Clinical Features,Antimicrobial Susceptibilities,and Outcomes of Acute-Onset Exogenous Nocardia Endophthalmitis

Case 1

A 44-year-old man was referred for evaluation of a painful, red left eye 6 days after revision of a glaucoma drainage implant. His ocular history was notable for remote cataract extraction with intraocular lens implantation and placement of 2 prior glaucoma drainage implants for primary open-angle glaucoma in the left eye.

On presentation, best-corrected visual acuity (BCVA) was light perception OS and 20/60 OD. Intraocular pressure was 17 mm Hg OS and 16 mm Hg OD, with no afferent pupillary defect noted in either eye. Slitlamp examination of the left eye demonstrated conjunctival injection and exposure of the superotemporal tube, corneal edema, and a mixed layer of hyphema, hypopyon, and fibrin reaction in the anterior chamber. The lens and posterior segment could not be visualized. Point-of-care B-scan ultrasonography demonstrated posterior segment membrane formation.

The patient was diagnosed with acute-onset exogenous endophthalmitis and underwent anterior chamber washout, removal of the glaucoma drainage implants, vitreous aspiration, and intravitreal (IVT) injection of vancomycin 1.0 mg, ceftazidime 2.25 mg, and dexamethasone 0.4 mg.

On postoperative day 2, BCVA remained light perception, and B-scan ultrasonography revealed persistent dense vitreous membranes (Figure 1A). The patient subsequently underwent repeat anterior chamber washout and pars plana vitrectomy (PPV) with fluid–air exchange, endolaser photocoagulation, placement of 1000 cs silicone oil tamponade, and repeat IVT injection of vancomycin 0.5 mg, ceftazidime 1.12 mg, and dexamethasone 0.2 mg. After the second PPV, Gram stain and vitreous cultures from the initial vitreous aspiration, grown on blood, chocolate, and Sabouraud agar, identified Nocardia brasiliensis. Antimicrobial susceptibility testing demonstrated sensitivity to amikacin (minimum inhibitory concentration 1 µg/mL), moxifloxacin (minimum inhibitory concentration 1 µg/mL), and sulfamethoxazole/trimethoprim (minimum inhibitory concentration 0.1 µg/mL), with resistance to ceftriaxone (minimum inhibitory concentration 64 µg/mL).

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Figure 1.

(A) B-scan ultrasonography of the left eye of Patient 1 demonstrating persistent dense vitreous membranes 2 days after anterior chamber washout, removal of the glaucoma drainage implants, vitreous aspiration, and intravitreal injection of vancomycin, ceftazidime, and dexamethasone. (B) Slitlamp image of the left eye obtained 2 weeks after pars plana vitrectomy demonstrating diffuse subconjunctival hemorrhage, corneal edema with nylon sutures, and a mixed layer of hypopyon and hyphema.

Because of progression to no-light-perception vision and worsening ocular pain (Figure 1B), the patient ultimately underwent enucleation.

Case 2

A 69-year-old immunocompetent man was referred for evaluation of a painful, red right eye for 3 days following removal of an extruded scleral buckle 1 month earlier. His ocular history was significant for rhegmatogenous retinal detachment repair in the right eye 10 years earlier and remote cataract extraction with intraocular lens implantation in both eyes. On presentation, BCVA was 20/70 OD and 20/20 OS. Examination revealed isolated inferonasal conjunctival injection and engorged vessels with few cells in the anterior chamber (Figure 2A). B-scan ultrasonography demonstrated an attached and flat retina without significant vitreous opacities (Figure 2B). The patient was treated with hourly fortified topical vancomycin 25 mg/mL and tobramycin 14 mg/mL.

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Figure 2.

Clinical course of Patient 2. (A) Slitlamp photograph of the right eye at presentation demonstrating focal inferonasal conjunctival injection and engorged episcleral vessels. (B) B-scan ultrasonography demonstrating no significant vitreous opacities and an attached retina. (C) Slitlamp photograph obtained on postoperative day 2 demonstrating an area of inferonasal scleral thinning and whitening covered by amniotic membrane. (D) Slitlamp photograph obtained at postoperative month 1 demonstrating diffuse conjunctival injection and a dense pupillary membrane. (E) Slitlamp photograph obtained at postoperative month 2 demonstrating white and quiet conjunctiva, and resolution of the pupillary membrane and aphakia. (F) Optical coherence tomography of the macula demonstrating diffuse retinal thinning and choroidal folds.

Three days later, BCVA declined to hand motion, with worsening ocular pain and fibrin formation in the anterior chamber. The patient was diagnosed with acute-onset exogenous endophthalmitis and underwent vitreous aspiration with IVT injection of vancomycin 1.0 mg, ceftazidime 2.25 mg, and voriconazole 0.1 mg, along with oral moxifloxacin 400 mg twice daily. Vitreous cultures from the initial aspiration, grown on blood, chocolate, and Sabouraud agar, identified Nocardia niwae. Antimicrobial susceptibility testing demonstrated susceptibility to amikacin (minimum inhibitory concentration 1 µg/mL) and sulfamethoxazole/trimethoprim (minimum inhibitory concentration 0.1 µg/mL), susceptibility to ceftriaxone (minimum inhibitory concentration 4 µg/mL), and intermediate susceptibility to moxifloxacin (minimum inhibitory concentration 2 µg/mL).

The patient subsequently underwent PPV, anterior chamber washout, and 2 scleral debridements (Figure 2C). At postoperative month 1 (Figure 2D), a dense pupillary membrane was noted, and the subretinal abscess had enlarged. The patient subsequently underwent a second and third PPV. At postoperative month 2 after the third PPV, visual acuity (VA) stabilized at 5/200 with aphakic correction (Figure 2E). Optical coherence tomography demonstrated diffuse retinal thinning with choroidal folds (Figure 2F).