade

Purpose:

To review the epidemiological characteristics, microbiological profile, and treatment outcome of patients with suspected microbial keratitis.

Materials and Methods:

Retrospective analysis of a non-comparative series from the database was done. All the patients presenting with corneal stromal infiltrate underwent standard microbiologic evaluation of their corneal scrapings, and smear and culture-guided antimicrobial therapy.

Results:

Out of 5897 suspected cases of microbial keratitis 3563 (60.4%) were culture-proven (bacterial – 1849, 51.9%; fungal – 1360, 38.2%; Acanthamoeba – 86, 2.4%; mixed – 268, 7.5%). Patients with agriculture-based activities were at 1.33 times (CI 1.16–1.51) greater risk of developing microbial keratitis and patients with ocular trauma were 5.33 times (CI 6.41–6.44) more likely to develop microbial keratitis. Potassium hydroxide with calcofluor white was most sensitive for detecting fungi (90.6%) and Acanthamoeba (84.0%) in corneal scrapings, however, Gram stain had a low sensitivity of 56.6% in detection of bacteria. Majority of the bacterial infections were caused by Staphylococcus epidermidis (42.3%) and Fusarium species (36.6%) was the leading cause of fungal infections. A significantly larger number of patients (691/1360, 50.8%) with fungal keratitis required surgical intervention compared to bacterial (799/1849, 43.2%) and Acanthamoeba (15/86, 17.4%) keratitis. Corneal healed scar was achieved in 75.5%, 64.8%, and 90.0% of patients with bacterial, fungal, and Acanthamoeba keratitis respectively.

Conclusions:

While diagnostic and treatment modalities are well in place the final outcome is suboptimal in fungal keratitis. With more effective treatment available for bacterial and Acanthamoeba keratitis, the treatment of fungal keratitis is truly a challenge.     

Serrated Margins in Pseudomonas aeruginosa Keratitis

Purpose

To describe 3 cases of culture-positive P. aeruginosa keratitis, who presented with a focus having serrated margins.

Methods

Observational case report.

Results

Three cases wearing contact lenses complained of symptoms such as pain, redness, and a decrease in vision. Slit-lamp biomicroscopic examination revealed a focus with serrated margins in all cases. The patients underwent corneal scraping for cultures, which confirmed the presence of P. aeruginosa. All 3 patients were treated with a combination of fluoroquinolone and tobramycin, 6–8 times per day. Corneal defects and infiltration disappeared within 2 weeks after initiating the therapy.

Conclusion

Serrated margins may also be a characteristic initial presentation of P. aeruginosa keratitis.Key words: Pseudomonas aeruginosa keratitis, Serrated margins, Contact lenses     

Keratitis after Implantation of Intrastromal Corneal Rings with Spontaneous Extrusion of the Segment

Purpose

To report a case of bacterial keratitis in a patient with a history of intrastromal corneal ring segments (INTACS®) implantation to correct keratoconus.

Methods

The patient''s history, clinical presentation, pathological analysis and therapeutic management were reviewed.

Results

A 36-year-old-man was referred to our department due to decreased vision and intense pain in his left eye, 40 days after INTACS® implantation for keratoconus. Slit-lamp examination revealed epithelial defects and stromal infiltrates in the lower channel without evidence of the inferior ring. The anterior chamber also showed a significant fibrin reaction to hypopyon. A low-tension suture was removed at the site of the incision. Microbiological study of the conjunctival swab was positive for Staphylococcus epidermidis, but the corneal culture was sterile. The patient was treated with topical fortified and systemic antibiotics. The infection slowly resolved, leaving opacity at the inferior segment site.

Conclusions

Infectious keratitis following INTACS implantation is an infrequent complication that can have important consequences without suitable and early therapeutic management.Key Words: INTACS®, Intrastromal rings, Keratitis, Segment extrusion     

Fungal Keratitis – Improving Diagnostics by Confocal Microscopy

Purpose

Introducing a simple image grading system to support the interpretation of in vivo confocal microscopy (IVCM) images in filamentous fungal keratitis.

Setting

Clinical and confocal studies took place at the Department of Ophthalmology, Aarhus University Hospital, Denmark. Histopathological analysis was performed at the Eye Pathology Institute, Department of Neuroscience and Pharmacology, University of Copenhagen, Denmark.

Methods

A recent series of consecutive patients with filamentous fungal keratitis is presented to demonstrate the results from in-house IVCM. Based upon our experience with IVCM and previously published images, we composed a grading system for interpreting IVCM images of filamentous fungal keratitis.

Results

A recent case series of filamentous fungal keratitis from 2011 to 2012 was examined. There were 3 male and 3 female patients. Mean age was 44.5 years (range 12–69), 6 out of 17 (35%) cultures were positive and a total of 6/7 (86%) IVCM scans were positive. Three different categories of IVCM results for the grading of diagnostic certainty were formed.

Conclusion

IVCM is a valuable tool for diagnosing filamentous fungal keratitis. In order to improve the reliability of IVCM, we suggest implementing a simple and clinically applicable grading system for aiding the interpretation of IVCM images of filamentous fungal keratitis.Key words: In vivo confocal microscopy, Fungal keratitis, Diagnostics     

Prospective comparison between conventional microbial work-up vs PCR in the diagnosis of fungal keratitis

Purpose

The PCR was compared with routine microbial studies for the detection of fungal pathogens in clinically suspected fungal keratitis.

Methods

A prospective nonrandomized study was undertaken at a tertiary eye care centre to evaluate 30 eyes of 30 patients with presumed fungal keratitis, both fresh and treated. Corneal scrapings were performed on each patient. The specimens were analysed by a semi-nested PCR assay using fungal-specific primers. PCR products were cloned and sequenced for identification, and compared with a conventional microbial work-up (smear and culture).

Results

Of the 30 samples, the PCR showed positivity in 93.3%, culture in 40%, and potassium hydroxide in 20%. Of the 28 PCR-positive cases, 12 were culture-positive and 16 were culture-negative. Two samples were both PCR and culture test negative. Culture-negative samples were PCR-positive in 16 of 18 (88.9%) cases. The PCR did not yield any false-negative findings in a culture-positive specimen. Both common and uncommon aetiologic fungi have been identified by DNA sequencing analysis.

Conclusion

The PCR was able to detect fungal DNA in a high proportion of culture-negative cases. Technical considerations of the PCR process include extraction of artifacts and amplification of non-pathogenic DNA. Nonetheless, our findings suggest that the PCR can be a useful adjunct to smear and culture in the rapid diagnosis of fungal keratitis, particularly in cases of failed detection from routine procedures.