Rhodotorula endophthalmitis associated with Baerveldt shunt implantation

Endophthalmitis is an uncommon complication of glaucoma drainage device surgery. Most cases are secondary to Gram-positive bacteria: Staphylococcus, Streptococcus, and Haemophilis. Cases caused by fungal pathogens are very rare. Rhodotorula is a common environmental yeast that has recently been recognized as a human pathogen. Infections are most commonly linked to frequent intensive care unit procedures such as central venous catheters. There is a paucity of literature describing Rhodotorula infections of the eye. To our knowledge, this is the first presented case of Rhodotorula endophthalmitis following glaucoma drainage device surgery.

An 88-year-old pseudophakic female presented with a painless decrease in right eye visual acuity. The patient's ocular history was significant for primary open-angle glaucoma and bilateral Baerveldt shunt placement (right eye 2009, left eye 2012). Visual acuity was 6/30 in the right eye and 6/15 in the left eye. Intraocular pressures via tonometry were 8 and 15mm Hg in the right and left eye, respectively. Fundus examination was unremarkable bilaterally. In the right eye, a well-positioned superotemporal Baerveldt shunt was identified; however, the tube was found to have eroded through a scleral graft and there was an overlying conjunctival defect. Mild inflammation was noted on examination by the glaucoma specialist in the right eye. Subsequently, the patient underwent an uncomplicated revision with donor corneal patch graft and conjunctival autograft.

On postoperative day 1, visual acuity was 6/120; slit-lamp examination revealed 4+ cells and a 1mm hypopyon. A plaque was noted on the anterior surface of the posterior chamber intraocular lens. A fibrinous-appearing extension from the plaque was observed to project into the tube shunt opening (Fig.1). Posterior pole examination was limited by vitreous haze. Vitreous and anterior chamber aspirations were performed, and empiric ceftazidime 2mg/0.1mL and vancomycin 1mg/0.1mL were injected intravitreally. Gram stain of the aqueous fluid revealed numerous neutrophils with no bacteria. Aqueous fluid cultures grew Rhodotorula and Cryptococcus laurentii colonies after 20days. Vitreous specimens had no growth of bacteria or fungi. Accordingly, the patient received intracameral voriconazole 100 μg/0.1mL and amphotericin B 10 μg/0.1mL. Oral voriconazole 400mg daily was initiated.

The patient was seen in follow-up 1 week later; at that time, visual acuity was 6/24. Anterior chamber examination revealed 1/2+ cells and mild flare. The plaque had decreased in size from initial presentation. Fundus examination revealed an absence of vitritis. The patient has since been followed by their local ophthalmologist and has remained stable. The glaucoma drainage device was not removed secondary to patient stability. The patient's overall frailty and multiple comorbidities was also taken into account.

Rhodotorula is an environmental yeast that is known to infect humans. The majority of known Rhodotorula cases are reported in immunocompromised patients. The incidence of fungemia caused by Rhodotorula is between 0.5% and 2.3% in the United States and Europe. Rhodotorula is a very rare cause of ophthalmologic infection. From our review of the literature, there are 12 cases of this fungus isolated from ocular structures. Four of these case reports were episodes of endophthalmitis. Of these, one case was an exogenous endophthalmitis following cataract surgery. Endophthalmitis can be divided into endogenous and exogenous subtypes. Endogenous endophthalmitis results from hematogenous spread of infection, whereas exogenous endophthalmitis results fromdirect inoculation of an organism. Direct inoculation can occur secondary to penetrating ocular trauma, intraocular extension of ocular surface infections, and postoperatively. Exogenous endophthalmitis is more common, making up approximately 85%–98% of all cases. Exogenous endophthalmitis is most commonly seen after cataract surgery, with incidence ranging from 0.02% to 0.30% of cases. In our case the Rhodotorula infection is possibly an acute exacerbation of a more chronic process. Typically fungal endophthalmitis presents later in the postoperative period than postoperative day 1. In the case of exogenous Rhodotorula in the literature, symptoms began approximately 2 months after surgery. There are no other cases in the literature to compare the infectious timeline of Rhodotorula postsurgical intervention.

Endophthalmitis following glaucoma drainage device surgery is a complication described in the literature. Incidence of endophthalmitis ranged between 1.10% and 2.77%, with the Baerveldt implant having an incidence of 1.10%. Common infectious organisms include Haemophilis, Streptococcus, and Pseudomonas species. To our knowledge there are no known cases of Rhodotorula infection following glaucoma drainage device implantation.

Treatment of systemic Rhodotorula includes antifungal agents such as amphotericin B and azoles (fluconazole, voriconazole, itraconazole). In vitro susceptibilities have shown that amphotericin B had the lowest minimum inhibitory concentration (MIC). Treatment of fungal endophthalmitis does not have a standardized protocol. Therapy often includes intravitreal injections of antifungal agents with systemic antifungal administration. Silva et al. investigated fungal susceptibilities in cases of exogenous fungal endophthalmitis. In their case series, susceptibilities were highest to intravitreal voriconazole; unfortunately this study did not include any cases of Rhodotorula endophthalmitis. Treatment regimens described in the literature include use of intravitreal amphotericin B and an intravitreal azole. Upon review of the 4 cases of Rhodotorula endophthalmitis described in the literature, the antifungal regimens included amphotericin B, ketoconazole, or a combination of the 2. Vitrectomy was performed in these cases as patients did not improve with antifungals alone. Unlike those cases, our patient did not require enucleation or vitrectomy and had improvement of vision with anterior chamber and vitreous tap and antifungal injection alone.

In conclusion, fungal endophthalmitis associated with glaucoma drainage procedure is exceedingly rare, with most infections caused by bacteria. In cases where bacterial cultures are negative, fungal pathogens should be suspected. Rhodotorula is an emerging fungal pathogen that affects the eye and should now be considered in postoperative endophthalmitis cases. Our patient received an anterior chamber (AC) aspiration along with intracameral and systemic antifungal agents and had improvement of vision.