From Cornea and Refractive Surgery Services (BC, NS, JST) and Department of Ocular Microbiology (NN, GS), Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Namrata Sharma, MD, Associate Professor, Cornea and Refractive Surgery Services, RP Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi 110029, India.
Automated lamellar therapeutic keratoplasty (ALTK) is a form of lamellar keratoplasty which has been reported to be a safe and effective procedure for the treatment of anterior to mid stromal corneal pathologies.1,2 While microbial keratitis can occur following penetrating or lamellar keratoplasty (LK), to our knowledge, no case of graft infection following ALTK has been reported so far. Aureobasidium pullulans, a rare cause of keratomycosis, has never been described as a causative organism for graft infection following keratoplasty. We herein describe the clinical course and management of an interesting case of infectious keratitis due to Aureobasidium pullulans that occurred following ALTK surgery which was performed for healed trachomatous keratopathy.
A 73-year-old man underwent ALTK surgery in his left eye at our centre for healed trachomatous keratopathy. Preoperatively, there was no history of any systemic ailment. ALTK surgery was performed using the ALTK System (Moria/Microtek Inc., Doylestown, PA). The donor button was prepared from a full-thickness donor cornea preserved in Mc-Karey-Kaufman (MK) medium for 16 hours. The death-enucleation time was one hour. The ALTK surgery was uneventful and post-operatively, the patient received topical prednisolone acetate 1% 6 times daily, moxifloxacin hydrochloride 0.5% 3 times daily, cycloplegics and lubricants.
Five days later, he complained of pain, redness and watering in the operated eye. On examination, BCVA was 20/120. On slit lamp biomicroscopy, a 2 × 3 mm stromal infiltrate with an overlying epithelial defect was noted at the 6-o’clock position in the graft. The infiltrate was involving the graft-host junction and also extending deeper into the recipient stromal bed (Fig. 1a). The anterior chamber was quiet. A corneal scraping was taken and subjected to microbiological analysis. Both Gram stained smear and KOH preparation showed the presence of fungal hyphae. Topical steroids were withheld and topical natamycin 5% one hourly was added. No growth was observed on bacterial culture. Culture on Saboraud’s Dextrose Agar (SDA) appeared as a black shiny leathery growth with wrinkled surface (Fig. 2a). Microscopic morphology was consistent with Aureobasidium pullulans (Fig. 2b). Bacterial and fungal culture of the donor button were sterile. The originally removed trachomatous cornea also did not show any features suggestive of infection on histopathology examination.
Figure 1. (a) Slit Lamp Biomicroscopic Photograph 5 Days Following ALTK Showing a 2 × 3 mm Stromal Infiltrate in the Graft. The Infiltrate was Seen to Involve the Graft-Host Junction at the 6-o’clock Position and was Extending Deeper into the Recipient Stromal Bed. (b) Worsening of the Infection with an Increase in the Size of Infiltrate to Involve the Inferior Half of the Graft with Associated Graft Melting. Exudates were Seen at the Graft-Host Interface, and a Diffuse Graft Edema was also Noted. (slit Lamp Biomicroscopic Photograph). (c) Dense Infiltrates Extending into the Recipient Stromal Bed After Removal of the Lamellar Graft (slit Lamp Biomicroscopic Photograph). (d) Slit Lamp Biomicroscopic Photograph Following a Therapeutic Penetrating Keratoplasty.
Figure 2. (a) Culture Showing Black, Shiny, Leathery Growth with a Wrinkled Surface. (b) Microscopic View of the Lactophenol Cotton Blue Preparation Showing Thick Walled Black Fungal Hyphae, Some with Attached Pyriform Conidia. Conidia Can also be Seen Dispersed Unevenly Throughout the Smear.
Systemic fluconazole tablets 150 mg twice daily and topical amphotericin B 0.15% (Fungizone; Sanabhai Chemicals, Baroda, India) hourly were added. However, the clinical condition worsened over the next few days with an increase in the size of infiltrate to involve the inferior half of the graft with associated graft melting. Exudates were seen at the graft-host interface, with a diffuse graft edema (Fig. 1b).Visual acuity was reduced to hand motion. Posterior segment evaluation by ultrasonography was unremarkable. Removal of the lamellar graft was performed (Fig. 1c) and the host bed was irrigated with Amphotericin B (Fungizone, 5 μg/0.1 mL 5% dextrose). Culture of the removed lamellar lenticule did not show any organisms.
The keratitis worsened and one month later, a therapeutic penetrating keratoplasty (PKP) was performed. During PKP, an intumescent cataractous lens was noted and therefore, an extracapsular cataract extraction was performed. An intraocular lens was not implanted in view of the infection and the eye was left aphakic (Fig. 1d). Post-operatively, topical antibiotic eyedrops (chloramphenicol 0.5%, polymyxin B sulphate 10,000 IU) 4 times daily, topical natamycin 5% eyedrops 5 times daily, cycloplegics and preservative free artificial tears were administered. Topical steroids were withheld for the initial two weeks after PKP and following epithelialization, prednisolone acetate 1% eyedrops 4 times daily were added to the treatment regimen. Topical natamycin was tapered over 12 weeks. Three months later, BCVA was 20/80. At 1 year follow-up, there was no recurrence of infection.
The incidence of infectious keratitis following LK has been reported to be 11.11%.3 ALTK is a form of lamellar keratoplasty which has been reported to be a safe and effective procedure for treatment of anterior to mid stromal corneal pathologies.1,2
To our knowledge, graft infection following ALTK has not been reported so far.
Aureobasidium pullulans is a dematiaceous fungi which is known to cause nosocomial infections such as peritoneal sepsis in patients undergoing peritoneal dialysis,4 disseminated fungal infection5 and opportunistic infections in immunocompromised patients.6 Among ocular infections, Aureobasidium pullulans infection has been described as a rare cause of keratomycosis7 and has also led to scleritis following therapeutic keratoplasty for A. pullulans keratitis.8 Recently, Aureobasidium pullulans fungal keratitis has also been reported following laser epithelial keratomileusis (LASEK).9
Isolation of Aureobasidium pullulans from clinical specimens is generally regarded as a contaminant. With regard to the possible source of infection in our patient, we cannot rule out the possibility that accidental contamination of the ALTK machine may have been the source of infection and the surgical procedure may have provided a potential site of entry for the micro-organism. There were no systemic host factors predisposing to infection in our patient as he was neither diabetic nor immunocompromised. There was no history of any prior drug therapy. The blood culture did not reveal any growth ruling out the possibility of haematogenous spread. Preoperatively, the eye had no infection and there were no local factors in the post-operative period such as persistent epithelial defects or suture abscesses which are known to predispose to microbial keratitis following keratoplasty.3 Bacterial and mycology cultures obtained from the donor cornea were also found to be sterile ruling out the possibility of donor-to-host transmission of Aureobasidium pullulans.
Treatment with antifungal therapy has been found to be effective for corneal ulcers caused by Aureobasidium pullulans.7 In a case of Aureobasidium pullulans fungal keratitis following LASEK, the infection responded to topical natamycin and systemic itraconazole.9 However, treatment of graft infection following LK can be a challenging proposition. Due to involvement of the graft-host interface in some of these cases, the infection may not be amenable to topical and systemic antimicrobial therapy and a therapeutic penetrating keratoplasty may be required.10 In our case, despite intensive topical and systemic antifungal medication, and removal of the lamellar graft, the infection could not be controlled and a therapeutic full thickness graft had to be performed in order to salvage the eye.
- Jiminez-Alfaro I, Perez-Santonja JJ, Gomez Telleria G, Bueno Palacin JL, Puy P. Therapeutic keratoplasty with an automated microkeratome. J Cataract Refract Surg. 2001;27:1161–1165. doi:10.1016/S0886-3350(00)00889-0 [CrossRef]
- Vajpayee RB, Vasudendra N, Titiyal JS, Tandon R, Sharma N, Sinha R. Automated Lamellar Therapeutic Keratoplasty (ALTK) in the treatment of anterior to mid-stromal corneal pathologies. Acta Ophthalmologica Scandinavia. 2006;84(6):771–773. doi:10.1111/j.1600-0420.2006.00722.x [CrossRef]
- Sharma N, Gupta V, Vanathi M, Agarwal T, Vajpayee RB, Satpathy G. Microbial Keratitis following lamellar keratoplasty. Cornea. 2004; 23(5):472–478. doi:10.1097/01.ico.0000116525.57227.59 [CrossRef]
- Caporale NE, Calegari L, Perez D, Gezuele E. Peritoneal catheter colonization and peritonitis with Aureobasidium pullulans. Peritoneal Dial. Int. 1996;16:97–98.